mirror_ubuntu-kernels/tools/objtool
Rong Xu 18e885099f objtool: Fix unreachable instruction warnings for weak functions
In the presence of both weak and strong function definitions, the
linker drops the weak symbol in favor of a strong symbol, but
leaves the code in place. Code in ignore_unreachable_insn() has
some heuristics to suppress the warning, but it does not work when
-ffunction-sections is enabled.

Suppose function foo has both strong and weak definitions.
Case 1: The strong definition has an annotated section name,
like .init.text. Only the weak definition will be placed into
.text.foo. But since the section has no symbols, there will be no
"hole" in the section.

Case 2: Both sections are without an annotated section name.
Both will be placed into .text.foo section, but there will be only one
symbol (the strong one). If the weak code is before the strong code,
there is no "hole" as it fails to find the right-most symbol before
the offset.

The fix is to use the first node to compute the hole if hole.sym
is empty. If there is no symbol in the section, the first node
will be NULL, in which case, -1 is returned to skip the whole
section.

Co-developed-by: Han Shen <shenhan@google.com>
Signed-off-by: Han Shen <shenhan@google.com>
Signed-off-by: Rong Xu <xur@google.com>
Suggested-by: Sriraman Tallam <tmsriram@google.com>
Suggested-by: Krzysztof Pszeniczny <kpszeniczny@google.com>
Tested-by: Yonghong Song <yonghong.song@linux.dev>
Tested-by: Yabin Cui <yabinc@google.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2024-11-06 22:41:10 +09:00
..
arch objtool: Handle frame pointer related instructions 2024-09-17 22:23:09 +08:00
Documentation x86/alternatives, kvm: Fix a couple of CALLs without a frame pointer 2024-07-01 12:41:11 +02:00
include/objtool objtool: Handle frame pointer related instructions 2024-09-17 22:23:09 +08:00
.gitignore objtool: Install libsubcmd in build 2023-01-30 16:27:46 -08:00
Build objtool: Install libsubcmd in build 2023-01-30 16:27:46 -08:00
builtin-check.c objtool: Use "action" in error message to be consistent with help 2024-07-02 23:40:24 -07:00
check.c kbuild: Add AutoFDO support for Clang build 2024-11-06 22:41:09 +09:00
elf.c objtool: Fix unreachable instruction warnings for weak functions 2024-11-06 22:41:10 +09:00
Makefile objtool/LoongArch: Enable orc to be built 2024-03-11 22:23:47 +08:00
noreturns.h objtool/rust: list noreturn Rust functions 2024-08-18 23:34:37 +02:00
objtool.c objtool: Propagate early errors 2023-10-05 17:01:11 -07:00
orc_dump.c objtool/x86: Separate arch-specific and generic parts 2024-03-11 22:23:47 +08:00
orc_gen.c objtool/x86: Separate arch-specific and generic parts 2024-03-11 22:23:47 +08:00
special.c x86/alternatives: Add nested alternatives macros 2024-06-11 17:13:08 +02:00
sync-check.sh objtool: Add objtool_types.h 2023-03-23 23:18:56 +01:00
weak.c objtool: Ditch subcommands 2022-04-22 12:32:01 +02:00