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2025-05-14objtool: Speed up SHT_GROUP reindexingJosh Poimboeuf1-0/+1
After elf_update_group_sh_info() was introduced, a prototype version of "objtool klp diff" went from taking ~1s to several minutes, due to looping almost endlessly in elf_update_group_sh_info() while creating thousands of local symbols in a file with thousands of sections. Dramatically improve the performance by marking all symbols' correlated SHT_GROUP sections while reading the object. That way there's no need to search for it every time a symbol gets reindexed. Fixes: 2cb291596e2c ("objtool: Fix up st_info in COMDAT group section") Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Rong Xu <xur@google.com> Link: https://lkml.kernel.org/r/2a33e583c87e3283706f346f9d59aac20653b7fd.1746662991.git.jpoimboe@kernel.org
2025-04-08objtool: Split INSN_CONTEXT_SWITCH into INSN_SYSCALL and INSN_SYSRETJosh Poimboeuf1-1/+2
INSN_CONTEXT_SWITCH is ambiguous. It can represent both call semantics (SYSCALL, SYSENTER) and return semantics (SYSRET, IRET, RETS, RETU). Those differ significantly: calls preserve control flow whereas returns terminate it. Objtool uses an arbitrary rule for INSN_CONTEXT_SWITCH that almost works by accident: if in a function, keep going; otherwise stop. It should instead be based on the semantics of the underlying instruction. In preparation for improving that, split INSN_CONTEXT_SWITCH into INSN_SYCALL and INSN_SYSRET. No functional change. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/19a76c74d2c051d3bc9a775823cafc65ad267a7a.1744095216.git.jpoimboe@kernel.org
2025-04-01objtool: Change "warning:" to "error: " for fatal errorsJosh Poimboeuf1-16/+35
This is similar to GCC's behavior and makes it more obvious why the build failed. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/0ea76f4b0e7a370711ed9f75fd0792bb5979c2bf.1743481539.git.jpoimboe@kernel.org
2025-04-01Revert "objtool: Increase per-function WARN_FUNC() rate limit"Josh Poimboeuf2-12/+4
This reverts commit 0a7fb6f07e3ad497d31ae9a2082d2cacab43d54a. The "skipping duplicate warnings" warning is technically not an actual warning, which can cause confusion. This feature isn't all that useful anyway. It's exceedingly rare for a function to have more than one unrelated warning. Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/e5abe5e858acf1a9207a5dfa0f37d17ac9dca872.1743481539.git.jpoimboe@kernel.org
2025-03-25objtool: Reduce CONFIG_OBJTOOL_WERROR verbosityJosh Poimboeuf1-2/+4
Remove the following from CONFIG_OBJTOOL_WERROR: * backtrace * "upgraded warnings to errors" message * cmdline args This makes the default output less cluttered and makes it easier to spot the actual warnings. Note the above options are still are available with --verbose or OBJTOOL_VERBOSE=1. Also, do the cmdline arg printing on all warnings, regardless of werror. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/d61df69f64b396fa6b2a1335588aad7a34ea9e71.1742852846.git.jpoimboe@kernel.org
2025-03-25objtool: Improve error handlingJosh Poimboeuf2-5/+10
Fix some error handling issues, improve error messages, properly distinguish betwee errors and warnings, and generally try to make all the error handling more consistent. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/3094bb4463dad29b6bd1bea03848d1571ace771c.1742852846.git.jpoimboe@kernel.org
2025-03-25objtool: Fix X86_FEATURE_SMAP alternative handlingJosh Poimboeuf2-4/+3
For X86_FEATURE_SMAP alternatives which replace NOP with STAC or CLAC, uaccess validation skips the NOP branch to avoid following impossible code paths, e.g. where a STAC would be patched but a CLAC wouldn't. However, it's not safe to assume an X86_FEATURE_SMAP alternative is patching STAC/CLAC. There can be other alternatives, like static_cpu_has(), where both branches need to be validated. Fix that by repurposing ANNOTATE_IGNORE_ALTERNATIVE for skipping either original instructions or new ones. This is a more generic approach which enables the removal of the feature checking hacks and the insn->ignore bit. Fixes the following warnings: arch/x86/mm/fault.o: warning: objtool: do_user_addr_fault+0x8ec: __stack_chk_fail() missing __noreturn in .c/.h or NORETURN() in noreturns.h arch/x86/mm/fault.o: warning: objtool: do_user_addr_fault+0x8f1: unreachable instruction [ mingo: Fix up conflicts with recent x86 changes. ] Fixes: ea24213d8088 ("objtool: Add UACCESS validation") Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/de0621ca242130156a55d5d74fed86994dfa4c9c.1742852846.git.jpoimboe@kernel.org Closes: https://lore.kernel.org/oe-kbuild-all/202503181736.zkZUBv4N-lkp@intel.com/
