From 2c2acca2eabf53a954ed5aacef987bbf909b9f12 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Thu, 20 Nov 2025 12:52:16 -0800 Subject: objtool: Fix .cold function detection for duplicate symbols 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 --- tools/objtool/include/objtool/elf.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'tools/objtool/include') diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h index 21d8b825fd8f..e12c516bd320 100644 --- a/tools/objtool/include/objtool/elf.h +++ b/tools/objtool/include/objtool/elf.h @@ -69,7 +69,7 @@ struct symbol { unsigned int idx, len; unsigned long offset; unsigned long __subtree_last; - struct symbol *pfunc, *cfunc, *alias; + struct symbol *pfunc, *cfunc, *alias, *file; unsigned char bind, type; u8 uaccess_safe : 1; u8 static_call_tramp : 1; -- cgit v1.2.3