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66c84731 |
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08-Mar-2024 |
Andrii Nakryiko <andrii@kernel.org> |
bpf: move sleepable flag from bpf_prog_aux to bpf_prog prog->aux->sleepable is checked very frequently as part of (some) BPF program run hot paths. So this extra aux indirection seems wasteful and on busy systems might cause unnecessary memory cache misses. Let's move sleepable flag into prog itself to eliminate unnecessary pointer dereference. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Jiri Olsa <jolsa@kernel.org> Message-ID: <20240309004739.2961431-1-andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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26ef208c |
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06-Dec-2023 |
Song Liu <song@kernel.org> |
bpf: Use arch_bpf_trampoline_size Instead of blindly allocating PAGE_SIZE for each trampoline, check the size of the trampoline with arch_bpf_trampoline_size(). This size is saved in bpf_tramp_image->size, and used for modmem charge/uncharge. The fallback arch_alloc_bpf_trampoline() still allocates a whole page because we need to use set_memory_* to protect the memory. struct_ops trampoline still uses a whole page for multiple trampolines. With this size check at caller (regular trampoline and struct_ops trampoline), remove arch_bpf_trampoline_size() from arch_prepare_bpf_trampoline() in archs. Also, update bpf_image_ksym_add() to handle symbol of different sizes. Signed-off-by: Song Liu <song@kernel.org> Acked-by: Ilya Leoshkevich <iii@linux.ibm.com> Tested-by: Ilya Leoshkevich <iii@linux.ibm.com> # on s390x Acked-by: Jiri Olsa <jolsa@kernel.org> Acked-by: Björn Töpel <bjorn@rivosinc.com> Tested-by: Björn Töpel <bjorn@rivosinc.com> # on riscv Link: https://lore.kernel.org/r/20231206224054.492250-7-song@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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96d1b7c0 |
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06-Dec-2023 |
Song Liu <song@kernel.org> |
bpf: Add arch_bpf_trampoline_size() This helper will be used to calculate the size of the trampoline before allocating the memory. arch_prepare_bpf_trampoline() for arm64 and riscv64 can use arch_bpf_trampoline_size() to check the trampoline fits in the image. OTOH, arch_prepare_bpf_trampoline() for s390 has to call the JIT process twice, so it cannot use arch_bpf_trampoline_size(). Signed-off-by: Song Liu <song@kernel.org> Acked-by: Ilya Leoshkevich <iii@linux.ibm.com> Tested-by: Ilya Leoshkevich <iii@linux.ibm.com> # on s390x Acked-by: Jiri Olsa <jolsa@kernel.org> Acked-by: Björn Töpel <bjorn@rivosinc.com> Tested-by: Björn Töpel <bjorn@rivosinc.com> # on riscv Link: https://lore.kernel.org/r/20231206224054.492250-6-song@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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82583daa |
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06-Dec-2023 |
Song Liu <song@kernel.org> |
bpf: Add helpers for trampoline image management As BPF trampoline of different archs moves from bpf_jit_[alloc|free]_exec() to bpf_prog_pack_[alloc|free](), we need to use different _alloc, _free for different archs during the transition. Add the following helpers for this transition: void *arch_alloc_bpf_trampoline(unsigned int size); void arch_free_bpf_trampoline(void *image, unsigned int size); void arch_protect_bpf_trampoline(void *image, unsigned int size); void arch_unprotect_bpf_trampoline(void *image, unsigned int size); The fallback version of these helpers require size <= PAGE_SIZE, but they are only called with size == PAGE_SIZE. They will be called with size < PAGE_SIZE when arch_bpf_trampoline_size() helper is introduced later. Signed-off-by: Song Liu <song@kernel.org> Acked-by: Ilya Leoshkevich <iii@linux.ibm.com> Tested-by: Ilya Leoshkevich <iii@linux.ibm.com> # on s390x Acked-by: Jiri Olsa <jolsa@kernel.org> Link: https://lore.kernel.org/r/20231206224054.492250-4-song@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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#
7a3d9a15 |
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06-Dec-2023 |
Song Liu <song@kernel.org> |
bpf: Adjust argument names of arch_prepare_bpf_trampoline() We are using "im" for "struct bpf_tramp_image" and "tr" for "struct bpf_trampoline" in most of the code base. The only exception is the prototype and fallback version of arch_prepare_bpf_trampoline(). Update them to match the rest of the code base. We mix "orig_call" and "func_addr" for the argument in different versions of arch_prepare_bpf_trampoline(). s/orig_call/func_addr/g so they match. Signed-off-by: Song Liu <song@kernel.org> Acked-by: Ilya Leoshkevich <iii@linux.ibm.com> Tested-by: Ilya Leoshkevich <iii@linux.ibm.com> # on s390x Acked-by: Jiri Olsa <jolsa@kernel.org> Link: https://lore.kernel.org/r/20231206224054.492250-3-song@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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2b5dcb31 |
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12-Sep-2023 |
Leon Hwang <hffilwlqm@gmail.com> |
bpf, x64: Fix tailcall infinite loop From commit ebf7d1f508a73871 ("bpf, x64: rework pro/epilogue and tailcall handling in JIT"), the tailcall on x64 works better than before. From commit e411901c0b775a3a ("bpf: allow for tailcalls in BPF subprograms for x64 JIT"), tailcall is able to run in BPF subprograms on x64. From commit 5b92a28aae4dd0f8 ("bpf: Support attaching tracing BPF program to other BPF programs"), BPF program is able to trace other BPF programs. How about combining them all together? 1. FENTRY/FEXIT on a BPF subprogram. 2. A tailcall runs in the BPF subprogram. 3. The tailcall calls the subprogram's caller. As a result, a tailcall infinite loop comes up. And the loop would halt the machine. As we know, in tail call context, the tail_call_cnt propagates by stack and rax register between BPF subprograms. So do in trampolines. Fixes: ebf7d1f508a7 ("bpf, x64: rework pro/epilogue and tailcall handling in JIT") Fixes: e411901c0b77 ("bpf: allow for tailcalls in BPF subprograms for x64 JIT") Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com> Signed-off-by: Leon Hwang <hffilwlqm@gmail.com> Link: https://lore.kernel.org/r/20230912150442.2009-3-hffilwlqm@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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6764e767 |
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30-Aug-2023 |
Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
bpf: Assign bpf_tramp_run_ctx::saved_run_ctx before recursion check. __bpf_prog_enter_recur() assigns bpf_tramp_run_ctx::saved_run_ctx before performing the recursion check which means in case of a recursion __bpf_prog_exit_recur() uses the previously set bpf_tramp_run_ctx::saved_run_ctx value. __bpf_prog_enter_sleepable_recur() assigns bpf_tramp_run_ctx::saved_run_ctx after the recursion check which means in case of a recursion __bpf_prog_exit_sleepable_recur() uses an uninitialized value. This does not look right. If I read the entry trampoline code right, then bpf_tramp_run_ctx isn't initialized upfront. Align __bpf_prog_enter_sleepable_recur() with __bpf_prog_enter_recur() and set bpf_tramp_run_ctx::saved_run_ctx before the recursion check is made. Remove the assignment of saved_run_ctx in kern_sys_bpf() since it happens a few cycles later. Fixes: e384c7b7b46d0 ("bpf, x86: Create bpf_tramp_run_ctx on the caller thread's stack") Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Jiri Olsa <jolsa@kernel.org> Link: https://lore.kernel.org/bpf/20230830080405.251926-3-bigeasy@linutronix.de
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#
108598c3 |
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15-May-2023 |
Yafang Shao <laoar.shao@gmail.com> |
bpf: Fix memleak due to fentry attach failure If it fails to attach fentry, the allocated bpf trampoline image will be left in the system. That can be verified by checking /proc/kallsyms. This meamleak can be verified by a simple bpf program as follows: SEC("fentry/trap_init") int fentry_run() { return 0; } It will fail to attach trap_init because this function is freed after kernel init, and then we can find the trampoline image is left in the system by checking /proc/kallsyms. $ tail /proc/kallsyms ffffffffc0613000 t bpf_trampoline_6442453466_1 [bpf] ffffffffc06c3000 t bpf_trampoline_6442453466_1 [bpf] $ bpftool btf dump file /sys/kernel/btf/vmlinux | grep "FUNC 'trap_init'" [2522] FUNC 'trap_init' type_id=119 linkage=static $ echo $((6442453466 & 0x7fffffff)) 2522 Note that there are two left bpf trampoline images, that is because the libbpf will fallback to raw tracepoint if -EINVAL is returned. Fixes: e21aa341785c ("bpf: Fix fexit trampoline.") Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Song Liu <song@kernel.org> Cc: Jiri Olsa <olsajiri@gmail.com> Link: https://lore.kernel.org/bpf/20230515130849.57502-2-laoar.shao@gmail.com
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47e79cbe |
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15-May-2023 |
Yafang Shao <laoar.shao@gmail.com> |
bpf: Remove bpf trampoline selector After commit e21aa341785c ("bpf: Fix fexit trampoline."), the selector is only used to indicate how many times the bpf trampoline image are updated and been displayed in the trampoline ksym name. After the trampoline is freed, the selector will start from 0 again. So the selector is a useless value to the user. We can remove it. If the user want to check whether the bpf trampoline image has been updated or not, the user can compare the address. Each time the trampoline image is updated, the address will change consequently. Jiri also pointed out another issue that perf is still using the old name "bpf_trampoline_%lu", so this change can fix the issue in perf. Fixes: e21aa341785c ("bpf: Fix fexit trampoline.") Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Song Liu <song@kernel.org> Cc: Jiri Olsa <olsajiri@gmail.com> Link: https://lore.kernel.org/bpf/ZFvOOlrmHiY9AgXE@krava Link: https://lore.kernel.org/bpf/20230515130849.57502-3-laoar.shao@gmail.com
