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4ae68b26 |
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14-Aug-2023 |
Peter Zijlstra <peterz@infradead.org> |
objtool/x86: Fix SRSO mess Objtool --rethunk does two things: - it collects all (tail) call's of __x86_return_thunk and places them into .return_sites. These are typically compiler generated, but RET also emits this same. - it fudges the validation of the __x86_return_thunk symbol; because this symbol is inside another instruction, it can't actually find the instruction pointed to by the symbol offset and gets upset. Because these two things pertained to the same symbol, there was no pressing need to separate these two separate things. However, alas, along comes SRSO and more crazy things to deal with appeared. The SRSO patch itself added the following symbol names to identify as rethunk: 'srso_untrain_ret', 'srso_safe_ret' and '__ret' Where '__ret' is the old retbleed return thunk, 'srso_safe_ret' is a new similarly embedded return thunk, and 'srso_untrain_ret' is completely unrelated to anything the above does (and was only included because of that INT3 vs UD2 issue fixed previous). Clear things up by adding a second category for the embedded instruction thing. Fixes: fb3bd914b3ec ("x86/srso: Add a Speculative RAS Overflow mitigation") Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/r/20230814121148.704502245@infradead.org
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3ee88df1 |
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08-Feb-2023 |
Peter Zijlstra <peterz@infradead.org> |
objtool: Make instruction::stack_ops a single-linked list struct instruction { struct list_head list; /* 0 16 */ struct hlist_node hash; /* 16 16 */ struct list_head call_node; /* 32 16 */ struct section * sec; /* 48 8 */ long unsigned int offset; /* 56 8 */ /* --- cacheline 1 boundary (64 bytes) --- */ unsigned int len; /* 64 4 */ enum insn_type type; /* 68 4 */ long unsigned int immediate; /* 72 8 */ u16 dead_end:1; /* 80: 0 2 */ u16 ignore:1; /* 80: 1 2 */ u16 ignore_alts:1; /* 80: 2 2 */ u16 hint:1; /* 80: 3 2 */ u16 save:1; /* 80: 4 2 */ u16 restore:1; /* 80: 5 2 */ u16 retpoline_safe:1; /* 80: 6 2 */ u16 noendbr:1; /* 80: 7 2 */ u16 entry:1; /* 80: 8 2 */ /* XXX 7 bits hole, try to pack */ s8 instr; /* 82 1 */ u8 visited; /* 83 1 */ /* XXX 4 bytes hole, try to pack */ struct alt_group * alt_group; /* 88 8 */ struct symbol * call_dest; /* 96 8 */ struct instruction * jump_dest; /* 104 8 */ struct instruction * first_jump_src; /* 112 8 */ struct reloc * jump_table; /* 120 8 */ /* --- cacheline 2 boundary (128 bytes) --- */ struct reloc * reloc; /* 128 8 */ struct list_head alts; /* 136 16 */ struct symbol * sym; /* 152 8 */ - struct list_head stack_ops; /* 160 16 */ - struct cfi_state * cfi; /* 176 8 */ + struct stack_op * stack_ops; /* 160 8 */ + struct cfi_state * cfi; /* 168 8 */ - /* size: 184, cachelines: 3, members: 29 */ - /* sum members: 178, holes: 1, sum holes: 4 */ + /* size: 176, cachelines: 3, members: 29 */ + /* sum members: 170, holes: 1, sum holes: 4 */ /* sum bitfield members: 9 bits, bit holes: 1, sum bit holes: 7 bits */ - /* last cacheline: 56 bytes */ + /* last cacheline: 48 bytes */ }; pre: 5:58.22 real, 226.69 user, 131.22 sys, 26221520 mem post: 5:58.50 real, 229.64 user, 128.65 sys, 26221520 mem Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Tested-by: Nathan Chancellor <nathan@kernel.org> # build only Tested-by: Thomas Weißschuh <linux@weissschuh.net> # compile and run Link: https://lore.kernel.org/r/20230208172245.362196959@infradead.org
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20a55463 |
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08-Feb-2023 |
Peter Zijlstra <peterz@infradead.org> |
objtool: Change arch_decode_instruction() signature In preparation to changing struct instruction around a bit, avoid passing it's members by pointer and instead pass the whole thing. A cleanup in it's own right too. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Tested-by: Nathan Chancellor <nathan@kernel.org> # build only Tested-by: Thomas Weißschuh <linux@weissschuh.net> # compile and run Link: https://lore.kernel.org/r/20230208172245.291087549@infradead.org
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a39818a3 |
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23-Nov-2022 |
Michael Ellerman <mpe@ellerman.id.au> |
objtool/powerpc: Implement arch_pc_relative_reloc() Provide an implementation for arch_pc_relative_reloc(). It is needed to pass the build once 61c6065ef7ec ("objtool: Allow !PC relative relocations") is merged. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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4ca993d4 |
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14-Nov-2022 |
Sathvika Vasireddy <sv@linux.ibm.com> |
