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[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>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
Paolo Galtieri 2005-11-29 14:26:47 -08:00 committed by Paul Mackerras
parent 12074a35b4
commit 8117ce76c2
1 changed files with 6 additions and 0 deletions
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6
arch/ppc/kernel/process.c
View File

@ -417,6 +417,7 @@ void show_regs(struct pt_regs * regs)
void exit_thread(void) void exit_thread(void)
{ {
preempt_disable();
if (last_task_used_math == current) if (last_task_used_math == current)
last_task_used_math = NULL; last_task_used_math = NULL;
if (last_task_used_altivec == current) if (last_task_used_altivec == current)
@ -425,10 +426,12 @@ void exit_thread(void)
if (last_task_used_spe == current) if (last_task_used_spe == current)
last_task_used_spe = NULL; last_task_used_spe = NULL;
#endif #endif
preempt_enable();
} }
void flush_thread(void) void flush_thread(void)
{ {
preempt_disable();
if (last_task_used_math == current) if (last_task_used_math == current)
last_task_used_math = NULL; last_task_used_math = NULL;
if (last_task_used_altivec == current) if (last_task_used_altivec == current)
@ -437,6 +440,7 @@ void flush_thread(void)
if (last_task_used_spe == current) if (last_task_used_spe == current)
last_task_used_spe = NULL; last_task_used_spe = NULL;
#endif #endif
preempt_enable();
} }
void void
@ -535,6 +539,7 @@ void start_thread(struct pt_regs *regs, unsigned long nip, unsigned long sp)
regs->nip = nip; regs->nip = nip;
regs->gpr[1] = sp; regs->gpr[1] = sp;
regs->msr = MSR_USER; regs->msr = MSR_USER;
preempt_disable();
if (last_task_used_math == current) if (last_task_used_math == current)
last_task_used_math = NULL; last_task_used_math = NULL;
if (last_task_used_altivec == current) if (last_task_used_altivec == current)
@ -543,6 +548,7 @@ void start_thread(struct pt_regs *regs, unsigned long nip, unsigned long sp)
if (last_task_used_spe == current) if (last_task_used_spe == current)
last_task_used_spe = NULL; last_task_used_spe = NULL;
#endif #endif
preempt_enable();
memset(current->thread.fpr, 0, sizeof(current->thread.fpr)); memset(current->thread.fpr, 0, sizeof(current->thread.fpr));
current->thread.fpscr.val = 0; current->thread.fpscr.val = 0;
#ifdef CONFIG_ALTIVEC #ifdef CONFIG_ALTIVEC