2 files changed, 246 insertions, 0 deletions

diff --git a/arch/loongarch/mm/Makefile b/arch/loongarch/mm/Makefile
index 8ffc6383f836..e4d1e581dbae 100644
--- a/arch/loongarch/mm/Makefile
+++ b/arch/loongarch/mm/Makefile
@@ -7,3 +7,6 @@ obj-y				+= init.o cache.o tlb.o tlbex.o extable.o \
 				   fault.o ioremap.o maccess.o mmap.o pgtable.o page.o
 
 obj-$(CONFIG_HUGETLB_PAGE)	+= hugetlbpage.o
+obj-$(CONFIG_KASAN)		+= kasan_init.o
+
+KASAN_SANITIZE_kasan_init.o     := n
diff --git a/arch/loongarch/mm/kasan_init.c b/arch/loongarch/mm/kasan_init.c
new file mode 100644
index 000000000000..da68bc1a4643
--- /dev/null
+++ b/arch/loongarch/mm/kasan_init.c
@@ -0,0 +1,243 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2023 Loongson Technology Corporation Limited
+ */
+#define pr_fmt(fmt) "kasan: " fmt
+#include <linux/kasan.h>
+#include <linux/memblock.h>
+#include <linux/sched/task.h>
+
+#include <asm/tlbflush.h>
+#include <asm/pgalloc.h>
+#include <asm-generic/sections.h>
+
+static pgd_t kasan_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE);
+
+#ifdef __PAGETABLE_PUD_FOLDED
+#define __p4d_none(early, p4d) (0)
+#else
+#define __p4d_none(early, p4d) (early ? (p4d_val(p4d) == 0) : \
+(__pa(p4d_val(p4d)) == (unsigned long)__pa(kasan_early_shadow_pud)))
+#endif
+
+#ifdef __PAGETABLE_PMD_FOLDED
+#define __pud_none(early, pud) (0)
+#else
+#define __pud_none(early, pud) (early ? (pud_val(pud) == 0) : \
+(__pa(pud_val(pud)) == (unsigned long)__pa(kasan_early_shadow_pmd)))
+#endif
+
+#define __pmd_none(early, pmd) (early ? (pmd_val(pmd) == 0) : \
+(__pa(pmd_val(pmd)) == (unsigned long)__pa(kasan_early_shadow_pte)))
+
+#define __pte_none(early, pte) (early ? pte_none(pte) : \
+((pte_val(pte) & _PFN_MASK) == (unsigned long)__pa(kasan_early_shadow_page)))
+
+bool kasan_early_stage = true;
+
+/*
+ * Alloc memory for shadow memory page table.
+ */
+static phys_addr_t __init kasan_alloc_zeroed_page(int node)
+{
+	void *p = memblock_alloc_try_nid(PAGE_SIZE, PAGE_SIZE,
+					__pa(MAX_DMA_ADDRESS), MEMBLOCK_ALLOC_ACCESSIBLE, node);
+	if (!p)
+		panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%llx\n",
+			__func__, PAGE_SIZE, PAGE_SIZE, node, __pa(MAX_DMA_ADDRESS));
+
+	return __pa(p);
+}
+
+static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node, bool early)
+{
+	if (__pmd_none(early, READ_ONCE(*pmdp))) {
+		phys_addr_t pte_phys = early ?
+				__pa_symbol(kasan_early_shadow_pte) : kasan_alloc_zeroed_page(node);
+		if (!early)
+			memcpy(__va(pte_phys), kasan_early_shadow_pte, sizeof(kasan_early_shadow_pte));
+		pmd_populate_kernel(NULL, pmdp, (pte_t *)__va(pte_phys));
+	}
+
+	return pte_offset_kernel(pmdp, addr);
+}
+
+static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node, bool early)
+{
+	if (__pud_none(early, READ_ONCE(*pudp))) {
+		phys_addr_t pmd_phys = early ?
+				__pa_symbol(kasan_early_shadow_pmd) : kasan_alloc_zeroed_page(node);
+		if (!early)
+			memcpy(__va(pmd_phys), kasan_early_shadow_pmd, sizeof(kasan_early_shadow_pmd));
+		pud_populate(&init_mm, pudp, (pmd_t *)__va(pmd_phys));
+	}
+
+	return pmd_offset(pudp, addr);
+}
+
+static pud_t *__init kasan_pud_offset(p4d_t *p4dp, unsigned long addr, int node, bool early)
+{
+	if (__p4d_none(early, READ_ONCE(*p4dp))) {
+		phys_addr_t pud_phys = early ?
+			__pa_symbol(kasan_early_shadow_pud) : kasan_alloc_zeroed_page(node);
+		if (!early)
+			memcpy(__va(pud_phys), kasan_early_shadow_pud, sizeof(kasan_early_shadow_pud));
+		p4d_populate(&init_mm, p4dp, (pud_t *)__va(pud_phys));
+	}
+
+	return pud_offset(p4dp, addr);
+}
+
+static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr,
+				      unsigned long end, int node, bool early)
+{
+	unsigned long next;
+	pte_t *ptep = kasan_pte_offset(pmdp, addr, node, early);
+
+	do {
+		phys_addr_t page_phys = early ?
