From patchwork Fri May 8 14:40:43 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joerg Roedel X-Patchwork-Id: 194210 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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT 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 2A010C54E7E for ; Fri, 8 May 2020 14:41:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0F10C24973 for ; Fri, 8 May 2020 14:41:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728240AbgEHOk7 (ORCPT ); Fri, 8 May 2020 10:40:59 -0400 Received: from 8bytes.org ([81.169.241.247]:41758 "EHLO theia.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728186AbgEHOk6 (ORCPT ); Fri, 8 May 2020 10:40:58 -0400 Received: by theia.8bytes.org (Postfix, from userid 1000) id 85B084D9; Fri, 8 May 2020 16:40:51 +0200 (CEST) From: Joerg Roedel To: x86@kernel.org Cc: hpa@zytor.com, Dave Hansen , Andy Lutomirski , Peter Zijlstra , rjw@rjwysocki.net, Arnd Bergmann , Andrew Morton , Steven Rostedt , Vlastimil Babka , Michal Hocko , Joerg Roedel , joro@8bytes.org, linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org Subject: [RFC PATCH 7/7] x86/mm: Remove vmalloc faulting Date: Fri, 8 May 2020 16:40:43 +0200 Message-Id: <20200508144043.13893-8-joro@8bytes.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200508144043.13893-1-joro@8bytes.org> References: <20200508144043.13893-1-joro@8bytes.org> Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org From: Joerg Roedel Remove fault handling on vmalloc areas, as the vmalloc code now takes care of synchronizing changes to all page-tables in the system. Signed-off-by: Joerg Roedel --- arch/x86/include/asm/switch_to.h | 23 ------ arch/x86/kernel/setup_percpu.c | 6 +- arch/x86/mm/fault.c | 134 ------------------------------- arch/x86/mm/pti.c | 8 +- 4 files changed, 4 insertions(+), 167 deletions(-) diff --git a/arch/x86/include/asm/switch_to.h b/arch/x86/include/asm/switch_to.h index 0e059b73437b..9f69cc497f4b 100644 --- a/arch/x86/include/asm/switch_to.h +++ b/arch/x86/include/asm/switch_to.h @@ -12,27 +12,6 @@ struct task_struct *__switch_to_asm(struct task_struct *prev, __visible struct task_struct *__switch_to(struct task_struct *prev, struct task_struct *next); -/* This runs runs on the previous thread's stack. */ -static inline void prepare_switch_to(struct task_struct *next) -{ -#ifdef CONFIG_VMAP_STACK - /* - * If we switch to a stack that has a top-level paging entry - * that is not present in the current mm, the resulting #PF will - * will be promoted to a double-fault and we'll panic. Probe - * the new stack now so that vmalloc_fault can fix up the page - * tables if needed. This can only happen if we use a stack - * in vmap space. - * - * We assume that the stack is aligned so that it never spans - * more than one top-level paging entry. - * - * To minimize cache pollution, just follow the stack pointer. - */ - READ_ONCE(*(unsigned char *)next->thread.sp); -#endif -} - asmlinkage void ret_from_fork(void); /* @@ -67,8 +46,6 @@ struct fork_frame { #define switch_to(prev, next, last) \ do { \ - prepare_switch_to(next); \ - \ ((last) = __switch_to_asm((prev), (next))); \ } while (0) diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c index e6d7894ad127..fd945ce78554 100644 --- a/arch/x86/kernel/setup_percpu.c +++ b/arch/x86/kernel/setup_percpu.c @@ -287,9 +287,9 @@ void __init setup_per_cpu_areas(void) /* * Sync back kernel address range again. We already did this in * setup_arch(), but percpu data also needs to be available in - * the smpboot asm. We can't reliably pick up percpu mappings - * using vmalloc_fault(), because exception dispatch needs - * percpu data. + * the smpboot asm and arch_sync_kernel_mappings() doesn't sync to + * swapper_pg_dir on 32-bit. The per-cpu mappings need to be available + * there too. * * FIXME: Can the later sync in setup_cpu_entry_areas() replace * this call? diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 255fc631b042..dffe8e4d3140 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -214,44 +214,6 @@ void arch_sync_kernel_mappings(unsigned long start, unsigned long end) } } -/* - * 32-bit: - * - * Handle a fault on the vmalloc or module mapping area - */ -static noinline int vmalloc_fault(unsigned long address) -{ - unsigned long pgd_paddr; - pmd_t *pmd_k; - pte_t *pte_k; - - /* Make sure we are in vmalloc area: */ - if (!