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s390: rework __switch_to() to allow larger task_struct offsets 

If GCC_PLUGIN_RANDSTRUCT is enabled the members of task_struct will be
shuffled around. The offsets of the "pid" and "stack" members within
task_struct may not necessarily fit into 12 bits anymore, which causes
compile errors within __switch_to, since instructions are used, which
only have a 12 bit displacement field.

Therefore rework __switch_to, to allow for larger offsets.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Heiko Carstens 2017-11-16 14:54:04 +01:00 committed by Martin Schwidefsky
parent 38389ec84e
commit 3241d3eb7d
1 changed files with 7 additions and 8 deletions
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15
arch/s390/kernel/entry.S
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@ -180,18 +180,17 @@ _PIF_WORK = (_PIF_PER_TRAP | _PIF_SYSCALL_RESTART)
*/
ENTRY(__switch_to)
stmg %r6,%r15,__SF_GPRS(%r15) # store gprs of prev task
lgr %r1,%r2
aghi %r1,__TASK_thread # thread_struct of prev task
lg %r5,__TASK_stack(%r3) # start of kernel stack of next
stg %r15,__THREAD_ksp(%r1) # store kernel stack of prev
lgr %r1,%r3
aghi %r1,__TASK_thread # thread_struct of next task
lghi %r4,__TASK_stack
lghi %r1,__TASK_thread
lg %r5,0(%r4,%r3) # start of kernel stack of next
stg %r15,__THREAD_ksp(%r1,%r2) # store kernel stack of prev
lgr %r15,%r5
aghi %r15,STACK_INIT # end of kernel stack of next
stg %r3,__LC_CURRENT # store task struct of next
stg %r15,__LC_KERNEL_STACK # store end of kernel stack
lg %r15,__THREAD_ksp(%r1) # load kernel stack of next
mvc __LC_CURRENT_PID(4,%r0),__TASK_pid(%r3) # store pid of next
lg %r15,__THREAD_ksp(%r1,%r3) # load kernel stack of next
aghi %r3,__TASK_pid
mvc __LC_CURRENT_PID(4,%r0),0(%r3) # store pid of next
lmg %r6,%r15,__SF_GPRS(%r15) # load gprs of next task
TSTMSK __LC_MACHINE_FLAGS,MACHINE_FLAG_LPP
bzr %r14