Commit 1e4b6191 authored by Josh Poimboeuf's avatar Josh Poimboeuf
Browse files

objtool: Allow stack operations in UNWIND_HINT_UNDEFINED regions 

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: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
parent ac27ecf6

tools/objtool/check.c

+12 −0
Original line number Diff line number Diff line
@@ -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;

tools/objtool/include/objtool/cfi.h

+1 −0
Original line number Diff line number Diff line
@@ -36,6 +36,7 @@ struct cfi_state { 
	bool drap;

	bool signal;

	bool end;

	bool force_undefined;

};



#endif /* _OBJTOOL_CFI_H */