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Commit d9fcf2a1 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

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: 34525e1f ("s390: store breaking event address only for program checks")
Reported-by: default avatarMichael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent e7c95eff

arch/s390/kernel/entry.S

+5 −5
Original line number Diff line number Diff line
@@ -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)