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#
da8bdfbd |
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21-Mar-2023 |
Florent Revest <revest@chromium.org> |
ftrace: Rename _ftrace_direct_multi APIs to _ftrace_direct APIs Now that the original _ftrace_direct APIs are gone, the "_multi" suffixes only add confusion. Link: https://lkml.kernel.org/r/20230321140424.345218-5-revest@chromium.org Signed-off-by: Florent Revest <revest@chromium.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Tested-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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59495740 |
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21-Mar-2023 |
Florent Revest <revest@chromium.org> |
ftrace: Let unregister_ftrace_direct_multi() call ftrace_free_filter() A common pattern when using the ftrace_direct_multi API is to unregister the ops and also immediately free its filter. We've noticed it's very easy for users to miss calling ftrace_free_filter(). This adds a "free_filters" argument to unregister_ftrace_direct_multi() to both remind the user they should free filters and also to make their life easier. Link: https://lkml.kernel.org/r/20230321140424.345218-2-revest@chromium.org Suggested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Florent Revest <revest@chromium.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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31bf1dbc |
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10-Mar-2023 |
Viktor Malik <vmalik@redhat.com> |
bpf: Fix attaching fentry/fexit/fmod_ret/lsm to modules This resolves two problems with attachment of fentry/fexit/fmod_ret/lsm to functions located in modules: 1. The verifier tries to find the address to attach to in kallsyms. This is always done by searching the entire kallsyms, not respecting the module in which the function is located. Such approach causes an incorrect attachment address to be computed if the function to attach to is shadowed by a function of the same name located earlier in kallsyms. 2. If the address to attach to is located in a module, the module reference is only acquired in register_fentry. If the module is unloaded between the place where the address is found (bpf_check_attach_target in the verifier) and register_fentry, it is possible that another module is loaded to the same address which may lead to potential errors. Since the attachment must contain the BTF of the program to attach to, we extract the module from it and search for the function address in the correct module (resolving problem no. 1). Then, the module reference is taken directly in bpf_check_attach_target and stored in the bpf program (in bpf_prog_aux). The reference is only released when the program is unloaded (resolving problem no. 2). Signed-off-by: Viktor Malik <vmalik@redhat.com> Acked-by: Jiri Olsa <jolsa@kernel.org> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Link: https://lore.kernel.org/r/3f6a9d8ae850532b5ef864ef16327b0f7a669063.1678432753.git.vmalik@redhat.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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#
9ed1d9ae |
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24-Dec-2022 |
Chuang Wang <nashuiliang@gmail.com> |
bpf: Fix panic due to wrong pageattr of im->image In the scenario where livepatch and kretfunc coexist, the pageattr of im->image is rox after arch_prepare_bpf_trampoline in bpf_trampoline_update, and then modify_fentry or register_fentry returns -EAGAIN from bpf_tramp_ftrace_ops_func, the BPF_TRAMP_F_ORIG_STACK flag will be configured, and arch_prepare_bpf_trampoline will be re-executed. At this time, because the pageattr of im->image is rox, arch_prepare_bpf_trampoline will read and write im->image, which causes a fault. as follows: insmod livepatch-sample.ko # samples/livepatch/livepatch-sample.c bpftrace -e 'kretfunc:cmdline_proc_show {}' BUG: unable to handle page fault for address: ffffffffa0206000 PGD 322d067 P4D 322d067 PUD 322e063 PMD 1297e067 PTE d428061 Oops: 0003 [#1] PREEMPT SMP PTI CPU: 2 PID: 270 Comm: bpftrace Tainted: G E K 6.1.0 #5 RIP: 0010:arch_prepare_bpf_trampoline+0xed/0x8c0 RSP: 0018:ffffc90001083ad8 EFLAGS: 00010202 RAX: ffffffffa0206000 RBX: 0000000000000020 RCX: 0000000000000000 RDX: ffffffffa0206001 RSI: ffffffffa0206000 RDI: 0000000000000030 RBP: ffffc90001083b70 R08: 0000000000000066 R09: ffff88800f51b400 R10: 000000002e72c6e5 R11: 00000000d0a15080 R12: ffff8880110a68c8 R13: 0000000000000000 R14: ffff88800f51b400 R15: ffffffff814fec10 FS: 00007f87bc0dc780(0000) GS:ffff88803e600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffa0206000 CR3: 0000000010b70000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> bpf_trampoline_update+0x25a/0x6b0 __bpf_trampoline_link_prog+0x101/0x240 bpf_trampoline_link_prog+0x2d/0x50 bpf_tracing_prog_attach+0x24c/0x530 bpf_raw_tp_link_attach+0x73/0x1d0 __sys_bpf+0x100e/0x2570 __x64_sys_bpf+0x1c/0x30 do_syscall_64+0x5b/0x80 entry_SYSCALL_64_after_hwframe+0x63/0xcd With this patch, when modify_fentry or register_fentry returns -EAGAIN from bpf_tramp_ftrace_ops_func, the pageattr of im->image will be reset to nx+rw. Cc: stable@vger.kernel.org Fixes: 00963a2e75a8 ("bpf: Support bpf_trampoline on functions with IPMODIFY (e.g. livepatch)") Signed-off-by: Chuang Wang <nashuiliang@gmail.com> Acked-by: Jiri Olsa <jolsa@kernel.org> Acked-by: Song Liu <song@kernel.org> Link: https://lore.kernel.org/r/20221224133146.780578-1-nashuiliang@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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d48567c9 |
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25-Oct-2022 |
Peter Zijlstra <peterz@infradead.org> |
mm: Introduce set_memory_rox() Because endlessly repeating: set_memory_ro() set_memory_x() is getting tedious. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/Y1jek64pXOsougmz@hirez.programming.kicks-ass.net
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271de525 |
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25-Oct-2022 |
Martin KaFai Lau <martin.lau@kernel.org> |
bpf: Remove prog->active check for bpf_lsm and bpf_iter The commit 64696c40d03c ("bpf: Add __bpf_prog_{enter,exit}_struct_ops for struct_ops trampoline") removed prog->active check for struct_ops prog. The bpf_lsm and bpf_iter is also using trampoline. Like struct_ops, the bpf_lsm and bpf_iter have fixed hooks for the prog to attach. The kernel does not call the same hook in a recursive way. This patch also removes the prog->active check for bpf_lsm and bpf_iter. A later patch has a test to reproduce the recursion issue for a sleepable bpf_lsm program. This patch appends the '_recur' naming to the existing enter and exit functions that track the prog->active counter. New __bpf_prog_{enter,exit}[_sleepable] function are added to skip the prog->active tracking. The '_struct_ops' version is also removed. It also moves the decision on picking the enter and exit function to the new bpf_trampoline_{enter,exit}(). It returns the '_recur' ones for all tracing progs to use. For bpf_lsm, bpf_iter, struct_ops (no prog->active tracking after 64696c40d03c), and bpf_lsm_cgroup (no prog->active tracking after 69fd337a975c7), it will return the functions that don't track the prog->active. Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org> Link: https://lore.kernel.org/r/20221025184524.3526117-2-martin.lau@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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64696c40 |
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29-Sep-2022 |
Martin KaFai Lau <martin.lau@kernel.org> |
bpf: Add __bpf_prog_{enter,exit}_struct_ops for struct_ops trampoline The struct_ops prog is to allow using bpf to implement the functions in a struct (eg. kernel module). The current usage is to implement the tcp_congestion. The kernel does not call the tcp-cc's ops (ie. the bpf prog) in a recursive way. The struct_ops is sharing the tracing-trampoline's enter/exit function which tracks prog->active to avoid recursion. It is needed for tracing prog. However, it turns out the struct_ops bpf prog will hit this prog->active and unnecessarily skipped running the struct_ops prog. eg. The '.ssthresh' may run in_task() and then interrupted by softirq that runs the same '.ssthresh'. Skip running the '.ssthresh' will end up returning random value to the caller. The patch adds __bpf_prog_{enter,exit}_struct_ops for the struct_ops trampoline. They do not track the prog->active to detect recursion. One exception is when the tcp_congestion's '.init' ops is doing bpf_setsockopt(TCP_CONGESTION) and then recurs to the same '.init' ops. This will be addressed in the following patches. Fixes: ca06f55b9002 ("bpf: Add per-program recursion prevention mechanism") Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org> Link: https://lore.kernel.org/r/20220929070407.965581-2-martin.lau@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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5b0d1c7b |
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26-Sep-2022 |
Song Liu <song@kernel.org> |
bpf: Enforce W^X for bpf trampoline Mark the trampoline as RO+X after arch_prepare_bpf_trampoline, so that the trampoine follows W^X rule strictly. This will turn off warnings like CPA refuse W^X violation: 8000000000000163 -> 0000000000000163 range: ... Also remove bpf_jit_alloc_exec_page(), since it is not used any more. Signed-off-by: Song Liu <song@kernel.org> Link: https://lore.kernel.org/r/20220926184739.3512547-3-song@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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05b24ff9 |
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16-Sep-2022 |
Jiri Olsa <jolsa@kernel.org> |
