ARM: 7661/1: mm: perform explicit branch predictor maintenance when required

The ARM ARM requires branch predictor maintenance if, for a given ASID,
the instructions at a specific virtual address appear to change.

From the kernel's point of view, that means:

	- Changing the kernel's view of memory (e.g. switching to the
	  identity map)
	- ASID rollover (since ASIDs will be re-allocated to new tasks)

This patch adds explicit branch predictor maintenance when either of the
two conditions above are met.

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

4 files changed, 6 insertions, 1 deletions

diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 1bdfd87c8e41..31644f1978d5 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -285,6 +285,7 @@ asmlinkage void __cpuinit secondary_start_kernel(void)
          * switch away from it before attempting any exclusive accesses.
          */
         cpu_switch_mm(mm->pgd, mm);
+        local_flush_bp_all();
         enter_lazy_tlb(mm, current);
         local_flush_tlb_all();
 
diff --git a/arch/arm/kernel/suspend.c b/arch/arm/kernel/suspend.c
index 358bca3a995e..c59c97ea8268 100644
--- a/arch/arm/kernel/suspend.c
+++ b/arch/arm/kernel/suspend.c
@@ -68,6 +68,7 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
         ret = __cpu_suspend(arg, fn);
         if (ret == 0) {
                 cpu_switch_mm(mm->pgd, mm);
+                local_flush_bp_all();
                 local_flush_tlb_all();
         }
 
diff --git a/arch/arm/mm/context.c b/arch/arm/mm/context.c
index 44d4ee52f3e2..a5a4b2bc42ba 100644
--- a/arch/arm/mm/context.c
+++ b/arch/arm/mm/context.c
@@ -212,8 +212,10 @@ void check_and_switch_context(struct mm_struct *mm, struct task_struct *tsk)
                 atomic64_set(&mm->context.id, asid);
         }
 
-        if (cpumask_test_and_clear_cpu(cpu, &tlb_flush_pending))
+        if (cpumask_test_and_clear_cpu(cpu, &tlb_flush_pending)) {
+                local_flush_bp_all();
                 local_flush_tlb_all();
+        }
 
         atomic64_set(&per_cpu(active_asids, cpu), asid);
         cpumask_set_cpu(cpu, mm_cpumask(mm));
diff --git a/arch/arm/mm/idmap.c b/arch/arm/mm/idmap.c
index 2dffc010cc41..5ee505c937d1 100644
--- a/arch/arm/mm/idmap.c
+++ b/arch/arm/mm/idmap.c
@@ -141,6 +141,7 @@ void setup_mm_for_reboot(void)
 {
         /* Switch to the identity mapping. */
         cpu_switch_mm(idmap_pgd, &init_mm);
+        local_flush_bp_all();
 
 #ifdef CONFIG_CPU_HAS_ASID
         /*