Commit 9365965d authored by Heiko Carstens's avatar Heiko Carstens
Browse files

s390: always clear kernel stack backchain before calling functions 



Clear the kernel stack backchain before potentially calling the
lockdep trace_hardirqs_off/on functions. Without this walking the
kernel backchain, e.g. during a panic, might stop too early.

Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
parent 58659247

arch/s390/kernel/entry.S

+6 −6
Original line number Diff line number Diff line
@@ -413,6 +413,7 @@ ENTRY(system_call) 
	mvc	__PT_PSW(16,%r11),__LC_SVC_OLD_PSW

	mvc	__PT_INT_CODE(4,%r11),__LC_SVC_ILC

	stg	%r14,__PT_FLAGS(%r11)

	xc	__SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)

	ENABLE_INTS

.Lsysc_do_svc:

	# clear user controlled register to prevent speculative use
@@ -429,7 +430,6 @@ ENTRY(system_call) 
	jnl	.Lsysc_nr_ok

	slag	%r8,%r1,3

.Lsysc_nr_ok:

	xc	__SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)

	stg	%r2,__PT_ORIG_GPR2(%r11)

	stg	%r7,STACK_FRAME_OVERHEAD(%r15)

	lg	%r9,0(%r8,%r10)			# get system call add.
@@ -698,8 +698,8 @@ ENTRY(pgm_check_handler) 
	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

6:	RESTORE_SM_CLEAR_PER

	xc	__SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)

6:	xc	__SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)

	RESTORE_SM_CLEAR_PER

	larl	%r1,pgm_check_table

	llgh	%r10,__PT_INT_CODE+2(%r11)

	nill	%r10,0x007f
@@ -730,8 +730,8 @@ ENTRY(pgm_check_handler) 
# PER event in supervisor state, must be kprobes

#

.Lpgm_kprobe:

	RESTORE_SM_CLEAR_PER

	xc	__SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)

	RESTORE_SM_CLEAR_PER

	lgr	%r2,%r11		# pass pointer to pt_regs

	brasl	%r14,do_per_trap

	j	.Lpgm_return
@@ -777,10 +777,10 @@ ENTRY(io_int_handler) 
.Lio_skip_asce:

	mvc	__PT_INT_CODE(12,%r11),__LC_SUBCHANNEL_ID

	xc	__PT_FLAGS(8,%r11),__PT_FLAGS(%r11)

	xc	__SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)

	TSTMSK	__LC_CPU_FLAGS,_CIF_IGNORE_IRQ

	jo	.Lio_restore

	TRACE_IRQS_OFF

	xc	__SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)

.Lio_loop:

	lgr	%r2,%r11		# pass pointer to pt_regs

	lghi	%r3,IO_INTERRUPT
@@ -965,10 +965,10 @@ ENTRY(ext_int_handler) 
	mvc	__PT_INT_PARM(4,%r11),__LC_EXT_PARAMS

	mvc	__PT_INT_PARM_LONG(8,%r11),0(%r1)

	xc	__PT_FLAGS(8,%r11),__PT_FLAGS(%r11)

	xc	__SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)

	TSTMSK	__LC_CPU_FLAGS,_CIF_IGNORE_IRQ

	jo	.Lio_restore

	TRACE_IRQS_OFF

	xc	__SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)

	lgr	%r2,%r11		# pass pointer to pt_regs

	lghi	%r3,EXT_INTERRUPT

	brasl	%r14,do_IRQ

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