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

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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: Will Deacon <will.deacon@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Marc Zyngier 2013-06-21 12:07:27 +01:00 • committed by Russell King
parent b8e4a4740f
commit 0d0752bca1
3 changed files with 39 additions and 18 deletions
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18
arch/arm/kernel/smp_tlb.c
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@ -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();
}