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authorPaul Burton <paul.burton@imgtec.com>2015-09-21 10:07:42 -0700
committerRalf Baechle <ralf@linux-mips.org>2015-10-02 19:16:46 +0200
commit085c2f25d36ef4a69bb1dab933daee0692426f15 (patch)
tree7fc03ac0ba5a66889daa06524abb8f5159c1ec09 /arch
parent0fa24340f7c88d2814547d8d24d5e3a1803009cc (diff)
downloadlinux-linaro-stable-085c2f25d36ef4a69bb1dab933daee0692426f15.tar.gz
MIPS: Fix R2300 FP context switch handling
Commit 1a3d59579b9f ("MIPS: Tidy up FPU context switching") removed FP context saving from the asm-written resume function in favour of reusing existing code to perform the same task. However it only removed the FP context saving code from the r4k_switch.S implementation of resume. Remove it from the r2300_switch.S implementation too in order to prevent attempting to save the FP context twice, which would likely lead to an exception from the second save because the FPU had already been disabled by the first save. This patch has only been build tested, using rbtx49xx_defconfig. Fixes: 1a3d59579b9f ("MIPS: Tidy up FPU context switching") Signed-off-by: Paul Burton <paul.burton@imgtec.com> Cc: linux-mips@linux-mips.org Cc: Maciej W. Rozycki <macro@linux-mips.org> Cc: linux-kernel@vger.kernel.org Cc: Manuel Lauss <manuel.lauss@gmail.com> Patchwork: https://patchwork.linux-mips.org/patch/11167/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/mips/kernel/r2300_switch.S28
1 files changed, 1 insertions, 27 deletions
diff --git a/arch/mips/kernel/r2300_switch.S b/arch/mips/kernel/r2300_switch.S
index 5087a4b72e6b..ac27ef7d4d0e 100644
--- a/arch/mips/kernel/r2300_switch.S
+++ b/arch/mips/kernel/r2300_switch.S
@@ -31,18 +31,8 @@
#define ST_OFF (_THREAD_SIZE - 32 - PT_SIZE + PT_STATUS)
/*
- * FPU context is saved iff the process has used it's FPU in the current
- * time slice as indicated by TIF_USEDFPU. In any case, the CU1 bit for user
- * space STATUS register should be 0, so that a process *always* starts its
- * userland with FPU disabled after each context switch.
- *
- * FPU will be enabled as soon as the process accesses FPU again, through
- * do_cpu() trap.
- */
-
-/*
* task_struct *resume(task_struct *prev, task_struct *next,
- * struct thread_info *next_ti, int usedfpu)
+ * struct thread_info *next_ti)
*/
LEAF(resume)
mfc0 t1, CP0_STATUS
@@ -50,22 +40,6 @@ LEAF(resume)
cpu_save_nonscratch a0
sw ra, THREAD_REG31(a0)
- beqz a3, 1f
-
- PTR_L t3, TASK_THREAD_INFO(a0)
-
- /*
- * clear saved user stack CU1 bit
- */
- lw t0, ST_OFF(t3)
- li t1, ~ST0_CU1
- and t0, t0, t1
- sw t0, ST_OFF(t3)
-
- fpu_save_single a0, t0 # clobbers t0
-
-1:
-
#if defined(CONFIG_CC_STACKPROTECTOR) && !defined(CONFIG_SMP)
PTR_LA t8, __stack_chk_guard
LONG_L t9, TASK_STACK_CANARY(a1)