Messages in this thread | | | Date | Wed, 9 Aug 2023 12:56:34 +0300 | Subject | Re: [RFC][PATCH 13/17] objtool/x86: Add arch_is_offset_insn() | From | Nikolay Borisov <> |
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On 9.08.23 г. 10:12 ч., Peter Zijlstra wrote: > Add a little wrappery to identify the magic symbols that are actually > inside another instruction -- yay for variable length instruction > encoding. > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > --- > tools/objtool/arch/x86/decode.c | 6 ++++++ > tools/objtool/check.c | 13 ++++++++++--- > tools/objtool/include/objtool/arch.h | 1 + > tools/objtool/include/objtool/elf.h | 1 + > 4 files changed, 18 insertions(+), 3 deletions(-) > > --- a/tools/objtool/arch/x86/decode.c > +++ b/tools/objtool/arch/x86/decode.c > @@ -826,3 +826,9 @@ bool arch_is_rethunk(struct symbol *sym) > { > return !strcmp(sym->name, "__x86_return_thunk"); > } > + > +bool arch_is_offset_insn(struct symbol *sym) > +{ > + return !strcmp(sym->name, "zen_return_thunk") || > + !strcmp(sym->name, "srso_safe_ret"); > +} > --- a/tools/objtool/check.c > +++ b/tools/objtool/check.c > @@ -459,8 +459,7 @@ static int decode_instructions(struct ob > * Both zen_return_thunk() and srso_safe_ret() are embedded inside > * another instruction and objtool doesn't grok that. Skip validating them. > */ > - if (!strcmp(func->name, "zen_return_thunk") || > - !strcmp(func->name, "srso_safe_ret") || func->alias != func) > + if (func->offset_insn || func->alias != func) > continue; > > if (!find_insn(file, sec, func->offset)) { > @@ -1303,6 +1302,11 @@ __weak bool arch_is_rethunk(struct symbo > return false; > } > > +__weak bool arch_is_offset_insn(struct symbol *sym) > +{ > + return false; > +} > + > static struct reloc *insn_reloc(struct objtool_file *file, struct instruction *insn) > { > struct reloc *reloc; > @@ -1588,7 +1592,7 @@ static int add_jump_destinations(struct > * middle of another instruction. Objtool only > * knows about the outer instruction. > */ > - if (sym && !strcmp(sym->name, "zen_return_thunk")) { > + if (sym && sym->offset_insn) { > add_return_call(file, insn, false); > continue; > } > @@ -2507,6 +2511,9 @@ static int classify_symbols(struct objto > if (arch_is_rethunk(func)) > func->return_thunk = true; > > + if (arch_is_offset_insn(func)) > + func->offset_insn = true; > + > if (arch_ftrace_match(func->name)) > func->fentry = true;
nit: Why go through this if when one can simply do:
func->foo = arch_is_foo(bar) ?
> > --- a/tools/objtool/include/objtool/arch.h > +++ b/tools/objtool/include/objtool/arch.h > @@ -90,6 +90,7 @@ int arch_decode_hint_reg(u8 sp_reg, int > > bool arch_is_retpoline(struct symbol *sym); > bool arch_is_rethunk(struct symbol *sym); > +bool arch_is_offset_insn(struct symbol *sym); > > int arch_rewrite_retpolines(struct objtool_file *file); > > --- a/tools/objtool/include/objtool/elf.h > +++ b/tools/objtool/include/objtool/elf.h > @@ -66,6 +66,7 @@ struct symbol { > u8 fentry : 1; > u8 profiling_func : 1; > u8 warned : 1; > + u8 offset_insn : 1; > struct list_head pv_target; > struct reloc *relocs; > }; > >
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