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(unknown [210.73.43.101]) by APP-03 (Coremail) with SMTP id rQCowACH2IK5nMJoo6pCAg--.44660S7; Thu, 11 Sep 2025 17:56:16 +0800 (CST) From: Chunyan Zhang To: linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Deepak Gupta , Ved Shanbhogue , Alexander Viro , Christian Brauner , Jan Kara , Andrew Morton , Peter Xu , Arnd Bergmann , David Hildenbrand , Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Axel Rasmussen , Yuanchu Xie , Chunyan Zhang Subject: [PATCH v11 5/5] riscv: mm: Add userfaultfd write-protect support Date: Thu, 11 Sep 2025 17:56:02 +0800 Message-Id: <20250911095602.1130290-6-zhangchunyan@iscas.ac.cn> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250911095602.1130290-1-zhangchunyan@iscas.ac.cn> References: <20250911095602.1130290-1-zhangchunyan@iscas.ac.cn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: rQCowACH2IK5nMJoo6pCAg--.44660S7 X-Coremail-Antispam: 1UD129KBjvJXoWxZF48ZF4kKF4xKFW5urWrAFb_yoWruw1rpr s5GayrurWDJF97tayftr4YgrWrZw4fWa4DWr9xCa1kJFy7K3yDXr95Kry3try8JFWvv347 WFWrKr1rCw47JrDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUmEb7Iv0xC_Zr1lb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I2 0VC2zVCF04k26cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI 8067AKxVWUAVCq3wA2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28C jxkF64kEwVA0rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVW5JVW7JwA2z4x0Y4vE2Ix0cI 8IcVCY1x0267AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E 87Iv6xkF7I0E14v26rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64 kE6c02F40Ex7xfMcIj6xIIjxv20xvE14v26r106r15McIj6I8E87Iv67AKxVW8JVWxJwAm 72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41lFIxGxcIEc7CjxVA2Y2ka0xkIwI 1lc7CjxVAaw2AFwI0_GFv_Wrylc2xSY4AK67AK6r4fMxAIw28IcxkI7VAKI48JMxC20s02 6xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_Jr I_JrWlx4CE17CEb7AF67AKxVW8ZVWrXwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v2 6r1I6r4UMIIF0xvE2Ix0cI8IcVCY1x0267AKxVW8Jr0_Cr1UMIIF0xvE42xK8VAvwI8IcI k0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I0E14v26r4U JVWxJrUvcSsGvfC2KfnxnUUI43ZEXa7IUnmhF7UUUUU== X-CM-SenderInfo: x2kd0wxfkx051dq6x2xfdvhtffof0/1tbiDAcCB2jCjVc9TAAAsP Content-Type: text/plain; charset="utf-8" The Svrsw60t59b extension allows to free the PTE reserved bits 60 and 59 for software, this patch uses bit 60 for uffd-wp tracking Additionally for tracking the uffd-wp state as a PTE swap bit, we borrow bit 4 which is not involved into swap entry computation. Signed-off-by: Chunyan Zhang --- arch/riscv/Kconfig | 1 + arch/riscv/include/asm/pgtable-bits.h | 18 +++++++ arch/riscv/include/asm/pgtable.h | 68 +++++++++++++++++++++++++++ 3 files changed, 87 insertions(+) diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 53b73e4bdf3f..f928768bb14a 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -147,6 +147,7 @@ config RISCV select HAVE_ARCH_TRANSPARENT_HUGEPAGE if 64BIT && MMU select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if 64BIT && MMU select HAVE_ARCH_USERFAULTFD_MINOR if 64BIT && USERFAULTFD + select HAVE_ARCH_USERFAULTFD_WP if 64BIT && MMU && USERFAULTFD && RISCV_I= SA_SVRSW60T59B select HAVE_ARCH_VMAP_STACK if MMU && 64BIT select HAVE_ASM_MODVERSIONS select