Commit 07a63cbe authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

s390/cputime: fix incorrect system time 



git commit c5328901 "[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.

Cc: stable@vger.kernel.org # 3.3+
Tested-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 89c9fea3

arch/s390/kernel/entry.S

+18 −3
Original line number Diff line number Diff line
@@ -312,6 +312,7 @@ 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)
@@ -623,6 +624,7 @@ 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)
@@ -1174,15 +1176,23 @@ 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:
@@ -1190,15 +1200,20 @@ 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:

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