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35e61e88 |
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30-Nov-2023 |
Song Shuai <suagrfillet@gmail.com> |
riscv: ftrace: Make function graph use ftrace directly Similar to commit 0c0593b45c9b ("x86/ftrace: Make function graph use ftrace directly") and commit c4a0ebf87ceb ("arm64/ftrace: Make function graph use ftrace directly"), RISC-V has no need for a special graph tracer hook. The graph_ops::func function can be used to install the return_hooker. This cleanup only changes the FTRACE_WITH_REGS implementation, leaving the mcount-based implementation is unaffected. Perform the simplification, and also cleanup the register save/restore macros. Signed-off-by: Song Shuai <suagrfillet@gmail.com> Tested-by: Guo Ren <guoren@kernel.org> Signed-off-by: Guo Ren <guoren@kernel.org> Acked-by: Björn Töpel <bjorn@rivosinc.com> Link: https://lore.kernel.org/r/20231130121531.1178502-3-bjorn@kernel.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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2a8db5ec |
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03-Mar-2023 |
Conor Dooley <conor.dooley@microchip.com> |
RISC-V: Don't check text_mutex during stop_machine We're currently using stop_machine() to update ftrace & kprobes, which means that the thread that takes text_mutex during may not be the same as the thread that eventually patches the code. This isn't actually a race because the lock is still held (preventing any other concurrent accesses) and there is only one thread running during stop_machine(), but it does trigger a lockdep failure. This patch just elides the lockdep check during stop_machine. Fixes: c15ac4fd60d5 ("riscv/ftrace: Add dynamic function tracer support") Suggested-by: Steven Rostedt <rostedt@goodmis.org> Reported-by: Changbin Du <changbin.du@gmail.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com> Signed-off-by: Conor Dooley <conor.dooley@microchip.com> Link: https://lore.kernel.org/r/20230303143754.4005217-1-conor.dooley@microchip.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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6724a76c |
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12-Jan-2023 |
Guo Ren <guoren@kernel.org> |
riscv: ftrace: Reduce the detour code size to half Use a temporary register to reduce the size of detour code from 16 bytes to 8 bytes. The previous implementation is from 'commit afc76b8b8011 ("riscv: Using PATCHABLE_FUNCTION_ENTRY instead of MCOUNT")'. Before the patch: <func_prolog>: 0: REG_S ra, -SZREG(sp) 4: auipc ra, ? 8: jalr ?(ra) 12: REG_L ra, -SZREG(sp) (func_boddy) After the patch: <func_prolog>: 0: auipc t0, ? 4: jalr t0, ?(t0) (func_boddy) This patch not just reduces the size of detour code, but also fixes an important issue: An Ftrace callback registered with FTRACE_OPS_FL_IPMODIFY flag can actually change the instruction pointer, e.g. to "replace" the given kernel function with a new one, which is needed for livepatching, etc. In this case, the trampoline (ftrace_regs_caller) would not return to <func_prolog+12> but would rather jump to the new function. So, "REG_L ra, -SZREG(sp)" would not run and the original return address would not be restored. The kernel is likely to hang or crash as a result. This can be easily demonstrated if one tries to "replace", say, cmdline_proc_show() with a new function with the same signature using instruction_pointer_set(&fregs->regs, new_func_addr) in the Ftrace callback. Link: https://lore.kernel.org/linux-riscv/20221122075440.1165172-1-suagrfillet@gmail.com/ Link: https://lore.kernel.org/linux-riscv/d7d5730b-ebef-68e5-5046-e763e1ee6164@yadro.com/ Co-developed-by: Song Shuai <suagrfillet@gmail.com> Signed-off-by: Song Shuai <suagrfillet@gmail.com> Signed-off-by: Guo Ren <guoren@linux.alibaba.com> Signed-off-by: Guo Ren <guoren@kernel.org> Cc: Evgenii Shatokhin <e.shatokhin@yadro.com> Reviewed-by: Evgenii Shatokhin <e.shatokhin@yadro.com> Link: https://lore.kernel.org/r/20230112090603.1295340-4-guoren@kernel.org Cc: stable@vger.kernel.org Fixes: 10626c32e382 ("riscv/ftrace: Add basic support") Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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3a2bfec0 |
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17-May-2022 |
Li kunyu <kunyu@nfschina.com> |
ftrace: Remove return value of ftrace_arch_modify_*() All instances of the function ftrace_arch_modify_prepare() and ftrace_arch_modify_post_process() return zero. There's no point in checking their return value. Just have them be void functions. Link: https://lkml.kernel.org/r/20220518023639.4065-1-kunyu@nfschina.com Signed-off-by: Li kunyu <kunyu@nfschina.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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6644c654 |
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09-Sep-2021 |
Weizhao Ouyang <o451686892@gmail.com> |
ftrace: Cleanup ftrace_dyn_arch_init() Most of ARCHs use empty ftrace_dyn_arch_init(), introduce a weak common ftrace_dyn_arch_init() to cleanup them. Link: https://lkml.kernel.org/r/20210909090216.1955240-1-o451686892@gmail.com Acked-by: Heiko Carstens <hca@linux.ibm.com> (s390) Acked-by: Helge Deller <deller@gmx.de> (parisc) Signed-off-by: Weizhao Ouyang <o451686892@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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afc76b8b |
