From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3FC6EC433FE for ; Mon, 28 Nov 2022 18:22:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=hsNtcvBJTCa2VAZH+sb5pYtiL/dgow4KZr2WlX+pNZA=; b=Tt0uYBGBA6CYHj l2LTTZwLhwYls8xkdbv8x4kvdOWhSSDTkv5OWmDwpxQOMNKkv1id1FMb8i6jguLFuR+FzAro2mEoj uhIVjv3TuXLwlgvQpx8KuRe+OCmXOIm2Ouez1hROeMQdadNH6LobsgDmmUg3OCAfI4Bh/E9b2AXqS 6fhoxakGKAuLyCuJIC8JJ3mnd9fw+8qGP18DinFWHCklpEPHrtK3iO58aMZDmtjB45O2ap9b2OZds 2UKQnjMHI1L7QbCKvr+moTg4OBOClglVv6Hzc1mW3yu53Cd4xqMbnL9kLtaITMfGRepFknlxtWzl5 SYIMWBtuZgcTcuG34PlQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1ozikj-003WDW-3N; Mon, 28 Nov 2022 18:21:13 +0000 Received: from ams.source.kernel.org ([2604:1380:4601:e00::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oziA1-003BRe-B1 for linux-arm-kernel@lists.infradead.org; Mon, 28 Nov 2022 17:43:19 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id F3F1FB80E56; Mon, 28 Nov 2022 17:43:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 86523C433C1; Mon, 28 Nov 2022 17:43:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1669657394; bh=6cAhwMlr8XeHBk3aMCDiSQIUV9nLEglWSxuRoNh3pt8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qNvCEKZN8Rf+8tGu4+vW39qWFTk6qGpe4wD1HktRNzzzEUfKEXvny3idf3xOpaYYP 3DeAF/CR0BLPVinllG1C3Mb9V7kGwynYaHYBi4YxFJw1BEYrw9rZ6OqlZyt7LmyV66 CoRSwui8JWYSlUzrG0Ex5KeD/u7f/fpQ+62UsjDxMUw2LAahhERDsDLqa+JrsV+LQ/ 4MqFg5ffbbaywH2tgh+qDAbGLgGts2FhoJCcjvkRa9Tdlx4R/q3VWbMuQ2gWZTEWx/ egOkbZmffyV0NhWDFCFrnhajTXnluPba+9KGrrb37b2LrGcGj/EZHiMZh4k4gmpp8V 2I3doZ2hUOXXQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Giulio Benetti , Arnd Bergmann , Russell King , Sasha Levin , linux@armlinux.org.uk, akpm@linux-foundation.org, anshuman.khandual@arm.com, wangkefeng.wang@huawei.com, will@kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH AUTOSEL 4.14 4/9] ARM: 9266/1: mm: fix no-MMU ZERO_PAGE() implementation Date: Mon, 28 Nov 2022 12:42:57 -0500 Message-Id: <20221128174303.1443008-4-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20221128174303.1443008-1-sashal@kernel.org> References: <20221128174303.1443008-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221128_094317_750415_F7D8846E X-CRM114-Status: GOOD ( 17.43 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Giulio Benetti [ Upstream commit 340a982825f76f1cff0daa605970fe47321b5ee7 ] Actually in no-MMU SoCs(i.e. i.MXRT) ZERO_PAGE(vaddr) expands to ``` virt_to_page(0) ``` that in order expands to: ``` pfn_to_page(virt_to_pfn(0)) ``` and then virt_to_pfn(0) to: ``` ((((unsigned long)(0) - PAGE_OFFSET) >> PAGE_SHIFT) + PHYS_PFN_OFFSET) ``` where PAGE_OFFSET and PHYS_PFN_OFFSET are the DRAM offset(0x80000000) and PAGE_SHIFT is 12. This way we obtain 16MB(0x01000000) summed to the base of DRAM(0x80000000). When ZERO_PAGE(0) is then used, for example in bio_add_page(), the page gets an address that is out of DRAM bounds. So instead of using fake virtual page 0 let's allocate a dedicated zero_page during paging_init() and assign it to a