+					__pa_symbol(kasan_early_shadow_page)
+					      : kasan_alloc_zeroed_page(node);
+		next = addr + PAGE_SIZE;
+		set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL));
+	} while (ptep++, addr = next, addr != end && __pte_none(early, READ_ONCE(*ptep)));
+}
+
+static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr,
+				      unsigned long end, int node, bool early)
+{
+	unsigned long next;
+	pmd_t *pmdp = kasan_pmd_offset(pudp, addr, node, early);
+
+	do {
+		next = pmd_addr_end(addr, end);
+		kasan_pte_populate(pmdp, addr, next, node, early);
+	} while (pmdp++, addr = next, addr != end && __pmd_none(early, READ_ONCE(*pmdp)));
+}
+
+static void __init kasan_pud_populate(p4d_t *p4dp, unsigned long addr,
+					    unsigned long end, int node, bool early)
+{
+	unsigned long next;
+	pud_t *pudp = kasan_pud_offset(p4dp, addr, node, early);
+
+	do {
+		next = pud_addr_end(addr, end);
+		kasan_pmd_populate(pudp, addr, next, node, early);
+	} while (pudp++, addr = next, addr != end);
+}
+
+static void __init kasan_p4d_populate(pgd_t *pgdp, unsigned long addr,
+					    unsigned long end, int node, bool early)
+{
+	unsigned long next;
+	p4d_t *p4dp = p4d_offset(pgdp, addr);
+
+	do {
+		next = p4d_addr_end(addr, end);
+		kasan_pud_populate(p4dp, addr, next, node, early);
+	} while (p4dp++, addr = next, addr != end);
+}
+
+static void __init kasan_pgd_populate(unsigned long addr, unsigned long end,
+				      int node, bool early)
+{
+	unsigned long next;
+	pgd_t *pgdp;
+
+	pgdp = pgd_offset_k(addr);
+
+	do {
+		next = pgd_addr_end(addr, end);
+		kasan_p4d_populate(pgdp, addr, next, node, early);
+	} while (pgdp++, addr = next, addr != end);
+
+}
+
+/* Set up full kasan mappings, ensuring that the mapped pages are zeroed */
+static void __init kasan_map_populate(unsigned long start, unsigned long end,
+				      int node)
+{
+	kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false);
+}
+
+asmlinkage void __init kasan_early_init(void)
+{
+	BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE));
+	BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE));
+}
+
+static inline void kasan_set_pgd(pgd_t *pgdp, pgd_t pgdval)
+{
+	WRITE_ONCE(*pgdp, pgdval);
+}
+
+static void __init clear_pgds(unsigned long start, unsigned long end)
+{
+	/*
+	 * Remove references to kasan page tables from
+	 * swapper_pg_dir. pgd_clear() can't be used
+	 * here because it's nop on 2,3-level pagetable setups
+	 */
+	for (; start < end; start += PGDIR_SIZE)
+		kasan_set_pgd((pgd_t *)pgd_offset_k(start), __pgd(0));
+}
+
+void __init kasan_init(void)
+{
+	u64 i;
+	phys_addr_t pa_start, pa_end;
+
+	/*
+	 * PGD was populated as invalid_pmd_table or invalid_pud_table
+	 * in pagetable_init() which depends on how many levels of page
+	 * table you are using, but we had to clean the gpd of kasan
+	 * shadow memory, as the pgd value is none-zero.
+	 * The assertion pgd_none is going to be false and the formal populate
+	 * afterwards is not going to create any new pgd at all.
+	 */
+	memcpy(kasan_pg_dir, swapper_pg_dir, sizeof(kasan_pg_dir));
+	csr_write64(__pa_symbol(kasan_pg_dir), LOONGARCH_CSR_PGDH);
+	local_flush_tlb_all();
+
+	clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
+
+	/* Maps everything to a single page of zeroes */
+	kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE, true);
+
+	kasan_populate_early_shadow(kasan_mem_to_shadow((void *)VMALLOC_START),
+					kasan_mem_to_shadow((void *)KFENCE_AREA_END));
+
+	kasan_early_stage = false;
+
+	/* Populate the linear mapping */
+	for_each_mem_range(i, &pa_start, &pa_end) {
+		void *start = (void *)phys_to_virt(pa_start);
+		void *end   = (void *)phys_to_virt(pa_end);
+
+		if (start >= end)
+			break;
+
+		kasan_map_populate((unsigned long)kasan_mem_to_shadow(start),
+			(unsigned long)kasan_mem_to_shadow(end), NUMA_NO_NODE);
+	}
+
+	/* Populate modules mapping */
+	kasan_map_populate((unsigned long)kasan_mem_to_shadow((void *)MODULES_VADDR),
+		(unsigned long)kasan_mem_to_shadow((void *)MODULES_END), NUMA_NO_NODE);
+	/*
+	 * KAsan may reuse the contents of kasan_early_shadow_pte directly, so we
+	 * should make sure that it maps the zero page read-only.
+	 */
+	for (i = 0; i < PTRS_PER_PTE; i++)
+		set_pte(&kasan_early_shadow_pte[i],
+			pfn_pte(__phys_to_pfn(__pa_symbol(kasan_early_shadow_page)), PAGE_KERNEL_RO));
+
+	memset(kasan_early_shadow_page, 0, PAGE_SIZE);
+	csr_write64(__pa_symbol(swapper_pg_dir), LOONGARCH_CSR_PGDH);
+	local_flush_tlb_all();
+
+	/* At this point kasan is fully initialized. Enable error messages */
+	init_task.kasan_depth = 0;
+	pr_info("KernelAddressSanitizer initialized.\n");
+}