kasan_init.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Copyright (C) 2023 Loongson Technology Corporation Limited
  4 */
  5#define pr_fmt(fmt) "kasan: " fmt
  6#include <linux/kasan.h>
  7#include <linux/memblock.h>
  8#include <linux/sched/task.h>
  9
 10#include <asm/tlbflush.h>
 11#include <asm/pgalloc.h>
 12#include <asm-generic/sections.h>
 13
 14static pgd_t kasan_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE);
 15
 16#ifdef __PAGETABLE_P4D_FOLDED
 17#define __pgd_none(early, pgd) (0)
 18#else
 19#define __pgd_none(early, pgd) (early ? (pgd_val(pgd) == 0) : \
 20(__pa(pgd_val(pgd)) == (unsigned long)__pa(kasan_early_shadow_p4d)))
 21#endif
 22
 23#ifdef __PAGETABLE_PUD_FOLDED
 24#define __p4d_none(early, p4d) (0)
 25#else
 26#define __p4d_none(early, p4d) (early ? (p4d_val(p4d) == 0) : \
 27(__pa(p4d_val(p4d)) == (unsigned long)__pa(kasan_early_shadow_pud)))
 28#endif
 29
 30#ifdef __PAGETABLE_PMD_FOLDED
 31#define __pud_none(early, pud) (0)
 32#else
 33#define __pud_none(early, pud) (early ? (pud_val(pud) == 0) : \
 34(__pa(pud_val(pud)) == (unsigned long)__pa(kasan_early_shadow_pmd)))
 35#endif
 36
 37#define __pmd_none(early, pmd) (early ? (pmd_val(pmd) == 0) : \
 38(__pa(pmd_val(pmd)) == (unsigned long)__pa(kasan_early_shadow_pte)))
 39
 40#define __pte_none(early, pte) (early ? pte_none(pte) : \
 41((pte_val(pte) & _PFN_MASK) == (unsigned long)__pa(kasan_early_shadow_page)))
 42
 43static void *mem_to_shadow(const void *addr)
 44{
 45	unsigned long offset = 0;
 46	unsigned long maddr = (unsigned long)addr;
 47	unsigned long xrange = (maddr >> XRANGE_SHIFT) & 0xffff;
 48
 49	if (maddr >= FIXADDR_START)
 50		return (void *)(kasan_early_shadow_page);
 51
 52	maddr &= XRANGE_SHADOW_MASK;
 53	switch (xrange) {
 54	case XKPRANGE_CC_SEG:
 55		offset = XKPRANGE_CC_SHADOW_OFFSET;
 56		break;
 57	case XKPRANGE_UC_SEG:
 58		offset = XKPRANGE_UC_SHADOW_OFFSET;
 59		break;
 60	case XKPRANGE_WC_SEG:
 61		offset = XKPRANGE_WC_SHADOW_OFFSET;
 62		break;
 63	case XKVRANGE_VC_SEG:
 64		offset = XKVRANGE_VC_SHADOW_OFFSET;
 65		break;
 66	default:
 67		WARN_ON(1);
 68		return NULL;
 69	}
 70
 71	return (void *)((maddr >> KASAN_SHADOW_SCALE_SHIFT) + offset);
 72}
 73
 74void *kasan_mem_to_shadow(const void *addr)
 75{
 76	if (kasan_enabled())
 77		return mem_to_shadow(addr);
 78	else
 79		return (void *)(kasan_early_shadow_page);
 80}
 81
 82const void *kasan_shadow_to_mem(const void *shadow_addr)
 83{
 84	unsigned long addr = (unsigned long)shadow_addr;
 85
 86	if (unlikely(addr > KASAN_SHADOW_END) ||
 87		unlikely(addr < KASAN_SHADOW_START)) {
 88		WARN_ON(1);
 89		return NULL;
 90	}
 91
 92	if (addr >= XKVRANGE_VC_SHADOW_OFFSET)
 93		return (void *)(((addr - XKVRANGE_VC_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT) + XKVRANGE_VC_START);
 94	else if (addr >= XKPRANGE_WC_SHADOW_OFFSET)
 95		return (void *)(((addr - XKPRANGE_WC_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT) + XKPRANGE_WC_START);
 96	else if (addr >= XKPRANGE_UC_SHADOW_OFFSET)
 97		return (void *)(((addr - XKPRANGE_UC_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT) + XKPRANGE_UC_START);
 98	else if (addr >= XKPRANGE_CC_SHADOW_OFFSET)
 99		return (void *)(((addr - XKPRANGE_CC_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT) + XKPRANGE_CC_START);
100	else {
101		WARN_ON(1);
102		return NULL;
103	}
104}
105
106/*
107 * Alloc memory for shadow memory page table.