2025-03-25objtool: Ignore entire functions rather than instructionsJosh Poimboeuf1-0/+1
STACK_FRAME_NON_STANDARD applies to functions. Use a function-specific ignore attribute in preparation for getting rid of insn->ignore. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/4af13376567f83331a9372ae2bb25e11a3d0f055.1742852846.git.jpoimboe@kernel.org
2025-03-25objtool: Fix detection of consecutive jump tables on Clang 20Josh Poimboeuf1-1/+26
The jump table detection code assumes jump tables are in the same order as their corresponding indirect branches. That's apparently not always true with Clang 20. Fix that by changing how multiple jump tables are detected. In the first detection pass, mark the beginning of each jump table so the second pass can tell where one ends and the next one begins. Fixes the following warnings: vmlinux.o: warning: objtool: SiS_GetCRT2Ptr+0x1ad: stack state mismatch: cfa1=4+8 cfa2=5+16 sound/core/seq/snd-seq.o: warning: objtool: cc_ev_to_ump_midi2+0x589: return with modified stack frame Fixes: be2f0b1e1264 ("objtool: Get rid of reloc->jump_table_start") Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/141752fff614eab962dba6bdfaa54aa67ff03bba.1742852846.git.jpoimboe@kernel.org Closes: https://lore.kernel.org/oe-kbuild-all/202503171547.LlCTJLQL-lkp@intel.com/ Closes: https://lore.kernel.org/oe-kbuild-all/202503200535.J3hAvcjw-lkp@intel.com/
2025-03-17objtool: Create backup on error and print argsJosh Poimboeuf1-1/+0
Recreating objtool errors can be a manual process. Kbuild removes the object, so it has to be compiled or linked again before running objtool. Then the objtool args need to be reversed engineered. Make that all easier by automatically making a backup of the object file on error, and print a modified version of the args which can be used to recreate. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/7571e30636359b3e173ce6e122419452bb31882f.1741975349.git.jpoimboe@kernel.org
2025-03-17objtool: Change "warning:" to "error:" for --WerrorJosh Poimboeuf1-2/+4
This is similar to GCC's behavior and makes it more obvious why the build failed. Suggested-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Brendan Jackman <jackmanb@google.com> Link: https://lore.kernel.org/r/56f0565b15b4b4caa9a08953fa9c679dfa973514.1741975349.git.jpoimboe@kernel.org
2025-03-17objtool: Add --Werror optionJosh Poimboeuf1-0/+1
Any objtool warning has the potential of reflecting (or triggering) a major bug in the kernel or compiler which could result in crashing the kernel or breaking the livepatch consistency model. In preparation for failing the build on objtool errors/warnings, add a new --Werror option. [ jpoimboe: commit log, comments, error out on fatal errors too ] Co-developed-by: Brendan Jackman <jackmanb@google.com> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/e423ea4ec297f510a108aa6c78b52b9fe30fa8c1.1741975349.git.jpoimboe@kernel.org
2025-03-17objtool: Add --output optionJosh Poimboeuf1-0/+1
Add option to allow writing the changed binary to a separate file rather than changing it in place. Libelf makes this suprisingly hard, so take the easy way out and just copy the file before editing it. Also steal the -o short option from --orc. Nobody will notice ;-) Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/0da308d42d82b3bbed16a31a72d6bde52afcd6bd.1741975349.git.jpoimboe@kernel.org
2025-03-17objtool: Increase per-function WARN_FUNC() rate limitJosh Poimboeuf2-4/+12
Increase the per-function WARN_FUNC() rate limit from 1 to 2. If the number of warnings for a given function goes beyond 2, print "skipping duplicate warning(s)". This helps root out additional warnings in a function that might be hiding behind the first one. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/aec318d66c037a51c9f376d6fb0e8ff32812a037.1741975349.git.jpoimboe@kernel.org
2025-03-12objtool: Handle PC relative relocation typeTiezhu Yang1-0/+1
