From patchwork Thu Sep 2 21:52:19 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 12472721 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4B565C00306 for ; Thu, 2 Sep 2021 21:52:22 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id ED0F5610CF for ; Thu, 2 Sep 2021 21:52:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org ED0F5610CF Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 8F33A6B0088; Thu, 2 Sep 2021 17:52:21 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8A0F26B008A; Thu, 2 Sep 2021 17:52:21 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 742306B008C; Thu, 2 Sep 2021 17:52:21 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0043.hostedemail.com [216.40.44.43]) by kanga.kvack.org (Postfix) with ESMTP id 633946B0088 for ; Thu, 2 Sep 2021 17:52:21 -0400 (EDT) Received: from smtpin32.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 262B6183F4509 for ; Thu, 2 Sep 2021 21:52:21 +0000 (UTC) X-FDA: 78543982482.32.76F8079 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf05.hostedemail.com (Postfix) with ESMTP id A91B05047442 for ; Thu, 2 Sep 2021 21:52:20 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 847CA60F12; Thu, 2 Sep 2021 21:52:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1630619540; bh=cdltCKFLenaJJzcV6FrpQMoL24r+PqxD36iFXS8gbRA=; h=Date:From:To:Subject:In-Reply-To:From; b=gClNhp5g2bUdcdElvweeQrJul5/Rk8IXLwSija3BpPgWFWOku//YUFZrIFX7TNoYD NxJVvMsHDkV4POV0mStfd38AaZQl+MLs03WPZI/184VtN4j4I2seC9aWgPppU1TlJ1 tP/xKxWH3W3ggsmKaQrpiD4Gcj7dCHf0CqlpCAo0= Date: Thu, 02 Sep 2021 14:52:19 -0700 From: Andrew Morton To: akpm@linux-foundation.org, aneesh.kumar@linux.ibm.com, anshuman.khandual@arm.com, cai@lca.pw, catalin.marinas@arm.com, christophe.leroy@csgroup.eu, chuhu@redhat.com, gerald.schaefer@linux.ibm.com, gshan@redhat.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org, vgupta@synopsys.com, will@kernel.org Subject: [patch 044/212] mm/debug_vm_pgtable: introduce struct pgtable_debug_args Message-ID: <20210902215219.8aARsh9pu%akpm@linux-foundation.org> In-Reply-To: <20210902144820.78957dff93d7bea620d55a89@linux-foundation.org> User-Agent: s-nail v14.8.16 Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=gClNhp5g; spf=pass (imf05.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none X-Stat-Signature: 6ogbsm89kmbpk5mioqqfokgfrpjxxqfo X-Rspamd-Queue-Id: A91B05047442 X-Rspamd-Server: rspam04 X-HE-Tag: 1630619540-419456 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Gavin Shan Subject: mm/debug_vm_pgtable: introduce struct pgtable_debug_args Patch series "mm/debug_vm_pgtable: Enhancements", v6. There are a couple of issues with current implementations and this series tries to resolve the issues: (a) All needed information are scattered in variables, passed to various test functions. The code is organized in pretty much relaxed fashion. (b) The page isn't allocated from buddy during page table entry modifying tests. The page can be invalid, conflicting to the implementations of set_xxx_at() on ARM64. The target page is accessed so that the iCache can be flushed when execution permission is given on ARM64. Besides, the target page can be unmapped and accessing to it causes kernel crash. "struct pgtable_debug_args" is introduced to address issue (a). For issue (b), the used page is allocated from buddy in