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-rw-r--r--mm/kasan/kasan_init.c152
1 files changed, 152 insertions, 0 deletions
diff --git a/mm/kasan/kasan_init.c b/mm/kasan/kasan_init.c
new file mode 100644
index 000000000000..3f9a41cf0ac6
--- /dev/null
+++ b/mm/kasan/kasan_init.c
@@ -0,0 +1,152 @@
+/*
+ * This file contains some kasan initialization code.
+ *
+ * Copyright (c) 2015 Samsung Electronics Co., Ltd.
+ * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/bootmem.h>
+#include <linux/init.h>
+#include <linux/kasan.h>
+#include <linux/kernel.h>
+#include <linux/memblock.h>
+#include <linux/pfn.h>
+
+#include <asm/page.h>
+#include <asm/pgalloc.h>
+
+/*
+ * This page serves two purposes:
+ * - It used as early shadow memory. The entire shadow region populated
+ * with this page, before we will be able to setup normal shadow memory.
+ * - Latter it reused it as zero shadow to cover large ranges of memory
+ * that allowed to access, but not handled by kasan (vmalloc/vmemmap ...).
+ */
+unsigned char kasan_zero_page[PAGE_SIZE] __page_aligned_bss;
+
+#if CONFIG_PGTABLE_LEVELS > 3
+pud_t kasan_zero_pud[PTRS_PER_PUD] __page_aligned_bss;
+#endif
+#if CONFIG_PGTABLE_LEVELS > 2
+pmd_t kasan_zero_pmd[PTRS_PER_PMD] __page_aligned_bss;
+#endif
+pte_t kasan_zero_pte[PTRS_PER_PTE] __page_aligned_bss;
+
+static __init void *early_alloc(size_t size, int node)
+{
+ return memblock_virt_alloc_try_nid(size, size, __pa(MAX_DMA_ADDRESS),
+ BOOTMEM_ALLOC_ACCESSIBLE, node);
+}
+
+static void __init zero_pte_populate(pmd_t *pmd, unsigned long addr,
+ unsigned long end)
+{
+ pte_t *pte = pte_offset_kernel(pmd, addr);
+ pte_t zero_pte;
+
+ zero_pte = pfn_pte(PFN_DOWN(__pa(kasan_zero_page)), PAGE_KERNEL);
+ zero_pte = pte_wrprotect(zero_pte);
+
+ while (addr + PAGE_SIZE <= end) {
+ set_pte_at(&init_mm, addr, pte, zero_pte);
+ addr += PAGE_SIZE;
+ pte = pte_offset_kernel(pmd, addr);
+ }
+}
+
+static void __init zero_pmd_populate(pud_t *pud, unsigned long addr,
+ unsigned long end)
+{
+ pmd_t *pmd = pmd_offset(pud, addr);
+ unsigned long next;
+
+ do {
+ next = pmd_addr_end(addr, end);
+
+ if (IS_ALIGNED(addr, PMD_SIZE) && end - addr >= PMD_SIZE) {
+ pmd_populate_kernel(&init_mm, pmd, kasan_zero_pte);
+ continue;
+ }
+
+ if (pmd_none(*pmd)) {
+ pmd_populate_kernel(&init_mm, pmd,
+ early_alloc(PAGE_SIZE, NUMA_NO_NODE));
+ }
+ zero_pte_populate(pmd, addr, next);
+ } while (pmd++, addr = next, addr != end);
+}
+
+static void __init zero_pud_populate(pgd_t *pgd, unsigned long addr,
+ unsigned long end)
+{
+ pud_t *pud = pud_offset(pgd, addr);
+ unsigned long next;
+
+ do {
+ next = pud_addr_end(addr, end);
+ if (IS_ALIGNED(addr, PUD_SIZE) && end - addr >= PUD_SIZE) {
+ pmd_t *pmd;
+
+ pud_populate(&init_mm, pud, kasan_zero_pmd);
+ pmd = pmd_offset(pud, addr);
+ pmd_populate_kernel(&init_mm, pmd, kasan_zero_pte);
+ continue;
+ }
+
+ if (pud_none(*pud)) {
+ pud_populate(&init_mm, pud,
+ early_alloc(PAGE_SIZE, NUMA_NO_NODE));
+ }
+ zero_pmd_populate(pud, addr, next);
+ } while (pud++, addr = next, addr != end);
+}
+
+/**
+ * kasan_populate_zero_shadow - populate shadow memory region with
+ * kasan_zero_page
+ * @shadow_start - start of the memory range to populate
+ * @shadow_end - end of the memory range to populate
+ */
+void __init kasan_populate_zero_shadow(const void *shadow_start,
+ const void *shadow_end)
+{
+ unsigned long addr = (unsigned long)shadow_start;
+ unsigned long end = (unsigned long)shadow_end;
+ pgd_t *pgd = pgd_offset_k(addr);
+ unsigned long next;
+
+ do {
+ next = pgd_addr_end(addr, end);
+
+ if (IS_ALIGNED(addr, PGDIR_SIZE) && end - addr >= PGDIR_SIZE) {
+ pud_t *pud;
+ pmd_t *pmd;
+
+ /*
+ * kasan_zero_pud should be populated with pmds
+ * at this moment.
+ * [pud,pmd]_populate*() below needed only for
+ * 3,2 - level page tables where we don't have
+ * puds,pmds, so pgd_populate(), pud_populate()
+ * is noops.
+ */
+ pgd_populate(&init_mm, pgd, kasan_zero_pud);
+ pud = pud_offset(pgd, addr);
+ pud_populate(&init_mm, pud, kasan_zero_pmd);
+ pmd = pmd_offset(pud, addr);
+ pmd_populate_kernel(&init_mm, pmd, kasan_zero_pte);
+ continue;
+ }
+
+ if (pgd_none(*pgd)) {
+ pgd_populate(&init_mm, pgd,
+ early_alloc(PAGE_SIZE, NUMA_NO_NODE));
+ }
+ zero_pud_populate(pgd, addr, next);
+ } while (pgd++, addr = next, addr != end);
+}