Commit 63b12246 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

[S390] virtual cpu accounting vs. machine checks. 



If a machine checks interrupts the external or the i/o interrupt
handler before they have completed the cpu time calculations, the
accounting goes wrong. After the cpu returned from the machine check
handler to the interrupted interrupt handler, a negative cpu time delta
can occur.  If the accumulated cpu time in lowcore is small enough
this value can get negative as well. The next jiffy interrupt will pick
up that negative value, shift it by 12 and add the now huge positive
value to the cpu time of the process.
To solve this the machine check handler is modified not to change any
of the timestamps in the lowcore if the machine check interrupted kernel
context.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 9faf0654

arch/s390/kernel/entry.S

+59 −20
Original line number Diff line number Diff line
@@ -93,13 +93,22 @@ STACK_SIZE = 1 << STACK_SHIFT 
	l	%r13,__LC_SVC_NEW_PSW+4	# load &system_call to %r13

	.endm



	.macro	SAVE_ALL psworg,savearea,sync

	.macro	SAVE_ALL_SYNC psworg,savearea

	la	%r12,\psworg

	.if	\sync

	tm	\psworg+1,0x01		# test problem state bit

	bz	BASED(2f)		# skip stack setup save

	l	%r15,__LC_KERNEL_STACK	# problem state -> load ksp

	.else

#ifdef CONFIG_CHECK_STACK

	b	BASED(3f)

2:	tml	%r15,STACK_SIZE - CONFIG_STACK_GUARD

	bz	BASED(stack_overflow)

3:

#endif

2:

	.endm



	.macro	SAVE_ALL_ASYNC psworg,savearea

	la	%r12,\psworg

	tm	\psworg+1,0x01		# test problem state bit

	bnz	BASED(1f)		# from user -> load async stack

	clc	\psworg+4(4),BASED(.Lcritical_end)
@@ -115,7 +124,6 @@ STACK_SIZE = 1 << STACK_SHIFT 
	sra	%r14,STACK_SHIFT

	be	BASED(2f)

1:	l	%r15,__LC_ASYNC_STACK

	.endif

#ifdef CONFIG_CHECK_STACK

	b	BASED(3f)

2:	tml	%r15,STACK_SIZE - CONFIG_STACK_GUARD
@@ -196,7 +204,7 @@ system_call: 
	STORE_TIMER __LC_SYNC_ENTER_TIMER

sysc_saveall:

	SAVE_ALL_BASE __LC_SAVE_AREA

        SAVE_ALL __LC_SVC_OLD_PSW,__LC_SAVE_AREA,1

	SAVE_ALL_SYNC __LC_SVC_OLD_PSW,__LC_SAVE_AREA

	CREATE_STACK_FRAME __LC_SVC_OLD_PSW,__LC_SAVE_AREA

	lh	%r7,0x8a	  # get svc number from lowcore

#ifdef CONFIG_VIRT_CPU_ACCOUNTING
@@ -425,7 +433,7 @@ pgm_check_handler: 
	SAVE_ALL_BASE __LC_SAVE_AREA

        tm      __LC_PGM_INT_CODE+1,0x80 # check whether we got a per exception

        bnz     BASED(pgm_per)           # got per exception -> special case

	SAVE_ALL __LC_PGM_OLD_PSW,__LC_SAVE_AREA,1

	SAVE_ALL_SYNC __LC_PGM_OLD_PSW,__LC_SAVE_AREA

	CREATE_STACK_FRAME __LC_PGM_OLD_PSW,__LC_SAVE_AREA

#ifdef CONFIG_VIRT_CPU_ACCOUNTING

	tm	SP_PSW+1(%r15),0x01	# interrupting from user ?
@@ -464,7 +472,7 @@ pgm_per: 
# Normal per exception

#

pgm_per_std:

