From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f198.google.com (mail-qt0-f198.google.com [209.85.216.198]) by kanga.kvack.org (Postfix) with ESMTP id B4DF76B0311 for ; Mon, 7 Aug 2017 16:39:50 -0400 (EDT) Received: by mail-qt0-f198.google.com with SMTP id l22so6642628qtf.9 for ; Mon, 07 Aug 2017 13:39:50 -0700 (PDT) Received: from aserp1040.oracle.com (aserp1040.oracle.com. [141.146.126.69]) by mx.google.com with ESMTPS id v68si7903902qkd.300.2017.08.07.13.39.48 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 07 Aug 2017 13:39:49 -0700 (PDT) From: Pavel Tatashin Subject: [v6 10/15] x86/kasan: explicitly zero kasan shadow memory Date: Mon, 7 Aug 2017 16:38:44 -0400 Message-Id: <1502138329-123460-11-git-send-email-pasha.tatashin@oracle.com> In-Reply-To: <1502138329-123460-1-git-send-email-pasha.tatashin@oracle.com> References: <1502138329-123460-1-git-send-email-pasha.tatashin@oracle.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-arm-kernel@lists.infradead.org, x86@kernel.org, kasan-dev@googlegroups.com, borntraeger@de.ibm.com, heiko.carstens@de.ibm.com, davem@davemloft.net, willy@infradead.org, mhocko@kernel.org, ard.biesheuvel@linaro.org, will.deacon@arm.com, catalin.marinas@arm.com, sam@ravnborg.org To optimize the performance of struct page initialization, vmemmap_populate() will no longer zero memory. We must explicitly zero the memory that is allocated by vmemmap_populate() for kasan, as this memory does not go through struct page initialization path. Signed-off-by: Pavel Tatashin Reviewed-by: Steven Sistare Reviewed-by: Daniel Jordan Reviewed-by: Bob Picco --- arch/x86/mm/kasan_init_64.c | 67 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 67 insertions(+) diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c index 02c9d7553409..ec6b2272fd80 100644 --- a/arch/x86/mm/kasan_init_64.c +++ b/arch/x86/mm/kasan_init_64.c @@ -84,6 +84,66 @@ static struct notifier_block kasan_die_notifier = { }; #endif +/* + * x86 variant of vmemmap_populate() uses either PMD_SIZE pages or base pages + * to map allocated memory. This routine determines the page size for the given + * address from vmemmap. + */ +static u64 get_vmemmap_pgsz(u64 addr) +{ + pgd_t *pgd; + p4d_t *p4d; + pud_t *pud; + pmd_t *pmd; + + pgd = pgd_offset_k(addr); + BUG_ON(pgd_none(*pgd) || pgd_large(*pgd)); + + p4d = p4d_offset(pgd, addr); + BUG_ON(p4d_none(*p4d) || p4d_large(*p4d)); + + pud = pud_offset(p4d, addr); + BUG_ON(pud_none(*pud) || pud_large(*pud)); + + pmd = pmd_offset(pud, addr); + BUG_ON(pmd_none(*pmd)); + + if (pmd_large(*pmd)) + return PMD_SIZE; + return PAGE_SIZE; +} + +/* + * Memory that was allocated by vmemmap_populate is not zeroed, so we must + * zero it here explicitly. + */ +static void +zero_vmemmap_populated_memory(void) +{ + u64 i, start, end; + + for (i = 0; i < E820_MAX_ENTRIES && pfn_mapped[i].end; i++) { + void *kaddr_start = pfn_to_kaddr(pfn_mapped[i].start); + void *kaddr_end = pfn_to_kaddr(pfn_mapped[i].end); + + start = (u64)kasan_mem_to_shadow(kaddr_start); + end = (u64)kasan_mem_to_shadow(kaddr_end); + + /* Round to the start end of the mapped pages */ + start = rounddown(start, get_vmemmap_pgsz(start)); + end = roundup(end, get_vmemmap_pgsz(start)); + memset((void *)start, 0, end - start); + } + + start = (u64)kasan_mem_to_shadow(_stext); + end = (u64)kasan_mem_to_shadow(_end); + + /* Round to the start end of the mapped pages */ + start = rounddown(start, get_vmemmap_pgsz(start)); + end = roundup(end, get_vmemmap_pgsz(start)); + memset((void *)start, 0, end - start); +} + void __init kasan_early_init(void) { int i; @@ -156,6 +216,13 @@ void __init kasan_init(void) pte_t pte = __pte(__pa(kasan_zero_page) | __PAGE_KERNEL_RO); set_pte(&kasan_zero_pte[i], pte); } + + /* + * vmemmap_populate does not zero the memory, so we need to zero it + * explicitly + */ + zero_vmemmap_populated_memory(); + /* Flush TLBs again to be sure that write protection applied. */ __flush_tlb_all(); -- 2.14.0 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org