bpf: Prevent bpf program recursion for raw tracepoint probes We got report from sysbot [1] about warnings that were caused by bpf program attached to contention_begin raw tracepoint triggering the same tracepoint by using bpf_trace_printk helper that takes trace_printk_lock lock. Call Trace: <TASK> ? trace_event_raw_event_bpf_trace_printk+0x5f/0x90 bpf_trace_printk+0x2b/0xe0 bpf_prog_a9aec6167c091eef_prog+0x1f/0x24 bpf_trace_run2+0x26/0x90 native_queued_spin_lock_slowpath+0x1c6/0x2b0 _raw_spin_lock_irqsave+0x44/0x50 bpf_trace_printk+0x3f/0xe0 bpf_prog_a9aec6167c091eef_prog+0x1f/0x24 bpf_trace_run2+0x26/0x90 native_queued_spin_lock_slowpath+0x1c6/0x2b0 _raw_spin_lock_irqsave+0x44/0x50 bpf_trace_printk+0x3f/0xe0 bpf_prog_a9aec6167c091eef_prog+0x1f/0x24 bpf_trace_run2+0x26/0x90 native_queued_spin_lock_slowpath+0x1c6/0x2b0 _raw_spin_lock_irqsave+0x44/0x50 bpf_trace_printk+0x3f/0xe0 bpf_prog_a9aec6167c091eef_prog+0x1f/0x24 bpf_trace_run2+0x26/0x90 native_queued_spin_lock_slowpath+0x1c6/0x2b0 _raw_spin_lock_irqsave+0x44/0x50 __unfreeze_partials+0x5b/0x160 ... The can be reproduced by attaching bpf program as raw tracepoint on contention_begin tracepoint. The bpf prog calls bpf_trace_printk helper. Then by running perf bench the spin lock code is forced to take slow path and call contention_begin tracepoint. Fixing this by skipping execution of the bpf program if it's already running, Using bpf prog 'active' field, which is being currently used by trampoline programs for the same reason. Moving bpf_prog_inc_misses_counter to syscall.c because trampoline.c is compiled in just for CONFIG_BPF_JIT option. Reviewed-by: Stanislav Fomichev <sdf@google.com> Reported-by: syzbot+2251879aa068ad9c960d@syzkaller.appspotmail.com [1] https://lore.kernel.org/bpf/YxhFe3EwqchC%2FfYf@krava/T/#t Signed-off-by: Jiri Olsa <jolsa@kernel.org> Link: https://lore.kernel.org/r/20220916071914.7156-1-jolsa@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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c89e843a |
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01-Sep-2022 |
Hou Tao <houtao1@huawei.com> |
bpf: Use this_cpu_{inc_return|dec} for prog->active Both __this_cpu_inc_return() and __this_cpu_dec() are not preemption safe and now migrate_disable() doesn't disable preemption, so the update of prog-active is not atomic and in theory under fully preemptible kernel recurisve prevention may do not work. Fixing by using the preemption-safe and IRQ-safe variants. Fixes: ca06f55b9002 ("bpf: Add per-program recursion prevention mechanism") Signed-off-by: Hou Tao <houtao1@huawei.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/r/20220901061938.3789460-3-houtao@huaweicloud.com Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
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62d468e5 |
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02-Aug-2022 |
Jiri Olsa <jolsa@kernel.org> |
bpf: Cleanup ftrace hash in bpf_trampoline_put We need to release possible hash from trampoline fops object before removing it, otherwise we leak it. Fixes: 00963a2e75a8 ("bpf: Support bpf_trampoline on functions with IPMODIFY (e.g. livepatch)") Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Song Liu <song@kernel.org> Link: https://lore.kernel.org/bpf/20220802135651.1794015-1-jolsa@kernel.org
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14250fa4 |
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25-Jul-2022 |
Yang Li <yang.lee@linux.alibaba.com> |
bpf: Remove unneeded semicolon Eliminate the following coccicheck warning: /kernel/bpf/trampoline.c:101:2-3: Unneeded semicolon Reported-by: Abaci Robot <abaci@linux.alibaba.com> Signed-off-by: Yang Li <yang.lee@linux.alibaba.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20220725222733.55613-1-yang.lee@linux.alibaba.com
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3b317abc |
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28-Jul-2022 |
Xu Kuohai <xukuohai@huawei.com> |
bpf: Fix NULL pointer dereference when registering bpf trampoline A panic was reported on arm64: [ 44.517109] audit: type=1334 audit(1658859870.268:59): prog-id=19 op=LOAD [ 44.622031] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010 [ 44.624321] Mem abort info: [ 44.625049] ESR = 0x0000000096000004 [ 44.625935] EC = 0x25: DABT (current EL), IL = 32 bits [ 44.627182] SET = 0, FnV = 0 [ 44.627930] EA = 0, S1PTW = 0 [ 44.628684] FSC = 0x04: level 0 translation fault [ 44.629788] Data abort info: [ 44.630474] ISV = 0, ISS = 0x00000004 [ 44.631362] CM = 0, WnR = 0 [ 44.632041] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000100ab5000 [ 44.633494] [0000000000000010] pgd=0000000000000000, p4d=0000000000000000 [ 44.635202] Internal error: Oops: 96000004 [#1] SMP [ 44.636452] Modules linked in: xfs crct10dif_ce ghash_ce virtio_blk virtio_console virtio_mmio qemu_fw_cfg [ 44.638713] CPU: 2 PID: 1 Comm: systemd Not tainted 5.19.0-rc7 #1 [ 44.640164] Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015 [ 44.641799] pstate: 00400005 (nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 44.643404] pc : ftrace_set_filter_ip+0x24/0xa0 [ 44.644659] lr : bpf_trampoline_update.constprop.0+0x428/0x4a0 [ 44.646118] sp : ffff80000803b9f0 [ 44.646950] x29: ffff80000803b9f0 x28: ffff0b5d80364400 x27: ffff80000803bb48 [ 44.648721] x26: ffff8000085ad000 x25: ffff0b5d809d2400 x24: 0000000000000000 [ 44.650493] x23: 00000000ffffffed x22: ffff0b5dd7ea0900 x21: 0000000000000000 [ 44.652279] x20: 0000000000000000 x19: 0000000000000000 x18: ffffffffffffffff [ 44.654067] x17: 0000000000000000 x16: 0000000000000000 x15: ffffffffffffffff [ 44.655787] x14: ffff0b5d809d2498 x13: ffff0b5d809d2432 x12: 0000000005f5e100 [ 44.657535] x11: abcc77118461cefd x10: 000000000000005f x9 : ffffa7219cb5b190 [ 44.659254] x8 : ffffa7219c8e0000 x7 : 0000000000000000 x6 : ffffa7219db075e0 [ 44.661066] x5 : ffffa7219d3130e0 x4 : ffffa7219cab9da0 x3 : 0000000000000000 [ 44.662837] x2 : 0000000000000000 x1 : ffffa7219cb7a5c0 x0 : 0000000000000000 [ 44.664675] Call trace: [ 44.665274] ftrace_set_filter_ip+0x24/0xa0 [ 44.666327] bpf_trampoline_update.constprop.0+0x428/0x4a0 [ 44.667696] __bpf_trampoline_link_prog+0xcc/0x1c0 [ 44.668834] bpf_trampoline_link_prog+0x40/0x64 [ 44.669919] bpf_tracing_prog_attach+0x120/0x490 [ 44.671011] link_create+0xe0/0x2b0 [ 44.671869] __sys_bpf+0x484/0xd30 [ 44.672706] __arm64_sys_bpf+0x30/0x40 [ 44.673678] invoke_syscall+0x78/0x100 [ 44.674623] el0_svc_common.constprop.0+0x4c/0xf4 [ 44.675783] do_el0_svc+0x38/0x4c [ 44.676624] el0_svc+0x34/0x100 [ 44.677429] el0t_64_sync_handler+0x11c/0x150 [ 44.678532] el0t_64_sync+0x190/0x194 [ 44.679439] Code: 2a0203f4 f90013f5 2a0303f5 f9001fe1 (f9400800) [ 44.680959] ---[ end trace 0000000000000000 ]--- [ 44.682111] Kernel panic - not syncing: Oops: Fatal exception [ 44.683488] SMP: stopping secondary CPUs [ 44.684551] Kernel Offset: 0x2721948e0000 from 0xffff800008000000 [ 44.686095] PHYS_OFFSET: 0xfffff4a380000000 [ 44.687144] CPU features: 0x010,00022811,19001080 [ 44.688308] Memory Limit: none [ 44.689082] ---[ end Kernel panic - not syncing: Oops: Fatal exception ]--- It's caused by a NULL tr->fops passed to ftrace_set_filter_ip(). tr->fops is initialized to NULL and is assigned to an allocated memory address if CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS is enabled. Since there is no direct call on arm64 yet, the config can't be enabled. To fix it, call ftrace_set_filter_ip() only if tr->fops is not NULL. Fixes: 00963a2e75a8 ("bpf: Support bpf_trampoline on functions with IPMODIFY (e.g. livepatch)") Reported-by: Bruno Goncalves <bgoncalv@redhat.com> Signed-off-by: Xu Kuohai <xukuohai@huawei.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Tested-by: Bruno Goncalves <bgoncalv@redhat.com> Acked-by: Song Liu <songliubraving@fb.com> Acked-by: Jiri Olsa <jolsa@kernel.org> Link: https://lore.kernel.org/bpf/20220728114048.3540461-1-xukuohai@huaweicloud.com
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dc81f8d1 |
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29-Jul-2022 |
Song Liu <song@kernel.org> |
bpf: Fix test_progs -j error with fentry/fexit tests When multiple threads are attaching/detaching fentry/fexit programs to the same trampoline, we may call register_fentry on the same trampoline twice: register_fentry(), unregister_fentry(), then register_fentry again. This causes ftrace_set_filter_ip() for the same ip on tr->fops twice, which leaves duplicated ip in tr->fops. The extra ip is not cleaned up properly on unregister and thus causes failures with further register in register_ftrace_direct_multi(): register_ftrace_direct_multi() { ... for (i = 0; i < size; i++) { hlist_for_each_entry(entry, &hash->buckets[i], hlist) { if (ftrace_find_rec_direct(entry->ip)) goto out_unlock; } } ... } This can be triggered with parallel fentry/fexit tests with test_progs: ./test_progs -t fentry,fexit -j Fix this by resetting tr->fops in ftrace_set_filter_ip(), so that there will never be duplicated entries in tr->fops. Fixes: 00963a2e75a8 ("bpf: Support bpf_trampoline on functions with IPMODIFY (e.g. livepatch)") Reported-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Song Liu <song@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20220729194106.1207472-1-song@kernel.org
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00963a2e |
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19-Jul-2022 |
Song Liu <song@kernel.org> |
bpf: Support bpf_trampoline on functions with IPMODIFY (e.g. livepatch) When tracing a function with IPMODIFY ftrace_ops (livepatch), the bpf trampoline must follow the instruction pointer saved on stack. This needs extra handling for bpf trampolines with BPF_TRAMP_F_CALL_ORIG flag. Implement bpf_tramp_ftrace_ops_func and use it for the ftrace_ops used by BPF trampoline. This enables tracing functions with livepatch. This also requires moving bpf trampoline to *_ftrace_direct_mult APIs. Signed-off-by: Song Liu <song@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/all/20220602193706.2607681-2-song@kernel.org/ Link: https://lore.kernel.org/bpf/20220720002126.803253-5-song@kernel.org
