diff options
| author | Tiezhu Yang <yangtiezhu@loongson.cn> | 2024-09-24 14:27:10 +0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-09-26 14:01:44 -0700 |
| commit | c5b1184decc819756ae549ba54c63b6790c4ddfd (patch) | |
| tree | 8c6eb6bac9b1ebbe7c3985fe67370fbc975f9e01 /include | |
| parent | 6901cf55de224b2ca51a5675b86c8ef241ae640c (diff) | |
compiler.h: specify correct attribute for .rodata..c_jump_table
Currently, there is an assembler message when generating kernel/bpf/core.o
under CONFIG_OBJTOOL with LoongArch compiler toolchain:
Warning: setting incorrect section attributes for .rodata..c_jump_table
This is because the section ".rodata..c_jump_table" should be readonly,
but there is a "W" (writable) part of the flags:
$ readelf -S kernel/bpf/core.o | grep -A 1 "rodata..c"
[34] .rodata..c_j[...] PROGBITS 0000000000000000 0000d2e0
0000000000000800 0000000000000000 WA 0 0 8
There is no above issue on x86 due to the generated section flag is only
"A" (allocatable). In order to silence the warning on LoongArch, specify
the attribute like ".rodata..c_jump_table,\"a\",@progbits #" explicitly,
then the section attribute of ".rodata..c_jump_table" must be readonly
in the kernel/bpf/core.o file.
Before:
$ objdump -h kernel/bpf/core.o | grep -A 1 "rodata..c"
21 .rodata..c_jump_table 00000800 0000000000000000 0000000000000000 0000d2e0 2**3
CONTENTS, ALLOC, LOAD, RELOC, DATA
After:
$ objdump -h kernel/bpf/core.o | grep -A 1 "rodata..c"
21 .rodata..c_jump_table 00000800 0000000000000000 0000000000000000 0000d2e0 2**3
CONTENTS, ALLOC, LOAD, RELOC, READONLY, DATA
By the way, AFAICT, maybe the root cause is related with the different
compiler behavior of various archs, so to some extent this change is a
workaround for LoongArch, and also there is no effect for x86 which is the
only port supported by objtool before LoongArch with this patch.
Link: https://lkml.kernel.org/r/20240924062710.1243-1-yangtiezhu@loongson.cn
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@vger.kernel.org> [6.9+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/compiler.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/compiler.h b/include/linux/compiler.h index ec55bcce4146..4d4e23b6e3e7 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -133,7 +133,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, #define annotate_unreachable() __annotate_unreachable(__COUNTER__) /* Annotate a C jump table to allow objtool to follow the code flow */ -#define __annotate_jump_table __section(".rodata..c_jump_table") +#define __annotate_jump_table __section(".rodata..c_jump_table,\"a\",@progbits #") #else /* !CONFIG_OBJTOOL */ #define annotate_reachable() |