From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932356AbeCOObv (ORCPT ); Thu, 15 Mar 2018 10:31:51 -0400 Received: from terminus.zytor.com ([198.137.202.136]:49603 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932308AbeCOObs (ORCPT ); Thu, 15 Mar 2018 10:31:48 -0400 Date: Thu, 15 Mar 2018 07:31:05 -0700 From: tip-bot for Toshi Kani Message-ID: Cc: mingo@kernel.org, tglx@linutronix.de, bp@alien8.de, linux-kernel@vger.kernel.org, hpa@zytor.com, toshi.kani@hpe.com, gratian.crisan@ni.com, luto@kernel.org Reply-To: mingo@kernel.org, tglx@linutronix.de, bp@alien8.de, linux-kernel@vger.kernel.org, hpa@zytor.com, toshi.kani@hpe.com, luto@kernel.org, gratian.crisan@ni.com In-Reply-To: <20180314205932.7193-1-toshi.kani@hpe.com> References: <20180314205932.7193-1-toshi.kani@hpe.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/mm] x86/mm: Remove pointless checks in vmalloc_fault Git-Commit-ID: 565977a3d929fc4427769117a8ac976ec16776d5 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 565977a3d929fc4427769117a8ac976ec16776d5 Gitweb: https://git.kernel.org/tip/565977a3d929fc4427769117a8ac976ec16776d5 Author: Toshi Kani AuthorDate: Wed, 14 Mar 2018 14:59:32 -0600 Committer: Thomas Gleixner CommitDate: Thu, 15 Mar 2018 15:27:47 +0100 x86/mm: Remove pointless checks in vmalloc_fault vmalloc_fault() sets user's pgd or p4d from the kernel page table. Once it's set, all tables underneath are identical. There is no point of following the same page table with two separate pointers and make sure they see the same with BUG(). Remove the pointless checks in vmalloc_fault(). Also rename the kernel pgd/p4d pointers to pgd_k/p4d_k so that their names are consistent in the file. Suggested-by: Andy Lutomirski Signed-off-by: Toshi Kani Signed-off-by: Thomas Gleixner Cc: linux-mm@kvack.org Cc: Borislav Petkov Cc: Gratian Crisan Link: https://lkml.kernel.org/r/20180314205932.7193-1-toshi.kani@hpe.com --- arch/x86/mm/fault.c | 56 ++++++++++++++++------------------------------------- 1 file changed, 17 insertions(+), 39 deletions(-) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 84d702a71afe..70c3b1c43676 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -417,11 +417,11 @@ void vmalloc_sync_all(void) */ static noinline int vmalloc_fault(unsigned long address) { - pgd_t *pgd, *pgd_ref; - p4d_t *p4d, *p4d_ref; - pud_t *pud, *pud_ref; - pmd_t *pmd, *pmd_ref; - pte_t *pte, *pte_ref; + 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)) @@ -435,73 +435,51 @@ static noinline int vmalloc_fault(unsigned long address) * case just flush: */ pgd = (pgd_t *)__va(read_cr3_pa()) + pgd_index(address); - pgd_ref = pgd_offset_k(address); - if (pgd_none(*pgd_ref)) + 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_ref); + set_pgd(pgd, *pgd_k); arch_flush_lazy_mmu_mode(); } else { - BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref)); + 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_ref = p4d_offset(pgd_ref, address); - if (p4d_none(*p4d_ref)) + 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_ref); + set_p4d(p4d, *p4d_k); arch_flush_lazy_mmu_mode(); } else { - BUG_ON(p4d_pfn(*p4d) != p4d_pfn(*p4d_ref)); + BUG_ON(p4d_pfn(*p4d) != p4d_pfn(*p4d_k)); } - /* - * Below here mismatches are bugs because these lower tables - * are shared: - */ BUILD_BUG_ON(CONFIG_PGTABLE_LEVELS < 4); pud = pud_offset(p4d, address); - pud_ref = pud_offset(p4d_ref, address); - if (pud_none(*pud_ref)) + if (pud_none(*pud)) return -1; - if (pud_none(*pud) || pud_pfn(*pud) != pud_pfn(*pud_ref)) - BUG(); - if (pud_large(*pud)) return 0; pmd = pmd_offset(pud, address); - pmd_ref = pmd_offset(pud_ref, address); - if (pmd_none(*pmd_ref)) + if (pmd_none(*pmd)) return -1; - if (pmd_none(*pmd) || pmd_pfn(*pmd) != pmd_pfn(*pmd_ref)) - BUG(); - if (pmd_large(*pmd)) return 0; - pte_ref = pte_offset_kernel(pmd_ref, address); - if (!pte_present(*pte_ref)) - return -1; - pte = pte_offset_kernel(pmd, address); - - /* - * Don't use pte_page here, because the mappings can point - * outside mem_map, and the NUMA hash lookup cannot handle - * that: - */ - if (!pte_present(*pte) || pte_pfn(*pte) != pte_pfn(*pte_ref)) - BUG(); + if (!pte_present(*pte)) + return -1; return 0; }