diff options
author | Paul Mackerras <paulus@samba.org> | 2007-06-26 14:49:11 +1000 |
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committer | Paul Mackerras <paulus@samba.org> | 2007-06-26 14:49:11 +1000 |
commit | ae62fbb5f1f796d87cbdbe6701e13f2b52d5c0a7 (patch) | |
tree | 42c190d210c90876dbc799fd58896fbdce9164ce /crypto/ecb.c | |
parent | 74609f4536f2b8fd6a48381bbbe3cd37da20a527 (diff) |
[POWERPC] Fix subtle FP state corruption bug in signal return on SMP
This fixes a bug which can cause corruption of the floating-point state
on return from a signal handler. If we have a signal handler that has
used the floating-point registers, and it happens to context-switch to
another task while copying the interrupted floating-point state from the
user stack into the thread struct (e.g. because of a page fault, or
because it gets preempted), the context switch code will think that the
FP registers contain valid FP state that needs to be copied into the
thread_struct, and will thus overwrite the values that the signal return
code has put into the thread_struct.
This can occur because we clear the MSR bits that indicate the presence
of valid FP state after copying the state into the thread_struct. To fix
this we just move the clearing of the MSR bits to before the copy. A
similar potential problem also occurs with the Altivec state, and this
fixes that in the same way.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'crypto/ecb.c')
0 files changed, 0 insertions, 0 deletions