1 files changed, 102 insertions, 0 deletions
diff --git a/arch/xtensa/mm/kasan_init.c b/arch/xtensa/mm/kasan_init.c
new file mode 100644
index 0000000000..f00d122aa8
--- /dev/null
+++ b/arch/xtensa/mm/kasan_init.c
@@ -0,0 +1,102 @@
+/*
+ * Xtensa KASAN shadow map initialization
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2017 Cadence Design Systems Inc.
+ */
+
+#include <linux/memblock.h>
+#include <linux/init_task.h>
+#include <linux/kasan.h>
+#include <linux/kernel.h>
+#include <asm/initialize_mmu.h>
+#include <asm/tlbflush.h>
+
+void __init kasan_early_init(void)
+{
+	unsigned long vaddr = KASAN_SHADOW_START;
+	pmd_t *pmd = pmd_off_k(vaddr);
+	int i;
+
+	for (i = 0; i < PTRS_PER_PTE; ++i)
+		set_pte(kasan_early_shadow_pte + i,
+			mk_pte(virt_to_page(kasan_early_shadow_page),
+				PAGE_KERNEL));
+
+	for (vaddr = 0; vaddr < KASAN_SHADOW_SIZE; vaddr += PMD_SIZE, ++pmd) {
+		BUG_ON(!pmd_none(*pmd));
+		set_pmd(pmd, __pmd((unsigned long)kasan_early_shadow_pte));
+	}
+}
+
+static void __init populate(void *start, void *end)
+{
+	unsigned long n_pages = (end - start) / PAGE_SIZE;
+	unsigned long n_pmds = n_pages / PTRS_PER_PTE;
+	unsigned long i, j;
+	unsigned long vaddr = (unsigned long)start;
+	pmd_t *pmd = pmd_off_k(vaddr);
+	pte_t *pte = memblock_alloc(n_pages * sizeof(pte_t), PAGE_SIZE);
+
+	if (!pte)
+		panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
+		      __func__, n_pages * sizeof(pte_t), PAGE_SIZE);
+
+	pr_debug("%s: %p - %p\n", __func__, start, end);
+
+	for (i = j = 0; i < n_pmds; ++i) {
+		int k;
+
+		for (k = 0; k < PTRS_PER_PTE; ++k, ++j) {
+			phys_addr_t phys =
+				memblock_phys_alloc_range(PAGE_SIZE, PAGE_SIZE,
+							  0,
+							  MEMBLOCK_ALLOC_ANYWHERE);
+
+			if (!phys)
+				panic("Failed to allocate page table page\n");
+
+			set_pte(pte + j, pfn_pte(PHYS_PFN(phys), PAGE_KERNEL));
+		}
+	}
+
+	for (i = 0; i < n_pmds ; ++i, pte += PTRS_PER_PTE)
+		set_pmd(pmd + i, __pmd((unsigned long)pte));
+
+	local_flush_tlb_all();
+	memset(start, 0, end - start);
+}
+
+void __init kasan_init(void)
+{
+	int i;
+
+	BUILD_BUG_ON(KASAN_SHADOW_OFFSET != KASAN_SHADOW_START -
+		     (KASAN_START_VADDR >> KASAN_SHADOW_SCALE_SHIFT));
+	BUILD_BUG_ON(VMALLOC_START < KASAN_START_VADDR);
+
+	/*
+	 * Replace shadow map pages that cover addresses from VMALLOC area
+	 * start to the end of KSEG with clean writable pages.
+	 */
+	populate(kasan_mem_to_shadow((void *)VMALLOC_START),
+		 kasan_mem_to_shadow((void *)XCHAL_KSEG_BYPASS_VADDR));
+
+	/*
+	 * Write protect kasan_early_shadow_page and zero-initialize it again.
+	 */
+	for (i = 0; i < PTRS_PER_PTE; ++i)
+		set_pte(kasan_early_shadow_pte + i,
+			mk_pte(virt_to_page(kasan_early_shadow_page),
+				PAGE_KERNEL_RO));
+
+	local_flush_tlb_all();
+	memset(kasan_early_shadow_page, 0, PAGE_SIZE);
+
+	/* At this point kasan is fully initialized. Enable error messages. */
+	current->kasan_depth = 0;
+	pr_info("KernelAddressSanitizer initialized\n");
+}