Commit 2acb94f4 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

s390/nmi: use the normal asynchronous stack for machine checks 



If a machine checks is received while the CPU is in the kernel, only
the s390_do_machine_check function will be called. The call to
s390_handle_mcck is postponed until the CPU returns to user space.
Because of this it is safe to use the asynchronous stack for machine
checks even if the CPU is already handling an interrupt.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent a359bb11

arch/s390/kernel/entry.S

+9 −16
Original line number Diff line number Diff line
@@ -83,7 +83,7 @@ _PIF_WORK = (_PIF_PER_TRAP) 
#endif

	.endm



	.macro	SWITCH_ASYNC savearea,stack,shift,timer

	.macro	SWITCH_ASYNC savearea,timer

	tmhh	%r8,0x0001		# interrupting from user ?

	jnz	1f

	lgr	%r14,%r9
@@ -94,16 +94,16 @@ _PIF_WORK = (_PIF_PER_TRAP) 
	brasl	%r14,cleanup_critical

	tmhh	%r8,0x0001		# retest problem state after cleanup

	jnz	1f

0:	lg	%r14,\stack		# are we already on the target stack?

0:	lg	%r14,__LC_ASYNC_STACK	# are we already on the async stack?

	slgr	%r14,%r15

	srag	%r14,%r14,\shift

	srag	%r14,%r14,STACK_SHIFT

	jnz	2f

	CHECK_STACK 1<<\shift,\savearea

	CHECK_STACK 1<<STACK_SHIFT,\savearea

	aghi	%r15,-(STACK_FRAME_OVERHEAD + __PT_SIZE)

	j	3f

1:	LAST_BREAK %r14

	UPDATE_VTIME %r14,%r15,\timer

2:	lg	%r15,\stack		# load target stack

2:	lg	%r15,__LC_ASYNC_STACK	# load async stack

3:	la	%r11,STACK_FRAME_OVERHEAD(%r15)

	.endm
@@ -539,8 +539,7 @@ ENTRY(io_int_handler) 
	lg	%r12,__LC_THREAD_INFO

	larl	%r13,cleanup_critical

	lmg	%r8,%r9,__LC_IO_OLD_PSW

	SWITCH_ASYNC __LC_SAVE_AREA_ASYNC,__LC_ASYNC_STACK,STACK_SHIFT,\

		     __LC_ASYNC_ENTER_TIMER

	SWITCH_ASYNC __LC_SAVE_AREA_ASYNC,__LC_ASYNC_ENTER_TIMER

	stmg	%r0,%r7,__PT_R0(%r11)

	mvc	__PT_R8(64,%r11),__LC_SAVE_AREA_ASYNC

	stmg	%r8,%r9,__PT_PSW(%r11)
@@ -712,8 +711,7 @@ ENTRY(ext_int_handler) 
	lg	%r12,__LC_THREAD_INFO

	larl	%r13,cleanup_critical

	lmg	%r8,%r9,__LC_EXT_OLD_PSW

	SWITCH_ASYNC __LC_SAVE_AREA_ASYNC,__LC_ASYNC_STACK,STACK_SHIFT,\

		     __LC_ASYNC_ENTER_TIMER

	SWITCH_ASYNC __LC_SAVE_AREA_ASYNC,__LC_ASYNC_ENTER_TIMER

	stmg	%r0,%r7,__PT_R0(%r11)

	mvc	__PT_R8(64,%r11),__LC_SAVE_AREA_ASYNC

	stmg	%r8,%r9,__PT_PSW(%r11)
@@ -892,8 +890,7 @@ ENTRY(mcck_int_handler) 
	mvc	__LC_MCCK_ENTER_TIMER(8),0(%r14)

3:	tm	__LC_MCCK_CODE+2,0x09	# mwp + ia of old psw valid?

	jno	.Lmcck_panic		# no -> skip cleanup critical

	SWITCH_ASYNC __LC_GPREGS_SAVE_AREA+64,__LC_PANIC_STACK,PAGE_SHIFT,\

		     __LC_MCCK_ENTER_TIMER

	SWITCH_ASYNC __LC_GPREGS_SAVE_AREA+64,__LC_MCCK_ENTER_TIMER

.Lmcck_skip:

	lghi	%r14,__LC_GPREGS_SAVE_AREA+64

	stmg	%r0,%r7,__PT_R0(%r11)
@@ -928,12 +925,8 @@ ENTRY(mcck_int_handler) 
	lpswe	__LC_RETURN_MCCK_PSW



.Lmcck_panic:

	lg	%r14,__LC_PANIC_STACK

	slgr	%r14,%r15

	srag	%r14,%r14,PAGE_SHIFT

	jz	0f

	lg	%r15,__LC_PANIC_STACK

0:	aghi	%r15,-(STACK_FRAME_OVERHEAD + __PT_SIZE)

	aghi	%r15,-(STACK_FRAME_OVERHEAD + __PT_SIZE)

	j	.Lmcck_skip



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