From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 4461347F782; Wed, 2 Sep 2026 11:59:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788350346; cv=none; b=L/JaC/+AGP4PuuX6JSt5jBDPFrTl60n9qVDxZpGlErztWyZUf7vUAcf/W05DMHD7s0zmksw2pW621Tpn6kK/uvezC1kO+eePGep+jkAzTEJRqnFhi8MYH7giIJkOdtZaRQHcbvSjmCEll7ifIEgFNR/YSrECJ811p/beBlAI2AA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788350346; c=relaxed/simple; bh=tVsLkLa07A4zHI8m1tAgMomiiERETV6ZHmwKKYasnOU=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=Ivp6Nslbcbrz4I6N6yUZYS7y7SKSIpEt9CWzmeiZuEJa+yCFdyTRSPYMc4hyCKZO5Uosr+/BHwCV8bGmyzkXW9fFJwPQQH5PSdVR/5rsLNQbyBhogJklwegoye+TpNwbMhnjBbnljA2GPpsvP69KuitKZLF0OFfzGOb3efl7HuI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=bafAV6hH; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="bafAV6hH" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 3E1291682; Wed, 2 Sep 2026 04:58:55 -0700 (PDT) Received: from e129823.arm.com (e129823.arm.com [10.2.213.3]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BB8893F85F; Wed, 2 Sep 2026 04:58:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1788350339; bh=tVsLkLa07A4zHI8m1tAgMomiiERETV6ZHmwKKYasnOU=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=bafAV6hHiMWf7UFGA2Jb1tgbVdcqzDWS6a4NkdWW3RSDN7omcp+MQvC85a47sP/CH 4AmzPQ2CiW6I0PTr+lcmGRlI3chW+Y8qNRmEJ/GXdjP+VVEtJXdyRwOER+zjM60QbL i4BmSXa8lfT+QCHzh7jE+OXdMQsSLpM15Zhbg3fs= From: Yeoreum Yun Date: Wed, 02 Sep 2026 12:56:21 +0100 Subject: [PATCH RFC v3 19/21] mm/pgtable: disallow calling (pgd|p4d|pud)_page, pgd_page_vaddr() and (p4d|pud)_pgtable with dummy Precedence: bulk X-Mailing-List: kvm@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: <20260902-dummy_ptxp3-v3-19-5d8f5b17c25c@arm.com> References: <20260902-dummy_ptxp3-v3-0-5d8f5b17c25c@arm.com> In-Reply-To: <20260902-dummy_ptxp3-v3-0-5d8f5b17c25c@arm.com> To: Russell King , Huacai Chen , WANG Xuerui , Thomas Bogendoerfer , Catalin Marinas , Will Deacon , Arnd Bergmann , Andrew Morton , Kairui Song , Qi Zheng , Shakeel Butt , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Johannes Weiner , David Hildenbrand , Michal Hocko , Lorenzo Stoakes , Tianrui Zhao , Bibo Mao , Anup Patel , Atish Patra , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jonas Bonn , Stefan Kristiansson , Stafford Horne Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, kvm@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-openrisc@vger.kernel.org, Yeoreum Yun X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3262; i=yeoreum.yun@arm.com; h=from:subject:message-id; bh=xhnn2pyfM9DLAHxbEw+j70fkBp5Hs9TfkBrZfLGw5KQ=; b=owEB7QES/pANAwAKAW3Vw9FaxTEzAcsmYgBqmA7qBnMyLZ0jKZbEx3DR97rH4+JY9IdCSD3OC ACU8w0jvsuJAbMEAAEKAB0WIQQtg+CS3QUzuFh1pJ1t1cPRWsUxMwUCapgO6gAKCRBt1cPRWsUx M1RlDACrNDx66AL+YlaceCy5fdL7utwGqmHqfKH4VSWSBKjq1xfzNL8PDRPqGW56m2nSz0oARim kR9d5Qen3Im7+xmbnh920AbeAyU1d+WW1h6jXmyptFSppLZDGhPesgf+Y3WdqDgu3gw0nG3c9Tu WU5E0d/FC72hOr8JAUhAJ9Dph9w6sm97I8Me0G+h/IBzGomkb9pVP+L4AuY9f7brkKVuRzBG6mv yLWWjBoEuzxGet3Swlt6wrXQtkblT5N/VCGbrkX+P79VNjv/NHlZ+8Iy7Rp8UvaKklrUTE/0o6/ gjm7zRus6ux+diSIo8r+TCsBwZe70whQLrtgQz7acxhsCFWMq8wMXcNkSXKi1Hwk6kwZzqoGnBt q0i4gZzhOj7Ouhbuptq1nX5OXdAxNezenqC6qupYJUnLCBJwJ5PAnpwkMeDRv4Db32ENM0HtfSf