Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 8117ce76 authored by Paolo Galtieri's avatar Paolo Galtieri Committed by Paul Mackerras
Browse files

[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: default avatarPaolo 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: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent 12074a35

arch/ppc/kernel/process.c

+6 −0
Original line number Diff line number Diff line
@@ -417,6 +417,7 @@ void show_regs(struct pt_regs * regs) 


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 @@ void exit_thread(void) 
	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 @@ void flush_thread(void) 
	if (last_task_used_spe == current)

		last_task_used_spe = NULL;

#endif

	preempt_enable();

}



void
@@ -535,6 +539,7 @@ void start_thread(struct pt_regs *regs, unsigned long nip, unsigned long sp) 
	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 @@ void start_thread(struct pt_regs *regs, unsigned long nip, unsigned long sp) 
	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