For the most part, an absolute relocation type is used for rodata. In the case of STT_SECTION, reloc->sym->offset is always zero, for the other symbol types, reloc_addend(reloc) is always zero, thus it can use a simple statement "reloc->sym->offset + reloc_addend(reloc)" to obtain the symbol offset for various symbol types. When compiling on LoongArch, there exist PC relative relocation types for rodata, it needs to calculate the symbol offset with "S + A - PC" according to the spec of "ELF for the LoongArch Architecture". If there is only one jump table in the rodata, the "PC" is the entry address which is equal with the value of reloc_offset(reloc), at this time, reloc_offset(table) is 0. If there are many jump tables in the rodata, the "PC" is the offset of the jump table's base address which is equal with the value of reloc_offset(reloc) - reloc_offset(table). So for LoongArch, if the relocation type is PC relative, it can use a statement "reloc_offset(reloc) - reloc_offset(table)" to get the "PC" value when calculating the symbol offset with "S + A - PC" for one or many jump tables in the rodata. Add an arch-specific function arch_jump_table_sym_offset() to assign the symbol offset, for the most part that is an absolute relocation, the default value is "reloc->sym->offset + reloc_addend(reloc)" in the weak definition, it can be overridden by each architecture that has different requirements. Link: https://github.com/loongson/la-abi-specs/blob/release/laelf.adoc Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> Link: https://lore.kernel.org/r/20250211115016.26913-4-yangtiezhu@loongson.cn Acked-by: Huacai Chen <chenhuacai@loongson.cn> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2025-03-12objtool: Handle different entry size of rodataTiezhu Yang1-0/+2
In the most cases, the entry size of rodata is 8 bytes because the relocation type is 64 bit. There are also 32 bit relocation types, the entry size of rodata should be 4 bytes in this case. Add an arch-specific function arch_reloc_size() to assign the entry size of rodata for x86, powerpc and LoongArch. Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> Link: https://lore.kernel.org/r/20250211115016.26913-3-yangtiezhu@loongson.cn Acked-by: Huacai Chen <chenhuacai@loongson.cn> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2025-02-25objtool: Fix C jump table annotations for ClangArd Biesheuvel1-1/+1
A C jump table (such as the one used by the BPF interpreter) is a const global array of absolute code addresses, and this means that the actual values in the table may not be known until the kernel is booted (e.g., when using KASLR or when the kernel VA space is sized dynamically). When using PIE codegen, the compiler will default to placing such const global objects in .data.rel.ro (which is annotated as writable), rather than .rodata (which is annotated as read-only). As C jump tables are explicitly emitted into .rodata, this used to result in warnings for LoongArch builds (which uses PIE codegen for the entire kernel) like Warning: setting incorrect section attributes for .rodata..c_jump_table due to the fact that the explicitly specified .rodata section inherited the read-write annotation that the compiler uses for such objects when using PIE codegen. This warning was suppressed by explicitly adding the read-only annotation to the __attribute__((section(""))) string, by commit c5b1184decc8 ("compiler.h: specify correct attribute for .rodata..c_jump_table") Unfortunately, this hack does not work on Clang's integrated assembler, which happily interprets the appended section type and permission specifiers as part of the section name, which therefore no longer matches the hard-coded pattern '.rodata..c_jump_table' that objtool expects, causing it to emit a warning kernel/bpf/core.o: warning: objtool: ___bpf_prog_run+0x20: sibling call from callable instruction with modified stack frame Work around this, by emitting C jump tables into .data.rel.ro instead, which is treated as .rodata by the linker script for all builds, not just PIE based ones. Fixes: c5b1184decc8 ("compiler.h: specify correct attribute for .rodata..c_jump_table") Tested-by: Tiezhu Yang <yangtiezhu@loongson.cn> # on LoongArch Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Link: https://lore.kernel.org/r/20250221135704.431269-6-ardb+git@google.com Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2024-12-02objtool: Allow arch code to discover jump table sizeArd Biesheuvel2-2/+6
