s390: fix in-kernel program checks

A program check inside the kernel takes a slightly different path in
entry.S compare to a normal user fault. A recent change moved the store
of the breaking event address into the path taken for in-kernel program
checks as well, but %r14 has not been setup to point to the correct
location. A wild store is the consequence.

Move the store of the breaking event address to the code path for
user space faults.

Fixes: 34525e1f7e8d ("s390: store breaking event address only for program checks")
Reported-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index dff2152350a7ebaaf3df6c8b000eb36b03afd19e..6a7d737d514c4c0064ddd8ef1ca80b824ae60c0c 100644 (file)
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -490,7 +490,7 @@ ENTRY(pgm_check_handler)
        jnz     .Lpgm_svcper            # -> single stepped svc
 1:     CHECK_STACK STACK_SIZE,__LC_SAVE_AREA_SYNC
        aghi    %r15,-(STACK_FRAME_OVERHEAD + __PT_SIZE)
-       j       3f
+       j       4f
 2:     UPDATE_VTIME %r14,%r15,__LC_SYNC_ENTER_TIMER
        lg      %r15,__LC_KERNEL_STACK
        lgr     %r14,%r12
@@ -499,8 +499,8 @@ ENTRY(pgm_check_handler)
        tm      __LC_PGM_ILC+2,0x02     # check for transaction abort
        jz      3f
        mvc     __THREAD_trap_tdb(256,%r14),0(%r13)
-3:     la      %r11,STACK_FRAME_OVERHEAD(%r15)
-       stg     %r10,__THREAD_last_break(%r14)
+3:     stg     %r10,__THREAD_last_break(%r14)
+4:     la      %r11,STACK_FRAME_OVERHEAD(%r15)
        stmg    %r0,%r7,__PT_R0(%r11)
        mvc     __PT_R8(64,%r11),__LC_SAVE_AREA_SYNC
        stmg    %r8,%r9,__PT_PSW(%r11)
@@ -509,14 +509,14 @@ ENTRY(pgm_check_handler)
        xc      __PT_FLAGS(8,%r11),__PT_FLAGS(%r11)
        stg     %r10,__PT_ARGS(%r11)
        tm      __LC_PGM_ILC+3,0x80     # check for per exception
-       jz      4f
+       jz      5f
        tmhh    %r8,0x0001              # kernel per event ?
        jz      .Lpgm_kprobe
        oi      __PT_FLAGS+7(%r11),_PIF_PER_TRAP
        mvc     __THREAD_per_address(8,%r14),__LC_PER_ADDRESS
        mvc     __THREAD_per_cause(2,%r14),__LC_PER_CODE
        mvc     __THREAD_per_paid(1,%r14),__LC_PER_ACCESS_ID
-4:     REENABLE_IRQS
+5:     REENABLE_IRQS
        xc      __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
        larl    %r1,pgm_check_table
        llgh    %r10,__PT_INT_CODE+2(%r11)