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MIPS: Loongson: Fix COP2 usage for preemptible kernel 

In preemptible kernel, only TIF_USEDFPU flag is reliable to distinguish
whether _init_fpu()/_restore_fp() is needed. Because the value of the
CP0_Status.CU1 isn't changed during preemption.

V2: Fix coding style.

Signed-off-by: Huacai Chen <chenhc@lemote.com>
Cc: John Crispin <john@phrozen.org>
Cc: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: linux-mips@linux-mips.org
Cc: Fuxin Zhang <zhangfx@lemote.com>
Cc: Zhangjin Wu <wuzhangjin@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/7515/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Huacai Chen 2014-08-11 17:10:38 +08:00 committed by Ralf Baechle
parent bbbf6d8768
commit bfcdf13063
1 changed files with 4 additions and 4 deletions
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8
arch/mips/loongson/loongson-3/cop2-ex.c
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@ -22,13 +22,13 @@
static int loongson_cu2_call(struct notifier_block *nfb, unsigned long action,
void *data)
{
int fpu_enabled;
int fpu_owned;
int fr = !test_thread_flag(TIF_32BIT_FPREGS);
switch (action) {
case CU2_EXCEPTION:
preempt_disable();
fpu_enabled = read_c0_status() & ST0_CU1;
fpu_owned = __is_fpu_owner();
if (!fr)
set_c0_status(ST0_CU1 | ST0_CU2);
else
@ -39,8 +39,8 @@ static int loongson_cu2_call(struct notifier_block *nfb, unsigned long action,
KSTK_STATUS(current) |= ST0_FR;
else
KSTK_STATUS(current) &= ~ST0_FR;
/* If FPU is enabled, we needn't init or restore fp */
if(!fpu_enabled) {
/* If FPU is owned, we needn't init or restore fp */
if (!fpu_owned) {
set_thread_flag(TIF_USEDFPU);
if (!used_math()) {
_init_fpu();