In preparation for adding support for annotated jump tables, where ELF relocations and symbols are used to describe the locations of jump tables in the executable, refactor the jump table discovery logic so the table size can be returned from arch_find_switch_table(). Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20241011170847.334429-12-ardb+git@google.com
2024-10-17objtool: Detect non-relocated text referencesJosh Poimboeuf1-0/+1
When kernel IBT is enabled, objtool detects all text references in order to determine which functions can be indirectly branched to. In text, such references look like one of the following: mov $0x0,%rax R_X86_64_32S .init.text+0x7e0a0 lea 0x0(%rip),%rax R_X86_64_PC32 autoremove_wake_function-0x4 Either way the function pointer is denoted by a relocation, so objtool just reads that. However there are some "lea xxx(%rip)" cases which don't use relocations because they're referencing code in the same translation unit. Objtool doesn't have visibility to those. The only currently known instances of that are a few hand-coded asm text references which don't actually need ENDBR. So it's not actually a problem at the moment. However if we enable -fpie, the compiler would start generating them and there would definitely be bugs in the IBT sealing. Detect non-relocated text references and handle them appropriately. [ Note: I removed the manual static_call_tramp check -- that should already be handled by the noendbr check. ] Reported-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Ard Biesheuvel <ardb@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2024-09-17objtool: Handle frame pointer related instructionsTiezhu Yang1-0/+1
After commit a0f7085f6a63 ("LoongArch: Add RANDOMIZE_KSTACK_OFFSET support"), there are three new instructions "addi.d $fp, $sp, 32", "sub.d $sp, $sp, $t0" and "addi.d $sp, $fp, -32" for the secondary stack in do_syscall(), then there is a objtool warning "return with modified stack frame" and no handle_syscall() which is the previous frame of do_syscall() in the call trace when executing the command "echo l > /proc/sysrq-trigger". objdump shows something like this: 0000000000000000 <do_syscall>: 0: 02ff8063 addi.d $sp, $sp, -32 4: 29c04076 st.d $fp, $sp, 16 8: 29c02077 st.d $s0, $sp, 8 c: 29c06061 st.d $ra, $sp, 24 10: 02c08076 addi.d $fp, $sp, 32 ... 74: 0011b063 sub.d $sp, $sp, $t0 ... a8: 4c000181 jirl $ra, $t0, 0 ... dc: 02ff82c3 addi.d $sp, $fp, -32 e0: 28c06061 ld.d $ra, $sp, 24 e4: 28c04076 ld.d $fp, $sp, 16 e8: 28c02077 ld.d $s0, $sp, 8 ec: 02c08063 addi.d $sp, $sp, 32 f0: 4c000020 jirl $zero, $ra, 0 The instruction "sub.d $sp, $sp, $t0" changes the stack bottom and the new stack size is a random value, in order to find the return address of do_syscall() which is stored in the original stack frame after executing "jirl $ra, $t0, 0", it should use fp which points to the original stack top. At the beginning, the thought is tended to decode the secondary stack instruction "sub.d $sp, $sp, $t0" and set it as a label, then check this label for the two frame pointer instructions to change the cfa base and cfa offset during the period of secondary stack in update_cfi_state(). This is valid for GCC but invalid for Clang due to there are different secondary stack instructions for ClangBuiltLinux on LoongArch, something like this: 0000000000000000 <do_syscall>: ... 88: 00119064 sub.d $a0, $sp, $a0 8c: 00150083 or $sp, $a0, $zero ... Actually, it equals to a single instruction "sub.d $sp, $sp, $a0", but there is no proper condition to check it as a label like GCC, and so the beginning thought is not a good way. Essentially, there are two special frame pointer instructions which are "addi.d $fp, $sp, imm" and "addi.d $sp, $fp, imm", the first one points fp to the original stack top and the second one restores the original stack bottom from fp. Based on the above analysis, in order to avoid adding an arch-specific update_cfi_state(), we just add a member "frame_pointer" in the "struct symbol" as a label to avoid affecting the current normal case, then set it as true only if there is "addi.d $sp, $fp, imm". The last is to check this label for the two frame pointer instructions to change the cfa base and cfa offset in update_cfi_state(). Tested with the following two configs: (1) CONFIG_RANDOMIZE_KSTACK_OFFSET=y && CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT=n (2) CONFIG_RANDOMIZE_KSTACK_OFFSET=y && CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT=y By the way, there is no effect for x86 with this patch, tested on the x86 machine with Fedora 40 system. Cc: stable@vger.kernel.org # 6.9+ Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2024-03-11objtool: Check local label in add_dead_ends()Tiezhu Yang1-0/+1