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17-Dec-2020 |
Guo Ren <guoren@linux.alibaba.com> |
riscv: Using PATCHABLE_FUNCTION_ENTRY instead of MCOUNT This patch changes the current detour mechanism of dynamic ftrace which has been discussed during LPC 2020 RISCV-MC [1]. Before the patch, we used mcount for detour: <funca>: addi sp,sp,-16 sd ra,8(sp) sd s0,0(sp) addi s0,sp,16 mv a5,ra mv a0,a5 auipc ra,0x0 -> nop jalr -296(ra) <_mcount@plt> ->nop ... After the patch, we use nop call site area for detour: <funca>: nop -> REG_S ra, -SZREG(sp) nop -> auipc ra, 0x? nop -> jalr ?(ra) nop -> REG_L ra, -SZREG(sp) ... The mcount mechanism is mixed with gcc function prologue which is not very clear. The patchable function entry just put 16 bytes nop before the front of the function prologue which could be filled with a separated detour mechanism. [1] https://www.linuxplumbersconf.org/event/7/contributions/807/ Signed-off-by: Guo Ren <guoren@linux.alibaba.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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9d750c75 |
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10-Oct-2020 |
Ryan Kosta <ryanpkosta@gmail.com> |
risc-v: kernel: ftrace: Fixes improper SPDX comment style Signed-off-by: Ryan Kosta <ryanpkosta@gmail.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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66d18dbd |
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24-Aug-2020 |
Palmer Dabbelt <palmerdabbelt@google.com> |
RISC-V: Take text_mutex in ftrace_init_nop() Without this we get lockdep failures. They're spurious failures as SMP isn't up when ftrace_init_nop() is called. As far as I can tell the easiest fix is to just take the lock, which also seems like the safest fix. Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com> Acked-by: Guo Ren <guoren@kernel.org> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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fe557319 |
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17-Jun-2020 |
Christoph Hellwig <hch@lst.de> |
maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault Better describe what these functions do. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0ff7c3b3 |
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21-Apr-2020 |
Zong Li <zong.li@sifive.com> |
riscv: Use text_mutex instead of patch_lock We don't need the additional lock protection when patching the text. There are two patching interfaces here: - patch_text: patch code and always synchronize with stop_machine() - patch_text_nosync: patch code without synchronization, it's caller's responsibility to synchronize all CPUs if needed. For the first one, stop_machine() is protected by its own mutex, and also the irq is already disabled here. For the second one, in risc-v real case now, it would be used to ftrace patching the mcount function, since it already running under kstop_machine(), no other thread will run, so we could use text_mutex on ftrace side. Signed-off-by: Zong Li <zong.li@sifive.com> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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b80b3d58 |
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21-Apr-2020 |
Zong Li <zong.li@sifive.com> |
riscv: Remove the 'riscv_' prefix of function name Refactor the function name by removing the 'riscv_' prefix, it would be better unless it could mix up with arch-independent functions. Signed-off-by: Zong Li <zong.li@sifive.com> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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8fdddb2e |
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09-Mar-2020 |
Zong Li <zong.li@sifive.com> |
riscv: patch code by fixmap mapping On strict kernel memory permission, the ftrace have to change the permission of text for dynamic patching the intructions. Use riscv_patch_text_nosync() to patch code instead of probe_kernel_write. Signed-off-by: Zong Li <zong.li@sifive.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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1d8f6579 |
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23-Dec-2019 |
Zong Li <zong.li@sifive.com> |
riscv: ftrace: correct the condition logic in function graph tracer The condition should be logical NOT to assign the hook address to parent address. Because the return value 0 of function_graph_enter upon success. Fixes: e949b6db51dc (riscv/function_graph: Simplify with function_graph_enter()) Signed-off-by: Zong Li <zong.li@sifive.com> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: stable@vger.kernel.org Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
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7265d103 |
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18-Jan-2019 |
Johan Hovold <johan@kernel.org> |
riscv: add missing newlines to printk messages Add missing newline characters to printk messages. Also replace two pr_warning with the shorter pr_warn, and fix up the tense of one error message while at it. Signed-off-by: Johan Hovold <johan@kernel.org> Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
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397182e0 |
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06-Dec-2018 |