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3908fcdd |
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14-Jul-2022 |
Stanislav Fomichev <sdf@google.com> |
bpf: fix lsm_cgroup build errors on esoteric configs This particular ones is about having the following: CONFIG_BPF_LSM=y # CONFIG_CGROUP_BPF is not set Also, add __maybe_unused to the args for the !CONFIG_NET cases. Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Stanislav Fomichev <sdf@google.com> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/r/20220714185404.3647772-1-sdf@google.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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535a57a7 |
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11-Jul-2022 |
Xu Kuohai <xukuohai@huawei.com> |
bpf: Remove is_valid_bpf_tramp_flags() Before generating bpf trampoline, x86 calls is_valid_bpf_tramp_flags() to check the input flags. This check is architecture independent. So, to be consistent with x86, arm64 should also do this check before generating bpf trampoline. However, the BPF_TRAMP_F_XXX flags are not used by user code and the flags argument is almost constant at compile time, so this run time check is a bit redundant. Remove is_valid_bpf_tramp_flags() and add some comments to the usage of BPF_TRAMP_F_XXX flags, as suggested by Alexei. Signed-off-by: Xu Kuohai <xukuohai@huawei.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20220711150823.2128542-2-xukuohai@huawei.com
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c0e19f2c |
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28-Jun-2022 |
Stanislav Fomichev <sdf@google.com> |
bpf: minimize number of allocated lsm slots per program Previous patch adds 1:1 mapping between all 211 LSM hooks and bpf_cgroup program array. Instead of reserving a slot per possible hook, reserve 10 slots per cgroup for lsm programs. Those slots are dynamically allocated on demand and reclaimed. struct cgroup_bpf { struct bpf_prog_array * effective[33]; /* 0 264 */ /* --- cacheline 4 boundary (256 bytes) was 8 bytes ago --- */ struct hlist_head progs[33]; /* 264 264 */ /* --- cacheline 8 boundary (512 bytes) was 16 bytes ago --- */ u8 flags[33]; /* 528 33 */ /* XXX 7 bytes hole, try to pack */ struct list_head storages; /* 568 16 */ /* --- cacheline 9 boundary (576 bytes) was 8 bytes ago --- */ struct bpf_prog_array * inactive; /* 584 8 */ struct percpu_ref refcnt; /* 592 16 */ struct work_struct release_work; /* 608 72 */ /* size: 680, cachelines: 11, members: 7 */ /* sum members: 673, holes: 1, sum holes: 7 */ /* last cacheline: 40 bytes */ }; Reviewed-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Stanislav Fomichev <sdf@google.com> Link: https://lore.kernel.org/r/20220628174314.1216643-5-sdf@google.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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69fd337a |
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28-Jun-2022 |
Stanislav Fomichev <sdf@google.com> |
bpf: per-cgroup lsm flavor Allow attaching to lsm hooks in the cgroup context. Attaching to per-cgroup LSM works exactly like attaching to other per-cgroup hooks. New BPF_LSM_CGROUP is added to trigger new mode; the actual lsm hook we attach to is signaled via existing attach_btf_id. For the hooks that have 'struct socket' or 'struct sock' as its first argument, we use the cgroup associated with that socket. For the rest, we use 'current' cgroup (this is all on default hierarchy == v2 only). Note that for some hooks that work on 'struct sock' we still take the cgroup from 'current' because some of them work on the socket that hasn't been properly initialized yet. Behind the scenes, we allocate a shim program that is attached to the trampoline and runs cgroup effective BPF programs array. This shim has some rudimentary ref counting and can be shared between several programs attaching to the same lsm hook from different cgroups. Note that this patch bloats cgroup size because we add 211 cgroup_bpf_attach_type(s) for simplicity sake. This will be addressed in the subsequent patch. Also note that we only add non-sleepable flavor for now. To enable sleepable use-cases, bpf_prog_run_array_cg has to grab trace rcu, shim programs have to be freed via trace rcu, cgroup_bpf.effective should be also trace-rcu-managed + maybe some other changes that I'm not aware of. Reviewed-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Stanislav Fomichev <sdf@google.com> Link: https://lore.kernel.org/r/20220628174314.1216643-4-sdf@google.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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af3f4134 |
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28-Jun-2022 |
Stanislav Fomichev <sdf@google.com> |
bpf: add bpf_func_t and trampoline helpers I'll be adding lsm cgroup specific helpers that grab trampoline mutex. No functional changes. Reviewed-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Stanislav Fomichev <sdf@google.com> Link: https://lore.kernel.org/r/20220628174314.1216643-2-sdf@google.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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a2aa95b7 |
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30-Apr-2022 |
Yuntao Wang <ytcoode@gmail.com> |
bpf: Fix potential array overflow in bpf_trampoline_get_progs() The cnt value in the 'cnt >= BPF_MAX_TRAMP_PROGS' check does not include BPF_TRAMP_MODIFY_RETURN bpf programs, so the number of the attached BPF_TRAMP_MODIFY_RETURN bpf programs in a trampoline can exceed BPF_MAX_TRAMP_PROGS. When this happens, the assignment '*progs++ = aux->prog' in bpf_trampoline_get_progs() will cause progs array overflow as the progs field in the bpf_tramp_progs struct can only hold at most BPF_MAX_TRAMP_PROGS bpf programs. Fixes: 88fd9e5352fe ("bpf: Refactor trampoline update code") Signed-off-by: Yuntao Wang <ytcoode@gmail.com> Link: https://lore.kernel.org/r/20220430130803.210624-1-ytcoode@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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2fcc8241 |
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10-May-2022 |
Kui-Feng Lee <kuifeng@fb.com> |
bpf, x86: Attach a cookie to fentry/fexit/fmod_ret/lsm. Pass a cookie along with BPF_LINK_CREATE requests. Add a bpf_cookie field to struct bpf_tracing_link to attach a cookie. The cookie of a bpf_tracing_link is available by calling bpf_get_attach_cookie when running the BPF program of the attached link. The value of a cookie will be set at bpf_tramp_run_ctx by the trampoline of the link. Signed-off-by: Kui-Feng Lee <kuifeng@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20220510205923.3206889-4-kuifeng@fb.com
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e384c7b7 |
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10-May-2022 |
Kui-Feng Lee <kuifeng@fb.com> |
bpf, x86: Create bpf_tramp_run_ctx on the caller thread's stack BPF trampolines will create a bpf_tramp_run_ctx, a bpf_run_ctx, on stacks and set/reset the current bpf_run_ctx before/after calling a bpf_prog. Signed-off-by: Kui-Feng Lee <kuifeng@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20220510205923.3206889-3-kuifeng@fb.com
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f7e0beaf |
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10-May-2022 |
Kui-Feng Lee <kuifeng@fb.com> |
bpf, x86: Generate trampolines from bpf_tramp_links Replace struct bpf_tramp_progs with struct bpf_tramp_links to collect struct bpf_tramp_link(s) for a trampoline. struct bpf_tramp_link extends bpf_link to act as a linked list node. arch_prepare_bpf_trampoline() accepts a struct bpf_tramp_links to collects all bpf_tramp_link(s) that a trampoline should call. Change BPF trampoline and bpf_struct_ops to pass bpf_tramp_links instead of bpf_tramp_progs. Signed-off-by: Kui-Feng Lee <kuifeng@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20220510205923.3206889-2-kuifeng@fb.com
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aebfd125 |
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08-Mar-2022 |
Peter Zijlstra <peterz@infradead.org> |
x86/ibt,ftrace: Search for __fentry__ location Currently a lot of ftrace code assumes __fentry__ is at sym+0. However with Intel IBT enabled the first instruction of a function will most likely be ENDBR. Change ftrace_location() to not only return the __fentry__ location when called for the __fentry__ location, but also when called for the sym+0 location. Then audit/update all callsites of this function to consistently use these new semantics. Suggested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/20220308154318.227581603@infradead.org
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c561d110 |
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20-Feb-2022 |
Tom Rix <trix@redhat.com> |
bpf: Cleanup comments Add leading space to spdx tag Use // for spdx c file comment Replacements resereved to reserved inbetween to in between everytime to every time intutivie to intuitive currenct to current encontered to encountered referenceing to referencing upto to up to exectuted to executed Signed-off-by: Tom Rix <trix@redhat.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20220220184055.3608317-1-trix@redhat.com
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3486bedd |
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04-Feb-2022 |
Song Liu <songliubraving@fb.com> |
bpf: Use bytes instead of pages for bpf_jit_[charge|uncharge]_modmem This enables sub-page memory charge and allocation. Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220204185742.271030-3-song@kernel.org
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0e3135d3 |
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22-Jan-2022 |
He Fengqing <hefengqing@huawei.com> |