page table entry modifying tests. The corresponding tets will be skipped if we fail to allocate the (huge) page. For other test cases, the original page around to kernel symbol (@start_kernel) is still used. The patches are organized as below. PATCH[2-10] could be combined to one patch, but it will make the review harder: PATCH[1] introduces "struct pgtable_debug_args" as place holder of all needed information. With it, the old and new implementation can coexist. PATCH[2-10] uses "struct pgtable_debug_args" in various test functions. PATCH[11] removes the unused code for old implementation. PATCH[12] fixes the issue of corrupted page flag for ARM64 This patch (of 6): In debug_vm_pgtable(), there are many local variables introduced to track the needed information and they are passed to the functions for various test cases. It'd better to introduce a struct as place holder for these information. With it, what the tests functions need is the struct. In this way, the code is simplified and easier to be maintained. Besides, set_xxx_at() could access the data on the corresponding pages in the page table modifying tests. So the accessed pages in the tests should have been allocated from buddy. Otherwise, we're accessing pages that aren't owned by us. This causes issues like page flag corruption or kernel crash on accessing unmapped page when CONFIG_DEBUG_PAGEALLOC is enabled. This introduces "struct pgtable_debug_args". The struct is initialized and destroyed, but the information in the struct isn't used yet. It will be used in subsequent patches. Link: https://lkml.kernel.org/r/20210809092631.1888748-1-gshan@redhat.com Link: https://lkml.kernel.org/r/20210809092631.1888748-2-gshan@redhat.com Signed-off-by: Gavin Shan Reviewed-by: Anshuman Khandual Tested-by: Christophe Leroy [powerpc 8xx] Tested-by: Gerald Schaefer [s390] Cc: Anshuman Khandual Cc: Aneesh Kumar K.V Cc: Qian Cai Cc: Catalin Marinas Cc: Will Deacon Cc: Vineet Gupta Cc: Chunyu Hu Signed-off-by: Andrew Morton --- mm/debug_vm_pgtable.c | 270 +++++++++++++++++++++++++++++++++++++++- 1 file changed, 269 insertions(+), 1 deletion(-) --- a/mm/debug_vm_pgtable.c~mm-debug_vm_pgtable-introduce-struct-pgtable_debug_args +++ a/mm/debug_vm_pgtable.c @@ -58,6 +58,37 @@ #define RANDOM_ORVALUE (GENMASK(BITS_PER_LONG - 1, 0) & ~ARCH_SKIP_MASK) #define RANDOM_NZVALUE GENMASK(7, 0) +struct pgtable_debug_args { + struct mm_struct *mm; + struct vm_area_struct *vma; + + pgd_t *pgdp; + p4d_t *p4dp; + pud_t *pudp; + pmd_t *pmdp; + pte_t *ptep; + + p4d_t *start_p4dp; + pud_t *start_pudp; + pmd_t *start_pmdp; + pgtable_t start_ptep; + + unsigned long vaddr; + pgprot_t page_prot; + pgprot_t page_prot_none; + + bool is_contiguous_page; + unsigned long pud_pfn; + unsigned long pmd_pfn; + unsigned long pte_pfn; + + unsigned long fixed_pgd_pfn; + unsigned long fixed_p4d_pfn; + unsigned long fixed_pud_pfn; + unsigned long fixed_pmd_pfn; + unsigned long fixed_pte_pfn; +}; + static void __init pte_basic_tests(unsigned long pfn, int idx) { pgprot_t prot = protection_map[idx]; @@ -955,8 +986,239 @@ static unsigned long __init get_random_v return random_vaddr; } +static void __init destroy_args(struct pgtable_debug_args *args) +{ + struct page *page = NULL; + + /* Free (huge) page */ + if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && + IS_ENABLED(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) && + has_transparent_hugepage() && + args->pud_pfn != ULONG_MAX) { + if (args->is_contiguous_page) { + free_contig_range(args->pud_pfn, + (1 << (HPAGE_PUD_SHIFT - PAGE_SHIFT))); + } else { + page = pfn_to_page(args->pud_pfn); + __free_pages(page, HPAGE_PUD_SHIFT - PAGE_SHIFT); + } + + args->pud_pfn = ULONG_MAX; + args->pmd_pfn = ULONG_MAX; + args->pte_pfn = ULONG_MAX; + } + + if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && + has_transparent_hugepage() && + args->pmd_pfn != ULONG_MAX) { + if (args->is_contiguous_page) { + free_contig_range(args->pmd_pfn, (1 << HPAGE_PMD_ORDER)); + } else { + page = pfn_to_page(args->pmd_pfn); + __free_pages(page, HPAGE_PMD_ORDER); + } + + args->pmd_pfn = ULONG_MAX; + args->pte_pfn = ULONG_MAX; + } + + if (args->pte_pfn != ULONG_MAX) { + page = pfn_to_page(args->pte_pfn); + __free_pages(page, 0); + + args->pte_pfn = ULONG_MAX; + } + + /* Free page table entries */ + if (args->start_ptep) { + pte_free(args->mm, args->start_ptep); + mm_dec_nr_ptes(args->mm); + } + + if (args->start_pmdp) { + pmd_free(args->mm, args->start_pmdp); + mm_dec_nr_pmds(args->mm); + } + + if (args->start_pudp) { + pud_free(args->mm, args->start_pudp); + mm_dec_nr_puds(args->mm); + } + + if (args->start_p4dp) + p4d_free(args->mm, args->start_p4dp); + + /* Free vma and mm struct */ + if (args->vma) + vm_area_free(args->vma); + + if (args->mm) + mmdrop(args->mm); +} + +static struct page * __init +debug_vm_pgtable_alloc_huge_page(struct pgtable_debug_args *args, int order) +{ + struct page *page = NULL; + +#ifdef CONFIG_CONTIG_ALLOC + if (order >= MAX_ORDER) { + page = alloc_contig_pages((1 << order), GFP_KERNEL, + first_online_node, NULL); + if (page) { + args->is_contiguous_page = true; + return page; + } + } +#endif + + if (order < MAX_ORDER) + page = alloc_pages(GFP_KERNEL, order); + + return page; +} + +static int __init init_args(struct pgtable_debug_args *args) +{ + struct page *page = NULL; + phys_addr_t phys; + int ret = 0; + + /* + * Initialize the debugging data. + * + * __P000 (or even __S000) will help create page table entries with + * PROT_NONE permission as required for pxx_protnone_tests(). + */ + memset(args, 0, sizeof(*args)); + args->vaddr = get_random_vaddr(); + args->page_prot = vm_get_page_prot(VMFLAGS); + args->page_prot_none = __P000; + args->is_contiguous_page = false; + args->pud_pfn = ULONG_MAX; + args->pmd_pfn = ULONG_MAX; + args->pte_pfn = ULONG_MAX; + args->fixed_pgd_pfn = ULONG_MAX; + args->fixed_p4d_pfn = ULONG_MAX; + args->fixed_pud_pfn = ULONG_MAX; + args->fixed_pmd_pfn = ULONG_MAX; + args->fixed_pte_pfn = ULONG_MAX; + + /* Allocate mm and vma */ + args->mm = mm_alloc(); + if (!args->mm) { + pr_err("Failed to allocate mm struct\n"); + ret = -ENOMEM; + goto error; + } + + args->vma = vm_area_alloc(args->mm); + if (!args->vma) { + pr_err("Failed to allocate vma\n"); + ret = -ENOMEM; + goto error; + } + + /* + * Allocate page table entries. They will be modified in the tests. + * Lets save the page table entries so that they can be released + * when the tests are completed. + */ + args->pgdp = pgd_offset(args->mm, args->vaddr); + args->p4dp = p4d_alloc(args->mm, args->pgdp, args->vaddr); + if (!args->p4dp) { + pr_err("Failed to allocate p4d entries\n"); + ret = -ENOMEM; + goto