diff options
| author | Catalin Marinas <catalin.marinas@arm.com> | 2013-07-23 15:15:36 (GMT) |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2013-07-26 11:02:09 (GMT) |
| commit | bdae73cd374e28db544fdd9b77de689a36e3c129 (patch) | |
| tree | aa22b6e3e1232f27fa50c24a2144daa65d61d7c6 | |
| parent | 1f49856bb029779d8f1b63517a3a3b34ffe672c7 (diff) | |
| download | linux-bdae73cd374e28db544fdd9b77de689a36e3c129.tar.xz | |
ARM: 7790/1: Fix deferred mm switch on VIVT processors
As of commit b9d4d42ad9 (ARM: Remove __ARCH_WANT_INTERRUPTS_ON_CTXSW on
pre-ARMv6 CPUs), the mm switching on VIVT processors is done in the
finish_arch_post_lock_switch() function to avoid whole cache flushing
with interrupts disabled. The need for deferred mm switch is stored as a
thread flag (TIF_SWITCH_MM). However, with preemption enabled, we can
have another thread switch before finish_arch_post_lock_switch(). If the
new thread has the same mm as the previous 'next' thread, the scheduler
will not call switch_mm() and the TIF_SWITCH_MM flag won't be set for
the new thread.
This patch moves the switch pending flag to the mm_context_t structure
since this is specific to the mm rather than thread.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: Marc Kleine-Budde <mkl@pengutronix.de>
Tested-by: Marc Kleine-Budde <mkl@pengutronix.de>
Cc: <stable@vger.kernel.org> # 3.5+
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
| -rw-r--r-- | arch/arm/include/asm/mmu.h | 2 | ||||
| -rw-r--r-- | arch/arm/include/asm/mmu_context.h | 20 | ||||
| -rw-r--r-- | arch/arm/include/asm/thread_info.h | 1 |
3 files changed, 18 insertions, 5 deletions
diff --git a/arch/arm/include/asm/mmu.h b/arch/arm/include/asm/mmu.h index e3d5554..d1b4998 100644 --- a/arch/arm/include/asm/mmu.h +++ b/arch/arm/include/asm/mmu.h @@ -6,6 +6,8 @@ typedef struct { #ifdef CONFIG_CPU_HAS_ASID atomic64_t id; +#else + int switch_pending; #endif unsigned int vmalloc_seq; } mm_context_t; diff --git a/arch/arm/include/asm/mmu_context.h b/arch/arm/include/asm/mmu_context.h index b5792b7..9b32f76 100644 --- a/arch/arm/include/asm/mmu_context.h +++ b/arch/arm/include/asm/mmu_context.h @@ -56,7 +56,7 @@ static inline void check_and_switch_context(struct mm_struct *mm, * on non-ASID CPUs, the old mm will remain valid until the * finish_arch_post_lock_switch() call. */ - set_ti_thread_flag(task_thread_info(tsk), TIF_SWITCH_MM); + mm->context.switch_pending = 1; else cpu_switch_mm(mm->pgd, mm); } @@ -65,9 +65,21 @@ static inline void check_and_switch_context(struct mm_struct *mm, finish_arch_post_lock_switch static inline void finish_arch_post_lock_switch(void) { - if (test_and_clear_thread_flag(TIF_SWITCH_MM)) { - struct mm_struct *mm = current->mm; - cpu_switch_mm(mm->pgd, mm); + struct mm_struct *mm = current->mm; + + if (mm && mm->context.switch_pending) { + /* + * Preemption must be disabled during cpu_switch_mm() as we + * have some stateful cache flush implementations. Check + * switch_pending again in case we were preempted and the + * switch to this mm was already done. + */ + preempt_disable(); + if (mm->context.switch_pending) { + mm->context.switch_pending = 0; + cpu_switch_mm(mm->pgd, mm); + } + preempt_enable_no_resched(); } } diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h index 214d415..2b8114f 100644 --- a/arch/arm/include/asm/thread_info.h +++ b/arch/arm/include/asm/thread_info.h @@ -156,7 +156,6 @@ extern int vfp_restore_user_hwstate(struct user_vfp __user *, #define TIF_USING_IWMMXT 17 #define TIF_MEMDIE 18 /* is terminating due to OOM killer */ #define TIF_RESTORE_SIGMASK 20 -#define TIF_SWITCH_MM 22 /* deferred switch_mm */ #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED) |