From: Pavel Tatashin <pasha.tatashin@oracle.com>
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,
mgorman@techsingularity.net, Steven.Sistare@oracle.com,
daniel.m.jordan@oracle.com, bob.picco@oracle.com
Subject: [PATCH v7 09/11] x86/kasan: explicitly zero kasan shadow memory
Date: Mon, 28 Aug 2017 22:02:20 -0400 [thread overview]
Message-ID: <1503972142-289376-10-git-send-email-pasha.tatashin@oracle.com> (raw)
In-Reply-To: <1503972142-289376-1-git-send-email-pasha.tatashin@oracle.com>
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 <pasha.tatashin@oracle.com>
Reviewed-by: Steven Sistare <steven.sistare@oracle.com>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Reviewed-by: Bob Picco <bob.picco@oracle.com>
---
arch/x86/mm/kasan_init_64.c | 66 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 66 insertions(+)
diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
index 02c9d7553409..96fde5bf9597 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;
@@ -146,6 +206,12 @@ void __init kasan_init(void)
load_cr3(init_top_pgt);
__flush_tlb_all();
+ /*
+ * vmemmap_populate does not zero the memory, so we need to zero it
+ * explicitly
+ */
+ zero_vmemmap_populated_memory();
+
/*
* kasan_zero_page has been used as early shadow memory, thus it may
* contain some garbage. Now we can clear and write protect it, since
--
2.14.1
next prev parent reply other threads:[~2017-08-29 2:03 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-29 2:02 [PATCH v7 00/11] complete deferred page initialization Pavel Tatashin
2017-08-29 2:02 ` [PATCH v7 01/11] x86/mm: setting fields in deferred pages Pavel Tatashin
2017-08-29 2:02 ` [PATCH v7 02/11] sparc64/mm: " Pavel Tatashin
2017-08-30 1:09 ` David Miller
2017-08-29 2:02 ` [PATCH v7 03/11] mm: deferred_init_memmap improvements Pavel Tatashin
2017-08-29 2:02 ` [PATCH v7 04/11] sparc64: simplify vmemmap_populate Pavel Tatashin
2017-08-30 1:08 ` David Miller
2017-08-29 2:02 ` [PATCH v7 05/11] mm: defining memblock_virt_alloc_try_nid_raw Pavel Tatashin
2017-08-29 2:02 ` [PATCH v7 06/11] mm: zero struct pages during initialization Pavel Tatashin
2017-08-29 2:02 ` [PATCH v7 07/11] sparc64: optimized struct page zeroing Pavel Tatashin
2017-08-30 1:12 ` David Miller
2017-08-30 13:19 ` Pasha Tatashin
2017-08-30 17:46 ` David Miller
2017-08-29 2:02 ` [PATCH v7 08/11] mm: zero reserved and unavailable struct pages Pavel Tatashin
2017-08-30 21:22 ` kbuild test robot
2017-08-30 23:12 ` kbuild test robot
2017-08-29 2:02 ` Pavel Tatashin [this message]
2017-08-29 2:02 ` [PATCH v7 10/11] arm64/kasan: explicitly zero kasan shadow memory Pavel Tatashin
2017-08-29 2:02 ` [PATCH v7 11/11] mm: stop zeroing memory during allocation in vmemmap Pavel Tatashin
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