objtool: Add arch specific function arch_ftrace_match() Add architecture specific function to look for relocation records pointing to architecture specific symbols. Suggested-by: Christophe Leroy <christophe.leroy@csgroup.eu> Tested-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Sathvika Vasireddy <sv@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20221114175754.1131267-15-sv@linux.ibm.com
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61c6065e |
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15-Sep-2022 |
Peter Zijlstra <peterz@infradead.org> |
objtool: Allow !PC relative relocations Objtool doesn't currently much like per-cpu usage in alternatives: arch/x86/entry/entry_64.o: warning: objtool: .altinstr_replacement+0xf: unsupported relocation in alternatives section f: 65 c7 04 25 00 00 00 00 00 00 00 80 movl $0x80000000,%gs:0x0 13: R_X86_64_32S __x86_call_depth Since the R_X86_64_32S relocation is location invariant (it's computation doesn't include P - the address of the location itself), it can be trivially allowed. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20220915111145.806607235@infradead.org
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d9e9d230 |
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14-Jun-2022 |
Peter Zijlstra <peterz@infradead.org> |
x86,objtool: Create .return_sites Find all the return-thunk sites and record them in a .return_sites section such that the kernel can undo this. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de>
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7d209d13 |
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08-Mar-2022 |
Peter Zijlstra <peterz@infradead.org> |
objtool: Add IBT/ENDBR decoding Intel IBT requires the target of any indirect CALL or JMP instruction to be the ENDBR instruction; optionally it allows those two instructions to have a NOTRACK prefix in order to avoid this requirement. The kernel will not enable the use of NOTRACK, as such any occurence of it in compiler generated code should be flagged. Teach objtool to Decode ENDBR instructions and WARN about NOTRACK prefixes. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/20220308154319.645963517@infradead.org
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1cc1e4c8 |
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04-Dec-2021 |
Peter Zijlstra <peterz@infradead.org> |
objtool: Add straight-line-speculation validation Teach objtool to validate the straight-line-speculation constraints: - speculation trap after indirect calls - speculation trap after RET Notable: when an instruction is annotated RETPOLINE_SAFE, indicating speculation isn't a problem, also don't care about sls for that instruction. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/20211204134908.023037659@infradead.org
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db2b0c5d |
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24-Jun-2021 |
Peter Zijlstra <peterz@infradead.org> |
objtool: Support pv_opsindirect calls for noinstr Normally objtool will now follow indirect calls; there is no need. However, this becomes a problem with noinstr validation; if there's an indirect call from noinstr code, we very much need to know it is to another noinstr function. Luckily there aren't many indirect calls in entry code with the obvious exception of paravirt. As such, noinstr validation didn't work with paravirt kernels. In order to track pv_ops[] call targets, objtool reads the static pv_ops[] tables as well as direct assignments to the pv_ops[] array, provided the compiler makes them a single instruction like: bf87: 48 c7 05 00 00 00 00 00 00 00 00 movq $0x0,0x0(%rip) bf92 <xen_init_spinlocks+0x5f> bf8a: R_X86_64_PC32 pv_ops+0x268 There are, as of yet, no warnings for when this goes wrong :/ Using the functions found with the above means, all pv_ops[] calls are now subject to noinstr validation. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210624095149.118815755@infradead.org
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f56dae88 |
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24-Jun-2021 |
Peter Zijlstra <peterz@infradead.org> |
objtool: Handle __sanitize_cov*() tail calls Turns out the compilers also generate tail calls to __sanitize_cov*(), make sure to also patch those out in noinstr code. Fixes: 0f1441b44e82 ("objtool: Fix noinstr vs KCOV") Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Marco Elver <elver@google.com> Link: https://lore.kernel.org/r/20210624095147.818783799@infradead.org
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8b946cc3 |
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24-Jun-2021 |
Peter Zijlstra <peterz@infradead.org> |
