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Commit 48abec07 authored by Paul Mackerras's avatar Paul Mackerras
Browse files

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: default avatarPaul Mackerras <paulus@samba.org>
parent 8117ce76

arch/powerpc/kernel/process.c

+25 −37
Original line number Diff line number Diff line
@@ -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