When update the latest upstream gcc and binutils, it generates more objtool warnings on LoongArch, like this: init/main.o: warning: objtool: unexpected relocation symbol type in .rela.discard.unreachable We can see that the reloc sym name is local label instead of section in relocation section '.rela.discard.unreachable', in this case, the reloc sym type is STT_NOTYPE instead of STT_SECTION. As suggested by Peter Zijlstra, we add a "local_label" member in struct symbol, then set it as true if symbol type is STT_NOTYPE and symbol name starts with ".L" string in classify_symbols(). Let's check reloc->sym->local_label to not return -1 in add_dead_ends(), and also use reloc->sym->offset instead of reloc addend which is 0 to find the corresponding instruction. At the same time, let's replace the variable "addend" with "offset" to reflect the reality. Here are some detailed info: [fedora@linux 6.8.test]$ gcc --version gcc (GCC) 14.0.1 20240129 (experimental) [fedora@linux 6.8.test]$ as --version GNU assembler (GNU Binutils) 2.42.50.20240129 [fedora@linux 6.8.test]$ readelf -r init/main.o | grep -A 2 "rela.discard.unreachable" Relocation section '.rela.discard.unreachable' at offset 0x6028 contains 1 entry: Offset Info Type Sym. Value Sym. Name + Addend 000000000000 00d900000063 R_LARCH_32_PCREL 00000000000002c4 .L500^B1 + 0 Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2024-03-11objtool/x86: Separate arch-specific and generic partsTiezhu Yang1-0/+14
Move init_orc_entry(), write_orc_entry(), reg_name(), orc_type_name() and print_reg() from generic orc_gen.c and orc_dump.c to arch-specific orc.c, then introduce a new function orc_print_dump() to print info. This is preparation for later patch, no functionality change. Co-developed-by: Jinyang He <hejinyang@loongson.cn> Signed-off-by: Jinyang He <hejinyang@loongson.cn> Co-developed-by: Youling Tang <tangyouling@loongson.cn> Signed-off-by: Youling Tang <tangyouling@loongson.cn> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2023-08-16objtool/x86: Fix SRSO messPeter Zijlstra2-0/+2
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
2023-06-07objtool: Get rid of reloc->rel[a]Josh Poimboeuf1-12/+82
Get the relocation entry info from the underlying rsec->data. With allyesconfig + CONFIG_DEBUG_INFO: - Before: peak heap memory consumption: 35.12G - After: peak heap memory consumption: 29.93G Link: https://lore.kernel.org/r/2be32323de6d8cc73179ee0ff14b71f4e7cefaa0.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Shrink elf hash nodesJosh Poimboeuf1-10/+14
Instead of using hlist for the 'struct elf' hashes, use a custom single-linked list scheme. With allyesconfig + CONFIG_DEBUG_INFO: - Before: peak heap memory consumption: 36.89G - After: peak heap memory consumption: 35.12G Link: https://lore.kernel.org/r/6e8cd305ed22e743c30d6e72cfdc1be20fb94cd4.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Shrink reloc->sym_reloc_entryJosh Poimboeuf1-2/+2
Convert it to a singly-linked list. With allyesconfig + CONFIG_DEBUG_INFO: - Before: peak heap memory consumption: 38.64G - After: peak heap memory consumption: 36.89G Link: https://lore.kernel.org/r/a51f0a6f9bbf2494d5a3a449807307e78a940988.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Get rid of reloc->jump_table_startJosh Poimboeuf1-1/+0
Rework the jump table logic slightly so 'jump_table_start' is no longer needed. With allyesconfig + CONFIG_DEBUG_INFO: - Before: peak heap memory consumption: 40.37G - After: peak heap memory consumption: 38.64G Link: https://lore.kernel.org/r/e1602ed8a6171ada3cfac0bd8449892ec82bd188.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Get rid of reloc->addendJosh Poimboeuf1-1/+5
Get the addend from the embedded GElf_Rel[a] struct. With allyesconfig + CONFIG_DEBUG_INFO: - Before: peak heap memory consumption: 42.10G - After: peak heap memory consumption: 40.37G Link: https://lore.kernel.org/r/ad2354f95d9ddd86094e3f7687acfa0750657784.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Get rid of reloc->typeJosh Poimboeuf1-1/+10
Get the type from the embedded GElf_Rel[a] struct. Link: https://lore.kernel.org/r/d1c1f8da31e4f052a2478aea585fcf355cacc53a.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Get rid of reloc->offsetJosh Poimboeuf1-2/+6
