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authorChristian Borntraeger <borntraeger@de.ibm.com>2009-11-13 15:43:54 +0100
committerMartin Schwidefsky <sky@mschwide.boeblingen.de.ibm.com>2009-11-13 15:45:03 +0100
commitbcc6525fb23d2cec7ffdf908d98826a66823bcb2 (patch)
treebf5bc71446c3ad861db386ca68e9221309f6ca8b /arch/s390/kernel/entry64.S
parent8b94c1ed4d8232a452aa9db0f5ac9141d942590f (diff)
[S390] s390: fix single stepping on svc0
On s390 there are two ways of specifying the system call number for the svc instruction. The standard way is to use the immediate field in the instruction (or to use EXecute for values unknown during assemble time). This can encode 256 system calls. The kernel ABI also allows to put the system call number in r1 and then execute svc 0 to enable system call numbers > 255. It turns out that single stepping svc 0 is broken, since the PER program check handler uses r1. We have to use a different register. Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/kernel/entry64.S')
-rw-r--r--arch/s390/kernel/entry64.S8
1 files changed, 4 insertions, 4 deletions
diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index a6f7b20df61..9aff1d449b6 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -543,10 +543,10 @@ pgm_svcper:
mvc __LC_LAST_UPDATE_TIMER(8),__LC_SYNC_ENTER_TIMER
llgh %r7,__LC_SVC_INT_CODE # get svc number from lowcore
lg %r9,__LC_THREAD_INFO # load pointer to thread_info struct
- lg %r1,__TI_task(%r9)
- mvc __THREAD_per+__PER_atmid(2,%r1),__LC_PER_ATMID
- mvc __THREAD_per+__PER_address(8,%r1),__LC_PER_ADDRESS
- mvc __THREAD_per+__PER_access_id(1,%r1),__LC_PER_ACCESS_ID
+ lg %r8,__TI_task(%r9)
+ mvc __THREAD_per+__PER_atmid(2,%r8),__LC_PER_ATMID
+ mvc __THREAD_per+__PER_address(8,%r8),__LC_PER_ADDRESS
+ mvc __THREAD_per+__PER_access_id(1,%r8),__LC_PER_ACCESS_ID
oi __TI_flags+7(%r9),_TIF_SINGLE_STEP # set TIF_SINGLE_STEP
TRACE_IRQS_ON
stosm __SF_EMPTY(%r15),0x03 # reenable interrupts