bpf: Fix possible race in inc_misses_counter It seems inc_misses_counter() suffers from same issue fixed in the commit d979617aa84d ("bpf: Fixes possible race in update_prog_stats() for 32bit arches"): As it can run while interrupts are enabled, it could be re-entered and the u64_stats syncp could be mangled. Fixes: 9ed9e9ba2337 ("bpf: Count the number of times recursion was prevented") Signed-off-by: He Fengqing <hefengqing@huawei.com> Acked-by: John Fastabend <john.fastabend@gmail.com> Link: https://lore.kernel.org/r/20220122102936.1219518-1-hefengqing@huawei.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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f92c1e18 |
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08-Dec-2021 |
Jiri Olsa <jolsa@redhat.com> |
bpf: Add get_func_[arg|ret|arg_cnt] helpers Adding following helpers for tracing programs: Get n-th argument of the traced function: long bpf_get_func_arg(void *ctx, u32 n, u64 *value) Get return value of the traced function: long bpf_get_func_ret(void *ctx, u64 *value) Get arguments count of the traced function: long bpf_get_func_arg_cnt(void *ctx) The trampoline now stores number of arguments on ctx-8 address, so it's easy to verify argument index and find return value argument's position. Moving function ip address on the trampoline stack behind the number of functions arguments, so it's now stored on ctx-16 address if it's needed. All helpers above are inlined by verifier. Also bit unrelated small change - using newly added function bpf_prog_has_trampoline in check_get_func_ip. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211208193245.172141-5-jolsa@kernel.org
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61a0abae |
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26-Oct-2021 |
Eric Dumazet <edumazet@google.com> |
bpf: Use u64_stats_t in struct bpf_prog_stats Commit 316580b69d0a ("u64_stats: provide u64_stats_t type") fixed possible load/store tearing on 64bit arches. For instance the following C code stats->nsecs += sched_clock() - start; Could be rightfully implemented like this by a compiler, confusing concurrent readers a lot: stats->nsecs += sched_clock(); // arbitrary delay stats->nsecs -= start; Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211026214133.3114279-4-eric.dumazet@gmail.com
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d979617a |
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26-Oct-2021 |
Eric Dumazet <edumazet@google.com> |
bpf: Fixes possible race in update_prog_stats() for 32bit arches It seems update_prog_stats() suffers from same issue fixed in the prior patch: As it can run while interrupts are enabled, it could be re-entered and the u64_stats syncp could be mangled. Fixes: fec56f5890d9 ("bpf: Introduce BPF trampoline") Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211026214133.3114279-3-eric.dumazet@gmail.com
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856c02db |
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10-Sep-2021 |
Song Liu <songliubraving@fb.com> |
bpf: Introduce helper bpf_get_branch_snapshot Introduce bpf_get_branch_snapshot(), which allows tracing pogram to get branch trace from hardware (e.g. Intel LBR). To use the feature, the user need to create perf_event with proper branch_record filtering on each cpu, and then calls bpf_get_branch_snapshot in the bpf function. On Intel CPUs, VLBR event (raw event 0x1b00) can be use for this. Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210910183352.3151445-3-songliubraving@fb.com
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fb7dd8bc |
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15-Aug-2021 |
Andrii Nakryiko <andrii@kernel.org> |
bpf: Refactor BPF_PROG_RUN into a function Turn BPF_PROG_RUN into a proper always inlined function. No functional and performance changes are intended, but it makes it much easier to understand what's going on with how BPF programs are actually get executed. It's more obvious what types and callbacks are expected. Also extra () around input parameters can be dropped, as well as `__` variable prefixes intended to avoid naming collisions, which makes the code simpler to read and write. This refactoring also highlighted one extra issue. BPF_PROG_RUN is both a macro and an enum value (BPF_PROG_RUN == BPF_PROG_TEST_RUN). Turning BPF_PROG_RUN into a function causes naming conflict compilation error. So rename BPF_PROG_RUN into lower-case bpf_prog_run(), similar to bpf_prog_run_xdp(), bpf_prog_run_pin_on_cpu(), etc. All existing callers of BPF_PROG_RUN, the macro, are switched to bpf_prog_run() explicitly. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20210815070609.987780-2-andrii@kernel.org
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1e37392c |
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14-Jul-2021 |
Jiri Olsa <jolsa@redhat.com> |
bpf: Enable BPF_TRAMP_F_IP_ARG for trampolines with call_get_func_ip Enabling BPF_TRAMP_F_IP_ARG for trampolines that actually need it. The BPF_TRAMP_F_IP_ARG adds extra 3 instructions to trampoline code and is used only by programs with bpf_get_func_ip helper, which is added in following patch and sets call_get_func_ip bit. This patch ensures that BPF_TRAMP_F_IP_ARG flag is used only for trampolines that have programs with call_get_func_ip set. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20210714094400.396467-3-jolsa@kernel.org
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8fb33b60 |
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24-May-2021 |
Zhen Lei <thunder.leizhen@huawei.com> |
bpf: Fix spelling mistakes Fix some spelling mistakes in comments: aother ==> another Netiher ==> Neither desribe ==> describe intializing ==> initializing funciton ==> function wont ==> won't and move the word 'the' at the end to the next line accross ==> across pathes ==> paths triggerred ==> triggered excute ==> execute ether ==> either conervative ==> conservative convetion ==> convention markes ==> marks interpeter ==> interpreter Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210525025659.8898-2-thunder.leizhen@huawei.com
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f3a95075 |
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14-Apr-2021 |
Jiri Olsa <jolsa@kernel.org> |
bpf: Allow trampoline re-attach for tracing and lsm programs Currently we don't allow re-attaching of trampolines. Once it's detached, it can't be re-attach even when the program is still loaded. Adding the possibility to re-attach the loaded tracing and lsm programs. Fixing missing unlock with proper cleanup goto jump reported by Julia. Reported-by: kernel test robot <lkp@intel.com> Reported-by: Julia Lawall <julia.lawall@lip6.fr> Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Acked-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: KP Singh <kpsingh@kernel.org> Link: https://lore.kernel.org/bpf/20210414195147.1624932-2-jolsa@kernel.org
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861de02e |
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26-Mar-2021 |
Jiri Olsa <jolsa@kernel.org> |
bpf: Take module reference for trampoline in module Currently module can be unloaded even if there's a trampoline register in it. It's easily reproduced by running in parallel: # while :; do ./test_progs -t module_attach; done # while :; do rmmod bpf_testmod; sleep 0.5; done Taking the module reference in case the trampoline's ip is within the module code. Releasing it when the trampoline's ip is unregistered. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20210326105900.151466-1-jolsa@kernel.org
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e21aa341 |
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16-Mar-2021 |
Alexei Starovoitov <ast@kernel.org> |
bpf: Fix fexit trampoline. The fexit/fmod_ret programs can be attached to kernel functions that can sleep. The synchronize_rcu_tasks() will not wait for such tasks to complete. In such case the trampoline image will be freed and when the task wakes up the return IP will point to freed memory causing the crash. Solve this by adding percpu_ref_get/put for the duration of trampoline and separate trampoline vs its image life times. The "half page" optimization has to be removed, since first_half->second_half->first_half transition cannot be guaranteed to complete in deterministic time. Every trampoline update becomes a new image. The image with fmod_ret or fexit progs will be freed via percpu_ref_kill and call_rcu_tasks. Together they will wait for the original function and trampoline asm to complete. The trampoline is patched from nop to jmp to skip fexit progs. They are freed independently from the trampoline. The image with fentry progs only will be freed via call_rcu_tasks_trace+call_rcu_tasks which will wait for both sleepable and non-sleepable progs to complete. Fixes: fec56f5890d9 ("bpf: Introduce BPF trampoline") Reported-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Paul E. McKenney <paulmck@kernel.org> # for RCU Link: https://lore.kernel.org/bpf/20210316210007.38949-1-alexei.starovoitov@gmail.com
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9ed9e9ba |
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09-Feb-2021 |
Alexei Starovoitov <ast@kernel.org> |
bpf: Count the number of times recursion was prevented Add per-program counter for number of times recursion prevention mechanism was triggered and expose it via show_fdinfo and bpf_prog_info. Teach bpftool to print it. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210210033634.62081-7-alexei.starovoitov@gmail.com
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ca06f55b |
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09-Feb-2021 |
Alexei Starovoitov <ast@kernel.org> |
bpf: Add per-program recursion prevention mechanism Since both sleepable and non-sleepable programs execute under migrate_disable add recursion prevention mechanism to both types of programs when they're executed via bpf trampoline. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210210033634.62081-5-alexei.starovoitov@gmail.com