Get the offset from the embedded GElf_Rel[a] struct. With allyesconfig + CONFIG_DEBUG_INFO: - Before: peak heap memory consumption: 43.83G - After: peak heap memory consumption: 42.10G Link: https://lore.kernel.org/r/2b9ec01178baa346a99522710bf2e82159412e3a.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Get rid of reloc->idxJosh Poimboeuf1-3/+7
Use the array offset to calculate the reloc index. With allyesconfig + CONFIG_DEBUG_INFO: - Before: peak heap memory consumption: 45.56G - After: peak heap memory consumption: 43.83G Link: https://lore.kernel.org/r/7351d2ebad0519027db14a32f6204af84952574a.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Get rid of reloc->listJosh Poimboeuf1-5/+13
Now that all relocs are allocated in an array, the linked list is no longer needed. With allyesconfig + CONFIG_DEBUG_INFO: - Before: peak heap memory consumption: 49.02G - After: peak heap memory consumption: 45.56G Link: https://lore.kernel.org/r/71e7a2c017dbc46bb497857ec97d67214f832d10.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Add for_each_reloc()Josh Poimboeuf1-0/+6
Link: https://lore.kernel.org/r/dbfcb1037d8b958e52d097b67829c4c6811c24bb.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Add elf_create_section_pair()Josh Poimboeuf1-6/+27
When creating an annotation section, allocate the reloc section data at the beginning. This simplifies the data model a bit and also saves memory due to the removal of malloc() in elf_rebuild_reloc_section(). With allyesconfig + CONFIG_DEBUG_INFO: - Before: peak heap memory consumption: 53.49G - After: peak heap memory consumption: 49.02G Link: https://lore.kernel.org/r/048e908f3ede9b66c15e44672b6dda992b1dae3e.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Add mark_sec_changed()Josh Poimboeuf1-1/+13
Ensure elf->changed always gets set when sec->changed gets set. Link: https://lore.kernel.org/r/9a810a8d2e28af6ba07325362d0eb4703bb09d3a.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Fix reloc_hash sizeJosh Poimboeuf1-1/+7
With CONFIG_DEBUG_INFO, DWARF creates a lot of relocations and reloc_hash is woefully undersized, which can affect performance significantly. Fix that. Link: https://lore.kernel.org/r/38ef60dc8043270bf3b9dfd139ae2a30ca3f75cc.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Consolidate rel/rela handlingJosh Poimboeuf1-5/+8
The GElf_Rel[a] structs have more similarities than differences. It's safe to hard-code the assumptions about their shared fields as they will never change. Consolidate their handling where possible, getting rid of duplicated code. Also, at least for now we only ever create rela sections, so simplify the relocation creation code to be rela-only. Link: https://lore.kernel.org/r/dcabf6df400ca500ea929f1e4284f5e5ec0b27c8.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Improve reloc namingJosh Poimboeuf1-1/+1
- The term "reloc" is overloaded to mean both "an instance of struct reloc" and "a reloc section". Change the latter to "rsec". - For variable names, use "sec" for regular sections and "rsec" for rela sections to prevent them getting mixed up. - For struct reloc variables, use "reloc" instead of "rel" everywhere for consistency. Link: https://lore.kernel.org/r/8b790e403df46f445c21003e7893b8f53b99a6f3.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Remove flags argument from elf_create_section()Josh Poimboeuf1-1/+1
Simplify the elf_create_section() interface a bit by removing the flags argument. Most callers don't care about changing the section header flags. If needed, they can be modified afterwards, just like any other section header field. Link: https://lore.kernel.org/r/515235d9cf62637a14bee37bfa9169ef20065471.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Tidy elf.hJosh Poimboeuf1-49/+47
Reorganize elf.h a bit: - Move the prototypes higher up so they can be used by the inline functions. - Move hash-related code to the bottom. - Remove the unused ELF_HASH_BITS macro. No functional changes. Link: https://lore.kernel.org/r/b1490ed85951868219a6ece177a7cd30a6454d66.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Allow stack operations in UNWIND_HINT_UNDEFINED regionsJosh Poimboeuf1-0/+1
