[PATCH v7 05/24] arm64: mm: Add asid_gen_match() helper
From: Jean-Philippe Brucker <hidden>
Date: 2020-05-19 18:01:55
Also in:
linux-arm-kernel, linux-iommu, linux-mm, linux-pci
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
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 <redacted> --- 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 9b26f9a88724..d702d60e64da 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); }
--
2.26.2