1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/kasan.h>
3 #include <linux/sched/task.h>
4 #include <linux/memblock.h>
5 #include <linux/pgtable.h>
6 #include <asm/pgalloc.h>
7 #include <asm/kasan.h>
8 #include <asm/mem_detect.h>
9 #include <asm/processor.h>
10 #include <asm/sclp.h>
11 #include <asm/facility.h>
12 #include <asm/sections.h>
13 #include <asm/setup.h>
14 #include <asm/uv.h>
15
16 unsigned long kasan_vmax;
17 static unsigned long segment_pos __initdata;
18 static unsigned long segment_low __initdata;
19 static unsigned long pgalloc_pos __initdata;
20 static unsigned long pgalloc_low __initdata;
21 static unsigned long pgalloc_freeable __initdata;
22 static bool has_edat __initdata;
23 static bool has_nx __initdata;
24
25 #define __sha(x) ((unsigned long)kasan_mem_to_shadow((void *)x))
26
27 static pgd_t early_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE);
28
kasan_early_panic(const char * reason)29 static void __init kasan_early_panic(const char *reason)
30 {
31 sclp_early_printk("The Linux kernel failed to boot with the KernelAddressSanitizer:\n");
32 sclp_early_printk(reason);
33 disabled_wait();
34 }
35
kasan_early_alloc_segment(void)36 static void * __init kasan_early_alloc_segment(void)
37 {
38 segment_pos -= _SEGMENT_SIZE;
39
40 if (segment_pos < segment_low)
41 kasan_early_panic("out of memory during initialisation\n");
42
43 return (void *)segment_pos;
44 }
45
kasan_early_alloc_pages(unsigned int order)46 static void * __init kasan_early_alloc_pages(unsigned int order)
47 {
48 pgalloc_pos -= (PAGE_SIZE << order);
49
50 if (pgalloc_pos < pgalloc_low)
51 kasan_early_panic("out of memory during initialisation\n");
52
53 return (void *)pgalloc_pos;
54 }
55
kasan_early_crst_alloc(unsigned long val)56 static void * __init kasan_early_crst_alloc(unsigned long val)
57 {
58 unsigned long *table;
59
60 table = kasan_early_alloc_pages(CRST_ALLOC_ORDER);
61 if (table)
62 crst_table_init(table, val);
63 return table;
64 }
65
kasan_early_pte_alloc(void)66 static pte_t * __init kasan_early_pte_alloc(void)
67 {
68 static void *pte_leftover;
69 pte_t *pte;
70
71 BUILD_BUG_ON(_PAGE_TABLE_SIZE * 2 != PAGE_SIZE);
72
73 if (!pte_leftover) {
74 pte_leftover = kasan_early_alloc_pages(0);
75 pte = pte_leftover + _PAGE_TABLE_SIZE;
76 } else {
77 pte = pte_leftover;
78 pte_leftover = NULL;
79 }
80 memset64((u64 *)pte, _PAGE_INVALID, PTRS_PER_PTE);
81 return pte;
82 }
83
84 enum populate_mode {
85 POPULATE_ONE2ONE,
86 POPULATE_MAP,
87 POPULATE_ZERO_SHADOW,
88 POPULATE_SHALLOW
89 };
kasan_early_vmemmap_populate(unsigned long address,unsigned long end,enum populate_mode mode)90 static void __init kasan_early_vmemmap_populate(unsigned long address,
91 unsigned long end,
92 enum populate_mode mode)
93 {
94 unsigned long pgt_prot_zero, pgt_prot, sgt_prot;
95 pgd_t *pg_dir;
96 p4d_t *p4_dir;
97 pud_t *pu_dir;
98 pmd_t *pm_dir;
99 pte_t *pt_dir;
100
101 pgt_prot_zero = pgprot_val(PAGE_KERNEL_RO);
102 if (!has_nx)
103 pgt_prot_zero &= ~_PAGE_NOEXEC;
104 pgt_prot = pgprot_val(PAGE_KERNEL);
105 sgt_prot = pgprot_val(SEGMENT_KERNEL);
106 if (!has_nx || mode == POPULATE_ONE2ONE) {
107 pgt_prot &= ~_PAGE_NOEXEC;
108 sgt_prot &= ~_SEGMENT_ENTRY_NOEXEC;
109 }
110
111 while (address < end) {
112 pg_dir = pgd_offset_k(address);
113 if (pgd_none(*pg_dir)) {
114 if (mode == POPULATE_ZERO_SHADOW &&
115 IS_ALIGNED(address, PGDIR_SIZE) &&
116 end - address >= PGDIR_SIZE) {
117 pgd_populate(&init_mm, pg_dir,
118 kasan_early_shadow_p4d);
119 address = (address + PGDIR_SIZE) & PGDIR_MASK;
120 continue;
121 }
122 p4_dir = kasan_early_crst_alloc(_REGION2_ENTRY_EMPTY);
123 pgd_populate(&init_mm, pg_dir, p4_dir);
