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 5810D47278D; Wed, 22 Jul 2026 15:30:55 +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=1784734257; cv=none; b=A7XnHtL4cxvohVgi+ED3i8dtV88Uiv9OpEvasBZZgaLBEUruKRQLjOi6zbQqWwDGsXY3vS9xUxuj1b2rUMOw/BQuMvV3OrGoKVe8kchTB61PHGDt6LxUVCpdeDYwwYcEKcWjJ7q2rkja89MxF/ptM3vBttJ5kZesqYKANBHuqqY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784734257; c=relaxed/simple; bh=NwLzJE9YUYcwQouyyHhdNDainQ0wboh6oH5R8Qr5IHk=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=IZSDNRx1bUBDv02mxJVkuLZvkNpdrQXxVDkwAkKkjMqqlsqNfc7HDzhc8L/YYx2SA4ZdAoz3EYcf7DCopXsJ/WUPqQ3O7gQj9+cmEKdKUowuOGE63riDNc7f8XGGaxRtidChJ3uBCFV4w3te2P1Sp5VKtT5xvQGLYA+bQK1Pv/Q= 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=CMfDyJKB; 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="CMfDyJKB" 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 914D81595; Wed, 22 Jul 2026 08:30:50 -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 EEB983F66F; Wed, 22 Jul 2026 08:30:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1784734254; bh=NwLzJE9YUYcwQouyyHhdNDainQ0wboh6oH5R8Qr5IHk=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=CMfDyJKBKmK50YTcejppNKTrTWiJP57IF6DHVLjdYdB2gqyRXO1180hCz77V7dhiw /Rhc6XGpzTsM9UJ2o8cGBXNsPlK7hInWAm0H7N+W5Ya7RehIy81zPyYAERNZ20t24L nfvmJqhMmxi974lDKs5uoKjcVHSlsRqupqgSxxk0= From: Yeoreum Yun Date: Wed, 22 Jul 2026 16:30:10 +0100 Subject: [PATCH RFC v2 02/20] ARM: mm: make 2-level pgd_t a scalar 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: <20260722-dummy_ptxp3-v2-2-d9e4bad31e0a@arm.com> References: <20260722-dummy_ptxp3-v2-0-d9e4bad31e0a@arm.com> In-Reply-To: <20260722-dummy_ptxp3-v2-0-d9e4bad31e0a@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 X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2168; i=yeoreum.yun@arm.com; h=from:subject:message-id; bh=3A02R9gJAFlGYYgA2zmEeHAxV0ZhWViB/KSchyi5T/4=; b=owEB7QES/pANAwAKAW3Vw9FaxTEzAcsmYgBqYOIQeAF4NvX+ghiLdlZcQA9dzdnJsUpGO89IJ Z0P4tNZzvGJAbMEAAEKAB0WIQQtg+CS3QUzuFh1pJ1t1cPRWsUxMwUCamDiEAAKCRBt1cPRWsUx M9cgDACmrJH7vGtwlt1q+G75J+q2g7DLACRd8qQ65REy5KW9VbVYXXmBfsv7k2aacinnF+IUr1m w3DvIXTMScFAlv6aZMEIqzXU9KuPuo24JNo8rMNKxi9T1m+acBCRHvLvSO2xL29IrbZAcioI4Wx p65yuAc9KS13mOJr3OIKeTM2uPBpc+Dm5DZte59tUdL88pUcKmgr5jOzWyXYdMRsz3hDwLYMW+2 xxjo5fmXJlXgap750FaoM8rT0iXoAT6YJTKSXBHneNtHjfELNOmnfR3FouecTJpQYreibBoY4Go wTzx/VMNWooLYFE7j0Suwe4IRqREcwTjIE7Sy0K+4hH8myO5maXRxcC6QsnckrWLVBUFmQB4lFH /yAaiETHizvEjofTsL+JjwiTrmaQq2gXigwhquNdb6UYzqGvR7neA73xa7ugREzMT8ojGHpTpOr l75oD4xe0+GWpdz7MWMp3Wqtq2t9VjFSsaVZperSbQsuUsnnV9f1oO35vpoX6HoDyNfd4= X-Developer-Key: i=yeoreum.yun@arm.com; a=openpgp; fpr=2D83E092DD0533B85875A49D6DD5C3D15AC53133 From: "David Hildenbrand (Arm)" We don't want pgd_t to be an array, as it prohibits returning it from a function, like pgdp_get(). So let's just use an u64, and extract the right 32bit value in pgd_val(). Leave the STRICT_MM_TYPECHECKS case alone for now. As an alternative, we could use the STRICT_MM_TYPECHECKS approach here as well, but using an u64 looks conceptually cleaner, even though pgd_val() gets a bit more involved. Signed-off-by: David Hildenbrand (Arm) --- arch/arm/include/asm/pgtable-2level-types.h | 24 +++++++++++++++++++++--- 1 file changed, 21 insertions(+), 3 deletions(-) diff --git a/arch/arm/include/asm/pgtable-2level-types.h b/arch/arm/include/asm/pgtable-2level-types.h index 650e793f4142..7f85384ac386 100644 --- a/arch/arm/include/asm/pgtable-2level-types.h +++ b/arch/arm/include/asm/pgtable-2level-types.h @@ -25,7 +25,7 @@ typedef struct { pteval_t pgprot; } pgprot_t; #define pte_val(x) ((x).pte) #define pmd_val(x) ((x).pmd) -#define pgd_val(x) ((x).pgd[0]) +#define pgd_val(x) ((x).pgd[0]) #define pgprot_val(x) ((x).pgprot) #define __pte(x) ((pte_t) { (x) } ) @@ -36,14 +36,32 @@ typedef struct { pteval_t pgprot; } pgprot_t; /* * .. while these make it easier on the compiler */ +typedef u64 pgdval_t; + typedef pteval_t pte_t; typedef pmdval_t pmd_t; -typedef pmdval_t pgd_t[2]; +typedef pgdval_t pgd_t; typedef pteval_t pgprot_t; #define pte_val(x) (x) #define pmd_val(x) (x) -#define pgd_val(x) ((x)[0]) + +static inline pmdval_t pgd_val(pgd_t pgd) +{ + /* + * The lower and higher pmdval_t values point to the same page. + * the only difference is their offset within that page. + * Therefore, whichever value is returned, the behavior of pmd_pfn(), + * pmd_page(), and other users of pgd_val() remains unchanged. + * + * However, pgd_val() has historically returned the lower pmdval_t, so + * keep returning the lower one. + * + * See the comments in include/asm/pgtable-2level. + */ + return (*(pmdval_t (*)[2])&pgd)[0]; +} + #define pgprot_val(x) (x) #define __pte(x) (x) -- 2.43.0