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s390: fix handling of runtime instrumentation psw bit

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Fix the following bugs:
- When returning from a signal the signal handler copies the saved psw mask
  from user space and uses parts of it. Especially it restores the RI bit
  unconditionally. If however the machine doesn't support RI, or RI is
  disabled for the task, the last lpswe instruction which returns to user
  space will generate a specification exception.
  To fix this check if the RI bit is allowed to be set and kill the task
  if not.
- In the compat mode signal handler code the RI bit of the psw mask gets
  propagated to the mask of the return psw: if user space enables RI in the
  signal handler, RI will also be enabled after the signal handler is
  finished.
  This is a different behaviour than with 64 bit tasks. So change this to
  match the 64 bit semantics, which restores the original RI bit value.
- Fix similar oddities within the ptrace code as well.

Reviewed-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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
2013-10-16 09:58:01 +02:00
committed by Martin Schwidefsky
parent 4725c86055
commit 5ebf250dab
6 changed files with 37 additions and 15 deletions
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arch/s390/include/asm/compat.h
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@@ -22,6 +22,7 @@
#define PSW32_MASK_ASC 0x0000C000UL
#define PSW32_MASK_CC 0x00003000UL
#define PSW32_MASK_PM 0x00000f00UL
#define PSW32_MASK_RI 0x00000080UL
#define PSW32_MASK_USER 0x0000FF00UL