Commit 5743654f authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Peter Zijlstra
Browse files

objtool: Generate ORC data for __pfx code 



Allow unwinding from prefix code by copying the CFI from the starting
instruction of the corresponding function.  Even when the NOPs are
replaced, they're still stack-invariant instructions so the same ORC
entry can be reused everywhere.

Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/bc3344e51f3e87102f1301a0be0f72a7689ea4a4.1681331135.git.jpoimboe@kernel.org
parent 4a2c3448

tools/objtool/check.c

+14 −0
Original line number Diff line number Diff line
@@ -4117,6 +4117,7 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio 
static int add_prefix_symbol(struct objtool_file *file, struct symbol *func)

{

	struct instruction *insn, *prev;

	struct cfi_state *cfi;



	insn = find_insn(file, func->sec, func->offset);

	if (!insn)
@@ -4145,6 +4146,19 @@ static int add_prefix_symbol(struct objtool_file *file, struct symbol *func) 
	if (!prev)

		return -1;



	if (!insn->cfi) {

		/*

		 * This can happen if stack validation isn't enabled or the

		 * function is annotated with STACK_FRAME_NON_STANDARD.

		 */

		return 0;

	}



	/* Propagate insn->cfi to the prefix code */

	cfi = cfi_hash_find_or_add(insn->cfi);

	for (; prev != insn; prev = next_insn_same_sec(file, prev))

		prev->cfi = cfi;



	return 0;

}