From 4fc92254bf86b19ac1ef81f61f4e690fccfcba4a Mon Sep 17 00:00:00 2001 From: Jean-Philippe Brucker Date: Tue, 19 May 2020 19:54:43 +0200 Subject: [PATCH] arm64: mm: Add asid_gen_match() helper Add a macro to check if an ASID is from the current generation, since a subsequent patch will introduce a third user for this test. Signed-off-by: Jean-Philippe Brucker Link: https://lore.kernel.org/r/20200519175502.2504091-6-jean-philippe@linaro.org Signed-off-by: Will Deacon --- arch/arm64/mm/context.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c index 9b26f9a..d702d60 100644 --- a/arch/arm64/mm/context.c +++ b/arch/arm64/mm/context.c @@ -92,6 +92,9 @@ static void set_reserved_asid_bits(void) bitmap_clear(asid_map, 0, NUM_USER_ASIDS); } +#define asid_gen_match(asid) \ + (!(((asid) ^ atomic64_read(&asid_generation)) >> asid_bits)) + static void flush_context(void) { int i; @@ -220,8 +223,7 @@ void check_and_switch_context(struct mm_struct *mm, unsigned int cpu) * because atomic RmWs are totally ordered for a given location. */ old_active_asid = atomic64_read(&per_cpu(active_asids, cpu)); - if (old_active_asid && - !((asid ^ atomic64_read(&asid_generation)) >> asid_bits) && + if (old_active_asid && asid_gen_match(asid) && atomic64_cmpxchg_relaxed(&per_cpu(active_asids, cpu), old_active_asid, asid)) goto switch_mm_fastpath; @@ -229,7 +231,7 @@ void check_and_switch_context(struct mm_struct *mm, unsigned int cpu) raw_spin_lock_irqsave(&cpu_asid_lock, flags); /* Check that our ASID belongs to the current generation. */ asid = atomic64_read(&mm->context.id); - if ((asid ^ atomic64_read(&asid_generation)) >> asid_bits) { + if (!asid_gen_match(asid)) { asid = new_context(mm); atomic64_set(&mm->context.id, asid); } -- 2.7.4