(address >= VMALLOC_START && address < VMALLOC_END)) - return -1; - - /* - * Synchronize this task's top level page-table - * with the 'reference' page table. - * - * Do _not_ use "current" here. We might be inside - * an interrupt in the middle of a task switch.. - */ - pgd_paddr = read_cr3_pa(); - pmd_k = vmalloc_sync_one(__va(pgd_paddr), address); - if (!pmd_k) - return -1; - - if (pmd_large(*pmd_k)) - return 0; - - pte_k = pte_offset_kernel(pmd_k, address); - if (!pte_present(*pte_k)) - return -1; - - return 0; -} -NOKPROBE_SYMBOL(vmalloc_fault); - /* * Did it hit the DOS screen memory VA from vm86 mode? */ @@ -316,79 +278,6 @@ static void dump_pagetable(unsigned long address) #else /* CONFIG_X86_64: */ -/* - * 64-bit: - * - * Handle a fault on the vmalloc area - */ -static noinline int vmalloc_fault(unsigned long address) -{ - pgd_t *pgd, *pgd_k; - p4d_t *p4d, *p4d_k; - pud_t *pud; - pmd_t *pmd; - pte_t *pte; - - /* Make sure we are in vmalloc area: */ - if (!(address >= VMALLOC_START && address < VMALLOC_END)) - return -1; - - /* - * Copy kernel mappings over when needed. This can also - * happen within a race in page table update. In the later - * case just flush: - */ - pgd = (pgd_t *)__va(read_cr3_pa()) + pgd_index(address); - pgd_k = pgd_offset_k(address); - if (pgd_none(*pgd_k)) - return -1; - - if (pgtable_l5_enabled()) { - if (pgd_none(*pgd)) { - set_pgd(pgd, *pgd_k); - arch_flush_lazy_mmu_mode(); - } else { - BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_k)); - } - } - - /* With 4-level paging, copying happens on the p4d level. */ - p4d = p4d_offset(pgd, address); - p4d_k = p4d_offset(pgd_k, address); - if (p4d_none(*p4d_k)) - return -1; - - if (p4d_none(*p4d) && !pgtable_l5_enabled()) { - set_p4d(p4d, *p4d_k); - arch_flush_lazy_mmu_mode(); - } else { - BUG_ON(p4d_pfn(*p4d) != p4d_pfn(*p4d_k)); - } - - BUILD_BUG_ON(CONFIG_PGTABLE_LEVELS < 4); - - pud = pud_offset(p4d, address); - if (pud_none(*pud)) - return -1; - - if (pud_large(*pud)) - return 0; - - pmd = pmd_offset(pud, address); - if (pmd_none(*pmd)) - return -1; - - if (pmd_large(*pmd)) - return 0; - - pte = pte_offset_kernel(pmd, address); - if (!pte_present(*pte)) - return -1; - - return 0; -} -NOKPROBE_SYMBOL(vmalloc_fault); - #ifdef CONFIG_CPU_SUP_AMD static const char errata93_warning[] = KERN_ERR @@ -1227,29 +1116,6 @@ do_kern_addr_fault(struct pt_regs *regs, unsigned long hw_error_code, */ WARN_ON_ONCE(hw_error_code & X86_PF_PK); - /* - * We can fault-in kernel-space virtual memory on-demand. The - * 'reference' page table is init_mm.pgd. - * - * NOTE! We MUST NOT take any locks for this case. We may - * be in an interrupt or a critical region, and should - * only copy the information from the master page table, - * nothing more. - * - * Before doing this on-demand faulting, ensure that the - * fault is not any of the following: - * 1. A fault on a PTE with a reserved bit set. - * 2. A fault caused by a user-mode access. (Do not demand- - * fault kernel memory due to user-mode accesses). - * 3. A fault caused by a page-level protection violation. - * (A demand fault would be on a non-present page which - * would have X86_PF_PROT==0). - */ - if (!(hw_error_code & (X86_PF_RSVD | X86_PF_USER | X86_PF_PROT))) { - if (vmalloc_fault(address) >= 0) - return; - } - /* Was the fault spurious, caused by lazy TLB invalidation? */ if (spurious_kernel_fault(hw_error_code, address)) return; diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c index 843aa10a4cb6..da0fb17a1a36 100644 --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -448,13 +448,7 @@ static void __init pti_clone_user_shared(void) * the sp1 and sp2 slots. * * This is done for all possible CPUs during boot to ensure - * that it's propagated to all mms. If we were to add one of - * these mappings during CPU hotplug, we would need to take - * some measure to make sure that every mm that subsequently - * ran on that CPU would have the relevant PGD entry in its - * pagetables. The usual vmalloc_fault() mechanism would not - * work for page faults taken in entry_SYSCALL_64 before RSP - * is set up. + * that it's propagated to all mms. */ unsigned long va = (unsigned long)&per_cpu(cpu_tss_rw, cpu);