	SAVE_ALL __LC_PGM_OLD_PSW,__LC_SAVE_AREA,1

	SAVE_ALL_SYNC __LC_PGM_OLD_PSW,__LC_SAVE_AREA

	CREATE_STACK_FRAME __LC_PGM_OLD_PSW,__LC_SAVE_AREA

#ifdef CONFIG_VIRT_CPU_ACCOUNTING

	tm	SP_PSW+1(%r15),0x01	# interrupting from user ?
@@ -490,7 +498,7 @@ pgm_no_vtime2: 
# it was a single stepped SVC that is causing all the trouble

#

pgm_svcper:

	SAVE_ALL __LC_SVC_OLD_PSW,__LC_SAVE_AREA,1

	SAVE_ALL_SYNC __LC_SVC_OLD_PSW,__LC_SAVE_AREA

	CREATE_STACK_FRAME __LC_SVC_OLD_PSW,__LC_SAVE_AREA

#ifdef CONFIG_VIRT_CPU_ACCOUNTING

	tm	SP_PSW+1(%r15),0x01	# interrupting from user ?
@@ -519,7 +527,7 @@ io_int_handler: 
	STORE_TIMER __LC_ASYNC_ENTER_TIMER

	stck	__LC_INT_CLOCK

	SAVE_ALL_BASE __LC_SAVE_AREA+16

        SAVE_ALL __LC_IO_OLD_PSW,__LC_SAVE_AREA+16,0

	SAVE_ALL_ASYNC __LC_IO_OLD_PSW,__LC_SAVE_AREA+16

	CREATE_STACK_FRAME __LC_IO_OLD_PSW,__LC_SAVE_AREA+16

#ifdef CONFIG_VIRT_CPU_ACCOUNTING

	tm	SP_PSW+1(%r15),0x01	# interrupting from user ?
@@ -631,7 +639,7 @@ ext_int_handler: 
	STORE_TIMER __LC_ASYNC_ENTER_TIMER

	stck	__LC_INT_CLOCK

	SAVE_ALL_BASE __LC_SAVE_AREA+16

        SAVE_ALL __LC_EXT_OLD_PSW,__LC_SAVE_AREA+16,0

	SAVE_ALL_ASYNC __LC_EXT_OLD_PSW,__LC_SAVE_AREA+16

	CREATE_STACK_FRAME __LC_EXT_OLD_PSW,__LC_SAVE_AREA+16

#ifdef CONFIG_VIRT_CPU_ACCOUNTING

	tm	SP_PSW+1(%r15),0x01	# interrupting from user ?
@@ -657,21 +665,31 @@ __critical_end: 
        .globl mcck_int_handler

mcck_int_handler:

	spt	__LC_CPU_TIMER_SAVE_AREA	# revalidate cpu timer

	mvc	__LC_ASYNC_ENTER_TIMER(8),__LC_CPU_TIMER_SAVE_AREA

	lm	%r0,%r15,__LC_GPREGS_SAVE_AREA	# revalidate gprs

	SAVE_ALL_BASE __LC_SAVE_AREA+32

	la	%r12,__LC_MCK_OLD_PSW

	tm	__LC_MCCK_CODE,0x80     # system damage?

	bo	BASED(mcck_int_main)	# yes -> rest of mcck code invalid

	tm	__LC_MCCK_CODE+5,0x02   # stored cpu timer value valid?

	bo	BASED(0f)

	spt	__LC_LAST_UPDATE_TIMER	# revalidate cpu timer

#ifdef CONFIG_VIRT_CPU_ACCOUNTING

	mvc	__LC_ASYNC_ENTER_TIMER(8),__LC_LAST_UPDATE_TIMER

	mvc	__LC_SYNC_ENTER_TIMER(8),__LC_LAST_UPDATE_TIMER

	mvc	__LC_EXIT_TIMER(8),__LC_LAST_UPDATE_TIMER

	mvc	__LC_SAVE_AREA+52(8),__LC_ASYNC_ENTER_TIMER

	mvc	__LC_ASYNC_ENTER_TIMER(8),__LC_CPU_TIMER_SAVE_AREA

	tm	__LC_MCCK_CODE+5,0x02	# stored cpu timer value valid?

