Re: [RFC V1 11/16] arm64/mm: Route all pgtable atomics to central helpers

Anshuman Khandual
2026-04-10T04:02:30Z

On 08/04/26 5:58 PM, David Hildenbrand (Arm) wrote:
> On 2/24/26 06:11, Anshuman Khandual wrote:
>> Route all cmpxchg() operations performed on various page table entries to a
>> new ptdesc_cmpxchg_relaxed() helper. Similarly route all xchg() operations
>> performed on page table entries to a new ptdesc_xchg_relaxed() helper.
>>
>> Currently these helpers just forward to the same APIs that were previously
>> called direct, but in future we will change the routing for D128 which is
>> too long to use the standard APIs.
>>
>> Cc: Catalin Marinas <catalin.marinas@arm.com>
>> Cc: Will Deacon <will@kernel.org>
>> Cc: Ryan Roberts <ryan.roberts@arm.com>
>> Cc: Mark Rutland <mark.rutland@arm.com>
>> Cc: linux-arm-kernel@lists.infradead.org
>> Cc: linux-kernel@vger.kernel.org
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
>> ---
>> arch/arm64/include/asm/pgtable.h | 23 +++++++++++++++++------
>> arch/arm64/mm/fault.c | 2 +-
>> 2 files changed, 18 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
>> index 42124d2f323d..cf69ce68f951 100644
>> --- a/arch/arm64/include/asm/pgtable.h
>> +++ b/arch/arm64/include/asm/pgtable.h
>> @@ -87,6 +87,17 @@ static inline void arch_leave_lazy_mmu_mode(void)
>> #define ptdesc_get(x) READ_ONCE(x)
>> #define ptdesc_set(x, val) WRITE_ONCE(x, val)
>>
>> +static inline ptdesc_t ptdesc_cmpxchg_relaxed(ptdesc_t *ptep, ptdesc_t old,
>> + ptdesc_t new)
>> +{
>> + return cmpxchg_relaxed(ptep, old, new);
>> +}
>> +
>> +static inline ptdesc_t ptdesc_xchg_relaxed(ptdesc_t *ptep, ptdesc_t new)
>> +{
>> + return xchg_relaxed(ptep, new);
>> +}
>> +
>
> We really want the rename of ptdesc_t before this change.
>

Planning to rename ptdesc_t as ptent_t in a pre-requisite
patch early in the series.