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authorLeonid Yegoshin <yegoshin@mips.com>2012-07-19 09:11:14 +0200
committerRalf Baechle <ralf@linux-mips.org>2012-07-19 11:23:43 +0200
commit2dd17030c940ef1199a07b095ec79c4660fa8734 (patch)
tree34261c3c27f418a785ef127afe6a1f0109310a53
parentdc34b05fea0cc9a869863b929f37f1e8ce30edf4 (diff)
MIPS: Fix race condition with FPU thread task flag during context switch.
[ralf@linux-mips.org: Cosmetic changes; also fixed up r2300_switch.S and octeon_switch.S which needed similar modifications.] Signed-off-by: Leonid Yegoshin <yegoshin@mips.com> Signed-off-by: Steven J. Hill <sjhill@mips.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/3784/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
-rw-r--r--arch/mips/include/asm/switch_to.h6
-rw-r--r--arch/mips/kernel/octeon_switch.S2
-rw-r--r--arch/mips/kernel/r2300_switch.S15
-rw-r--r--arch/mips/kernel/r4k_switch.S12
4 files changed, 11 insertions, 24 deletions
diff --git a/arch/mips/include/asm/switch_to.h b/arch/mips/include/asm/switch_to.h
index 5d33621b565..4f8ddba8c36 100644
--- a/arch/mips/include/asm/switch_to.h
+++ b/arch/mips/include/asm/switch_to.h
@@ -22,7 +22,7 @@ struct task_struct;
* switch_to(n) should switch tasks to task nr n, first
* checking that n isn't the current task, in which case it does nothing.
*/
-extern asmlinkage void *resume(void *last, void *next, void *next_ti);
+extern asmlinkage void *resume(void *last, void *next, void *next_ti, u32 __usedfpu);
extern unsigned int ll_bit;
extern struct task_struct *ll_task;
@@ -66,11 +66,13 @@ do { \
#define switch_to(prev, next, last) \
do { \
+ u32 __usedfpu; \
__mips_mt_fpaff_switch_to(prev); \
if (cpu_has_dsp) \
__save_dsp(prev); \
__clear_software_ll_bit(); \
- (last) = resume(prev, next, task_thread_info(next)); \
+ __usedfpu = test_and_clear_tsk_thread_flag(prev, TIF_USEDFPU); \
+ (last) = resume(prev, next, task_thread_info(next), __usedfpu); \
} while (0)
#define finish_arch_switch(prev) \
diff --git a/arch/mips/kernel/octeon_switch.S b/arch/mips/kernel/octeon_switch.S
index ce89c806170..0441f54b2a6 100644
--- a/arch/mips/kernel/octeon_switch.S
+++ b/arch/mips/kernel/octeon_switch.S
@@ -31,7 +31,7 @@
/*
* task_struct *resume(task_struct *prev, task_struct *next,
- * struct thread_info *next_ti)
+ * struct thread_info *next_ti, int usedfpu)
*/
.align 7
LEAF(resume)
diff --git a/arch/mips/kernel/r2300_switch.S b/arch/mips/kernel/r2300_switch.S
index 293898391e6..9c51be5a163 100644
--- a/arch/mips/kernel/r2300_switch.S
+++ b/arch/mips/kernel/r2300_switch.S
@@ -43,7 +43,7 @@
/*
* task_struct *resume(task_struct *prev, task_struct *next,
- * struct thread_info *next_ti) )
+ * struct thread_info *next_ti, int usedfpu)
*/
LEAF(resume)
mfc0 t1, CP0_STATUS
@@ -51,18 +51,9 @@ LEAF(resume)
cpu_save_nonscratch a0
sw ra, THREAD_REG31(a0)
- /*
- * check if we need to save FPU registers
- */
- lw t3, TASK_THREAD_INFO(a0)
- lw t0, TI_FLAGS(t3)
- li t1, _TIF_USEDFPU
- and t2, t0, t1
- beqz t2, 1f
- nor t1, zero, t1
+ beqz a3, 1f
- and t0, t0, t1
- sw t0, TI_FLAGS(t3)
+ PTR_L t3, TASK_THREAD_INFO(a0)
/*
* clear saved user stack CU1 bit
diff --git a/arch/mips/kernel/r4k_switch.S b/arch/mips/kernel/r4k_switch.S
index 9414f935446..42d2a393842 100644
--- a/arch/mips/kernel/r4k_switch.S
+++ b/arch/mips/kernel/r4k_switch.S
@@ -41,7 +41,7 @@
/*
* task_struct *resume(task_struct *prev, task_struct *next,
- * struct thread_info *next_ti)
+ * struct thread_info *next_ti, int usedfpu)
*/
.align 5
LEAF(resume)
@@ -53,16 +53,10 @@
/*
* check if we need to save FPU registers
*/
- PTR_L t3, TASK_THREAD_INFO(a0)
- LONG_L t0, TI_FLAGS(t3)
- li t1, _TIF_USEDFPU
- and t2, t0, t1
- beqz t2, 1f
- nor t1, zero, t1
- and t0, t0, t1
- LONG_S t0, TI_FLAGS(t3)
+ beqz a3, 1f
+ PTR_L t3, TASK_THREAD_INFO(a0)
/*
* clear saved user stack CU1 bit
*/