diff options
| author |   Tiezhu Yang <yangtiezhu@loongson.cn> | 2025-02-11 19:50:12 +0800 |
|---|---|---|
| committer |   Josh Poimboeuf <jpoimboe@kernel.org> | 2025-03-12 15:43:38 -0700 |
| commit | c4b93b06230ae49870187189d9f7342f6ad4f14e (patch) | |
| tree | c25214b97535013103da961544c1dac694dd2dd7 /tools/objtool/include | |
| parent | objtool: Handle different entry size of rodata (diff) | |
| download | wireguard-linux-c4b93b06230ae49870187189d9f7342f6ad4f14e.tar.xz wireguard-linux-c4b93b06230ae49870187189d9f7342f6ad4f14e.zip | |
objtool: Handle PC relative relocation type
For the most part, an absolute relocation type is used for rodata.
In the case of STT_SECTION, reloc->sym->offset is always zero, for
the other symbol types, reloc_addend(reloc) is always zero, thus it
can use a simple statement "reloc->sym->offset + reloc_addend(reloc)"
to obtain the symbol offset for various symbol types.
When compiling on LoongArch, there exist PC relative relocation types
for rodata, it needs to calculate the symbol offset with "S + A - PC"
according to the spec of "ELF for the LoongArch Architecture".
If there is only one jump table in the rodata, the "PC" is the entry
address which is equal with the value of reloc_offset(reloc), at this
time, reloc_offset(table) is 0.
If there are many jump tables in the rodata, the "PC" is the offset
of the jump table's base address which is equal with the value of
reloc_offset(reloc) - reloc_offset(table).
So for LoongArch, if the relocation type is PC relative, it can use a
statement "reloc_offset(reloc) - reloc_offset(table)" to get the "PC"
value when calculating the symbol offset with "S + A - PC" for one or
many jump tables in the rodata.
Add an arch-specific function arch_jump_table_sym_offset() to assign
the symbol offset, for the most part that is an absolute relocation,
the default value is "reloc->sym->offset + reloc_addend(reloc)" in
the weak definition, it can be overridden by each architecture that
has different requirements.
Link: https://github.com/loongson/la-abi-specs/blob/release/laelf.adoc
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Link: https://lore.kernel.org/r/20250211115016.26913-4-yangtiezhu@loongson.cn
Acked-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Diffstat (limited to 'tools/objtool/include')
| -rw-r--r-- | tools/objtool/include/objtool/arch.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/tools/objtool/include/objtool/arch.h b/tools/objtool/include/objtool/arch.h index 396f7c6c81c0..089a1acc48a8 100644 --- a/tools/objtool/include/objtool/arch.h +++ b/tools/objtool/include/objtool/arch.h @@ -98,5 +98,6 @@ int arch_rewrite_retpolines(struct objtool_file *file); bool arch_pc_relative_reloc(struct reloc *reloc); unsigned int arch_reloc_size(struct reloc *reloc); +unsigned long arch_jump_table_sym_offset(struct reloc *reloc, struct reloc *table); #endif /* _ARCH_H */ |