[patch 14/24] s390: virtual cpu accounting vs. machine checks.
From: Martin Schwidefsky
Date: Wed Jun 14 2006 - 10:02:27 EST
From: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
[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: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
---
arch/s390/kernel/entry.S | 79 +++++++++++++++++++++++++++++++++------------
arch/s390/kernel/entry64.S | 78 ++++++++++++++++++++++++++++++++------------
2 files changed, 116 insertions(+), 41 deletions(-)
diff -urpN linux-2.6/arch/s390/kernel/entry64.S linux-2.6-patched/arch/s390/kernel/entry64.S
--- linux-2.6/arch/s390/kernel/entry64.S 2006-03-20 06:53:29.000000000 +0100
+++ linux-2.6-patched/arch/s390/kernel/entry64.S 2006-06-14 14:29:50.000000000 +0200
@@ -87,13 +87,22 @@ _TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_
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_
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:
@@ -815,6 +846,11 @@ cleanup_critical:
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
clc 8(8,%r12),BASED(cleanup_table_io_leave+8)
@@ -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)
diff -urpN linux-2.6/arch/s390/kernel/entry.S linux-2.6-patched/arch/s390/kernel/entry.S
--- linux-2.6/arch/s390/kernel/entry.S 2006-03-20 06:53:29.000000000 +0100
+++ linux-2.6-patched/arch/s390/kernel/entry.S 2006-06-14 14:29:50.000000000 +0200
@@ -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:
@@ -807,6 +841,11 @@ cleanup_critical:
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)
clc 4(4,%r12),BASED(cleanup_table_io_leave+4)
@@ -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)
-
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