kernel/linux.git/tools/objtool/elf.c, branch v6.19.11

objtool: Fix data alignment in elf_add_data()

2026-03-19T15:15:07+00:00

[ Upstream commit 356e4b2f5b80f757965f3f4d0219c81fca91b6f2 ] Any data added to a section needs to be aligned in accordance with the section's sh_addralign value. Particularly strings added to a .str1.8 section. Otherwise you may get some funky strings. Fixes: dd590d4d57eb ("objtool/klp: Introduce klp diff subcommand for diffing object files") Link: https://patch.msgid.link/d962fc0ca24fa0825cca8dad71932dccdd9312a9.1772681234.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf Signed-off-by: Sasha Levin

objtool: Replace custom macros in elf.c with shared ones

2026-01-27T16:20:41+00:00

The source file tools/objtool/elf.c defines the macros ALIGN_UP(), ALIGN_UP_POW2() and MAX(). These macros unnecessarily duplicate functionality already available under tools/include/, specifically ALIGN(), roundup_pow_of_two() and max(). More importantly, the definition of ALIGN_UP_POW2() is incorrect when the input is 1, as it results in a call to __builtin_clz(0), which produces an undefined result. This issue impacts the function elf_alloc_reloc(). When adding the first relocation to a section, the function allocates an undefined number of relocations. Replace the custom macros with the shared functionality to resolve these issues. Fixes: 2c05ca026218 ("objtool: Add elf_create_reloc() and elf_init_reloc()") Signed-off-by: Petr Pavlu Link: https://patch.msgid.link/20260126151356.3924887-1-petr.pavlu@suse.com Signed-off-by: Josh Poimboeuf

objtool: Remove second pass of .cold function correlation

2025-11-21T09:04:08+00:00

The .cold function parent/child correlation logic has two passes: one in read_symbols() and one in add_jump_destinations(). The second pass was added with commit cd77849a69cf ("objtool: Fix GCC 8 cold subfunction detection for aliased functions") to ensure that if the parent symbol had aliases then the canonical symbol was chosen as the parent. That solution was rather clunky, not to mention incomplete due to the existence of alternatives and switch tables. Now that we have sym->alias, the canonical alias fix can be done much simpler in the first pass, making the second pass obsolete. Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/bdab245a38000a5407f663a031f39e14c67a43d4.1763671318.git.jpoimboe@kernel.org

objtool: Return canonical symbol when aliases exist in symbol finding helpers

2025-11-21T09:04:08+00:00

When symbol alias ambiguity exists in the symbol finding helper functions, return the canonical sym->alias, as that's the one which gets used by validate_branch() and elsewhere. This doesn't fix any known issues, just makes the symbol alias behavior more robust. Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/450470a4897706af77453ad333e18af5ebab653c.1763671318.git.jpoimboe@kernel.org

objtool: Don't alias undefined symbols

2025-11-21T09:04:08+00:00

Objtool is mistakenly aliasing all undefined symbols. That's obviously wrong, though it has no consequence since objtool happens to only use sym->alias for defined symbols. Fix it regardless. Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/bc401173a7717757eee672fc1ca5a20451d77b86.1763671318.git.jpoimboe@kernel.org

objtool: Fix .cold function detection for duplicate symbols

2025-11-21T09:04:07+00:00

The objtool .cold child/parent correlation is done in two phases: first in elf_add_symbol() and later in add_jump_destinations(). The first phase is rather crude and can pick the wrong parent if there are duplicates with the same name. The second phase usually fixes that, but only if the parent has a direct jump to the child. It does *not* work if the only branch from the parent to the child is an alternative or jump table entry. Make the first phase more robust by looking for the parent in the same STT_FILE as the child. Fixes the following objtool warnings in an AutoFDO build with a large CLANG_AUTOFDO_PROFILE profile: vmlinux.o: warning: objtool: rdev_add_key() falls through to next function rdev_add_key.cold() vmlinux.o: warning: objtool: rdev_set_default_key() falls through to next function rdev_set_default_key.cold() Fixes: 13810435b9a7 ("objtool: Support GCC 8's cold subfunctions") Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/82c7b52e40efa75dd10e1c550cc75c1ce10ac2c9.1763671318.git.jpoimboe@kernel.org

objtool: Support Clang AUTOFDO .cold functions

2025-11-21T09:04:07+00:00

AutoFDO enables -fsplit-machine-functions which can move the cold parts of a function to a .cold symbol in a .text.split. section. Unlike GCC, the Clang .cold symbols are not marked STT_FUNC. This confuses objtool in several ways, resulting in warnings like the following: vmlinux.o: warning: objtool: apply_retpolines.cold+0xfc: unsupported instruction in callable function vmlinux.o: warning: objtool: machine_check_poll.cold+0x2e: unsupported instruction in callable function vmlinux.o: warning: objtool: free_deferred_objects.cold+0x1f: relocation to !ENDBR: free_deferred_objects.cold+0x26 vmlinux.o: warning: objtool: rpm_idle.cold+0xe0: relocation to !ENDBR: rpm_idle.cold+0xe7 vmlinux.o: warning: objtool: tcp_rcv_state_process.cold+0x1c: relocation to !ENDBR: tcp_rcv_state_process.cold+0x23 Fix it by marking the .cold symbols as STT_FUNC. Fixes: 2fd65f7afd5a ("AutoFDO: Enable machine function split optimization for AutoFDO") Closes: https://lore.kernel.org/20251103215244.2080638-2-xur@google.com Reported-by: Rong Xu Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: xur@google.com Tested-by: xur@google.com Link: https://patch.msgid.link/20a67326f04b2a361c031b56d58e8a803b3c5893.1763671318.git.jpoimboe@kernel.org

objtool: Remove unneeded semicolon

2025-10-30T15:29:46+00:00

Remove unnecessary semicolons reported by Coccinelle/coccicheck and the semantic patch at scripts/coccinelle/misc/semicolon.cocci. Signed-off-by: Chen Ni Link: https://patch.msgid.link/20251020020916.1070369-1-nichen@iscas.ac.cn Signed-off-by: Josh Poimboeuf

objtool: Add base objtool support for livepatch modules

2025-10-14T21:50:18+00:00

In preparation for klp-build, enable "classic" objtool to work on livepatch modules: - Avoid duplicate symbol/section warnings for prefix symbols and the .static_call_sites and __mcount_loc sections which may have already been extracted by klp diff. - Add __klp_funcs to the IBT function pointer section whitelist. - Prevent KLP symbols from getting incorrectly classified as cold subfunctions. Acked-by: Petr Mladek Tested-by: Joe Lawrence Signed-off-by: Josh Poimboeuf

objtool: Refactor prefix symbol creation code

2025-10-14T21:50:18+00:00

The prefix symbol creation code currently ignores all errors, presumably because some functions don't have the leading NOPs. Shuffle the code around a bit, improve the error handling and document why some errors are ignored. Acked-by: Petr Mladek Tested-by: Joe Lawrence Signed-off-by: Josh Poimboeuf