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Sat, 05 Sep 2026 12:29:51 -0700 (PDT) From: Matt Turner Date: Sat, 05 Sep 2026 15:29:33 -0400 Subject: [PATCH v2 12/22] alpha: add ARCH_HAS_PTE_SPECIAL support Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260905-arch-kconfig-options-v2-v2-12-83e8245761a2@gmail.com> References: <20260905-arch-kconfig-options-v2-v2-0-83e8245761a2@gmail.com> In-Reply-To: <20260905-arch-kconfig-options-v2-v2-0-83e8245761a2@gmail.com> To: Richard Henderson , Magnus Lindholm , Kees Cook , Marco Elver , Andrey Konovalov , Andrey Ryabinin , Jonathan Corbet , Shuah Khan , Randy Dunlap Cc: linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-hardening@vger.kernel.org, linux-doc@vger.kernel.org, Matt Turner X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=3352; i=mattst88@gmail.com; h=from:subject:message-id; bh=zzgkpi5XpmGcRMZyu8vsECazz4eqXkY706CC/FyJHWE=; b=owGbwMvMwCW25rVmCc8sv+mMp9WSGLLm5E6pOr77eVFl5HwxvcZ//6V+le/lYEl6doD/cKSp2 eMj1b4ZHR9ZGMS4GGaKKbLErVdkmdW2Y6nPaelfMHNYmUCGSIs0MAABCwNfbmJeqZGOkZ6ptqGe IZChYxQPkdNj0MgsLi5NLdJNKyhyyMsvSSzJzM8r1ssvSM0rSC/QS8tMK8nIyC8qTgUaoZeXWmL q6uhmZGhgYuloYeZk4Whq4uzsZOjk5ujo7OpkZGluYuBs6WjiamnOwMUpAHONThvD/6y4VSJbrN JYVi+at1bx2SQPLbNfP439fWs5zKS+SxiWiDL8L37d+/HthISUSfMn/ucV7mVjP/zInr+l7QBvr uOhpduWMQAA X-Developer-Key: i=mattst88@gmail.com; a=openpgp; fpr=3BB639E56F861FA2E86505690FDD682D974CA72A Add _PAGE_SPECIAL using bit 19 (0x80000), which is unused in the Alpha PTE layout. This enables pte_special()/pte_mkspecial() for marking PTEs that are not backed by struct page (VDSO mappings, zero page, io_remap_pfn_range, etc.). Include _PAGE_SPECIAL in _PAGE_CHG_MASK so it is preserved across pte_modify() calls. Assisted-by: Claude:claude-opus-4-6 Signed-off-by: Matt Turner Also mark Alpha as "ok" in the pte_special feature matrix. Tested-by: Magnus Lindholm Reviewed-by: Magnus Lindholm --- Documentation/features/vm/pte_special/arch-support.txt | 2 +- arch/alpha/Kconfig | 1 + arch/alpha/include/asm/pgtable.h | 5 ++++- 3 files changed, 6 insertions(+), 2 deletions(-) diff --git a/Documentation/features/vm/pte_special/arch-support.txt b/Documentation/features/vm/pte_special/arch-support.txt index 3f777f8b67d5..1485bb7c73eb 100644 --- a/Documentation/features/vm/pte_special/arch-support.txt +++ b/Documentation/features/vm/pte_special/arch-support.txt @@ -6,7 +6,7 @@ ----------------------- | arch |status| ----------------------- - | alpha: | TODO | + | alpha: | ok | | arc: | ok | | arm: | ok | | arm64: | ok | diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig index cc69f94a1c5b..1d28fa8d3b66 100644 --- a/arch/alpha/Kconfig +++ b/arch/alpha/Kconfig @@ -10,6 +10,7 @@ config ALPHA select ARCH_HAS_FAST_MULTIPLIER select ARCH_HAS_GCOV_PROFILE_ALL select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE + select ARCH_HAS_PTE_SPECIAL select ARCH_HAS_UBSAN select ARCH_MIGHT_HAVE_PC_PARPORT select ARCH_MIGHT_HAVE_PC_SERIO diff --git a/arch/alpha/include/asm/pgtable.h b/arch/alpha/include/asm/pgtable.h index 8e00cf9dc39d..bdff33b505bc 100644 --- a/arch/alpha/include/asm/pgtable.h +++ b/arch/alpha/include/asm/pgtable.h @@ -73,6 +73,7 @@ struct vm_area_struct; /* .. and these are ours ... */ #define _PAGE_DIRTY 0x20000 #define _PAGE_ACCESSED 0x40000 +#define _PAGE_SPECIAL 0x80000 /* We borrow bit 39 to store the exclusive marker in swap PTEs. */ #define _PAGE_SWP_EXCLUSIVE 0x8000000000UL @@ -94,7 +95,7 @@ struct vm_area_struct; #define _PFN_MASK 0xFFFFFFFF00000000UL #define _PAGE_TABLE (_PAGE_VALID | __DIRTY_BITS | __ACCESS_BITS) -#define _PAGE_CHG_MASK (_PFN_MASK | __DIRTY_BITS | __ACCESS_BITS) +#define _PAGE_CHG_MASK (_PFN_MASK | __DIRTY_BITS | __ACCESS_BITS | _PAGE_SPECIAL) /* * All the normal masks have the "page accessed" bits on, as any time they are used, @@ -238,6 +239,8 @@ extern inline pte_t pte_mkold(pte_t pte) { pte_val(pte) &= ~(__ACCESS_BITS); ret extern inline pte_t pte_mkwrite_novma(pte_t pte){ pte_val(pte) &= ~_PAGE_FOW; return pte; } extern inline pte_t pte_mkdirty(pte_t pte) { pte_val(pte) |= __DIRTY_BITS; return pte; } extern inline pte_t pte_mkyoung(pte_t pte) { pte_val(pte) |= __ACCESS_BITS; return pte; } +extern inline int pte_special(pte_t pte) { return pte_val(pte) & _PAGE_SPECIAL; } +extern inline pte_t pte_mkspecial(pte_t pte) { pte_val(pte) |= _PAGE_SPECIAL; return pte; } /* * The smp_rmb() in the following functions are required to order the load of -- 2.54.0