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Subject[PATCH v3 5/6] ARM: Remove current_mm per-cpu variable
Date
The current_mm variable was used to store the new mm between the
switch_mm() and switch_to() calls where an IPI to reset the context
could have set the wrong mm. Since the interrupts are disabled during
context switch, there is no need for this variable, current->active_mm
already points to the current mm when interrupts are re-enabled.

Reviewed-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Frank Rowand <frank.rowand@am.sony.com>
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
---
arch/arm/include/asm/mmu_context.h | 7 -------
arch/arm/mm/context.c | 12 +-----------
2 files changed, 1 insertions(+), 18 deletions(-)

diff --git a/arch/arm/include/asm/mmu_context.h b/arch/arm/include/asm/mmu_context.h
index 35483a8..6c42d51 100644
--- a/arch/arm/include/asm/mmu_context.h
+++ b/arch/arm/include/asm/mmu_context.h
@@ -42,9 +42,6 @@ void __check_kvm_seq(struct mm_struct *mm);
#define ASID_FIRST_VERSION (1 << ASID_BITS)

extern unsigned int cpu_last_asid;
-#ifdef CONFIG_SMP
-DECLARE_PER_CPU(struct mm_struct *, current_mm);
-#endif

void __init_new_context(struct task_struct *tsk, struct mm_struct *mm);
void __new_context(struct mm_struct *mm);
@@ -159,10 +156,6 @@ switch_mm(struct mm_struct *prev, struct mm_struct *next,
__flush_icache_all();
#endif
if (!cpumask_test_and_set_cpu(cpu, mm_cpumask(next)) || prev != next) {
-#ifdef CONFIG_SMP
- struct mm_struct **crt_mm = &per_cpu(current_mm, cpu);
- *crt_mm = next;
-#endif
check_and_switch_context(next, tsk);
if (cache_is_vivt())
cpumask_clear_cpu(cpu, mm_cpumask(prev));
diff --git a/arch/arm/mm/context.c b/arch/arm/mm/context.c
index ab35a86..1be5a55 100644
--- a/arch/arm/mm/context.c
+++ b/arch/arm/mm/context.c
@@ -18,9 +18,6 @@

static DEFINE_RAW_SPINLOCK(cpu_asid_lock);
unsigned int cpu_last_asid = ASID_FIRST_VERSION;
-#ifdef CONFIG_SMP
-DEFINE_PER_CPU(struct mm_struct *, current_mm);
-#endif

#ifdef CONFIG_ARM_LPAE
void cpu_set_reserved_ttbr0(void)
@@ -108,14 +105,7 @@ static void reset_context(void *info)
{
unsigned int asid;
unsigned int cpu = smp_processor_id();
- struct mm_struct *mm = per_cpu(current_mm, cpu);
-
- /*
- * Check if a current_mm was set on this CPU as it might still
- * be in the early booting stages and using the reserved ASID.
- */
- if (!mm)
- return;
+ struct mm_struct *mm = current->active_mm;

smp_rmb();
asid = cpu_last_asid + cpu;


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