	bo	BASED(1f)

	la	%r14,__LC_SYNC_ENTER_TIMER

	clc	0(8,%r14),__LC_ASYNC_ENTER_TIMER

	bl	BASED(0f)

	la	%r14,__LC_ASYNC_ENTER_TIMER

0:	clc	0(8,%r14),__LC_EXIT_TIMER

	bl	BASED(0f)

	la	%r14,__LC_EXIT_TIMER

0:	clc	0(8,%r14),__LC_LAST_UPDATE_TIMER

	bl	BASED(0f)

	la	%r14,__LC_LAST_UPDATE_TIMER

0:	spt	0(%r14)

	mvc	__LC_ASYNC_ENTER_TIMER(8),0(%r14)

1:

#endif

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

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

	bno	BASED(mcck_int_main)	# no -> skip cleanup critical

	tm	__LC_MCK_OLD_PSW+1,0x01	# test problem state bit

	bnz	BASED(mcck_int_main)	# from user -> load async stack
@@ -691,7 +709,7 @@ mcck_int_main: 
#ifdef CONFIG_VIRT_CPU_ACCOUNTING

	tm	__LC_MCCK_CODE+2,0x08   # mwp of old psw valid?

	bno	BASED(mcck_no_vtime)	# no -> skip cleanup critical

	tm	__LC_MCK_OLD_PSW+1,0x01 # interrupting from user ?

	tm	SP_PSW+1(%r15),0x01	# interrupting from user ?

	bz	BASED(mcck_no_vtime)

	UPDATE_VTIME __LC_EXIT_TIMER,__LC_ASYNC_ENTER_TIMER,__LC_USER_TIMER

	UPDATE_VTIME __LC_LAST_UPDATE_TIMER,__LC_EXIT_TIMER,__LC_SYSTEM_TIMER
@@ -715,6 +733,20 @@ mcck_no_vtime: 
	l	%r1,BASED(.Ls390_handle_mcck)

	basr	%r14,%r1		# call machine check handler

mcck_return:

	mvc	__LC_RETURN_MCCK_PSW(8),SP_PSW(%r15) # move return PSW

	ni	__LC_RETURN_MCCK_PSW+1,0xfd # clear wait state bit

#ifdef CONFIG_VIRT_CPU_ACCOUNTING

	mvc	__LC_ASYNC_ENTER_TIMER(8),__LC_SAVE_AREA+52

	tm	__LC_RETURN_MCCK_PSW+1,0x01 # returning to user ?

	bno	BASED(0f)

	lm	%r0,%r15,SP_R0(%r15)	# load gprs 0-15

	stpt	__LC_EXIT_TIMER

	lpsw	__LC_RETURN_MCCK_PSW	# back to caller

0:

#endif

	lm	%r0,%r15,SP_R0(%r15)	# load gprs 0-15

	lpsw	__LC_RETURN_MCCK_PSW	# back to caller



        RESTORE_ALL __LC_RETURN_MCCK_PSW,0



#ifdef CONFIG_SMP
@@ -781,6 +813,8 @@ cleanup_table_sysc_leave: 
	.long	sysc_leave + 0x80000000, sysc_work_loop + 0x80000000

cleanup_table_sysc_work_loop:

	.long	sysc_work_loop + 0x80000000, sysc_reschedule + 0x80000000

cleanup_table_io_return:

	.long	io_return + 0x80000000, io_leave + 0x80000000

cleanup_table_io_leave:

	.long	io_leave + 0x80000000, io_done + 0x80000000

cleanup_table_io_work_loop:
@@ -806,6 +840,11 @@ cleanup_critical: 
	bl	BASED(0f)

	clc	4(4,%r12),BASED(cleanup_table_sysc_work_loop+4)

	bl	BASED(cleanup_sysc_return)

0:

	clc	4(4,%r12),BASED(cleanup_table_io_return)

	bl	BASED(0f)

	clc	4(4,%r12),BASED(cleanup_table_io_return+4)

	bl	BASED(cleanup_io_return)

0:

	clc	4(4,%r12),BASED(cleanup_table_io_leave)

	bl	BASED(0f)
@@ -839,7 +878,7 @@ cleanup_system_call: 
	mvc	__LC_SAVE_AREA(16),0(%r12)

