From c9bfb460c3e4da2462e16b0f0b200990b36b1dd2 Mon Sep 17 00:00:00 2001 From: Nico Boehr Date: Tue, 24 May 2022 15:43:20 +0200 Subject: [PATCH] s390/perf: obtain sie_block from the right address Since commit 1179f170b6f0 ("s390: fix fpu restore in entry.S"), the sie_block pointer is located at empty1[1], but in sie_block() it was taken from empty1[0]. This leads to a random pointer being dereferenced, possibly causing system crash. This problem can be observed when running a simple guest with an endless loop and recording the cpu-clock event: sudo perf kvm --guestvmlinux= --guest top -e cpu-clock With this fix, the correct guest address is shown. Fixes: 1179f170b6f0 ("s390: fix fpu restore in entry.S") Cc: stable@vger.kernel.org Acked-by: Christian Borntraeger Acked-by: Claudio Imbrenda Reviewed-by: Heiko Carstens Signed-off-by: Nico Boehr Signed-off-by: Heiko Carstens --- arch/s390/kernel/perf_event.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/s390/kernel/perf_event.c b/arch/s390/kernel/perf_event.c index ea7729b..a7f8db7 100644 --- a/arch/s390/kernel/perf_event.c +++ b/arch/s390/kernel/perf_event.c @@ -30,7 +30,7 @@ static struct kvm_s390_sie_block *sie_block(struct pt_regs *regs) if (!stack) return NULL; - return (struct kvm_s390_sie_block *) stack->empty1[0]; + return (struct kvm_s390_sie_block *)stack->empty1[1]; } static bool is_in_guest(struct pt_regs *regs) -- 2.7.4