spinlock torture tests made it clear that checking mmu_enabled()
every time we call spin_lock is a bad idea. As most tests will
want the MMU enabled the entire time, then we can inline a light
weight "nobody disabled the mmu" check, and bail out early.
Adding a light weight inlined check vs. a compile-time flag
suggested by Paolo.
Signed-off-by: Andrew Jones <drjones@xxxxxxxxxx>
---
lib/arm/asm/mmu-api.h | 7 ++++++-
lib/arm/mmu.c | 9 +++++++--
2 files changed, 13 insertions(+), 3 deletions(-)
diff --git a/lib/arm/asm/mmu-api.h b/lib/arm/asm/mmu-api.h
index 12fdc57918c27..b2fc900a30add 100644
--- a/lib/arm/asm/mmu-api.h
+++ b/lib/arm/asm/mmu-api.h
@@ -1,7 +1,12 @@
#ifndef __ASMARM_MMU_API_H_
#define __ASMARM_MMU_API_H_
extern pgd_t *mmu_idmap;
-extern bool mmu_enabled(void);
+extern unsigned int mmu_disabled_cpu_count;
+extern bool __mmu_enabled(void);
+static inline bool mmu_enabled(void)
+{
+ return mmu_disabled_cpu_count == 0 || __mmu_enabled();
+}
extern void mmu_enable(pgd_t *pgtable);
extern void mmu_disable(void);
extern void mmu_enable_idmap(void);
diff --git a/lib/arm/mmu.c b/lib/arm/mmu.c
index ad558e177dd1c..e661d4f26e4b7 100644
--- a/lib/arm/mmu.c
+++ b/lib/arm/mmu.c
@@ -15,8 +15,9 @@ extern unsigned long etext;
pgd_t *mmu_idmap;
static cpumask_t mmu_disabled_cpumask;
+unsigned int mmu_disabled_cpu_count;
-bool mmu_enabled(void)
+bool __mmu_enabled(void)
{
int cpu = current_thread_info()->cpu;
@@ -30,7 +31,9 @@ void mmu_enable(pgd_t *pgtable)
asm_mmu_enable(__pa(pgtable));
flush_tlb_all();
- cpumask_clear_cpu(cpu, &mmu_disabled_cpumask);
+
+ if (cpumask_test_and_clear_cpu(cpu, &mmu_disabled_cpumask))
+ --mmu_disabled_cpu_count;
}
extern void asm_mmu_disable(void);
@@ -39,6 +42,8 @@ void mmu_disable(void)
int cpu = current_thread_info()->cpu;
cpumask_set_cpu(cpu, &mmu_disabled_cpumask);
+ ++mmu_disabled_cpu_count;
+
asm_mmu_disable();
}
--
2.4.3
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
