UPSTREAM: ARM: Remove current_mm per-cpu variable

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>
Tested-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Frank Rowand <frank.rowand@am.sony.com>
Tested-by: Marc Zyngier <Marc.Zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
(cherry picked from commit e323969ccda2d69f02e047c08b03faa09215c72a)

BUG=chromium-os:34007
TEST=generic system testing

Change-Id: I3ba9043520e275d593526f97aa2ecdd877effa4a
Signed-off-by: Olof Johansson <olofj@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/31852
Reviewed-by: Mandeep Singh Baines <msb@chromium.org>

diff --git a/arch/arm/include/asm/mmu_context.h b/arch/arm/include/asm/mmu_context.h
index 94e265c..8da4b9c 100644 (file)
--- a/arch/arm/include/asm/mmu_context.h
+++ b/arch/arm/include/asm/mmu_context.h
@@ -43,9 +43,6 @@ 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);
@@ -160,10 +157,6 @@ 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 4babb4a..119bc52 100644 (file)
--- a/arch/arm/mm/context.c
+++ b/arch/arm/mm/context.c
@@ -19,9 +19,6 @@
 
 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)
@@ -143,14 +140,7 @@ 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 + 1;