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s390: fix floating point register corruption

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The critical section cleanup code misses to add the offset of the
thread_struct to the task address.
Therefore, if the critical section code gets executed, it may corrupt
the task struct or restore the contents of the floating point registers
from the wrong memory location.
Fixes d0164ee20d "s390/kernel: remove save_fpu_regs() parameter and use
__LC_CURRENT instead".

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Heiko Carstens 2015-09-09 13:15:00 +02:00 committed by Martin Schwidefsky
parent 88d6425378
commit 9380cf5a88
1 changed files with 2 additions and 0 deletions
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2
arch/s390/kernel/entry.S
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@ -1191,6 +1191,7 @@ cleanup_critical:
clg %r9,BASED(.Lcleanup_save_fpu_fpc_end)
jhe 1f
lg %r2,__LC_CURRENT
aghi %r2,__TASK_thread
0: # Store floating-point controls
stfpc __THREAD_FPU_fpc(%r2)
1: # Load register save area and check if VX is active
@ -1252,6 +1253,7 @@ cleanup_critical:
clg %r9,BASED(.Lcleanup_load_fpu_regs_vx_ctl)
jhe 6f
lg %r4,__LC_CURRENT
aghi %r4,__TASK_thread
lfpc __THREAD_FPU_fpc(%r4)
tm __THREAD_FPU_flags+3(%r4),FPU_USE_VX # VX-enabled task ?
lg %r4,__THREAD_FPU_regs(%r4) # %r4 <- reg save area