From patchwork Mon Aug 1 08:04:18 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mike Rapoport X-Patchwork-Id: 12933612 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 AF675C00144 for ; Mon, 1 Aug 2022 08:06:51 +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=gxYBbJ7ga8PqqMvUW8IJs9dxyv9ZAnmpGU8EIuGDykc=; b=1Tbd/LsAx9/pDR SNo14PiTMSuHcpP9hPvpBO9Bn87vPnIBir3llrjb/boIZyiDkqLzuMjjyljOCwQIVCyyRCBnCMlnw Ex0O9wD35Qi7SQkg/EjcfepwEVCRVHAOcALDotMewXgB8g4ZR6DhM+fq/FhCg+fAdlWFsA6F3AQam 3lKX5TPdPyx7O5wy0zIaxAhWfsw1n+dSpC9qQn4aRJulr0dM0Ug3YVGsVD11VjOEVFE36Mcm89RVn HdhkQ9g24S6tVeamAvjGA6czoAXlFsSqZCT817v+KXX0EIwWnjNl4UA9CAHKqSHKbgxqwT1IgRwLj eFL12aAhrOgi7ahrlrXQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oIQQj-003lDO-H1; Mon, 01 Aug 2022 08:05:37 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oIQPy-003kqf-EV for linux-arm-kernel@lists.infradead.org; Mon, 01 Aug 2022 08:04:52 +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 dfw.source.kernel.org (Postfix) with ESMTPS id 0243B60F7A; Mon, 1 Aug 2022 08:04:50 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 26360C433D6; Mon, 1 Aug 2022 08:04:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659341089; bh=qKJExSsMZxxR+aUTqOoUvDyCTHTRATeezFg2ogsh8+Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ebTy4eAPxdr5U3gaHN547xPcezVzmKmRICjgBlcfJvgPMu1wIRAr9Y7RI9Usc+Yp+ wHakJin/06O2DipcHWg5yUWr7xsSjwx72cOPR+oMFP/850pvkyqIauVmyqREF/HqTi 1RGHn1v/NrmYthQzj/C6K1a3IXiG+orb65+mvyXn+Z1zLjcTuaMK1JzA/Biugza1qm l9ey9VAOBFvLRggzSdhb0VO0+1ysXdhEY+ERIpG3rnHUKsSWL5M0WK5vVp9i6wbyCO FKfRYj7npF85Wq2Q32da3EyKRnt/6xNEEqh+76pPtWc4Ac9L0q+xyfWk412UQ2I4dR Rb854hDm7cInA== From: Mike Rapoport To: linux-arm-kernel@lists.infradead.org Cc: Ard Biesheuvel , Catalin Marinas , Guanghui Feng , Mark Rutland , Mike Rapoport , Mike Rapoport , Will Deacon , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [RFC PATCH 4/4] arm64/mm: remap crash kernel with base pages even if rodata_full disabled Date: Mon, 1 Aug 2022 11:04:18 +0300 Message-Id: <20220801080418.120311-5-rppt@kernel.org> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20220801080418.120311-1-rppt@kernel.org> References: <20220801080418.120311-1-rppt@kernel.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220801_010450_594958_D909CFA7 X-CRM114-Status: GOOD ( 24.78 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Mike Rapoport For server systems it is important to protect crash kernel memory for post-mortem analysis. In order to protect this memory it should be mapped at PTE level. When CONFIG_ZONE_DMA or CONFIG_ZONE_DMA32 is enabled, usage of crash kernel essentially forces mapping of the entire linear map with base pages even if rodata_full is not set (commit 2687275a5843 ("arm64: Force NO_BLOCK_MAPPINGS if crashkernel reservation is required")) and this causes performance degradation. With ZONE_DMA/DMA32 enabled, the crash kernel memory is reserved after the linear map is created, but before multiprocessing and multithreading are enabled, so it is safe to remap the crash kernel memory with base pages as long as the page table entries that would be changed do not map the memory that might be accessed during the remapping. To ensure there are no memory accesses in the range that will be remapped, align crash memory reservation to PUD_SIZE boundaries, remap the entire PUD-aligned area and than free the memory that was allocated beyond the crash_size requested by the user. Signed-off-by: Mike Rapoport --- arch/arm64/include/asm/mmu.h | 2 ++ arch/arm64/mm/init.c | 40 ++++++++++++++++++++++++++++++++++-- arch/arm64/mm/mmu.c | 40 +++++++++++++++++++++++++++++++----- 3 files changed, 75 insertions(+), 7 deletions(-) diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h index 48f8466a4be9..d9829a7def69 100644 --- a/arch/arm64/include/asm/mmu.h +++ b/arch/arm64/include/asm/mmu.h @@ -71,6 +71,8 @@ extern void create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys, extern void *fixmap_remap_fdt(phys_addr_t dt_phys, int *size, pgprot_t prot); extern void mark_linear_text_alias_ro(void); extern