This is a note to let you know that I've just added the patch titled
x86/cpu: Fix up srso_safe_ret() and __x86_return_thunk()
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-cpu-fix-up-srso_safe_ret-and-__x86_return_thunk.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From af023ef335f13c8b579298fc432daeef609a9e60 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Date: Mon, 14 Aug 2023 13:44:28 +0200
Subject: x86/cpu: Fix up srso_safe_ret() and __x86_return_thunk()
From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
commit af023ef335f13c8b579298fc432daeef609a9e60 upstream.
vmlinux.o: warning: objtool: srso_untrain_ret() falls through to next function __x86_return_skl()
vmlinux.o: warning: objtool: __x86_return_thunk() falls through to next function __x86_return_skl()
This is because these functions (can) end with CALL, which objtool
does not consider a terminating instruction. Therefore, replace the
INT3 instruction (which is a non-fatal trap) with UD2 (which is a
fatal-trap).
This indicates execution will not continue past this point.
Fixes: fb3bd914b3ec ("x86/srso: Add a Speculative RAS Overflow mitigation")
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Link: https://lore.kernel.org/r/20230814121148.637802730@xxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/lib/retpoline.S | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/arch/x86/lib/retpoline.S
+++ b/arch/x86/lib/retpoline.S
@@ -202,7 +202,7 @@ SYM_INNER_LABEL(srso_safe_ret, SYM_L_GLO
int3
lfence
call srso_safe_ret
- int3
+ ud2
SYM_CODE_END(srso_safe_ret)
SYM_FUNC_END(srso_untrain_ret)
__EXPORT_THUNK(srso_untrain_ret)
@@ -212,7 +212,7 @@ SYM_CODE_START(__x86_return_thunk)
ANNOTATE_NOENDBR
ALTERNATIVE_2 "jmp __ret", "call srso_safe_ret", X86_FEATURE_SRSO, \
"call srso_safe_ret_alias", X86_FEATURE_SRSO_ALIAS
- int3
+ ud2
SYM_CODE_END(__x86_return_thunk)
EXPORT_SYMBOL(__x86_return_thunk)
Patches currently in stable-queue which might be from peterz@xxxxxxxxxxxxx are
queue-6.1/x86-cpu-fix-up-srso_safe_ret-and-__x86_return_thunk.patch
queue-6.1/sched-fair-remove-capacity-inversion-detection.patch
queue-6.1/iopoll-call-cpu_relax-in-busy-loops.patch
queue-6.1/x86-alternative-make-custom-return-thunk-unconditional.patch
queue-6.1/sched-fair-unlink-misfit-task-from-cpu-overutilized.patch
queue-6.1/x86-cpu-fix-__x86_return_thunk-symbol-type.patch