N/kEaP+Gk6HX4bkAietsNqW5YNEMTF81R4dM0W/ru9ZfLn8tD6EWdADBsCIlah027kv/w= X-Developer-Key: i=yeoreum.yun@arm.com; a=openpgp; fpr=2D83E092DD0533B85875A49D6DD5C3D15AC53133 From: "David Hildenbrand (Arm)" These helpers silently fallback to the folded helpers. With e.g., pdgp_get() returning dummy values, pgd_page_vaddr(pgdp_get(pgdp)) will now behave differently than pgd_page_vaddr(*pgdp). Disallow calling (pgd|p4d|pud)_page() entirely, and catch when passing a dummy value to pgd_page_vaddr() and (p4d|pud)_pgtable. This will catch most abuse of dummy pXdp value at compile time -- so far there were none, and it better stay that way. Signed-off-by: David Hildenbrand (Arm) Co-developed-by: Yeoreum Yun Signed-off-by: Yeoreum Yun --- include/asm-generic/pgtable-nop4d.h | 8 ++++++-- include/asm-generic/pgtable-nopmd.h | 8 ++++++-- include/asm-generic/pgtable-nopud.h | 8 ++++++-- 3 files changed, 18 insertions(+), 6 deletions(-) diff --git a/include/asm-generic/pgtable-nop4d.h b/include/asm-generic/pgtable-nop4d.h index 2d86325235da..d2dccf7542da 100644 --- a/include/asm-generic/pgtable-nop4d.h +++ b/include/asm-generic/pgtable-nop4d.h @@ -70,8 +70,12 @@ static __always_inline p4d_t *__p4d_offset_lockless(pgd_t *pgdp, pgd_t pgd, #define p4d_val(x) (pgd_val((x).pgd)) #define __p4d(x) ((p4d_t) { __pgd(x) }) -#define pgd_page(pgd) (p4d_page((p4d_t){ pgd })) -#define pgd_page_vaddr(pgd) ((unsigned long)(p4d_pgtable((p4d_t){ pgd }))) +#define pgd_page(pgd) ({ BUILD_BUG(); (struct page *)NULL; }) +#define pgd_page_vaddr(pgd) \ +({ \ + pgd_check_dummy(pgd); \ + (unsigned long)p4d_pgtable((p4d_t) { pgd }); \ +}) /* * allocating and freeing a p4d is trivial: the 1-entry p4d is diff --git a/include/asm-generic/pgtable-nopmd.h b/include/asm-generic/pgtable-nopmd.h index bd40d3a5743f..2afbf2d8659d 100644 --- a/include/asm-generic/pgtable-nopmd.h +++ b/include/asm-generic/pgtable-nopmd.h @@ -79,8 +79,12 @@ static __always_inline pmd_t *__pmd_offset_lockless(pud_t *pudp, pud_t pud, #define pmd_val(x) (pud_val((x).pud)) #define __pmd(x) ((pmd_t) { __pud(x) } ) -#define pud_page(pud) (pmd_page((pmd_t){ pud })) -#define pud_pgtable(pud) ((pmd_t *)(pmd_page_vaddr((pmd_t){ pud }))) +#define pud_page(pud) ({ BUILD_BUG(); (struct page *)NULL; }) +#define pud_pgtable(pud) \ +({ \ + pud_check_dummy(pud); \ + ((pmd_t *)(pmd_page_vaddr((pmd_t) { pud }))); \ +}) /* * allocating and freeing a pmd is trivial: the 1-entry pmd is diff --git a/include/asm-generic/pgtable-nopud.h b/include/asm-generic/pgtable-nopud.h index 7475d0bd0f2e..3264673c0c38 100644 --- a/include/asm-generic/pgtable-nopud.h +++ b/include/asm-generic/pgtable-nopud.h @@ -77,8 +77,12 @@ static __always_inline pud_t *__pud_offset_lockless(p4d_t *p4dp, p4d_t p4d, #define pud_val(x) (p4d_val((x).p4d)) #define __pud(x) ((pud_t) { __p4d(x) }) -#define p4d_page(p4d) (pud_page((pud_t){ p4d })) -#define p4d_pgtable(p4d) ((pud_t *)(pud_pgtable((pud_t){ p4d }))) +#define p4d_page(p4d) ({ BUILD_BUG(); (struct page *)NULL; }) +#define p4d_pgtable(p4d) \ +({ \ + p4d_check_dummy(p4d); \ + ((pud_t *)(pud_pgtable((pud_t) { p4d }))); \ +}) /* * allocating and freeing a pud is trivial: the 1-entry pud is -- 2.43.0