If the code specified UNWIND_HINT_UNDEFINED, skip the "undefined stack state" warning due to a stack operation. Just ignore the stack op and continue to propagate the undefined state. Link: https://lore.kernel.org/r/820c5b433f17c84e8761fb7465a8d319d706b1cf.1685981486.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-05-16objtool: Include backtrace in verbose modeJosh Poimboeuf1-6/+8
Include backtrace in verbose mode. This makes it easy to gather all the information needed for diagnosing objtool warnings. Reviewed-by: Miroslav Benes <mbenes@suse.cz> Link: https://lore.kernel.org/r/c255224fabcf7e64bac232fec1c77c9fc2d7d7ab.1681853186.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-05-16objtool: Add verbose option for disassembling affected functionsJosh Poimboeuf1-0/+1
When a warning is associated with a function, add an option to disassemble that function. This makes it easier for reporters to submit the information needed to diagnose objtool warnings. Reviewed-by: Miroslav Benes <mbenes@suse.cz> Link: https://lore.kernel.org/r/dd0fe13428ede186f09c74059a8001f4adcea5fc.1681853186.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-05-16objtool: Limit unreachable warnings to once per functionJosh Poimboeuf2-1/+7
Unreachable instruction warnings are limited to once per object file. That no longer makes sense for vmlinux validation, which might have more unreachable instructions lurking in other places. Change it to once per function. Note this affects some other (much rarer) non-fatal warnings as well. In general I think one-warning-per-function makes sense, as related warnings can accumulate quickly and we want to eventually get back to failing the build with -Werror anyway. Reviewed-by: Miroslav Benes <mbenes@suse.cz> Link: https://lore.kernel.org/r/9d38f881bfc34e031c74e4e90064ccb3e49f599a.1681853186.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-04-14objtool: Add symbol iteration helpersJosh Poimboeuf1-0/+9
Add [sec_]for_each_sym() and use them. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/59023e5886ab125aa30702e633be7732b1acaa7e.1681325924.git.jpoimboe@kernel.org
2023-04-14objtool: Add WARN_INSN()Josh Poimboeuf1-0/+5
It's easier to use and also gives easy access to the instruction's containing function, which is useful for printing that function's symbol. It will also be useful in the future for rate-limiting and disassembly of warned functions. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/2eaa3155c90fba683d8723599f279c46025b75f3.1681325924.git.jpoimboe@kernel.org
2023-03-23x86,objtool: Separate unret validation from unwind hintsJosh Poimboeuf1-2/+2
The ENTRY unwind hint type is serving double duty as both an empty unwind hint and an unret validation annotation. Unret validation is unrelated to unwinding. Separate it out into its own annotation. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/ff7448d492ea21b86d8a90264b105fbd0d751077.1677683419.git.jpoimboe@kernel.org
2023-02-23objtool: Fix ORC 'signal' propagationJosh Poimboeuf1-0/+1
There have been some recently reported ORC unwinder warnings like: WARNING: can't access registers at entry_SYSCALL_64_after_hwframe+0x63/0xcd WARNING: stack going in the wrong direction? at __sys_setsockopt+0x2c6/0x5b0 net/socket.c:2271 And a KASAN warning: BUG: KASAN: stack-out-of-bounds in unwind_next_frame (arch/x86/include/asm/ptrace.h:136 arch/x86/kernel/unwind_orc.c:455) It turns out the 'signal' bit isn't getting propagated from the unwind hints to the ORC entries, making the unwinder confused at times. Fixes: ffb1b4a41016 ("x86/unwind/orc: Add 'signal' field to ORC metadata") Reported-by: kernel test robot <oliver.sang@intel.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/97eef9db60cd86d376a9a40d49d77bb67a8f6526.1676579666.git.jpoimboe@kernel.org
2023-02-23objtool: Remove instruction::listPeter Zijlstra2-25/+27
Replace the instruction::list by allocating instructions in arrays of 256 entries and stringing them together by (amortized) find_insn(). This shrinks instruction by 16 bytes and brings it down to 128. 