bool kaslr_requires_kpti(void); +extern int remap_crashkernel(phys_addr_t start, phys_addr_t size, + phys_addr_t aligned_size); #define INIT_MM_CONTEXT(name) \ .pgd = init_pg_dir, diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index fa2260040c0f..be74e091bef7 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -40,6 +40,7 @@ #include #include #include +#include #include #include #include @@ -116,6 +117,38 @@ static int __init reserve_crashkernel_low(unsigned long long low_size) return 0; } +static unsigned long long __init +reserve_remap_crashkernel(unsigned long long crash_base, + unsigned long long crash_size, + unsigned long long crash_max) +{ + unsigned long long size; + + if (!have_zone_dma()) + return 0; + + if (can_set_direct_map() || IS_ENABLED(CONFIG_KFENCE)) + return 0; + + if (crash_base) + return 0; + + size = ALIGN(crash_size, PUD_SIZE); + + crash_base = memblock_phys_alloc_range(size, PUD_SIZE, 0, crash_max); + if (!crash_base) + return 0; + + if (remap_crashkernel(crash_base, crash_size, size)) { + memblock_phys_free(crash_base, size); + return 0; + } + + memblock_phys_free(crash_base + crash_size, size - crash_size); + + return crash_base; +} + /* * reserve_crashkernel() - reserves memory for crash kernel * @@ -162,8 +195,11 @@ static void __init reserve_crashkernel(void) if (crash_base) crash_max = crash_base + crash_size; - crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN, - crash_base, crash_max); + crash_base = reserve_remap_crashkernel(crash_base, crash_size, + crash_max); + if (!crash_base) + crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN, + crash_base, crash_max); if (!crash_base) { pr_warn("cannot allocate crashkernel (size:0x%llx)\n", crash_size); diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 2f548fb2244c..183936775fab 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -528,10 +528,8 @@ static void __init map_mem(pgd_t *pgdp) memblock_mark_nomap(kernel_start, kernel_end - kernel_start); #ifdef CONFIG_KEXEC_CORE - if (crash_mem_map) { - if (have_zone_dma()) - flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; - else if (crashk_res.end) + if (crash_mem_map && !have_zone_dma()) { + if (crashk_res.end) memblock_mark_nomap(crashk_res.start, resource_size(&crashk_res)); } @@ -825,7 +823,7 @@ int kern_addr_valid(unsigned long addr) return pfn_valid(pte_pfn(pte)); } -#ifdef CONFIG_MEMORY_HOTPLUG +#if defined(CONFIG_MEMORY_HOTPLUG) || defined(CONFIG_KEXEC_CORE) static void free_hotplug_page_range(struct page *page, size_t size, struct vmem_altmap *altmap) { @@ -968,7 +966,9 @@ static void unmap_range(unsigned long addr, unsigned long end, unmap_p4d_range(pgdp, addr, next, free_mapped, altmap); } while (addr = next, addr < end); } +#endif /* CONFIG_MEMORY_HOTPLUG || CONFIG_KEXEC_CORE */ +#ifdef CONFIG_MEMORY_HOTPLUG static bool pgtable_range_aligned(unsigned long start, unsigned long end, unsigned long floor, unsigned long ceiling, unsigned long mask) @@ -1213,6 +1213,36 @@ void vmemmap_free(unsigned long start, unsigned long end, } #endif /* CONFIG_MEMORY_HOTPLUG */ +int __init remap_crashkernel(phys_addr_t start, phys_addr_t size, + phys_addr_t aligned_size) +{ +#ifdef CONFIG_KEXEC_CORE + phys_addr_t end = start + size; + phys_addr_t aligned_end = start + aligned_size; + + if (!IS_ALIGNED(start, PUD_SIZE) || !IS_ALIGNED(aligned_end, PUD_SIZE)) + return -EINVAL; + + /* Clear PUDs containing crash kernel memory */ + unmap_range(__phys_to_virt(start), __phys_to_virt(aligned_end), + false, NULL); + + /* map crash kernel memory with base pages */ + __create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start), + size, PAGE_KERNEL, early_pgtable_alloc, + NO_EXEC_MAPPINGS | NO_BLOCK_MAPPINGS | + NO_CONT_MAPPINGS); + + /* map area from end of crash kernel to PUD end with large pages */ + size = aligned_end - end; + if (size) + __create_pgd_mapping(swapper_pg_dir, end, __phys_to_virt(end), + size, PAGE_KERNEL, early_pgtable_alloc, 0); +#endif + + return 0; +} + static inline pud_t *fixmap_pud(unsigned long addr) { pgd_t *pgdp = pgd_offset_k(addr);