0:	st	%r13,4(%r12)

	st	%r12,__LC_SAVE_AREA+48	# argh

	SAVE_ALL __LC_SVC_OLD_PSW,__LC_SAVE_AREA,1

	SAVE_ALL_SYNC __LC_SVC_OLD_PSW,__LC_SAVE_AREA

	CREATE_STACK_FRAME __LC_SVC_OLD_PSW,__LC_SAVE_AREA

	l	%r12,__LC_SAVE_AREA+48	# argh

	st	%r15,12(%r12)

arch/s390/kernel/entry64.S

+57 −21
Original line number Diff line number Diff line
@@ -87,13 +87,22 @@ _TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK | _TIF_NEED_RESCHED | \ 
	larl	%r13,system_call

	.endm



        .macro  SAVE_ALL psworg,savearea,sync

	.macro	SAVE_ALL_SYNC psworg,savearea

	la	%r12,\psworg

	.if	\sync

	tm	\psworg+1,0x01		# test problem state bit

	jz	2f			# skip stack setup save

	lg	%r15,__LC_KERNEL_STACK	# problem state -> load ksp

	.else

#ifdef CONFIG_CHECK_STACK

	j	3f

2:	tml	%r15,STACK_SIZE - CONFIG_STACK_GUARD

	jz	stack_overflow

3:

#endif

2:

	.endm



	.macro	SAVE_ALL_ASYNC psworg,savearea

	la	%r12,\psworg

	tm	\psworg+1,0x01		# test problem state bit

	jnz	1f			# from user -> load kernel stack

	clc	\psworg+8(8),BASED(.Lcritical_end)
@@ -108,7 +117,6 @@ _TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK | _TIF_NEED_RESCHED | \ 
	srag	%r14,%r14,STACK_SHIFT

	jz	2f

1:	lg	%r15,__LC_ASYNC_STACK	# load async stack

	.endif

#ifdef CONFIG_CHECK_STACK

	j	3f

2:	tml	%r15,STACK_SIZE - CONFIG_STACK_GUARD
@@ -187,7 +195,7 @@ system_call: 
	STORE_TIMER __LC_SYNC_ENTER_TIMER

sysc_saveall:

	SAVE_ALL_BASE __LC_SAVE_AREA

        SAVE_ALL __LC_SVC_OLD_PSW,__LC_SAVE_AREA,1

	SAVE_ALL_SYNC __LC_SVC_OLD_PSW,__LC_SAVE_AREA

        CREATE_STACK_FRAME __LC_SVC_OLD_PSW,__LC_SAVE_AREA

	llgh    %r7,__LC_SVC_INT_CODE # get svc number from lowcore

#ifdef CONFIG_VIRT_CPU_ACCOUNTING
@@ -446,7 +454,7 @@ pgm_check_handler: 
	SAVE_ALL_BASE __LC_SAVE_AREA

        tm      __LC_PGM_INT_CODE+1,0x80 # check whether we got a per exception

        jnz     pgm_per                  # got per exception -> special case

	SAVE_ALL __LC_PGM_OLD_PSW,__LC_SAVE_AREA,1

	SAVE_ALL_SYNC __LC_PGM_OLD_PSW,__LC_SAVE_AREA

	CREATE_STACK_FRAME __LC_PGM_OLD_PSW,__LC_SAVE_AREA

#ifdef CONFIG_VIRT_CPU_ACCOUNTING

	tm	SP_PSW+1(%r15),0x01	# interrupting from user ?
@@ -485,7 +493,7 @@ pgm_per: 
# Normal per exception

#

pgm_per_std:

	SAVE_ALL __LC_PGM_OLD_PSW,__LC_SAVE_AREA,1

	SAVE_ALL_SYNC __LC_PGM_OLD_PSW,__LC_SAVE_AREA

	CREATE_STACK_FRAME __LC_PGM_OLD_PSW,__LC_SAVE_AREA

#ifdef CONFIG_VIRT_CPU_ACCOUNTING

	tm	SP_PSW+1(%r15),0x01	# interrupting from user ?
@@ -511,7 +519,7 @@ pgm_no_vtime2: 
# it was a single stepped SVC that is causing all the trouble