error; + } + args->start_p4dp = p4d_offset(args->pgdp, 0UL); + WARN_ON(!args->start_p4dp); + + args->pudp = pud_alloc(args->mm, args->p4dp, args->vaddr); + if (!args->pudp) { + pr_err("Failed to allocate pud entries\n"); + ret = -ENOMEM; + goto error; + } + args->start_pudp = pud_offset(args->p4dp, 0UL); + WARN_ON(!args->start_pudp); + + args->pmdp = pmd_alloc(args->mm, args->pudp, args->vaddr); + if (!args->pmdp) { + pr_err("Failed to allocate pmd entries\n"); + ret = -ENOMEM; + goto error; + } + args->start_pmdp = pmd_offset(args->pudp, 0UL); + WARN_ON(!args->start_pmdp); + + if (pte_alloc(args->mm, args->pmdp)) { + pr_err("Failed to allocate pte entries\n"); + ret = -ENOMEM; + goto error; + } + args->start_ptep = pmd_pgtable(READ_ONCE(*args->pmdp)); + WARN_ON(!args->start_ptep); + + /* + * PFN for mapping at PTE level is determined from a standard kernel + * text symbol. But pfns for higher page table levels are derived by + * masking lower bits of this real pfn. These derived pfns might not + * exist on the platform but that does not really matter as pfn_pxx() + * helpers will still create appropriate entries for the test. This + * helps avoid large memory block allocations to be used for mapping + * at higher page table levels in some of the tests. + */ + phys = __pa_symbol(&start_kernel); + args->fixed_pgd_pfn = __phys_to_pfn(phys & PGDIR_MASK); + args->fixed_p4d_pfn = __phys_to_pfn(phys & P4D_MASK); + args->fixed_pud_pfn = __phys_to_pfn(phys & PUD_MASK); + args->fixed_pmd_pfn = __phys_to_pfn(phys & PMD_MASK); + args->fixed_pte_pfn = __phys_to_pfn(phys & PAGE_MASK); + WARN_ON(!pfn_valid(args->fixed_pte_pfn)); + + /* + * Allocate (huge) pages because some of the tests need to access + * the data in the pages. The corresponding tests will be skipped + * if we fail to allocate (huge) pages. + */ + if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && + IS_ENABLED(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) && + has_transparent_hugepage()) { + page = debug_vm_pgtable_alloc_huge_page(args, + HPAGE_PUD_SHIFT - PAGE_SHIFT); + if (page) { + args->pud_pfn = page_to_pfn(page); + args->pmd_pfn = args->pud_pfn; + args->pte_pfn = args->pud_pfn; + return 0; + } + } + + if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && + has_transparent_hugepage()) { + page = debug_vm_pgtable_alloc_huge_page(args, HPAGE_PMD_ORDER); + if (page) { + args->pmd_pfn = page_to_pfn(page); + args->pte_pfn = args->pmd_pfn; + return 0; + } + } + + page = alloc_pages(GFP_KERNEL, 0); + if (page) + args->pte_pfn = page_to_pfn(page); + + return 0; + +error: + destroy_args(args); + return ret; +} + static int __init debug_vm_pgtable(void) { + struct pgtable_debug_args args; struct vm_area_struct *vma; struct mm_struct *mm; pgd_t *pgdp; @@ -970,9 +1232,13 @@ static int __init debug_vm_pgtable(void) unsigned long vaddr, pte_aligned, pmd_aligned; unsigned long pud_aligned, p4d_aligned, pgd_aligned; spinlock_t *ptl = NULL; - int idx; + int idx, ret; pr_info("Validating architecture page table helpers\n"); + ret = init_args(&args); + if (ret) + return ret; + prot = vm_get_page_prot(VMFLAGS); vaddr = get_random_vaddr(); mm = mm_alloc(); @@ -1127,6 +1393,8 @@ static int __init debug_vm_pgtable(void) mm_dec_nr_pmds(mm); mm_dec_nr_ptes(mm); mmdrop(mm); + + destroy_args(&args); return 0; } late_initcall(debug_vm_pgtable);