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objtool: Allow stack operations in UNWIND_HINT_UNDEFINED regions

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If the code specified UNWIND_HINT_UNDEFINED, skip the "undefined stack
state" warning due to a stack operation.  Just ignore the stack op and
continue to propagate the undefined state.

Link: https://lore.kernel.org/r/820c5b433f17c84e8761fb7465a8d319d706b1cf.1685981486.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
This commit is contained in:
Josh Poimboeuf 2023-06-05 09:12:21 -07:00
parent ac27ecf68a
commit 1e4b619185
2 changed files with 13 additions and 0 deletions
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12
tools/objtool/check.c
View File

@ -33,6 +33,7 @@ static unsigned long nr_cfi, nr_cfi_reused, nr_cfi_cache;
static struct cfi_init_state initial_func_cfi;
static struct cfi_state init_cfi;
static struct cfi_state func_cfi;
static struct cfi_state force_undefined_cfi;
struct instruction *find_insn(struct objtool_file *file,
struct section *sec, unsigned long offset)
@ -2240,6 +2241,11 @@ static int read_unwind_hints(struct objtool_file *file)
insn->hint = true;
if (hint->type == UNWIND_HINT_TYPE_UNDEFINED) {
insn->cfi = &force_undefined_cfi;
continue;
}
if (hint->type == UNWIND_HINT_TYPE_SAVE) {
insn->hint = false;
insn->save = true;
@ -2793,6 +2799,10 @@ static int update_cfi_state(struct instruction *insn,
struct cfi_reg *cfa = &cfi->cfa;
struct cfi_reg *regs = cfi->regs;
/* ignore UNWIND_HINT_UNDEFINED regions */
if (cfi->force_undefined)
return 0;
/* stack operations don't make sense with an undefined CFA */
if (cfa->base == CFI_UNDEFINED) {
if (insn_func(insn)) {
@ -4607,6 +4617,8 @@ int check(struct objtool_file *file)
init_cfi_state(&init_cfi);
init_cfi_state(&func_cfi);
set_func_state(&func_cfi);
init_cfi_state(&force_undefined_cfi);
force_undefined_cfi.force_undefined = true;
if (!cfi_hash_alloc(1UL << (file->elf->symbol_bits - 3)))
goto out;

1
tools/objtool/include/objtool/cfi.h
View File

@ -36,6 +36,7 @@ struct cfi_state {
bool drap;
bool signal;
bool end;
bool force_undefined;
};
#endif /* _OBJTOOL_CFI_H */