global 'struct page * empty_zero_page' the same way mmu.c does and it's the same approach used in m68k with commit dc068f462179 as discussed here[0]. Then let's move ZERO_PAGE() definition to the top of pgtable.h to be in common between mmu.c and nommu.c. [0]: https://lore.kernel.org/linux-m68k/2a462b23-5b8e-bbf4-ec7d-778434a3b9d7@google.com/T/#m1266ceb63 ad140743174d6b3070364d3c9a5179b Signed-off-by: Giulio Benetti Reviewed-by: Arnd Bergmann Signed-off-by: Russell King (Oracle) Signed-off-by: Sasha Levin --- arch/arm/include/asm/pgtable-nommu.h | 6 ------ arch/arm/include/asm/pgtable.h | 16 +++++++++------- arch/arm/mm/nommu.c | 19 +++++++++++++++++++ 3 files changed, 28 insertions(+), 13 deletions(-) diff --git a/arch/arm/include/asm/pgtable-nommu.h b/arch/arm/include/asm/pgtable-nommu.h index a0d726a47c8a..e7ca798513c1 100644 --- a/arch/arm/include/asm/pgtable-nommu.h +++ b/arch/arm/include/asm/pgtable-nommu.h @@ -54,12 +54,6 @@ typedef pte_t *pte_addr_t; -/* - * ZERO_PAGE is a global shared page that is always zero: used - * for zero-mapped memory areas etc.. - */ -#define ZERO_PAGE(vaddr) (virt_to_page(0)) - /* * Mark the prot value as uncacheable and unbufferable. */ diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h index 1c462381c225..ce89af40651d 100644 --- a/arch/arm/include/asm/pgtable.h +++ b/arch/arm/include/asm/pgtable.h @@ -13,6 +13,15 @@ #include #include +#ifndef __ASSEMBLY__ +/* + * ZERO_PAGE is a global shared page that is always zero: used + * for zero-mapped memory areas etc.. + */ +extern struct page *empty_zero_page; +#define ZERO_PAGE(vaddr) (empty_zero_page) +#endif + #ifndef CONFIG_MMU #include @@ -166,13 +175,6 @@ extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, #define __S111 __PAGE_SHARED_EXEC #ifndef __ASSEMBLY__ -/* - * ZERO_PAGE is a global shared page that is always zero: used - * for zero-mapped memory areas etc.. - */ -extern struct page *empty_zero_page; -#define ZERO_PAGE(vaddr) (empty_zero_page) - extern pgd_t swapper_pg_dir[PTRS_PER_PGD]; diff --git a/arch/arm/mm/nommu.c b/arch/arm/mm/nommu.c index 91537d90f5f5..d58dd8af2cf0 100644 --- a/arch/arm/mm/nommu.c +++ b/arch/arm/mm/nommu.c @@ -25,6 +25,13 @@ unsigned long vectors_base; +/* + * empty_zero_page is a special page that is used for + * zero-initialized data and COW. + */ +struct page *empty_zero_page; +EXPORT_SYMBOL(empty_zero_page); + #ifdef CONFIG_ARM_MPU struct mpu_rgn_info mpu_rgn_info; @@ -366,9 +373,21 @@ void __init adjust_lowmem_bounds(void) */ void __init paging_init(const struct machine_desc *mdesc) { + void *zero_page; + early_trap_init((void *)vectors_base); mpu_setup(); + + /* allocate the zero page. */ + zero_page = memblock_alloc(PAGE_SIZE, PAGE_SIZE); + if (!zero_page) + panic("%s: Failed to allocate %lu bytes align=0x%lx\n", + __func__, PAGE_SIZE, PAGE_SIZE); + bootmem_init(); + + empty_zero_page = virt_to_page(zero_page); + flush_dcache_page(empty_zero_page); } /* -- 2.35.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel