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authorCatalin Marinas <catalin.marinas@arm.com>2013-07-23 16:15:36 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-08-11 18:35:20 -0700
commit8271eb9ffaaa3390fb0478f94c88f91623b5af78 (patch)
tree29c57b7774dc916dd62f8ccf58439034e2fb76ba /arch
parent340631138430a7ca215ca76ae74ef70f0be7ac20 (diff)
ARM: 7790/1: Fix deferred mm switch on VIVT processors
commit bdae73cd374e28db544fdd9b77de689a36e3c129 upstream. 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> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm/include/asm/mmu.h2
-rw-r--r--arch/arm/include/asm/mmu_context.h20
-rw-r--r--arch/arm/include/asm/thread_info.h1
3 files changed, 18 insertions, 5 deletions
diff --git a/arch/arm/include/asm/mmu.h b/arch/arm/include/asm/mmu.h
index 7345e37155d..6f18da09668 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;
unsigned long sigpage;
diff --git a/arch/arm/include/asm/mmu_context.h b/arch/arm/include/asm/mmu_context.h
index dc90203c6dd..e0b10f19d67 100644
--- a/arch/arm/include/asm/mmu_context.h
+++ b/arch/arm/include/asm/mmu_context.h
@@ -55,7 +55,7 @@ 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);
}
@@ -64,9 +64,21 @@ 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 1995d1a8406..f00b5692cd9 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)