#

pgm_svcper:

	SAVE_ALL __LC_SVC_OLD_PSW,__LC_SAVE_AREA,1

	SAVE_ALL_SYNC __LC_SVC_OLD_PSW,__LC_SAVE_AREA

	CREATE_STACK_FRAME __LC_SVC_OLD_PSW,__LC_SAVE_AREA

#ifdef CONFIG_VIRT_CPU_ACCOUNTING

	tm	SP_PSW+1(%r15),0x01	# interrupting from user ?
@@ -539,7 +547,7 @@ io_int_handler: 
	STORE_TIMER __LC_ASYNC_ENTER_TIMER

	stck	__LC_INT_CLOCK

	SAVE_ALL_BASE __LC_SAVE_AREA+32

        SAVE_ALL __LC_IO_OLD_PSW,__LC_SAVE_AREA+32,0

	SAVE_ALL_ASYNC __LC_IO_OLD_PSW,__LC_SAVE_AREA+32

	CREATE_STACK_FRAME __LC_IO_OLD_PSW,__LC_SAVE_AREA+32

#ifdef CONFIG_VIRT_CPU_ACCOUNTING

	tm	SP_PSW+1(%r15),0x01	# interrupting from user ?
@@ -647,7 +655,7 @@ ext_int_handler: 
	STORE_TIMER __LC_ASYNC_ENTER_TIMER

	stck	__LC_INT_CLOCK

	SAVE_ALL_BASE __LC_SAVE_AREA+32

        SAVE_ALL __LC_EXT_OLD_PSW,__LC_SAVE_AREA+32,0

	SAVE_ALL_ASYNC __LC_EXT_OLD_PSW,__LC_SAVE_AREA+32

	CREATE_STACK_FRAME __LC_EXT_OLD_PSW,__LC_SAVE_AREA+32

#ifdef CONFIG_VIRT_CPU_ACCOUNTING

	tm	SP_PSW+1(%r15),0x01	# interrupting from user ?
@@ -672,21 +680,32 @@ __critical_end: 
mcck_int_handler:

	la	%r1,4095		# revalidate r1

	spt	__LC_CPU_TIMER_SAVE_AREA-4095(%r1)	# revalidate cpu timer

	mvc	__LC_ASYNC_ENTER_TIMER(8),__LC_CPU_TIMER_SAVE_AREA-4095(%r1)

  	lmg     %r0,%r15,__LC_GPREGS_SAVE_AREA-4095(%r1)# revalidate gprs

	SAVE_ALL_BASE __LC_SAVE_AREA+64

	la	%r12,__LC_MCK_OLD_PSW

	tm	__LC_MCCK_CODE,0x80     # system damage?

	jo	mcck_int_main		# yes -> rest of mcck code invalid

	tm	__LC_MCCK_CODE+5,0x02   # stored cpu timer value valid?

	jo	0f

	spt	__LC_LAST_UPDATE_TIMER

#ifdef CONFIG_VIRT_CPU_ACCOUNTING

	mvc	__LC_ASYNC_ENTER_TIMER(8),__LC_LAST_UPDATE_TIMER

	mvc	__LC_SYNC_ENTER_TIMER(8),__LC_LAST_UPDATE_TIMER

	mvc	__LC_EXIT_TIMER(8),__LC_LAST_UPDATE_TIMER

	la	%r14,4095

	mvc	__LC_SAVE_AREA+104(8),__LC_ASYNC_ENTER_TIMER

	mvc	__LC_ASYNC_ENTER_TIMER(8),__LC_CPU_TIMER_SAVE_AREA-4095(%r14)

	tm	__LC_MCCK_CODE+5,0x02	# stored cpu timer value valid?