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f2dd3b39 |
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09-Feb-2021 |
Alexei Starovoitov <ast@kernel.org> |
bpf: Compute program stats for sleepable programs Since sleepable programs don't migrate from the cpu the excution stats can be computed for them as well. Reuse the same infrastructure for both sleepable and non-sleepable programs. run_cnt -> the number of times the program was executed. run_time_ns -> the program execution time in nanoseconds including the off-cpu time when the program was sleeping. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: KP Singh <kpsingh@kernel.org> Link: https://lore.kernel.org/bpf/20210210033634.62081-4-alexei.starovoitov@gmail.com
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031d6e02 |
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09-Feb-2021 |
Alexei Starovoitov <ast@kernel.org> |
bpf: Run sleepable programs with migration disabled In older non-RT kernels migrate_disable() was the same as preempt_disable(). Since commit 74d862b682f5 ("sched: Make migrate_disable/enable() independent of RT") migrate_disable() is real and doesn't prevent sleeping. Running sleepable programs with migration disabled allows to add support for program stats and per-cpu maps later. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: KP Singh <kpsingh@kernel.org> Link: https://lore.kernel.org/bpf/20210210033634.62081-3-alexei.starovoitov@gmail.com
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700d4796 |
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09-Feb-2021 |
Alexei Starovoitov <ast@kernel.org> |
bpf: Optimize program stats Move bpf_prog_stats from prog->aux into prog to avoid one extra load in critical path of program execution. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210210033634.62081-2-alexei.starovoitov@gmail.com
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3aac1ead |
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29-Sep-2020 |
Toke Høiland-Jørgensen <toke@redhat.com> |
bpf: Move prog->aux->linked_prog and trampoline into bpf_link on attach In preparation for allowing multiple attachments of freplace programs, move the references to the target program and trampoline into the bpf_tracing_link structure when that is created. To do this atomically, introduce a new mutex in prog->aux to protect writing to the two pointers to target prog and trampoline, and rename the members to make it clear that they are related. With this change, it is no longer possible to attach the same tracing program multiple times (detaching in-between), since the reference from the tracing program to the target disappears on the first attach. However, since the next patch will let the caller supply an attach target, that will also make it possible to attach to the same place multiple times. Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/160138355059.48470.2503076992210324984.stgit@toke.dk
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f7b12b6f |
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25-Sep-2020 |
Toke Høiland-Jørgensen <toke@redhat.com> |
bpf: verifier: refactor check_attach_btf_id() The check_attach_btf_id() function really does three things: 1. It performs a bunch of checks on the program to ensure that the attachment is valid. 2. It stores a bunch of state about the attachment being requested in the verifier environment and struct bpf_prog objects. 3. It allocates a trampoline for the attachment. This patch splits out (1.) and (3.) into separate functions which will perform the checks, but return the computed values instead of directly modifying the environment. This is done in preparation for reusing the checks when the actual attachment is happening, which will allow tracing programs to have multiple (compatible) attachments. This also fixes a bug where a bunch of checks were skipped if a trampoline already existed for the tracing target. Fixes: 6ba43b761c41 ("bpf: Attachment verification for BPF_MODIFY_RETURN") Fixes: 1e6c62a88215 ("bpf: Introduce sleepable BPF programs") Acked-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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f56407fa |
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31-Aug-2020 |
Alexei Starovoitov <ast@kernel.org> |
bpf: Remove bpf_lsm_file_mprotect from sleepable list. Technically the bpf programs can sleep while attached to bpf_lsm_file_mprotect, but such programs need to access user memory. So they're in might_fault() category. Which means they cannot be called from file_mprotect lsm hook that takes write lock on mm->mmap_lock. Adjust the test accordingly. Also add might_fault() to __bpf_prog_enter_sleepable() to catch such deadlocks early. Fixes: 1e6c62a88215 ("bpf: Introduce sleepable BPF programs") Fixes: e68a144547fc ("selftests/bpf: Add sleepable tests") Reported-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200831201651.82447-1-alexei.starovoitov@gmail.com
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1e6c62a8 |
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27-Aug-2020 |
Alexei Starovoitov <ast@kernel.org> |
bpf: Introduce sleepable BPF programs Introduce sleepable BPF programs that can request such property for themselves via BPF_F_SLEEPABLE flag at program load time. In such case they will be able to use helpers like bpf_copy_from_user() that might sleep. At present only fentry/fexit/fmod_ret and lsm programs can request to be sleepable and only when they are attached to kernel functions that are known to allow sleeping. The non-sleepable programs are relying on implicit rcu_read_lock() and migrate_disable() to protect life time of programs, maps that they use and per-cpu kernel structures used to pass info between bpf programs and the kernel. The sleepable programs cannot be enclosed into rcu_read_lock(). migrate_disable() maps to preempt_disable() in non-RT kernels, so the progs should not be enclosed in migrate_disable() as well. Therefore rcu_read_lock_trace is used to protect the life time of sleepable progs. There are many networking and tracing program types. In many cases the 'struct bpf_prog *' pointer itself is rcu protected within some other kernel data structure and the kernel code is using rcu_dereference() to load that program pointer and call BPF_PROG_RUN() on it. All these cases are not touched. Instead sleepable bpf programs are allowed with bpf trampoline only. The program pointers are hard-coded into generated assembly of bpf trampoline and synchronize_rcu_tasks_trace() is used to protect the life time of the program. The same trampoline can hold both sleepable and non-sleepable progs. When rcu_read_lock_trace is held it means that some sleepable bpf program is running from bpf trampoline. Those programs can use bpf arrays and preallocated hash/lru maps. These map types are waiting on programs to complete via synchronize_rcu_tasks_trace(); Updates to trampoline now has to do synchronize_rcu_tasks_trace() and synchronize_rcu_tasks() to wait for sleepable progs to finish and for trampoline assembly to finish. This is the first step of introducing sleepable progs. Eventually dynamically allocated hash maps can be allowed and networking program types can become sleepable too. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: KP Singh <kpsingh@google.com> Link: https://lore.kernel.org/bpf/20200827220114.69225-3-alexei.starovoitov@gmail.com
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9e4e01df |
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28-Mar-2020 |
KP Singh <kpsingh@google.com> |
bpf: lsm: Implement attach, detach and execution JITed BPF programs are dynamically attached to the LSM hooks using BPF trampolines. The trampoline prologue generates code to handle conversion of the signature of the hook to the appropriate BPF context. The allocated trampoline programs are attached to the nop functions initialized as LSM hooks. BPF_PROG_TYPE_LSM programs must have a GPL compatible license and and need CAP_SYS_ADMIN (required for loading eBPF programs). Upon attachment: * A BPF fexit trampoline is used for LSM hooks with a void return type. * A BPF fmod_ret trampoline is used for LSM hooks which return an int. The attached programs can override the return value of the bpf LSM hook to indicate a MAC Policy decision. Signed-off-by: KP Singh <kpsingh@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Brendan Jackman <jackmanb@google.com> Reviewed-by: Florent Revest <revest@google.com> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: James Morris <jamorris@linux.microsoft.com> Link: https://lore.kernel.org/bpf/20200329004356.27286-5-kpsingh@chromium.org
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dcce11d5 |
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10-Mar-2020 |
Jules Irenge <jbi.octave@gmail.com> |
bpf: Add missing annotations for __bpf_prog_enter() and __bpf_prog_exit() Sparse reports a warning at __bpf_prog_enter() and __bpf_prog_exit() warning: context imbalance in __bpf_prog_enter() - wrong count at exit warning: context imbalance in __bpf_prog_exit() - unexpected unlock The root cause is the missing annotation at __bpf_prog_enter() and __bpf_prog_exit() Add the missing __acquires(RCU) annotation Add the missing __releases(RCU) annotation Signed-off-by: Jules Irenge <jbi.octave@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200311010908.42366-2-jbi.octave@gmail.com
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7ac88eba |
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12-Mar-2020 |
Jiri Olsa <jolsa@kernel.org> |
