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[S390] virtual cpu accounting vs. machine checks.
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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: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Martin Schwidefsky committed Jun 29, 2006
1 parent 9faf065 commit 63b1224
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Showing 2 changed files with 116 additions and 41 deletions.
79 changes: 59 additions & 20 deletions arch/s390/kernel/entry.S
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)
Expand All @@ -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
Expand Down Expand Up @@ -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
Expand Down Expand Up @@ -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 ?
Expand Down Expand Up @@ -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 ?
Expand All @@ -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 ?
Expand Down Expand Up @@ -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 ?
Expand Down Expand Up @@ -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 ?
Expand All @@ -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
Expand All @@ -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
Expand All @@ -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
Expand Down Expand Up @@ -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:
Expand All @@ -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)
Expand Down Expand Up @@ -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)
Expand Down
78 changes: 57 additions & 21 deletions arch/s390/kernel/entry64.S
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)
Expand All @@ -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
Expand Down Expand Up @@ -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
Expand Down Expand Up @@ -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 ?
Expand Down Expand Up @@ -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 ?
Expand All @@ -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 ?
Expand Down Expand Up @@ -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 ?
Expand Down Expand Up @@ -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 ?
Expand All @@ -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
Expand All @@ -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
Expand All @@ -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
/*
Expand Down Expand Up @@ -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:
Expand All @@ -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
Expand Down Expand Up @@ -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)
Expand Down

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