ARM: 5905/1: ARM: Global ASID allocation on SMP

The current ASID allocation algorithm doesn't ensure the notification
of the other CPUs when the ASID rolls over. This may lead to two
processes using the same ASID (but different generation) or multiple
threads of the same process using different ASIDs.

This patch adds the broadcasting of the ASID rollover event to the
other CPUs. To avoid a race on multiple CPUs modifying "cpu_last_asid"
during the handling of the broadcast, the ASID numbering now starts at
"smp_processor_id() + 1". At rollover, the cpu_last_asid will be set
to NR_CPUS.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/arm/include/asm/mmu.h b/arch/arm/include/asm/mmu.h
index b561584d04a1..68870c776671 100644
--- a/arch/arm/include/asm/mmu.h
+++ b/arch/arm/include/asm/mmu.h
@@ -6,6 +6,7 @@
 typedef struct {
 #ifdef CONFIG_CPU_HAS_ASID
         unsigned int id;
+        spinlock_t id_lock;
 #endif
         unsigned int kvm_seq;
 } mm_context_t;