bpf: Remove bpf_image tree Now that we have all the objects (bpf_prog, bpf_trampoline, bpf_dispatcher) linked in bpf_tree, there's no need to have separate bpf_image tree for images. Reverting the bpf_image tree together with struct bpf_image, because it's no longer needed. Also removing bpf_image_alloc function and adding the original bpf_jit_alloc_exec_page interface instead. The kernel_text_address function can now rely only on is_bpf_text_address, because it checks the bpf_tree that contains all the objects. Keeping bpf_image_ksym_add and bpf_image_ksym_del because they are useful wrappers with perf's ksymbol interface calls. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200312195610.346362-13-jolsa@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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a108f7dc |
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12-Mar-2020 |
Jiri Olsa <jolsa@kernel.org> |
bpf: Add trampolines to kallsyms Adding trampolines to kallsyms. It's displayed as bpf_trampoline_<ID> [bpf] where ID is the BTF id of the trampoline function. Adding bpf_image_ksym_add/del functions that setup the start/end values and call KSYMBOL perf events handlers. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200312195610.346362-11-jolsa@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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ae240823 |
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04-Mar-2020 |
KP Singh <kpsingh@google.com> |
bpf: Introduce BPF_MODIFY_RETURN When multiple programs are attached, each program receives the return value from the previous program on the stack and the last program provides the return value to the attached function. The fmod_ret bpf programs are run after the fentry programs and before the fexit programs. The original function is only called if all the fmod_ret programs return 0 to avoid any unintended side-effects. The success value, i.e. 0 is not currently configurable but can be made so where user-space can specify it at load time. For example: int func_to_be_attached(int a, int b) { <--- do_fentry do_fmod_ret: <update ret by calling fmod_ret> if (ret != 0) goto do_fexit; original_function: <side_effects_happen_here> } <--- do_fexit The fmod_ret program attached to this function can be defined as: SEC("fmod_ret/func_to_be_attached") int BPF_PROG(func_name, int a, int b, int ret) { // This will skip the original function logic. return 1; } The first fmod_ret program is passed 0 in its return argument. Signed-off-by: KP Singh <kpsingh@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200304191853.1529-4-kpsingh@chromium.org
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88fd9e53 |
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04-Mar-2020 |
KP Singh <kpsingh@google.com> |
bpf: Refactor trampoline update code As we need to introduce a third type of attachment for trampolines, the flattened signature of arch_prepare_bpf_trampoline gets even more complicated. Refactor the prog and count argument to arch_prepare_bpf_trampoline to use bpf_tramp_progs to simplify the addition and accounting for new attachment types. Signed-off-by: KP Singh <kpsingh@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200304191853.1529-2-kpsingh@chromium.org
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02ad0596 |
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24-Feb-2020 |
David Miller <davem@davemloft.net> |
bpf: Use migrate_disable/enabe() in trampoline code. Instead of preemption disable/enable to reflect the purpose. This allows PREEMPT_RT to substitute it with an actual migration disable implementation. On non RT kernels this is still mapped to preempt_disable/enable(). Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200224145643.891428873@linutronix.de
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e9b4e606 |
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23-Jan-2020 |
Jiri Olsa <jolsa@kernel.org> |
bpf: Allow to resolve bpf trampoline and dispatcher in unwind When unwinding the stack we need to identify each address to successfully continue. Adding latch tree to keep trampolines for quick lookup during the unwind. The patch uses first 48 bytes for latch tree node, leaving 4048 bytes from the rest of the page for trampoline or dispatcher generated code. It's still enough not to affect trampoline and dispatcher progs maximum counts. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200123161508.915203-3-jolsa@kernel.org
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be8704ff |
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20-Jan-2020 |
Alexei Starovoitov <ast@kernel.org> |
bpf: Introduce dynamic program extensions Introduce dynamic program extensions. The users can load additional BPF functions and replace global functions in previously loaded BPF programs while these programs are executing. Global functions are verified individually by the verifier based on their types only. Hence the global function in the new program which types match older function can safely replace that corresponding function. This new function/program is called 'an extension' of old program. At load time the verifier uses (attach_prog_fd, attach_btf_id) pair to identify the function to be replaced. The BPF program type is derived from the target program into extension program. Technically bpf_verifier_ops is copied from target program. The BPF_PROG_TYPE_EXT program type is a placeholder. It has empty verifier_ops. The extension program can call the same bpf helper functions as target program. Single BPF_PROG_TYPE_EXT type is used to extend XDP, SKB and all other program types. The verifier allows only one level of replacement. Meaning that the extension program cannot recursively extend an extension. That also means that the maximum stack size is increasing from 512 to 1024 bytes and maximum function nesting level from 8 to 16. The programs don't always consume that much. The stack usage is determined by the number of on-stack variables used by the program. The verifier could have enforced 512 limit for combined original plus extension program, but it makes for difficult user experience. The main use case for extensions is to provide generic mechanism to plug external programs into policy program or function call chaining. BPF trampoline is used to track both fentry/fexit and program extensions because both are using the same nop slot at the beginning of every BPF function. Attaching fentry/fexit to a function that was replaced is not allowed. The opposite is true as well. Replacing a function that currently being analyzed with fentry/fexit is not allowed. The executable page allocated by BPF trampoline is not used by program extensions. This inefficiency will be optimized in future patches. Function by function verification of global function supports scalars and pointer to context only. Hence program extensions are supported for such class of global functions only. In the future the verifier will be extended with support to pointers to structures, arrays with sizes, etc. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/bpf/20200121005348.2769920-2-ast@kernel.org
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05d57f17 |
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20-Jan-2020 |
Alexei Starovoitov <ast@kernel.org> |
bpf: Fix trampoline usage in preempt Though the second half of trampoline page is unused a task could be preempted in the middle of the first half of trampoline and two updates to trampoline would change the code from underneath the preempted task. Hence wait for tasks to voluntarily schedule or go to userspace. Add similar wait before freeing the trampoline. Fixes: fec56f5890d9 ("bpf: Introduce BPF trampoline") Reported-by: Jann Horn <jannh@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Paul E. McKenney <paulmck@kernel.org> Link: https://lore.kernel.org/bpf/20200121032231.3292185-1-ast@kernel.org
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85d33df3 |
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08-Jan-2020 |
Martin KaFai Lau <kafai@fb.com> |
bpf: Introduce BPF_MAP_TYPE_STRUCT_OPS The patch introduces BPF_MAP_TYPE_STRUCT_OPS. The map value is a kernel struct with its func ptr implemented in bpf prog. This new map is the interface to register/unregister/introspect a bpf implemented kernel struct. The kernel struct is actually embedded inside another new struct (or called the "value" struct in the code). For example, "struct tcp_congestion_ops" is embbeded in: struct bpf_struct_ops_tcp_congestion_ops { refcount_t refcnt; enum bpf_struct_ops_state state; struct tcp_congestion_ops data; /* <-- kernel subsystem struct here */ } The map value is "struct bpf_struct_ops_tcp_congestion_ops". The "bpftool map dump" will then be able to show the state ("inuse"/"tobefree") and the number of subsystem's refcnt (e.g. number of tcp_sock in the tcp_congestion_ops case). This "value" struct is created automatically by a macro. Having a separate "value" struct will also make extending "struct bpf_struct_ops_XYZ" easier (e.g. adding "void (*init)(void)" to "struct bpf_struct_ops_XYZ" to do some initialization works before registering the struct_ops to the kernel subsystem). The libbpf will take care of finding and populating the "struct bpf_struct_ops_XYZ" from "struct XYZ". Register a struct_ops to a kernel subsystem: 1. Load all needed BPF_PROG_TYPE_STRUCT_OPS prog(s) 2. Create a BPF_MAP_TYPE_STRUCT_OPS with attr->btf_vmlinux_value_type_id set to the btf id "struct bpf_struct_ops_tcp_congestion_ops" of the running kernel. Instead of reusing the attr->btf_value_type_id, btf_vmlinux_value_type_id s added such that attr->btf_fd can still be used as the "user" btf which could store other useful sysadmin/debug info that may be introduced in the furture, e.g. creation-date/compiler-details/map-creator...etc. 3. Create a "struct bpf_struct_ops_tcp_congestion_ops" object as described in the running kernel btf. Populate the value of this object. The function ptr should be populated with the prog fds. 4. Call BPF_MAP_UPDATE with the object created in (3) as the map value. The key is always "0". During BPF_MAP_UPDATE, the code that saves the kernel-func-ptr's args as