On Tue, Oct 24, 2023 at 05:47:54PM +0000, John Sperbeck wrote:
5.10-stable review patch. If anyone has any objections, please let me know.
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 @@ -2079,12 +2079,17 @@ 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->call_dest->fentry)return true;
- if (insn->type == INSN_CALL) {
struct symbol *dest = insn->call_dest;if (!dest)return false;if (dest->fentry)return true;- }
return false; } @@ -2958,7 +2963,7 @@ static int validate_branch(struct objtoo if (ret) return ret;
if (!no_fp && func && !is_fentry_call(insn) &&
if (!no_fp && func && !is_special_call(insn) && !has_valid_stack_frame(&state)) { WARN_FUNC("call without frame pointer save/setup", sec, insn->offset);We still see the 'srso_untrain_ret+0xd: call without frame pointer save/setup' warning with v5.15.136. It looks like the backport might be incomplete. Is this additional change needed?
diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 36ad0b6b94a9..c3bb96e5bfa6 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -2202,7 +2202,7 @@ static bool is_special_call(struct instruction *insn) if (!dest) return false;
if (dest->fentry)
if (dest->fentry || dest->embedded_insn) return true;
Possibly, I remember this was a pain to backport. Can you try this and see? If so, can you send a working and tested patch?
thanks,
greg k-h