3.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: Marc Zyngier <Marc.Zyngier@xxxxxxx>
commit 0d0752bca1f9a91fb646647aa4abbb21156f316c upstream.
Looking into the active_asids array is not enough, as we also need
to look into the reserved_asids array (they both represent processes
that are currently running).
Also, not holding the ASID allocator lock is racy, as another CPU
could schedule that process and trigger a rollover, making the erratum
workaround miss an IPI.
Exposing this outside of context.c is a little ugly on the side, so
let's define a new entry point that the erratum workaround can call
to obtain the cpumask.
Acked-by: Will Deacon <will.deacon@xxxxxxx>
Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm/include/asm/mmu_context.h | 10 +++++++++-
arch/arm/kernel/smp_tlb.c | 18 ++----------------
arch/arm/mm/context.c | 29 ++++++++++++++++++++++++++++-
3 files changed, 39 insertions(+), 18 deletions(-)
--- a/arch/arm/include/asm/mmu_context.h
+++ b/arch/arm/include/asm/mmu_context.h
@@ -27,7 +27,15 @@ void __check_vmalloc_seq(struct mm_struc
void check_and_switch_context(struct mm_struct *mm, struct task_struct *tsk);
#define init_new_context(tsk,mm) ({ atomic64_set(&mm->context.id, 0); 0; })
-DECLARE_PER_CPU(atomic64_t, active_asids);
+#ifdef CONFIG_ARM_ERRATA_798181
+void a15_erratum_get_cpumask(int this_cpu, struct mm_struct *mm,
+ cpumask_t *mask);
+#else /* !CONFIG_ARM_ERRATA_798181 */
+static inline void a15_erratum_get_cpumask(int this_cpu, struct mm_struct *mm,
+ cpumask_t *mask)
+{
+}
+#endif /* CONFIG_ARM_ERRATA_798181 */
#else /* !CONFIG_CPU_HAS_ASID */
--- a/arch/arm/kernel/smp_tlb.c
+++ b/arch/arm/kernel/smp_tlb.c
@@ -103,7 +103,7 @@ static void broadcast_tlb_a15_erratum(vo
static void broadcast_tlb_mm_a15_erratum(struct mm_struct *mm)
{
- int cpu, this_cpu;
+ int this_cpu;
cpumask_t mask = { CPU_BITS_NONE };
if (!erratum_a15_798181())
@@ -111,21 +111,7 @@ static void broadcast_tlb_mm_a15_erratum
dummy_flush_tlb_a15_erratum();
this_cpu = get_cpu();
- for_each_online_cpu(cpu) {
- if (cpu == this_cpu)
- continue;
- /*
- * We only need to send an IPI if the other CPUs are running
- * the same ASID as the one being invalidated. There is no
- * need for locking around the active_asids check since the
- * switch_mm() function has at least one dmb() (as required by
- * this workaround) in case a context switch happens on
- * another CPU after the condition below.
- */
- if (atomic64_read(&mm->context.id) ==
- atomic64_read(&per_cpu(active_asids, cpu)))
- cpumask_set_cpu(cpu, &mask);
- }
+ a15_erratum_get_cpumask(this_cpu, mm, &mask);
smp_call_function_many(&mask, ipi_flush_tlb_a15_erratum, NULL, 1);
put_cpu();
}
--- a/arch/arm/mm/context.c
+++ b/arch/arm/mm/context.c
@@ -45,10 +45,37 @@ static DEFINE_RAW_SPINLOCK(cpu_asid_lock
static atomic64_t asid_generation = ATOMIC64_INIT(ASID_FIRST_VERSION);
static DECLARE_BITMAP(asid_map, NUM_USER_ASIDS);
-DEFINE_PER_CPU(atomic64_t, active_asids);
+static DEFINE_PER_CPU(atomic64_t, active_asids);
static DEFINE_PER_CPU(u64, reserved_asids);
static cpumask_t tlb_flush_pending;
+#ifdef CONFIG_ARM_ERRATA_798181
+void a15_erratum_get_cpumask(int this_cpu, struct mm_struct *mm,
+ cpumask_t *mask)
+{
+ int cpu;
+ unsigned long flags;
+ u64 context_id, asid;
+
+ raw_spin_lock_irqsave(&cpu_asid_lock, flags);
+ context_id = mm->context.id.counter;
+ for_each_online_cpu(cpu) {
+ if (cpu == this_cpu)
+ continue;
+ /*
+ * We only need to send an IPI if the other CPUs are
+ * running the same ASID as the one being invalidated.
+ */
+ asid = per_cpu(active_asids, cpu).counter;
+ if (asid == 0)
+ asid = per_cpu(reserved_asids, cpu);
+ if (context_id == asid)
+ cpumask_set_cpu(cpu, mask);
+ }
+ raw_spin_unlock_irqrestore(&cpu_asid_lock, flags);
+}
+#endif
+
#ifdef CONFIG_ARM_LPAE
static void cpu_set_reserved_ttbr0(void)
{
--
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