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b=Q5i3/kOmW/i0sUqzxJ3FKLi2yeBskmRPGb6DY6Ec1H+TYDc/Qrhdr5WHM/I2q1WO0 Z7YdJeXtqkKmjW15QmTb1pbAicnNyXc8qgKFxFJ2v0wCr/p31kOfMGmtsw+MTJXnT7 50phJM1WxA+FvNNnksGF0NXwd2PY0vuPXebF0YEuH8ZqG3CQW4tDVyWQOmDc4/ZFcJ MuaQHxrEtdTAE/GH/Xgm1Wy0nwf1+pP6K30ZENYjDjJKyWJckKf6wLEneM6BOgg7mz 6O4loYJhwm23/jqut/hEvS3Q6xIXrMak9UDUMMkfq1ux7Ca6bAz7EVS1XaedQg4Snz irg8fkIn0Ezuw== Date: Sat, 28 Feb 2026 13:17:51 +0200 From: Mike Rapoport To: Anshuman Khandual Cc: linux-arm-kernel@lists.infradead.org, Catalin Marinas , Will Deacon , Ryan Roberts , Mark Rutland , Lorenzo Stoakes , Andrew Morton , David Hildenbrand , Linu Cherian , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC V1 09/16] arm64/mm: Route all pgtable reads via ptdesc_get() Message-ID: References: <20260224051153.3150613-1-anshuman.khandual@arm.com> <20260224051153.3150613-10-anshuman.khandual@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260224051153.3150613-10-anshuman.khandual@arm.com> X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 0A45EA0005 X-Stat-Signature: ziskac8o4qatcnszzxfyw7gfj86ch3ya X-HE-Tag: 1772277478-454317 X-HE-Meta: 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 P8gVbGMv n29dp/F7nXZHWbfqCZEYkVjHWzhwP8ICRAYYpHok9zy6M3DjH/d6ncpur4EzQZA9fb389Y/ske9ktBh2eEBUJV2215UMxdvJB4KRRQ7TzX0Il957RRvwlBxw22xLYZl9BgiZQ98nqlBlreN4dkX5pTdJbnO4kMU754U4zPx/7X13XDetFSCa9e1TIa0gfuIJou/rLmvQGk6vAcj3CVvH66fLCQg/1GFVNUaKGnJsQu9sndzT1kUpbP2Wokx09kIqp5hzlSJh8ihcCOGNlHf1SJwCLhKkaxnuM4JM4aYnM0K2aJ9g6VLYDyZK9/ORwBbnCV/tJIUaOL9nOVYj13S4vX+RRZABQTkYXUCXPvOrZDrZaevThbzFCUhd1tyHjE7NgN7DJ6OjLdAGF0u4TKF20MSyGgfMPZG5bJR6mRfMObL9pMrXzrEt1QhvO0Zu4ywUnYszS Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Anshuman, On Tue, Feb 24, 2026 at 10:41:46AM +0530, Anshuman Khandual wrote: > Define arm64 platform specific implementations for new pXdp_get() helpers. > These resolve into READ_ONCE(), thus ensuring required single copy atomic > semantics for the page table entry reads. > > In future this infrastructure can be used for D128 to maintain single copy > atomicity semantics with inline asm blocks. > > Cc: Catalin Marinas > Cc: Will Deacon > Cc: Ryan Roberts > Cc: Mark Rutland > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-kernel@vger.kernel.org > Signed-off-by: Anshuman Khandual > --- > arch/arm64/include/asm/pgtable.h | 28 +++++++++++++++++++++++++++- > 1 file changed, 27 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h > index 257af1c3015d..804ef49aea88 100644 > --- a/arch/arm64/include/asm/pgtable.h > +++ b/arch/arm64/include/asm/pgtable.h > @@ -84,6 +84,32 @@ static inline void arch_leave_lazy_mmu_mode(void) > arch_flush_lazy_mmu_mode(); > } > > +#define ptdesc_get(x) READ_ONCE(x) This will be confusing with 'struct ptdesc' APIs, maybe ptent_get()? > +#define pmdp_get pmdp_get > +static inline pmd_t pmdp_get(pmd_t *pmdp) > +{ > + return ptdesc_get(*pmdp); > +} > + > +#define pudp_get pudp_get > +static inline pud_t pudp_get(pud_t *pudp) > +{ > + return ptdesc_get(*pudp); > +} > + > +#define p4dp_get p4dp_get > +static inline p4d_t p4dp_get(p4d_t *p4dp) > +{ > + return ptdesc_get(*p4dp); > +} > + > +#define pgdp_get pgdp_get > +static inline pgd_t pgdp_get(pgd_t *pgdp) > +{ > + return ptdesc_get(*pgdp); > +} > + > #ifdef CONFIG_TRANSPARENT_HUGEPAGE > #define __HAVE_ARCH_FLUSH_PMD_TLB_RANGE > > @@ -384,7 +410,7 @@ static inline void __set_pte(pte_t *ptep, pte_t pte) > > static inline pte_t __ptep_get(pte_t *ptep) > { > - return READ_ONCE(*ptep); > + return ptdesc_get(*ptep); > } > > extern void __sync_icache_dcache(pte_t pteval); > -- > 2.43.0 > -- Sincerely yours, Mike.