an array of u64 is generated. BPF_MAP_UPDATE also allows the specific struct_ops to do some final checks in "st_ops->init_member()" (e.g. ensure all mandatory func ptrs are implemented). If everything looks good, it will register this kernel struct to the kernel subsystem. The map will not allow further update from this point. Unregister a struct_ops from the kernel subsystem: BPF_MAP_DELETE with key "0". Introspect a struct_ops: BPF_MAP_LOOKUP_ELEM with key "0". The map value returned will have the prog _id_ populated as the func ptr. The map value state (enum bpf_struct_ops_state) will transit from: INIT (map created) => INUSE (map updated, i.e. reg) => TOBEFREE (map value deleted, i.e. unreg) The kernel subsystem needs to call bpf_struct_ops_get() and bpf_struct_ops_put() to manage the "refcnt" in the "struct bpf_struct_ops_XYZ". This patch uses a separate refcnt for the purose of tracking the subsystem usage. Another approach is to reuse the map->refcnt and then "show" (i.e. during map_lookup) the subsystem's usage by doing map->refcnt - map->usercnt to filter out the map-fd/pinned-map usage. However, that will also tie down the future semantics of map->refcnt and map->usercnt. The very first subsystem's refcnt (during reg()) holds one count to map->refcnt. When the very last subsystem's refcnt is gone, it will also release the map->refcnt. All bpf_prog will be freed when the map->refcnt reaches 0 (i.e. during map_free()). Here is how the bpftool map command will look like: [root@arch-fb-vm1 bpf]# bpftool map show 6: struct_ops name dctcp flags 0x0 key 4B value 256B max_entries 1 memlock 4096B btf_id 6 [root@arch-fb-vm1 bpf]# bpftool map dump id 6 [{ "value": { "refcnt": { "refs": { "counter": 1 } }, "state": 1, "data": { "list": { "next": 0, "prev": 0 }, "key": 0, "flags": 2, "init": 24, "release": 0, "ssthresh": 25, "cong_avoid": 30, "set_state": 27, "cwnd_event": 28, "in_ack_event": 26, "undo_cwnd": 29, "pkts_acked": 0, "min_tso_segs": 0, "sndbuf_expand": 0, "cong_control": 0, "get_info": 0, "name": [98,112,102,95,100,99,116,99,112,0,0,0,0,0,0,0 ], "owner": 0 } } } ] Misc Notes: * bpf_struct_ops_map_sys_lookup_elem() is added for syscall lookup. It does an inplace update on "*value" instead returning a pointer to syscall.c. Otherwise, it needs a separate copy of "zero" value for the BPF_STRUCT_OPS_STATE_INIT to avoid races. * The bpf_struct_ops_map_delete_elem() is also called without preempt_disable() from map_delete_elem(). It is because the "->unreg()" may requires sleepable context, e.g. the "tcp_unregister_congestion_control()". * "const" is added to some of the existing "struct btf_func_model *" function arg to avoid a compiler warning caused by this patch. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20200109003505.3855919-1-kafai@fb.com
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98e8627e |
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13-Dec-2019 |
Björn Töpel <bjorn@kernel.org> |
bpf: Move trampoline JIT image allocation to a function Refactor the image allocation in the BPF trampoline code into a separate function, so it can be shared with the BPF dispatcher in upcoming commits. Signed-off-by: Björn Töpel <bjorn.topel@intel.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20191213175112.30208-2-bjorn.topel@gmail.com
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b91e014f |
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08-Dec-2019 |
Alexei Starovoitov <ast@kernel.org> |
bpf: Make BPF trampoline use register_ftrace_direct() API Make BPF trampoline attach its generated assembly code to kernel functions via register_ftrace_direct() API. It helps ftrace-based tracers co-exist with BPF trampoline on the same kernel function. It also switches attaching logic from arch specific text_poke to generic ftrace that is available on many architectures. text_poke is still necessary for bpf-to-bpf attach and for bpf_tail_call optimization. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20191209000114.1876138-3-ast@kernel.org
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b553a6ec |
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23-Nov-2019 |
Daniel Borkmann <daniel@iogearbox.net> |
bpf: Simplify __bpf_arch_text_poke poke type handling Given that we have BPF_MOD_NOP_TO_{CALL,JUMP}, BPF_MOD_{CALL,JUMP}_TO_NOP and BPF_MOD_{CALL,JUMP}_TO_{CALL,JUMP} poke types and that we also pass in old_addr as well as new_addr, it's a bit redundant and unnecessarily complicates __bpf_arch_text_poke() itself since we can derive the same from the *_addr that were passed in. Hence simplify and use BPF_MOD_{CALL,JUMP} as types which also allows to clean up call-sites. In addition to that, __bpf_arch_text_poke() currently verifies that text matches expected old_insn before we invoke text_poke_bp(). Also add a check on new_insn and skip rewrite if it already matches. Reason why this is rather useful is that it avoids making any special casing in prog_array_map_poke_run() when old and new prog were NULL and has the benefit that also for this case we perform a check on text whether it really matches our expectations. Suggested-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/fcb00a2b0b288d6c73de4ef58116a821c8fe8f2f.1574555798.git.daniel@iogearbox.net
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fec56f58 |
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14-Nov-2019 |
Alexei Starovoitov <ast@kernel.org> |
bpf: Introduce BPF trampoline Introduce BPF trampoline concept to allow kernel code to call into BPF programs with practically zero overhead. The trampoline generation logic is architecture dependent. It's converting native calling convention into BPF calling convention. BPF ISA is 64-bit (even on 32-bit architectures). The registers R1 to R5 are used to pass arguments into BPF functions. The main BPF program accepts only single argument "ctx" in R1. Whereas CPU native calling convention is different. x86-64 is passing first 6 arguments in registers and the rest on the stack. x86-32 is passing first 3 arguments in registers. sparc64 is passing first 6 in registers. And so on. The trampolines between BPF and kernel already exist. BPF_CALL_x macros in include/linux/filter.h statically compile trampolines from BPF into kernel helpers. They convert up to five u64 arguments into kernel C pointers and integers. On 64-bit architectures this BPF_to_kernel trampolines are nops. On 32-bit architecture they're meaningful. The opposite job kernel_to_BPF trampolines is done by CAST_TO_U64 macros and __bpf_trace_##call() shim functions in include/trace/bpf_probe.h. They convert kernel function arguments into array of u64s that BPF program consumes via R1=ctx pointer. This patch set is doing the same job as __bpf_trace_##call() static trampolines, but dynamically for any kernel function. There are ~22k global kernel functions that are attachable via nop at function entry. The function arguments and types are described in BTF. The job of btf_distill_func_proto() function is to extract useful information from BTF into "function model" that architecture dependent trampoline generators will use to generate assembly code to cast kernel function arguments into array of u64s. For example the kernel function eth_type_trans has two pointers. They will be casted to u64 and stored into stack of generated trampoline. The pointer to that stack space will be passed into BPF program in R1. On x86-64 such generated trampoline will consume 16 bytes of stack and two stores of %rdi and %rsi into stack. The verifier will make sure that only two u64 are accessed read-only by BPF program. The verifier will also recognize the precise type of the pointers being accessed and will not allow typecasting of the pointer to a different type within BPF program. The tracing use case in the datacenter demonstrated that certain key kernel functions have (like tcp_retransmit_skb) have 2 or more kprobes that are always active. Other functions have both kprobe and kretprobe. So it is essential to keep both kernel code and BPF programs executing at maximum speed. Hence generated BPF trampoline is re-generated every time new program is attached or detached to maintain maximum performance. To avoid the high cost of retpoline the attached BPF programs are called directly. __bpf_prog_enter/exit() are used to support per-program execution stats. In the future this logic will be optimized further by adding support for bpf_stats_enabled_key inside generated assembly code. Introduction of preemptible and sleepable BPF programs will completely remove the need to call to __bpf_prog_enter/exit(). Detach of a BPF program from the trampoline should not fail. To avoid memory allocation in detach path the half of the page is used as a reserve and flipped after each attach/detach. 2k bytes is enough to call 40+ BPF programs directly which is enough for BPF tracing use cases. This limit can be increased in the future. BPF_TRACE_FENTRY programs have access to raw kernel function arguments while BPF_TRACE_FEXIT programs have access to kernel return value as well. Often kprobe BPF program remembers function arguments in a map while kretprobe fetches arguments from a map and analyzes them together with return value. BPF_TRACE_FEXIT accelerates this typical use case. Recursion prevention for kprobe BPF programs is done via per-cpu bpf_prog_active counter. In practice that turned out to be a mistake. It caused programs to randomly skip execution. The tracing tools missed results they were looking for. Hence BPF trampoline doesn't provide builtin recursion prevention. It's a job of BPF program itself and will be addressed in the follow up patches. BPF trampoline is intended to be used beyond tracing and fentry/fexit use cases in the future. For example to remove retpoline cost from XDP programs. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20191114185720.1641606-5-ast@kernel.org
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