[PATCH] ppc: fix floating point register corruption
I recently discovered a bug on PPC which causes the floating point
registers to get corrupted when CONFIG_PREEMPT=y.
The problem occurred while running a multi threaded Java application that
does floating point. The problem could be reproduced in anywhere from 2 to
6 hours. With the patch I have included below it ran for over a week
without failure.
Signed-off-by: Paolo Galtieri <pgaltieri@mvista.com>
Cc: Kumar Gala <galak@gate.crashing.org>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Tom Rini <trini@kernel.crashing.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/ppc/kernel/process.c b/arch/ppc/kernel/process.c
index cb1c7b9..25cbdc8 100644
--- a/arch/ppc/kernel/process.c
+++ b/arch/ppc/kernel/process.c
@@ -417,6 +417,7 @@
void exit_thread(void)
{
+ preempt_disable();
if (last_task_used_math == current)
last_task_used_math = NULL;
if (last_task_used_altivec == current)
@@ -425,10 +426,12 @@
if (last_task_used_spe == current)
last_task_used_spe = NULL;
#endif
+ preempt_enable();
}
void flush_thread(void)
{
+ preempt_disable();
if (last_task_used_math == current)
last_task_used_math = NULL;
if (last_task_used_altivec == current)
@@ -437,6 +440,7 @@
if (last_task_used_spe == current)
last_task_used_spe = NULL;
#endif
+ preempt_enable();
}
void
@@ -535,6 +539,7 @@
regs->nip = nip;
regs->gpr[1] = sp;
regs->msr = MSR_USER;
+ preempt_disable();
if (last_task_used_math == current)
last_task_used_math = NULL;
if (last_task_used_altivec == current)
@@ -543,6 +548,7 @@
if (last_task_used_spe == current)
last_task_used_spe = NULL;
#endif
+ preempt_enable();
memset(current->thread.fpr, 0, sizeof(current->thread.fpr));
current->thread.fpscr.val = 0;
#ifdef CONFIG_ALTIVEC