diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2022-10-28 15:50:42 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2022-11-01 13:44:09 +0100 |
| commit | 9f2899fe36a623885d8576604cb582328ad32b3c (patch) | |
| tree | 2287e0ce43e4c90c254c565f5c63849d365cd614 /tools/objtool/include | |
| parent | 13f60e80e15dd0657c90bcca372ba045630ed9de (diff) | |
| download | lwn-9f2899fe36a623885d8576604cb582328ad32b3c.tar.gz lwn-9f2899fe36a623885d8576604cb582328ad32b3c.zip | |
objtool: Add option to generate prefix symbols
When code is compiled with:
-fpatchable-function-entry=${PADDING_BYTES},${PADDING_BYTES}
functions will have PADDING_BYTES of NOP in front of them. Unwinders
and other things that symbolize code locations will typically
attribute these bytes to the preceding function.
Given that these bytes nominally belong to the following symbol this
mis-attribution is confusing.
Inspired by the fact that CFI_CLANG emits __cfi_##name symbols to
claim these bytes, allow objtool to emit __pfx_##name symbols to do
the same.
Therefore add the objtool --prefix=N argument, to conditionally place
a __pfx_##name symbol at N bytes ahead of symbol 'name' when: all
these preceding bytes are NOP and name-N is an instruction boundary.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Yujie Liu <yujie.liu@intel.com>
Link: https://lkml.kernel.org/r/20221028194453.526899822@infradead.org
Diffstat (limited to 'tools/objtool/include')
| -rw-r--r-- | tools/objtool/include/objtool/builtin.h | 1 | ||||
| -rw-r--r-- | tools/objtool/include/objtool/elf.h | 2 |
2 files changed, 3 insertions, 0 deletions
diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h index 22092a9f3cf6..f341b620dead 100644 --- a/tools/objtool/include/objtool/builtin.h +++ b/tools/objtool/include/objtool/builtin.h @@ -26,6 +26,7 @@ struct opts { bool stackval; bool static_call; bool uaccess; + int prefix; /* options: */ bool backtrace; diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h index 9e96a613c50f..b6974e3173aa 100644 --- a/tools/objtool/include/objtool/elf.h +++ b/tools/objtool/include/objtool/elf.h @@ -146,6 +146,8 @@ static inline bool has_multiple_files(struct elf *elf) struct elf *elf_open_read(const char *name, int flags); struct section *elf_create_section(struct elf *elf, const char *name, unsigned int sh_flags, size_t entsize, int nr); +struct symbol *elf_create_prefix_symbol(struct elf *elf, struct symbol *orig, long size); + int elf_add_reloc(struct elf *elf, struct section *sec, unsigned long offset, unsigned int type, struct symbol *sym, s64 addend); int elf_add_reloc_to_insn(struct elf *elf, struct section *sec, |