108 */
109static phys_addr_t __init kasan_alloc_zeroed_page(int node)
110{
111	void *p = memblock_alloc_try_nid(PAGE_SIZE, PAGE_SIZE,
112					__pa(MAX_DMA_ADDRESS), MEMBLOCK_ALLOC_ACCESSIBLE, node);
113	if (!p)
114		panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%llx\n",
115			__func__, PAGE_SIZE, PAGE_SIZE, node, __pa(MAX_DMA_ADDRESS));
116
117	return __pa(p);
118}
119
120static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node, bool early)
121{
122	if (__pmd_none(early, pmdp_get(pmdp))) {
123		phys_addr_t pte_phys = early ?
124				__pa_symbol(kasan_early_shadow_pte) : kasan_alloc_zeroed_page(node);
125		if (!early)
126			memcpy(__va(pte_phys), kasan_early_shadow_pte, sizeof(kasan_early_shadow_pte));
127		pmd_populate_kernel(NULL, pmdp, (pte_t *)__va(pte_phys));
128	}
129
130	return pte_offset_kernel(pmdp, addr);
131}
132
133static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node, bool early)
134{
135	if (__pud_none(early, pudp_get(pudp))) {
136		phys_addr_t pmd_phys = early ?
137				__pa_symbol(kasan_early_shadow_pmd) : kasan_alloc_zeroed_page(node);
138		if (!early)
139			memcpy(__va(pmd_phys), kasan_early_shadow_pmd, sizeof(kasan_early_shadow_pmd));
140		pud_populate(&init_mm, pudp, (pmd_t *)__va(pmd_phys));
141	}
142
143	return pmd_offset(pudp, addr);
144}
145
146static pud_t *__init kasan_pud_offset(p4d_t *p4dp, unsigned long addr, int node, bool early)
147{
148	if (__p4d_none(early, p4dp_get(p4dp))) {
149		phys_addr_t pud_phys = early ?
150			__pa_symbol(kasan_early_shadow_pud) : kasan_alloc_zeroed_page(node);
151		if (!early)
152			memcpy(__va(pud_phys), kasan_early_shadow_pud, sizeof(kasan_early_shadow_pud));
153		p4d_populate(&init_mm, p4dp, (pud_t *)__va(pud_phys));
154	}
155
156	return pud_offset(p4dp, addr);
157}
158
159static p4d_t *__init kasan_p4d_offset(pgd_t *pgdp, unsigned long addr, int node, bool early)
160{
161	if (__pgd_none(early, pgdp_get(pgdp))) {
162		phys_addr_t p4d_phys = early ?
163			__pa_symbol(kasan_early_shadow_p4d) : kasan_alloc_zeroed_page(node);
164		if (!early)
165			memcpy(__va(p4d_phys), kasan_early_shadow_p4d, sizeof(kasan_early_shadow_p4d));
166		pgd_populate(&init_mm, pgdp, (p4d_t *)__va(p4d_phys));
167	}
168
169	return p4d_offset(pgdp, addr);
170}
171
172static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr,
173				      unsigned long end, int node, bool early)
174{
175	unsigned long next;
176	pte_t *ptep = kasan_pte_offset(pmdp, addr, node, early);
177
178	do {
179		phys_addr_t page_phys = early ?
180					__pa_symbol(kasan_early_shadow_page)
181					      : kasan_alloc_zeroed_page(node);
182		next = addr + PAGE_SIZE;
183		set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL));
184	} while (ptep++, addr = next, addr != end && __pte_none(early, ptep_get(ptep)));
185}
186
187static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr,
188				      unsigned long end, int node, bool early)
189{
190	unsigned long next;
191	pmd_t *pmdp = kasan_pmd_offset(pudp, addr, node, early);
192
193	do {
194		next = pmd_addr_end(addr, end);
195		kasan_pte_populate(pmdp, addr, next, node, early);
196	} while (pmdp++, addr = next, addr != end && __pmd_none(early, pmdp_get(pmdp)));
197}
198
199static void __init kasan_pud_populate(p4d_t *p4dp, unsigned long addr,
200					    unsigned long end, int node, bool early)
201{
202	unsigned long next;
203	pud_t *pudp = kasan_pud_offset(p4dp, addr, node, early);
204
205	do {
206		next = pud_addr_end(addr, end);
207		kasan_pmd_populate(pudp, addr, next, node, early);
208	} while (pudp++, addr = next, addr != end && __pud_none(early, READ_ONCE(*pudp)));
209}
210
211static void __init kasan_p4d_populate(pgd_t *pgdp, unsigned long addr,
212					    unsigned long end, int node, bool early)
213{
214	unsigned long next;
215	p4d_t *p4dp = kasan_p4d_offset(pgdp, addr, node, early);
216
217	do {
218		next = p4d_addr_end(addr, end);
219		kasan_pud_populate(p4dp, addr, next, node, early);
