arm64: Update comment for ASID() macro

Commit 25b92693a1 ("arm64: mm: convert cpu_do_switch_mm() to C") added
a new use of the ASID() macro, so update the comment in asm/mmu.h which
reasons about why an atomic reload of 'mm->context.id.counter' is not
required.

Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Will Deacon 2020-02-28 12:43:55 +00:00 committed by Catalin Marinas
parent 25b92693a1
commit 90765f745b

View File

@ -23,9 +23,9 @@ typedef struct {
} mm_context_t;
/*
* This macro is only used by the TLBI code, which cannot race with an
* ASID change and therefore doesn't need to reload the counter using
* atomic64_read.
* This macro is only used by the TLBI and low-level switch_mm() code,
* neither of which can race with an ASID change. We therefore don't
* need to reload the counter using atomic64_read().
*/
#define ASID(mm) ((mm)->context.id.counter & 0xffff)