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powerpc: Fix bug causing FP registers corruption on UP + preempt 

This fixes a bug noticed by Paolo Galtieri and fixed for ARCH=ppc in
the previous commit (ppc: fix floating point register corruption).
This fixes the arch/powerpc code by adding preempt_disable/enable,
and also cleans it up a bit by pulling out the code that discards
any lazily-switched CPU register state into a new function, rather
than having that code repeated in three places.

Signed-off-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
Paul Mackerras 2005-11-30 13:20:54 +11:00
parent 8117ce76c2
commit 48abec07cf
1 changed files with 25 additions and 37 deletions
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62
arch/powerpc/kernel/process.c
View File

@ -201,6 +201,28 @@ int dump_spe(struct pt_regs *regs, elf_vrregset_t *evrregs)
}
#endif /* CONFIG_SPE */
/*
* If we are doing lazy switching of CPU state (FP, altivec or SPE),
* and the current task has some state, discard it.
*/
static inline void discard_lazy_cpu_state(void)
{
#ifndef CONFIG_SMP
preempt_disable();
if (last_task_used_math == current)
last_task_used_math = NULL;
#ifdef CONFIG_ALTIVEC
if (last_task_used_altivec == current)
last_task_used_altivec = NULL;
#endif /* CONFIG_ALTIVEC */
#ifdef CONFIG_SPE
if (last_task_used_spe == current)
last_task_used_spe = NULL;
#endif
preempt_enable();
#endif /* CONFIG_SMP */
}
int set_dabr(unsigned long dabr)
{
if (ppc_md.set_dabr)
@ -434,19 +456,7 @@ void show_regs(struct pt_regs * regs)
void exit_thread(void)
{
kprobe_flush_task(current);
#ifndef CONFIG_SMP
if (last_task_used_math == current)
last_task_used_math = NULL;
#ifdef CONFIG_ALTIVEC
if (last_task_used_altivec == current)
last_task_used_altivec = NULL;
#endif /* CONFIG_ALTIVEC */
#ifdef CONFIG_SPE
if (last_task_used_spe == current)
last_task_used_spe = NULL;
#endif
#endif /* CONFIG_SMP */
discard_lazy_cpu_state();
}
void flush_thread(void)
@ -458,18 +468,7 @@ void flush_thread(void)
t->flags ^= (_TIF_ABI_PENDING | _TIF_32BIT);
#endif
#ifndef CONFIG_SMP
if (last_task_used_math == current)
last_task_used_math = NULL;
#ifdef CONFIG_ALTIVEC
if (last_task_used_altivec == current)
last_task_used_altivec = NULL;
#endif /* CONFIG_ALTIVEC */
#ifdef CONFIG_SPE
if (last_task_used_spe == current)
last_task_used_spe = NULL;
#endif
#endif /* CONFIG_SMP */
discard_lazy_cpu_state();
#ifdef CONFIG_PPC64 /* for now */
if (current->thread.dabr) {
@ -635,18 +634,7 @@ void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp)
}
#endif
#ifndef CONFIG_SMP
if (last_task_used_math == current)
last_task_used_math = NULL;
#ifdef CONFIG_ALTIVEC
if (last_task_used_altivec == current)
last_task_used_altivec = NULL;
#endif
#ifdef CONFIG_SPE
if (last_task_used_spe == current)
last_task_used_spe = NULL;
#endif
#endif /* CONFIG_SMP */
discard_lazy_cpu_state();
memset(current->thread.fpr, 0, sizeof(current->thread.fpr));
current->thread.fpscr.val = 0;
#ifdef CONFIG_ALTIVEC