	jo	1f

	la	%r14,__LC_SYNC_ENTER_TIMER

	clc	0(8,%r14),__LC_ASYNC_ENTER_TIMER

	jl	0f

	la	%r14,__LC_ASYNC_ENTER_TIMER

0:	clc	0(8,%r14),__LC_EXIT_TIMER

	jl	0f

	la	%r14,__LC_EXIT_TIMER

0:	clc	0(8,%r14),__LC_LAST_UPDATE_TIMER

	jl	0f

	la	%r14,__LC_LAST_UPDATE_TIMER

0:	spt	0(%r14)

	mvc	__LC_ASYNC_ENTER_TIMER(8),0(%r14)

1:

#endif

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

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

	jno	mcck_int_main		# no -> skip cleanup critical

	tm      __LC_MCK_OLD_PSW+1,0x01 # test problem state bit

	jnz	mcck_int_main		# from user -> load kernel stack
@@ -705,7 +724,7 @@ mcck_int_main: 
#ifdef CONFIG_VIRT_CPU_ACCOUNTING

	tm	__LC_MCCK_CODE+2,0x08	# mwp of old psw valid?

	jno	mcck_no_vtime		# no -> no timer update

	tm      __LC_MCK_OLD_PSW+1,0x01 # interrupting from user ?

	tm	SP_PSW+1(%r15),0x01	# interrupting from user ?

	jz	mcck_no_vtime

	UPDATE_VTIME __LC_EXIT_TIMER,__LC_ASYNC_ENTER_TIMER,__LC_USER_TIMER

	UPDATE_VTIME __LC_LAST_UPDATE_TIMER,__LC_EXIT_TIMER,__LC_SYSTEM_TIMER
@@ -727,7 +746,17 @@ mcck_no_vtime: 
	jno	mcck_return

	brasl	%r14,s390_handle_mcck

mcck_return:

        RESTORE_ALL __LC_RETURN_MCCK_PSW,0

	mvc	__LC_RETURN_MCCK_PSW(16),SP_PSW(%r15) # move return PSW

	ni	__LC_RETURN_MCCK_PSW+1,0xfd # clear wait state bit

	lmg	%r0,%r15,SP_R0(%r15)	# load gprs 0-15

#ifdef CONFIG_VIRT_CPU_ACCOUNTING

	mvc	__LC_ASYNC_ENTER_TIMER(8),__LC_SAVE_AREA+104

	tm	__LC_RETURN_MCCK_PSW+1,0x01 # returning to user ?

	jno	0f

	stpt	__LC_EXIT_TIMER

0:

#endif

	lpswe	__LC_RETURN_MCCK_PSW	# back to caller



#ifdef CONFIG_SMP

/*
@@ -789,6 +818,8 @@ cleanup_table_sysc_leave: 
	.quad	sysc_leave, sysc_work_loop

cleanup_table_sysc_work_loop:

	.quad	sysc_work_loop, sysc_reschedule

cleanup_table_io_return:

	.quad	io_return, io_leave

cleanup_table_io_leave:

	.quad	io_leave, io_done

cleanup_table_io_work_loop:
@@ -814,6 +845,11 @@ cleanup_critical: 
	jl	0f

	clc	8(8,%r12),BASED(cleanup_table_sysc_work_loop+8)

	jl	cleanup_sysc_return

0:

	clc	8(8,%r12),BASED(cleanup_table_io_return)

	jl	0f

	clc	8(8,%r12),BASED(cleanup_table_io_return+8)

	jl	cleanup_io_return

0:

	clc	8(8,%r12),BASED(cleanup_table_io_leave)

	jl	0f
@@ -847,7 +883,7 @@ cleanup_system_call: 
	mvc	__LC_SAVE_AREA(32),0(%r12)

0:	stg	%r13,8(%r12)

	stg	%r12,__LC_SAVE_AREA+96	# argh

	SAVE_ALL __LC_SVC_OLD_PSW,__LC_SAVE_AREA,1

	SAVE_ALL_SYNC __LC_SVC_OLD_PSW,__LC_SAVE_AREA

	CREATE_STACK_FRAME __LC_SVC_OLD_PSW,__LC_SAVE_AREA

	lg	%r12,__LC_SAVE_AREA+96	# argh

	stg	%r15,24(%r12)

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