From dbf46008775516f7f25c95b7760041c286299783 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 16 Aug 2023 13:59:21 +0200 Subject: [PATCH] objtool/x86: Fixup frame-pointer vs rethunk For stack-validation of a frame-pointer build, objtool validates that every CALL instruction is preceded by a frame-setup. The new SRSO return thunks violate this with their RSB stuffing trickery. Extend the __fentry__ exception to also cover the embedded_insn case used for this. This cures: vmlinux.o: warning: objtool: srso_untrain_ret+0xd: call without frame pointer save/setup Fixes: 4ae68b26c3ab ("objtool/x86: Fix SRSO mess") Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Borislav Petkov (AMD) Acked-by: Josh Poimboeuf Link: https://lore.kernel.org/r/20230816115921.GH980931@hirez.programming.kicks-ass.net --- tools/objtool/check.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 7a9aaf400873..1384090530db 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -2650,12 +2650,17 @@ static int decode_sections(struct objtool_file *file) return 0; } -static bool is_fentry_call(struct instruction *insn) +static bool is_special_call(struct instruction *insn) { - if (insn->type == INSN_CALL && - insn_call_dest(insn) && - insn_call_dest(insn)->fentry) - return true; + if (insn->type == INSN_CALL) { + struct symbol *dest = insn_call_dest(insn); + + if (!dest) + return false; + + if (dest->fentry || dest->embedded_insn) + return true; + } return false; } @@ -3656,7 +3661,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, if (ret) return ret; - if (opts.stackval && func && !is_fentry_call(insn) && + if (opts.stackval && func && !is_special_call(insn) && !has_valid_stack_frame(&state)) { WARN_INSN(insn, "call without frame pointer save/setup"); return 1;