Commit 0d0752bc authored by Marc Zyngier's avatar Marc Zyngier Committed by Russell King
Browse files

ARM: 7769/1: Cortex-A15: fix erratum 798181 implementation 



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.

Cc: <stable@vger.kernel.org> # 3.9
Acked-by: default avatarWill Deacon <will.deacon@arm.com>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent b8e4a474

arch/arm/include/asm/mmu_context.h

+9 −1
Original line number Diff line number Diff line
@@ -28,7 +28,15 @@ void __check_vmalloc_seq(struct mm_struct *mm); 
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 */

arch/arm/kernel/smp_tlb.c

+2 −16
Original line number Diff line number Diff line
@@ -103,7 +103,7 @@ static void broadcast_tlb_a15_erratum(void) 


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(struct mm_struct *mm) 


	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();

}

arch/arm/mm/context.c

+28 −1
Original line number Diff line number Diff line
@@ -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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