From nobody Sun Dec 14 11:18:35 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A8B423168F2; Thu, 11 Dec 2025 17:21:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765473667; cv=none; b=SPhEI7msKkmaCeiSR4774fMMply8kGzzzWPuO4Koe8uUAZ2HkQSnY0IeZnw+mzgrvGGiNgyPgxYaZl/fF4+1tvubv99+FlfgrOTKw626qsFGcxhvuyZcicG/1WP5l5RL6ST4cejb/W2pN/cVQxxGLLcxfCOqco9DESA4AizqVC4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765473667; c=relaxed/simple; bh=04gVJXOYw7Ju2c/7DpEHB2s0kbuucyi2foZBfgP2tHg=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=aMMHdK0a63/2kWwh/td6dbeHzw+OlzseBAXN6R6vBZVjA9KZqu+Okq3hFi/n41wI9fu8GEfPs5aEN0s5mATj2a1eHeKfmiibJHXiwGgF4UhfnzC0i9cJaxd1bBaqAjtpNxxh7M2/EPoBGAgIdkOfH21ydhQS40uMCu73plQrySc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=OCpAsr1O; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="OCpAsr1O" Received: by smtp.kernel.org (Postfix) with ESMTPS id 3E56DC2BCAF; Thu, 11 Dec 2025 17:21:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1765473667; bh=04gVJXOYw7Ju2c/7DpEHB2s0kbuucyi2foZBfgP2tHg=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=OCpAsr1Oah2IC1WUiR+F+qmoVx03kfKjO5ul4TmrKjdNWt19LHqvTST4ZB2RUq1CR NEtzlpt+tbK/vkBJH0OA2icZt4KiJe10Ga7WLcHVbiJw8lXe4haTFNISBchUT8Ebj+ XnBvRjgRnEYVnit1J0yPzGqQWyOQRE2EMwcOBL6y0Pl02vaxZbe9z8guMNqjZHZQqH W0oW7Xs3l+QoWhJETZ/gXR695ia2e2aFysYWXbliVb4Cj0jIiIKo0eNIdWHAxmDn/Q 3egHFl7g9dZTsUeUVzj8ot9W/2oexpllzYecP6QUqxo8+QagY3fcPHzeJwKp4yRwwU t1IlUnZxHNvCw== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id 255D5D41D6D; Thu, 11 Dec 2025 17:21:07 +0000 (UTC) From: Deepak Gupta via B4 Relay Date: Thu, 11 Dec 2025 09:20:41 -0800 Subject: [PATCH v26 08/28] riscv/mm: teach pte_mkwrite to manufacture shadow stack PTEs 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: quoted-printable Message-Id: <20251211-v5_user_cfi_series-v26-8-f0f419e81ac0@rivosinc.com> References: <20251211-v5_user_cfi_series-v26-0-f0f419e81ac0@rivosinc.com> In-Reply-To: <20251211-v5_user_cfi_series-v26-0-f0f419e81ac0@rivosinc.com> To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Lorenzo Stoakes , Paul Walmsley , Palmer Dabbelt , Albert Ou , Conor Dooley , Rob Herring , Krzysztof Kozlowski , Arnd Bergmann , Christian Brauner , Peter Zijlstra , Oleg Nesterov , Eric Biederman , Kees Cook , Jonathan Corbet , Shuah Khan , Jann Horn , Conor Dooley , Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Andreas Hindborg , Alice Ryhl , Trevor Gross , Benno Lossin Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, devicetree@vger.kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, alistair.francis@wdc.com, richard.henderson@linaro.org, jim.shu@sifive.com, andybnac@gmail.com, kito.cheng@sifive.com, charlie@rivosinc.com, atishp@rivosinc.com, evan@rivosinc.com, cleger@rivosinc.com, alexghiti@rivosinc.com, samitolvanen@google.com, broonie@kernel.org, rick.p.edgecombe@intel.com, rust-for-linux@vger.kernel.org, Zong Li , Andreas Korb , Valentin Haudiquet , Deepak Gupta X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1765473664; l=2371; i=debug@rivosinc.com; s=20251023; h=from:subject:message-id; bh=t88tD6h5jGJWywn6Tz9bzXAVcX1Z5iY6bKQeGfJKelY=; b=2eVX9clVHze7ulKPpPv+R2k2xcoyYfboAVjhbcXbqF72Iv1e7pp49F2bHxf0gP5GgR/QmHs4n ILGolFzplBOBXJnDxgwDpdGNoU+rmmyqKLAJdAaQWB5pGIXvIhx5d7p X-Developer-Key: i=debug@rivosinc.com; a=ed25519; pk=O37GQv1thBhZToXyQKdecPDhtWVbEDRQ0RIndijvpjk= X-Endpoint-Received: by B4 Relay for debug@rivosinc.com/20251023 with auth_id=553 X-Original-From: Deepak Gupta Reply-To: debug@rivosinc.com From: Deepak Gupta pte_mkwrite creates PTEs with WRITE encodings for underlying arch. Underlying arch can have two types of writeable mappings. One that can be written using regular store instructions. Another one that can only be written using specialized store instructions (like shadow stack stores). pte_mkwrite can select write PTE encoding based on VMA range (i.e. VM_SHADOW_STACK) Reviewed-by: Alexandre Ghiti Reviewed-by: Zong Li Tested-by: Andreas Korb Tested-by: Valentin Haudiquet Signed-off-by: Deepak Gupta --- arch/riscv/include/asm/pgtable.h | 7 +++++++ arch/riscv/mm/pgtable.c | 16 ++++++++++++++++ 2 files changed, 23 insertions(+) diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgta= ble.h index e4eb4657e1b6..b03e8f85221f 100644 --- a/arch/riscv/include/asm/pgtable.h +++ b/arch/riscv/include/asm/pgtable.h @@ -420,6 +420,10 @@ static inline pte_t pte_wrprotect(pte_t pte) =20 /* static inline pte_t pte_mkread(pte_t pte) */ =20 +struct vm_area_struct; +pte_t pte_mkwrite(pte_t pte, struct vm_area_struct *vma); +#define pte_mkwrite pte_mkwrite + static inline pte_t pte_mkwrite_novma(pte_t pte) { return __pte(pte_val(pte) | _PAGE_WRITE); @@ -765,6 +769,9 @@ static inline pmd_t pmd_mkyoung(pmd_t pmd) return pte_pmd(pte_mkyoung(pmd_pte(pmd))); } =20 +pmd_t pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma); +#define pmd_mkwrite pmd_mkwrite + static inline pmd_t pmd_mkwrite_novma(pmd_t pmd) { return pte_pmd(pte_mkwrite_novma(pmd_pte(pmd))); diff --git a/arch/riscv/mm/pgtable.c b/arch/riscv/mm/pgtable.c index 8b6c0a112a8d..17a4bd05a02f 100644 --- a/arch/riscv/mm/pgtable.c +++ b/arch/riscv/mm/pgtable.c @@ -165,3 +165,19 @@ pud_t pudp_invalidate(struct vm_area_struct *vma, unsi= gned long address, return old; } #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ + +pte_t pte_mkwrite(pte_t pte, struct vm_area_struct *vma) +{ + if (vma->vm_flags & VM_SHADOW_STACK) + return pte_mkwrite_shstk(pte); + + return pte_mkwrite_novma(pte); +} + +pmd_t pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) +{ + if (vma->vm_flags & VM_SHADOW_STACK) + return pmd_mkwrite_shstk(pmd); + + return pmd_mkwrite_novma(pmd); +} --=20 2.43.0