From: Peter Zijlstra peterz@infradead.org
commit dbf46008775516f7f25c95b7760041c286299783 upstream.
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) peterz@infradead.org Signed-off-by: Borislav Petkov (AMD) bp@alien8.de Acked-by: Josh Poimboeuf jpoimboe@kernel.org Link: https://lore.kernel.org/r/20230816115921.GH980931@hirez.programming.kicks-as... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- tools/objtool/check.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-)
--- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -2698,12 +2698,17 @@ static int decode_sections(struct objtoo 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; } @@ -3701,7 +3706,7 @@ static int validate_branch(struct objtoo 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;