220	} while (p4dp++, addr = next, addr != end && __p4d_none(early, READ_ONCE(*p4dp)));
221}
222
223static void __init kasan_pgd_populate(unsigned long addr, unsigned long end,
224				      int node, bool early)
225{
226	unsigned long next;
227	pgd_t *pgdp;
228
229	pgdp = pgd_offset_k(addr);
230
231	do {
232		next = pgd_addr_end(addr, end);
233		kasan_p4d_populate(pgdp, addr, next, node, early);
234	} while (pgdp++, addr = next, addr != end);
235
236}
237
238/* Set up full kasan mappings, ensuring that the mapped pages are zeroed */
239static void __init kasan_map_populate(unsigned long start, unsigned long end,
240				      int node)
241{
242	kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false);
243}
244
245asmlinkage void __init kasan_early_init(void)
246{
247	BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE));
248	BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END + 1, PGDIR_SIZE));
249}
250
251static inline void kasan_set_pgd(pgd_t *pgdp, pgd_t pgdval)
252{
253	WRITE_ONCE(*pgdp, pgdval);
254}
255
256static void __init clear_pgds(unsigned long start, unsigned long end)
257{
258	/*
259	 * Remove references to kasan page tables from
260	 * swapper_pg_dir. pgd_clear() can't be used
261	 * here because it's nop on 2,3-level pagetable setups
262	 */
263	for (; start < end; start = pgd_addr_end(start, end))
264		kasan_set_pgd((pgd_t *)pgd_offset_k(start), __pgd(0));
265}
266
267void __init kasan_init(void)
268{
269	u64 i;
270	phys_addr_t pa_start, pa_end;
271
272	/*
273	 * If PGDIR_SIZE is too large for cpu_vabits, KASAN_SHADOW_END will
274	 * overflow UINTPTR_MAX and then looks like a user space address.
275	 * For example, PGDIR_SIZE of CONFIG_4KB_4LEVEL is 2^39, which is too
276	 * large for Loongson-2K series whose cpu_vabits = 39.
277	 */
278	if (KASAN_SHADOW_END < vm_map_base) {
279		pr_warn("PGDIR_SIZE too large for cpu_vabits, KernelAddressSanitizer disabled.\n");
280		return;
281	}
282
283	/*
284	 * PGD was populated as invalid_pmd_table or invalid_pud_table
285	 * in pagetable_init() which depends on how many levels of page
286	 * table you are using, but we had to clean the gpd of kasan
287	 * shadow memory, as the pgd value is none-zero.
288	 * The assertion pgd_none is going to be false and the formal populate
289	 * afterwards is not going to create any new pgd at all.
290	 */
291	memcpy(kasan_pg_dir, swapper_pg_dir, sizeof(kasan_pg_dir));
292	csr_write64(__pa_symbol(kasan_pg_dir), LOONGARCH_CSR_PGDH);
293	local_flush_tlb_all();
294
295	clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
296
297	/* Maps everything to a single page of zeroes */
298	kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE, true);
299
300	kasan_populate_early_shadow(mem_to_shadow((void *)VMALLOC_START),
301					mem_to_shadow((void *)KFENCE_AREA_END));
302
303	/* Populate the linear mapping */
304	for_each_mem_range(i, &pa_start, &pa_end) {
305		void *start = (void *)phys_to_virt(pa_start);
306		void *end   = (void *)phys_to_virt(pa_end);
307
308		if (start >= end)
309			break;
310
311		kasan_map_populate((unsigned long)mem_to_shadow(start),
312			(unsigned long)mem_to_shadow(end), NUMA_NO_NODE);
313	}
314
315	/* Populate modules mapping */
316	kasan_map_populate((unsigned long)mem_to_shadow((void *)MODULES_VADDR),
317		(unsigned long)mem_to_shadow((void *)MODULES_END), NUMA_NO_NODE);
318	/*
319	 * KAsan may reuse the contents of kasan_early_shadow_pte directly, so we
320	 * should make sure that it maps the zero page read-only.
321	 */
322	for (i = 0; i < PTRS_PER_PTE; i++)
323		set_pte(&kasan_early_shadow_pte[i],
324			pfn_pte(__phys_to_pfn(__pa_symbol(kasan_early_shadow_page)), PAGE_KERNEL_RO));
325
326	memset(kasan_early_shadow_page, 0, PAGE_SIZE);
327	csr_write64(__pa_symbol(swapper_pg_dir), LOONGARCH_CSR_PGDH);
328	local_flush_tlb_all();
329
330	/* At this point kasan is fully initialized. Enable error messages */
331	init_task.kasan_depth = 0;
332	kasan_init_generic();
333}