This is a note to let you know that I've just added the patch titled
s390/cputime: fix incorrect system time
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
s390-cputime-fix-incorrect-system-time.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 07a63cbe8bcb6ba72fb989dcab1ec55ec6c36c7e Mon Sep 17 00:00:00 2001
From: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Date: Tue, 2 May 2017 13:36:00 +0200
Subject: s390/cputime: fix incorrect system time
From: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/s390/kernel/entry.S | 21 ++++++++++++++++++---
1 file changed, 18 insertions(+), 3 deletions(-)
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -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:
Patches currently in stable-queue which might be from schwidefsky@xxxxxxxxxx are
queue-4.9/s390-kdump-add-final-note.patch
queue-4.9/s390-cputime-fix-incorrect-system-time.patch