[S390] fix single stepped svcs with TRACE_IRQFLAGS=y

If irq flags tracing is enabled the TRACE_IRQS_ON macros expands to
a function call which clobbers registers %r0-%r5. The macro is used
in the code path for single stepped system calls. The argument
registers %r2-%r6 need to be restored from the stack before the system
call function is called.

Cc: stable@kernel.org
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 48215d15762b..e8ef21c51bbe 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -571,6 +571,7 @@ pgm_svcper:
         mvc     __THREAD_per+__PER_access_id(1,%r8),__LC_PER_ACCESS_ID
         oi      __TI_flags+3(%r9),_TIF_SINGLE_STEP # set TIF_SINGLE_STEP
         TRACE_IRQS_ON
+        lm      %r2,%r6,SP_R2(%r15)     # load svc arguments
         stosm   __SF_EMPTY(%r15),0x03   # reenable interrupts
         b       BASED(sysc_do_svc)