objtool: Introduce CFI hash Andi reported that objtool on vmlinux.o consumes more memory than his system has, leading to horrific performance. This is in part because we keep a struct instruction for every instruction in the file in-memory. Shrink struct instruction by removing the CFI state (which includes full register state) from it and demand allocating it. Given most instructions don't actually change CFI state, there's lots of repetition there, so add a hash table to find previous CFI instances. Reduces memory consumption (and runtime) for processing an x86_64-allyesconfig: pre: 4:40.84 real, 143.99 user, 44.18 sys, 30624988 mem post: 2:14.61 real, 108.58 user, 25.04 sys, 16396184 mem Suggested-by: Andi Kleen <andi@firstfloor.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210624095147.756759107@infradead.org
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ffc7e74f |
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09-Feb-2021 |
Peter Zijlstra <peterz@infradead.org> |
objtool,x86: Rewrite LEAVE Since we can now have multiple stack-ops per instruction, we don't need to special case LEAVE and can simply emit the composite operations. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Link: https://lkml.kernel.org/r/20210211173627.253273977@infradead.org
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43d5430a |
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26-Mar-2021 |
Peter Zijlstra <peterz@infradead.org> |
objtool: Keep track of retpoline call sites Provide infrastructure for architectures to rewrite/augment compiler generated retpoline calls. Similar to what we do for static_call()s, keep track of the instructions that are retpoline calls. Use the same list_head, since a retpoline call cannot also be a static_call. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Link: https://lkml.kernel.org/r/20210326151300.130805730@infradead.org
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530b4ddd |
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26-Mar-2021 |
Peter Zijlstra <peterz@infradead.org> |
objtool: Handle per arch retpoline naming The __x86_indirect_ naming is obviously not generic. Shorten to allow matching some additional magic names later. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Link: https://lkml.kernel.org/r/20210326151259.630296706@infradead.org
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ab4e0744 |
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17-Dec-2020 |
Josh Poimboeuf <jpoimboe@redhat.com> |
objtool: Refactor ORC section generation Decouple ORC entries from instructions. This simplifies the control/data flow, and is going to make it easier to support alternative instructions which change the stack layout. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
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7786032e |
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12-Nov-2020 |
Vasily Gorbik <gor@linux.ibm.com> |
objtool: Rework header include paths Currently objtool headers are being included either by their base name or included via ../ from a parent directory. In case of a base name usage: #include "warn.h" #include "arch_elf.h" it does not make it apparent from which directory the file comes from. To make it slightly better, and actually to avoid name clashes some arch specific files have "arch_" suffix. And files from an arch folder have to revert to including via ../ e.g: #include "../../elf.h" With additional architectures support and the code base growth there is a need for clearer headers naming scheme for multiple reasons: 1. to make it instantly obvious where these files come from (objtool itself / objtool arch|generic folders / some other external files), 2. to avoid name clashes of objtool arch specific headers, potential obtool arch generic headers and the system header files (there is /usr/include/elf.h already), 3. to avoid ../ includes and improve code readability. 4. to give a warm fuzzy feeling to developers who are mostly kernel developers and are accustomed to linux kernel headers arranging scheme. Doesn't this make it instantly obvious where are these files come from? #include <objtool/warn.h> #include <arch/elf.h> And doesn't it look nicer to avoid ugly ../ includes? Which also guarantees this is elf.h from the objtool and not /usr/include/elf.h. #include <objtool/elf.h> This patch defines and implements new objtool headers arranging scheme. Which is: - all generic headers go to include/objtool (similar to include/linux) - all arch headers go to arch/$(SRCARCH)/include/arch (to get arch prefix). This is similar to linux arch specific "asm/*" headers but we are not abusing "asm" name and calling it what it is. This also helps to prevent name clashes (arch is not used in system headers or kernel exports). To bring objtool to this state the following things are done: 1. current top level tools/objtool/ headers are moved into include/objtool/ subdirectory, 2. arch specific headers, currently only arch/x86/include/ are moved into arch/x86/include/arch/ and were stripped of "arch_" suffix, 3. new -I$(srctree)/tools/objtool/include include path to make includes like <objtool/warn.h> possible, 4. rewriting file includes, 5. make git not to ignore include/objtool/ subdirectory. Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
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