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[PATCH] i386: fix broken FP exception handling

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The FXSAVE information leak patch introduced a bug in FP exception
handling: it clears FP exceptions only when there are already
none outstanding.  Mikael Pettersson reported that causes problems
with the Erlang runtime and has tested this fix.

Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com>
Acked-by: Mikael Pettersson <mikpe@it.uu.se>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Chuck Ebbert 2006-04-29 14:07:49 -04:00 committed by Linus Torvalds
parent 693f7d3620
commit 543f2a3382
1 changed files with 2 additions and 2 deletions
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4
include/asm-i386/i387.h
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@ -58,13 +58,13 @@ static inline void __save_init_fpu( struct task_struct *tsk )
alternative_input(
"fnsave %[fx] ;fwait;" GENERIC_NOP8 GENERIC_NOP4,
"fxsave %[fx]\n"
"bt $7,%[fsw] ; jc 1f ; fnclex\n1:",
"bt $7,%[fsw] ; jnc 1f ; fnclex\n1:",
X86_FEATURE_FXSR,
[fx] "m" (tsk->thread.i387.fxsave),
[fsw] "m" (tsk->thread.i387.fxsave.swd) : "memory");
/* AMD K7/K8 CPUs don't save/restore FDP/FIP/FOP unless an exception
is pending. Clear the x87 state here by setting it to fixed
values. __per_cpu_offset[0] is a random variable that should be in L1 */
values. safe_address is a random variable that should be in L1 */
alternative_input(
GENERIC_NOP8 GENERIC_NOP2,
"emms\n\t" /* clear stack tags */