124 }
125
126 if (IS_ENABLED(CONFIG_KASAN_S390_4_LEVEL_PAGING) &&
127 mode == POPULATE_SHALLOW) {
128 address = (address + P4D_SIZE) & P4D_MASK;
129 continue;
130 }
131
132 p4_dir = p4d_offset(pg_dir, address);
133 if (p4d_none(*p4_dir)) {
134 if (mode == POPULATE_ZERO_SHADOW &&
135 IS_ALIGNED(address, P4D_SIZE) &&
136 end - address >= P4D_SIZE) {
137 p4d_populate(&init_mm, p4_dir,
138 kasan_early_shadow_pud);
139 address = (address + P4D_SIZE) & P4D_MASK;
140 continue;
141 }
142 pu_dir = kasan_early_crst_alloc(_REGION3_ENTRY_EMPTY);
143 p4d_populate(&init_mm, p4_dir, pu_dir);
144 }
145
146 if (!IS_ENABLED(CONFIG_KASAN_S390_4_LEVEL_PAGING) &&
147 mode == POPULATE_SHALLOW) {
148 address = (address + PUD_SIZE) & PUD_MASK;
149 continue;
150 }
151
152 pu_dir = pud_offset(p4_dir, address);
153 if (pud_none(*pu_dir)) {
154 if (mode == POPULATE_ZERO_SHADOW &&
155 IS_ALIGNED(address, PUD_SIZE) &&
156 end - address >= PUD_SIZE) {
157 pud_populate(&init_mm, pu_dir,
158 kasan_early_shadow_pmd);
159 address = (address + PUD_SIZE) & PUD_MASK;
160 continue;
161 }
162 pm_dir = kasan_early_crst_alloc(_SEGMENT_ENTRY_EMPTY);
163 pud_populate(&init_mm, pu_dir, pm_dir);
164 }
165
166 pm_dir = pmd_offset(pu_dir, address);
167 if (pmd_none(*pm_dir)) {
168 if (mode == POPULATE_ZERO_SHADOW &&
169 IS_ALIGNED(address, PMD_SIZE) &&
170 end - address >= PMD_SIZE) {
171 pmd_populate(&init_mm, pm_dir,
172 kasan_early_shadow_pte);
173 address = (address + PMD_SIZE) & PMD_MASK;
174 continue;
175 }
176 /* the first megabyte of 1:1 is mapped with 4k pages */
177 if (has_edat && address && end - address >= PMD_SIZE &&
178 mode != POPULATE_ZERO_SHADOW) {
179 void *page;
180
181 if (mode == POPULATE_ONE2ONE) {
182 page = (void *)address;
183 } else {
184 page = kasan_early_alloc_segment();
185 memset(page, 0, _SEGMENT_SIZE);
186 }
187 pmd_val(*pm_dir) = __pa(page) | sgt_prot;
188 address = (address + PMD_SIZE) & PMD_MASK;
189 continue;
190 }
191
192 pt_dir = kasan_early_pte_alloc();
193 pmd_populate(&init_mm, pm_dir, pt_dir);
194 } else if (pmd_large(*pm_dir)) {
195 address = (address + PMD_SIZE) & PMD_MASK;
196 continue;
197 }
198
199 pt_dir = pte_offset_kernel(pm_dir, address);
200 if (pte_none(*pt_dir)) {
201 void *page;
202
203 switch (mode) {
204 case POPULATE_ONE2ONE:
205 page = (void *)address;
206 pte_val(*pt_dir) = __pa(page) | pgt_prot;
207 break;
208 case POPULATE_MAP:
209 page = kasan_early_alloc_pages(0);
210 memset(page, 0, PAGE_SIZE);
211 pte_val(*pt_dir) = __pa(page) | pgt_prot;
212 break;
213 case POPULATE_ZERO_SHADOW:
214 page = kasan_early_shadow_page;
215 pte_val(*pt_dir) = __pa(page) | pgt_prot_zero;
216 break;
217 case POPULATE_SHALLOW:
218 /* should never happen */
219 break;
220 }
221 }
222 address += PAGE_SIZE;
223 }
224 }
225
kasan_set_pgd(pgd_t * pgd,unsigned long asce_type)226 static void __init kasan_set_pgd(pgd_t *pgd, unsigned long asce_type)
227 {
228 unsigned long asce_bits;
229
230 asce_bits = asce_type | _ASCE_TABLE_LENGTH;
231 S390_lowcore.kernel_asce = (__pa(pgd) & PAGE_MASK) | asce_bits;
232 S390_lowcore.user_asce = S390_lowcore.kernel_asce;
233
234 __ctl_load(S390_lowcore.kernel_asce, 1, 1);
235 __ctl_load(S390_lowcore.kernel_asce, 7, 7);
236 __ctl_load(S390_lowcore.kernel_asce, 13, 13);
237 }
238
kasan_enable_dat(void)239 static void __init kasan_enable_dat(void)
240 {
241 psw_t psw;
242
243 psw.mask = __extract_psw();
244 psw_bits(psw).dat = 1;
245 psw_bits(psw).as = PSW_BITS_AS_HOME;
246 __load_psw_mask(psw.mask);
247 }
248
kasan_early_detect_facilities(void)249 static void __init kasan_early_detect_facilities(void)
250 {
251 if (test_facility(8)) {
252 has_edat = true;
253 __ctl_set_bit(0, 23);
