Josh Poimboeuf 2c2acca2ea 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: 13810435b9 ("objtool: Support GCC 8's cold subfunctions")
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/82c7b52e40efa75dd10e1c550cc75c1ce10ac2c9.1763671318.git.jpoimboe@kernel.org
2025-11-21 10:04:07 +01:00
2022-09-28 09:02:20 +02:00
2025-02-19 14:53:27 -07:00
2025-11-09 15:10:19 -08:00
2024-03-18 03:36:32 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
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Please read the Documentation/process/changes.rst file, as it contains the
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