David Abdurachmanov <david.abdurachmanov@gmail.com> |
riscv: remove unused variable in ftrace Noticed while building kernel-4.20.0-0.rc5.git2.1.fc30 for Fedora 30/RISCV. [..] BUILDSTDERR: arch/riscv/kernel/ftrace.c: In function 'prepare_ftrace_return': BUILDSTDERR: arch/riscv/kernel/ftrace.c:135:6: warning: unused variable 'err' [-Wunused-variable] BUILDSTDERR: int err; BUILDSTDERR: ^~~ [..] Signed-off-by: David Abdurachmanov <david.abdurachmanov@gmail.com> Fixes: e949b6db51dc1 ("riscv/function_graph: Simplify with function_graph_enter()") Reviewed-by: Olof Johansson <olof@lixom.net> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
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e949b6db |
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18-Nov-2018 |
Steven Rostedt (VMware) <rostedt@goodmis.org> |
riscv/function_graph: Simplify with function_graph_enter() The function_graph_enter() function does the work of calling the function graph hook function and the management of the shadow stack, simplifying the work done in the architecture dependent prepare_ftrace_return(). Have riscv use the new code, and remove the shadow stack management as well as having to set up the trace structure. This is needed to prepare for a fix of a design bug on how the curr_ret_stack is used. Cc: Greentime Hu <greentime@andestech.com> Cc: Alan Kao <alankao@andestech.com> Cc: stable@kernel.org Fixes: 03274a3ffb449 ("tracing/fgraph: Adjust fgraph depth before calling trace return callback") Reviewed-by: Palmer Dabbelt <palmer@sifive.com> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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b785ec12 |
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12-Feb-2018 |
Alan Kao <alankao@andestech.com> |
riscv/ftrace: Add HAVE_FUNCTION_GRAPH_RET_ADDR_PTR support In walk_stackframe, the pc now receives the address from calling ftrace_graph_ret_addr instead of manual calculation. Note that the original calculation, pc = frame->ra - 4 is buggy when the instruction at the return address happened to be a compressed inst. But since it is not a critical part of ftrace, it is ignored for now to ease the review process. Cc: Greentime Hu <greentime@andestech.com> Signed-off-by: Alan Kao <alankao@andestech.com> Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
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aea4c671 |
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12-Feb-2018 |
Alan Kao <alankao@andestech.com> |
riscv/ftrace: Add DYNAMIC_FTRACE_WITH_REGS support Cc: Greentime Hu <greentime@andestech.com> Signed-off-by: Alan Kao <alankao@andestech.com> Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
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bc1a4c3a |
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12-Feb-2018 |
Alan Kao <alankao@andestech.com> |
riscv/ftrace: Add dynamic function graph tracer support Once the function_graph tracer is enabled, a filtered function has the following call sequence: * ftracer_caller ==> on/off by ftrace_make_call/ftrace_make_nop * ftrace_graph_caller * ftrace_graph_call ==> on/off by ftrace_en/disable_ftrace_graph_caller * prepare_ftrace_return Considering the following DYNAMIC_FTRACE_WITH_REGS feature, it would be more extendable to have a ftrace_graph_caller function, instead of calling prepare_ftrace_return directly in ftrace_caller. Cc: Greentime Hu <greentime@andestech.com> Signed-off-by: Alan Kao <alankao@andestech.com> Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
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c15ac4fd |
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12-Feb-2018 |
Alan Kao <alankao@andestech.com> |
riscv/ftrace: Add dynamic function tracer support We now have dynamic ftrace with the following added items: * ftrace_make_call, ftrace_make_nop (in kernel/ftrace.c) The two functions turn each recorded call site of filtered functions into a call to ftrace_caller or nops * ftracce_update_ftrace_func (in kernel/ftrace.c) turns the nops at ftrace_call into a call to a generic entry for function tracers. * ftrace_caller (in kernel/mcount-dyn.S) The entry where each _mcount call sites calls to once they are filtered to be traced. Also, this patch fixes the semantic problems in mcount.S, which will be treated as only a reference implementation once we have the dynamic ftrace. Cc: Greentime Hu <greentime@andestech.com> Signed-off-by: Alan Kao <alankao@andestech.com> Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
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10626c32 |
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18-Dec-2017 |
Alan Kao <nonerkao@gmail.com> |
riscv/ftrace: Add basic support This patch contains basic ftrace support for RV64I platform. Specifically, function tracer (HAVE_FUNCTION_TRACER), function graph tracer (HAVE_FUNCTION_GRAPH_TRACER), and a frame pointer test (HAVE_FUNCTION_GRAPH_FP_TEST) are implemented following the instructions in Documentation/trace/ftrace-design.txt. Note that the functions in both ftrace.c and setup.c should not be hooked with the compiler's -pg option: to prevent infinite self- referencing for the former, and to ignore early setup stuff for the latter. Signed-off-by: Alan Kao <alankao@andestech.com> Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
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