HAVE_CONTEXT_TRACKING_USER diff --git a/arch/riscv/include/asm/pgtable-bits.h b/arch/riscv/include/asm= /pgtable-bits.h index f3bac2bbc157..b422d9691e60 100644 --- a/arch/riscv/include/asm/pgtable-bits.h +++ b/arch/riscv/include/asm/pgtable-bits.h @@ -38,6 +38,24 @@ #define _PAGE_SWP_SOFT_DIRTY 0 #endif /* CONFIG_MEM_SOFT_DIRTY */ =20 +#ifdef CONFIG_HAVE_ARCH_USERFAULTFD_WP + +/* ext_svrsw60t59b: Bit(60) for uffd-wp tracking */ +#define _PAGE_UFFD_WP \ + ((riscv_has_extension_unlikely(RISCV_ISA_EXT_SVRSW60T59B)) ? \ + (1UL << 60) : 0) +/* + * Bit 4 is not involved into swap entry computation, so we + * can borrow it for swap page uffd-wp tracking. + */ +#define _PAGE_SWP_UFFD_WP \ + ((riscv_has_extension_unlikely(RISCV_ISA_EXT_SVRSW60T59B)) ? \ + _PAGE_USER : 0) +#else +#define _PAGE_UFFD_WP 0 +#define _PAGE_SWP_UFFD_WP 0 +#endif + #define _PAGE_TABLE _PAGE_PRESENT =20 /* diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgta= ble.h index 77344ff0298b..5d3f17e175e5 100644 --- a/arch/riscv/include/asm/pgtable.h +++ b/arch/riscv/include/asm/pgtable.h @@ -416,6 +416,41 @@ static inline pte_t pte_wrprotect(pte_t pte) return __pte(pte_val(pte) & ~(_PAGE_WRITE)); } =20 +#ifdef CONFIG_HAVE_ARCH_USERFAULTFD_WP +#define pgtable_uffd_wp_supported() \ + riscv_has_extension_unlikely(RISCV_ISA_EXT_SVRSW60T59B) + +static inline bool pte_uffd_wp(pte_t pte) +{ + return !!(pte_val(pte) & _PAGE_UFFD_WP); +} + +static inline pte_t pte_mkuffd_wp(pte_t pte) +{ + return pte_wrprotect(__pte(pte_val(pte) | _PAGE_UFFD_WP)); +} + +static inline pte_t pte_clear_uffd_wp(pte_t pte) +{ + return __pte(pte_val(pte) & ~(_PAGE_UFFD_WP)); +} + +static inline bool pte_swp_uffd_wp(pte_t pte) +{ + return !!(pte_val(pte) & _PAGE_SWP_UFFD_WP); +} + +static inline pte_t pte_swp_mkuffd_wp(pte_t pte) +{ + return __pte(pte_val(pte) | _PAGE_SWP_UFFD_WP); +} + +static inline pte_t pte_swp_clear_uffd_wp(pte_t pte) +{ + return __pte(pte_val(pte) & ~(_PAGE_SWP_UFFD_WP)); +} +#endif /* CONFIG_HAVE_ARCH_USERFAULTFD_WP */ + /* static inline pte_t pte_mkread(pte_t pte) */ =20 static inline pte_t pte_mkwrite_novma(pte_t pte) @@ -838,6 +873,38 @@ static inline pud_t pud_mkspecial(pud_t pud) } #endif =20 +#ifdef CONFIG_HAVE_ARCH_USERFAULTFD_WP +static inline bool pmd_uffd_wp(pmd_t pmd) +{ + return pte_uffd_wp(pmd_pte(pmd)); +} + +static inline pmd_t pmd_mkuffd_wp(pmd_t pmd) +{ + return pte_pmd(pte_mkuffd_wp(pmd_pte(pmd))); +} + +static inline pmd_t pmd_clear_uffd_wp(pmd_t pmd) +{ + return pte_pmd(pte_clear_uffd_wp(pmd_pte(pmd))); +} + +static inline bool pmd_swp_uffd_wp(pmd_t pmd) +{ + return pte_swp_uffd_wp(pmd_pte(pmd)); +} + +static inline pmd_t pmd_swp_mkuffd_wp(pmd_t pmd) +{ + return pte_pmd(pte_swp_mkuffd_wp(pmd_pte(pmd))); +} + +static inline pmd_t pmd_swp_clear_uffd_wp(pmd_t pmd) +{ + return pte_pmd(pte_swp_clear_uffd_wp(pmd_pte(pmd))); +} +#endif /* CONFIG_HAVE_ARCH_USERFAULTFD_WP */ + #ifdef CONFIG_HAVE_ARCH_SOFT_DIRTY static inline bool pmd_soft_dirty(pmd_t pmd) { @@ -1055,6 +1122,7 @@ static inline pud_t pud_modify(pud_t pud, pgprot_t ne= wprot) * bit 0: _PAGE_PRESENT (zero) * bit 1 to 2: (zero) * bit 3: _PAGE_SWP_SOFT_DIRTY + * bit 4: _PAGE_SWP_UFFD_WP * bit 5: _PAGE_PROT_NONE (zero) * bit 6: exclusive marker * bits 7 to 11: swap type --=20 2.34.1