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author | Michael Neuling | 2009-04-01 20:02:42 +0200 |
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committer | Paul Mackerras | 2009-04-07 07:18:59 +0200 |
commit | 7e875e9dc8af70d126fa632446e967327ac3fdda (patch) | |
tree | 22757e6faff097d01931194c4af051017cb1c359 /scripts/unifdef.c | |
parent | powerpc/pseries: Enable relay in pseries_defconfig (diff) | |
download | kernel-qcow2-linux-7e875e9dc8af70d126fa632446e967327ac3fdda.tar.gz kernel-qcow2-linux-7e875e9dc8af70d126fa632446e967327ac3fdda.tar.xz kernel-qcow2-linux-7e875e9dc8af70d126fa632446e967327ac3fdda.zip |
powerpc: Disable VSX or current process in giveup_fpu/altivec
When we call giveup_fpu, we need to need to turn off VSX for the
current process. If we don't, on return to userspace it may execute a
VSX instruction before the next FP instruction, and not have its
register state refreshed correctly from the thread_struct. Ditto for
altivec.
This caused a bug where an unaligned lfs or stfs results in
fix_alignment calling giveup_fpu so it can use the FPRs (in order to
do a single <-> double conversion), and then returning to userspace
with FP off but VSX on. Then if a VSX instruction is executed, before
another FP instruction, it will proceed without another exception and
hence have the incorrect register state for VSX registers 0-31.
lfs unaligned <- alignment exception turns FP off but leaves VSX on
VSX instruction <- no exception since VSX on, hence we get the
wrong VSX register values for VSX registers 0-31,
which overlap the FPRs.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'scripts/unifdef.c')
0 files changed, 0 insertions, 0 deletions