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s390: use 64-bit lctlg to load task pid to cr4 on context switch 

The 32-bit lctl instruction is quite a bit slower than the 64-bit
counter part lctlg. Use the faster instruction.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky 2017-04-03 13:30:23 +02:00
parent 6fb81d69d0
commit cab36c262e
1 changed files with 3 additions and 1 deletions
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4
arch/s390/kernel/entry.S
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@ -190,7 +190,9 @@ ENTRY(__switch_to)
stg %r15,__LC_KERNEL_STACK # store end of kernel stack stg %r15,__LC_KERNEL_STACK # store end of kernel stack
lg %r15,__THREAD_ksp(%r1) # load kernel stack of next lg %r15,__THREAD_ksp(%r1) # load kernel stack of next
/* c4 is used in guest detection: arch/s390/kernel/perf_cpum_sf.c */ /* c4 is used in guest detection: arch/s390/kernel/perf_cpum_sf.c */
lctl %c4,%c4,__TASK_pid(%r3) # load pid to control reg. 4 xc __SF_EMPTY(8,%r15),__SF_EMPTY(%r15)
mvc __SF_EMPTY+4(4,%r15),__TASK_pid(%r3)
lctlg %c4,%c4,__SF_EMPTY(%r15) # load pid to control reg. 4
mvc __LC_CURRENT_PID(4,%r0),__TASK_pid(%r3) # store pid of next mvc __LC_CURRENT_PID(4,%r0),__TASK_pid(%r3) # store pid of next
lmg %r6,%r15,__SF_GPRS(%r15) # load gprs of next task lmg %r6,%r15,__SF_GPRS(%r15) # load gprs of next task
TSTMSK __LC_MACHINE_FLAGS,MACHINE_FLAG_LPP TSTMSK __LC_MACHINE_FLAGS,MACHINE_FLAG_LPP