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) --- */ - long unsigned int immediate; /* 64 8 */ - unsigned int len; /* 72 4 */ - u8 type; /* 76 1 */ - - /* Bitfield combined with previous fields */ + struct hlist_node hash; /* 0 16 */ + struct list_head call_node; /* 16 16 */ + struct section * sec; /* 32 8 */ + long unsigned int offset; /* 40 8 */ + long unsigned int immediate; /* 48 8 */ + u8 len; /* 56 1 */ + u8 prev_len; /* 57 1 */ + u8 type; /* 58 1 */ + s8 instr; /* 59 1 */ + u32 idx:8; /* 60: 0 4 */ + u32 dead_end:1; /* 60: 8 4 */ + u32 ignore:1; /* 60: 9 4 */ + u32 ignore_alts:1; /* 60:10 4 */ + u32 hint:1; /* 60:11 4 */ + u32 save:1; /* 60:12 4 */ + u32 restore:1; /* 60:13 4 */ + u32 retpoline_safe:1; /* 60:14 4 */ + u32 noendbr:1; /* 60:15 4 */ + u32 entry:1; /* 60:16 4 */ + u32 visited:4; /* 60:17 4 */ + u32 no_reloc:1; /* 60:21 4 */ - u16 dead_end:1; /* 76: 8 2 */ - u16 ignore:1; /* 76: 9 2 */ - u16 ignore_alts:1; /* 76:10 2 */ - u16 hint:1; /* 76:11 2 */ - u16 save:1; /* 76:12 2 */ - u16 restore:1; /* 76:13 2 */ - u16 retpoline_safe:1; /* 76:14 2 */ - u16 noendbr:1; /* 76:15 2 */ - u16 entry:1; /* 78: 0 2 */ - u16 visited:4; /* 78: 1 2 */ - u16 no_reloc:1; /* 78: 5 2 */ + /* XXX 10 bits hole, try to pack */ - /* XXX 2 bits hole, try to pack */ - /* Bitfield combined with next fields */ - - s8 instr; /* 79 1 */ - struct alt_group * alt_group; /* 80 8 */ - struct instruction * jump_dest; /* 88 8 */ - struct instruction * first_jump_src; /* 96 8 */ + /* --- cacheline 1 boundary (64 bytes) --- */ + struct alt_group * alt_group; /* 64 8 */ + struct instruction * jump_dest; /* 72 8 */ + struct instruction * first_jump_src; /* 80 8 */ union { - struct symbol * _call_dest; /* 104 8 */ - struct reloc * _jump_table; /* 104 8 */ - }; /* 104 8 */ - struct alternative * alts; /* 112 8 */ - struct symbol * sym; /* 120 8 */ - /* --- cacheline 2 boundary (128 bytes) --- */ - struct stack_op * stack_ops; /* 128 8 */ - struct cfi_state * cfi; /* 136 8 */ + struct symbol * _call_dest; /* 88 8 */ + struct reloc * _jump_table; /* 88 8 */ + }; /* 88 8 */ + struct alternative * alts; /* 96 8 */ + struct symbol * sym; /* 104 8 */ + struct stack_op * stack_ops; /* 112 8 */ + struct cfi_state * cfi; /* 120 8 */ - /* size: 144, cachelines: 3, members: 28 */ - /* sum members: 142 */ - /* sum bitfield members: 14 bits, bit holes: 1, sum bit holes: 2 bits */ - /* last cacheline: 16 bytes */ + /* size: 128, cachelines: 2, members: 29 */ + /* sum members: 124 */ + /* sum bitfield members: 22 bits, bit holes: 1, sum bit holes: 10 bits */ }; pre: 5:38.18 real, 213.25 user, 124.90 sys, 23449040 mem post: 5:03.34 real, 210.75 user, 88.80 sys, 20241232 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/20230208172245.851307606@infradead.org
2023-02-23objtool: Union instruction::{call_dest,jump_table}Peter Zijlstra1-2/+4
The instruction call_dest and jump_table members can never be used at the same time, their usage depends on type. 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) --- */ long unsigned int immediate; /* 64 8 */ unsigned int len; /* 72 4 */ u8 type; /* 76 1 */ /* Bitfield combined with previous fields */ u16 dead_end:1; /* 76: 8 2 */ u16 ignore:1; /* 76: 9 2 */ u16 ignore_alts:1; /* 76:10 2 */ u16 hint:1; /* 76:11 2 */ u16 save:1; /* 76:12 2 */ u16 restore:1; /* 76:13 2 */ u16 retpoline_safe:1; /* 76:14 2 */ u16 noendbr:1; /* 76:15 2 */ u16 entry:1; /* 78: 0 2 */ u16 visited:4; /* 78: 1 2 */ u16 no_reloc:1; /* 78: 5 2 */ /* XXX 2 bits hole, try to pack */ /* Bitfield combined with next fields */ s8 instr; /* 79 1 */ struct alt_group * alt_group; /* 80 8 */ - struct symbol * call_dest; /* 88 8 */ - struct instruction * jump_dest; /* 96 8 */ - struct instruction * first_jump_src; /* 104 8 */ - struct reloc * jump_table; /* 112 8 */ - struct alternative * alts; /* 120 8 */ + struct instruction * jump_dest; /* 88 8 */ + struct instruction * first_jump_src; /* 96 8 */ + union { + struct symbol * _call_dest; /* 104 8 */ + struct reloc * _jump_table; /* 104 8 */ + }; /* 104 8 */ + struct alternative * alts; /* 112 8 */ + struct symbol * sym; /* 120 8 */ /* --- cacheline 2 boundary (128 bytes) --- */ - struct symbol * sym; /* 128 8 */ - struct stack_op * stack_ops; /* 136 8 */ - struct cfi_state * cfi; /* 144 8 */ + struct stack_op * stack_ops; /* 128 8 */ + struct cfi_state * cfi; /* 136 8 */ - /* size: 152, cachelines: 3, members: 29 */ - /* sum members: 150 */ + /* size: 144, cachelines: 3, members: 28 */ + /* sum members: 142 */ /* sum bitfield members: 14 bits, bit holes: 1, sum bit holes: 2 bits */ - /* last cacheline: 24 bytes */ + /* last cacheline: 16 bytes */ }; pre: 5:39.35 real, 215.58 user, 123.69 sys, 23448736 mem post: 5:38.18 real, 213.25 user, 124.90 sys, 23449040 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/20230208172245.640914454@infradead.org
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