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s390/cputime: fix incorrect system time

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commit 07a63cbe8bcb6ba72fb989dcab1ec55ec6c36c7e upstream.

git commit c5328901aa1db134 "[S390] entry[64].S improvements" removed
the update of the exit_timer lowcore field from the critical section
cleanup of the .Lsysc_restore/.Lsysc_done and .Lio_restore/.Lio_done
blocks. If the PSW is updated by the critical section cleanup to point to
user space again, the interrupt entry code will do a vtime calculation
after the cleanup completed with an exit_timer value which has *not* been
updated. Due to this incorrect system time deltas are calculated.

If an interrupt occured with an old PSW between .Lsysc_restore/.Lsysc_done
or .Lio_restore/.Lio_done update __LC_EXIT_TIMER with the system entry
time of the interrupt.

Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Martin Schwidefsky 2017-05-02 13:36:00 +02:00 committed by Greg Kroah-Hartman
parent 8c5157c196
commit 768ae64b2a
1 changed files with 18 additions and 3 deletions
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21
arch/s390/kernel/entry.S
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@ -321,6 +321,7 @@ ENTRY(system_call)
lg %r14,__LC_VDSO_PER_CPU
lmg %r0,%r10,__PT_R0(%r11)
mvc __LC_RETURN_PSW(16),__PT_PSW(%r11)
.Lsysc_exit_timer:
stpt __LC_EXIT_TIMER
mvc __VDSO_ECTG_BASE(16,%r14),__LC_EXIT_TIMER
lmg %r11,%r15,__PT_R11(%r11)
@ -606,6 +607,7 @@ ENTRY(io_int_handler)
lg %r14,__LC_VDSO_PER_CPU
lmg %r0,%r10,__PT_R0(%r11)
mvc __LC_RETURN_PSW(16),__PT_PSW(%r11)
.Lio_exit_timer:
stpt __LC_EXIT_TIMER
mvc __VDSO_ECTG_BASE(16,%r14),__LC_EXIT_TIMER
lmg %r11,%r15,__PT_R11(%r11)
@ -1135,15 +1137,23 @@ cleanup_critical:
br %r14
.Lcleanup_sysc_restore:
# check if stpt has been executed
clg %r9,BASED(.Lcleanup_sysc_restore_insn)
jh 0f
mvc __LC_EXIT_TIMER(8),__LC_ASYNC_ENTER_TIMER
cghi %r11,__LC_SAVE_AREA_ASYNC
je 0f
mvc __LC_EXIT_TIMER(8),__LC_MCCK_ENTER_TIMER
0: clg %r9,BASED(.Lcleanup_sysc_restore_insn+8)
je 1f
lg %r9,24(%r11) # get saved pointer to pt_regs
mvc __LC_RETURN_PSW(16),__PT_PSW(%r9)
mvc 0(64,%r11),__PT_R8(%r9)
lmg %r0,%r7,__PT_R0(%r9)
0: lmg %r8,%r9,__LC_RETURN_PSW
1: lmg %r8,%r9,__LC_RETURN_PSW
br %r14
.Lcleanup_sysc_restore_insn:
.quad .Lsysc_exit_timer
.quad .Lsysc_done - 4
.Lcleanup_io_tif:
@ -1151,15 +1161,20 @@ cleanup_critical:
br %r14
.Lcleanup_io_restore:
# check if stpt has been executed
clg %r9,BASED(.Lcleanup_io_restore_insn)
je 0f
jh 0f
mvc __LC_EXIT_TIMER(8),__LC_MCCK_ENTER_TIMER
0: clg %r9,BASED(.Lcleanup_io_restore_insn+8)
je 1f
lg %r9,24(%r11) # get saved r11 pointer to pt_regs
mvc __LC_RETURN_PSW(16),__PT_PSW(%r9)
mvc 0(64,%r11),__PT_R8(%r9)
lmg %r0,%r7,__PT_R0(%r9)
0: lmg %r8,%r9,__LC_RETURN_PSW
1: lmg %r8,%r9,__LC_RETURN_PSW
br %r14
.Lcleanup_io_restore_insn:
.quad .Lio_exit_timer
.quad .Lio_done - 4
.Lcleanup_idle: