diff options
author | Will Deacon <will.deacon@arm.com> | 2015-10-06 18:46:27 +0100 |
---|---|---|
committer | Catalin Marinas <catalin.marinas@arm.com> | 2015-10-07 11:56:25 +0100 |
commit | c2775b2ee5caca19f661ee2ab5af92462596db71 (patch) | |
tree | ebcc6eb88426e864d8f716543e69f398f1fc1c91 /arch/arm64/mm/context.c | |
parent | 5a7862e83000ccfd36db927c6f060458fe271157 (diff) | |
download | linux-c2775b2ee5caca19f661ee2ab5af92462596db71.tar.gz linux-c2775b2ee5caca19f661ee2ab5af92462596db71.tar.bz2 linux-c2775b2ee5caca19f661ee2ab5af92462596db71.zip |
arm64: switch_mm: simplify mm and CPU checks
switch_mm performs some checks to try and avoid entering the ASID
allocator:
(1) If we're switching to the init_mm (no user mappings), then simply
set a reserved TTBR0 value with no page table (the zero page)
(2) If prev == next *and* the mm_cpumask indicates that we've run on
this CPU before, then we can skip the allocator.
However, there is plenty of redundancy here. With the new ASID allocator,
if prev == next, then we know that our ASID is valid and do not need to
worry about re-allocation. Consequently, we can drop the mm_cpumask check
in (2) and move the prev == next check before the init_mm check, since
if prev == next == init_mm then there's nothing to do.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/mm/context.c')
-rw-r--r-- | arch/arm64/mm/context.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c index e902229b1a3d..4b9ec4484e3f 100644 --- a/arch/arm64/mm/context.c +++ b/arch/arm64/mm/context.c @@ -166,10 +166,10 @@ void check_and_switch_context(struct mm_struct *mm, unsigned int cpu) local_flush_tlb_all(); atomic64_set(&per_cpu(active_asids, cpu), asid); - cpumask_set_cpu(cpu, mm_cpumask(mm)); raw_spin_unlock_irqrestore(&cpu_asid_lock, flags); switch_mm_fastpath: + cpumask_set_cpu(cpu, mm_cpumask(mm)); cpu_switch_mm(mm->pgd, mm); } |