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s390/perf: obtain sie_block from the right address

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Since commit 1179f170b6 ("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=<guestkernel> --guest top -e cpu-clock

With this fix, the correct guest address is shown.

Fixes: 1179f170b6 ("s390: fix fpu restore in entry.S")
Cc: stable@vger.kernel.org
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
Nico Boehr 2022-05-24 15:43:20 +02:00 committed by Heiko Carstens
parent 3384f135e9
commit c9bfb460c3
1 changed files with 1 additions and 1 deletions
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arch/s390/kernel/perf_event.c
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@ -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)