254 }
255 if (!noexec_disabled && test_facility(130)) {
256 has_nx = true;
257 __ctl_set_bit(0, 20);
258 }
259 }
260
has_uv_sec_stor_limit(void)261 static bool __init has_uv_sec_stor_limit(void)
262 {
263 /*
264 * keep these conditions in line with setup_uv()
265 */
266 if (!is_prot_virt_host())
267 return false;
268
269 if (is_prot_virt_guest())
270 return false;
271
272 if (!test_facility(158))
273 return false;
274
275 return !!uv_info.max_sec_stor_addr;
276 }
277
kasan_early_init(void)278 void __init kasan_early_init(void)
279 {
280 unsigned long untracked_mem_end;
281 unsigned long shadow_alloc_size;
282 unsigned long vmax_unlimited;
283 unsigned long initrd_end;
284 unsigned long asce_type;
285 unsigned long memsize;
286 unsigned long pgt_prot = pgprot_val(PAGE_KERNEL_RO);
287 pte_t pte_z;
288 pmd_t pmd_z = __pmd(__pa(kasan_early_shadow_pte) | _SEGMENT_ENTRY);
289 pud_t pud_z = __pud(__pa(kasan_early_shadow_pmd) | _REGION3_ENTRY);
290 p4d_t p4d_z = __p4d(__pa(kasan_early_shadow_pud) | _REGION2_ENTRY);
291
292 kasan_early_detect_facilities();
293 if (!has_nx)
294 pgt_prot &= ~_PAGE_NOEXEC;
295 pte_z = __pte(__pa(kasan_early_shadow_page) | pgt_prot);
296
297 memsize = get_mem_detect_end();
298 if (!memsize)
299 kasan_early_panic("cannot detect physical memory size\n");
300 /* respect mem= cmdline parameter */
301 if (memory_end_set && memsize > memory_end)
302 memsize = memory_end;
303 if (IS_ENABLED(CONFIG_CRASH_DUMP) && OLDMEM_BASE)
304 memsize = min(memsize, OLDMEM_SIZE);
305 memsize = min(memsize, KASAN_SHADOW_START);
306
307 if (IS_ENABLED(CONFIG_KASAN_S390_4_LEVEL_PAGING)) {
308 /* 4 level paging */
309 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, P4D_SIZE));
310 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, P4D_SIZE));
311 crst_table_init((unsigned long *)early_pg_dir,
312 _REGION2_ENTRY_EMPTY);
313 untracked_mem_end = kasan_vmax = vmax_unlimited = _REGION1_SIZE;
314 if (has_uv_sec_stor_limit())
315 kasan_vmax = min(vmax_unlimited, uv_info.max_sec_stor_addr);
316 asce_type = _ASCE_TYPE_REGION2;
317 } else {
318 /* 3 level paging */
319 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PUD_SIZE));
320 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PUD_SIZE));
321 crst_table_init((unsigned long *)early_pg_dir,
322 _REGION3_ENTRY_EMPTY);
323 untracked_mem_end = kasan_vmax = vmax_unlimited = _REGION2_SIZE;
324 asce_type = _ASCE_TYPE_REGION3;
325 }
326
327 /* init kasan zero shadow */
328 crst_table_init((unsigned long *)kasan_early_shadow_p4d,
329 p4d_val(p4d_z));
330 crst_table_init((unsigned long *)kasan_early_shadow_pud,
331 pud_val(pud_z));
332 crst_table_init((unsigned long *)kasan_early_shadow_pmd,
333 pmd_val(pmd_z));
334 memset64((u64 *)kasan_early_shadow_pte, pte_val(pte_z), PTRS_PER_PTE);
335
336 shadow_alloc_size = memsize >> KASAN_SHADOW_SCALE_SHIFT;
337 pgalloc_low = round_up((unsigned long)_end, _SEGMENT_SIZE);
338 if (IS_ENABLED(CONFIG_BLK_DEV_INITRD)) {
339 initrd_end =
340 round_up(INITRD_START + INITRD_SIZE, _SEGMENT_SIZE);
341 pgalloc_low = max(pgalloc_low, initrd_end);
342 }
343
344 if (pgalloc_low + shadow_alloc_size > memsize)
345 kasan_early_panic("out of memory during initialisation\n");
346
347 if (has_edat) {
348 segment_pos = round_down(memsize, _SEGMENT_SIZE);
349 segment_low = segment_pos - shadow_alloc_size;
350 pgalloc_pos = segment_low;
351 } else {
352 pgalloc_pos = memsize;
353 }
354 init_mm.pgd = early_pg_dir;
355 /*
356 * Current memory layout:
357 * +- 0 -------------+ +- shadow start -+
358 * | 1:1 ram mapping | /| 1/8 ram |
359 * | | / | |
360 * +- end of ram ----+ / +----------------+
361 * | ... gap ... | / | |
362 * | |/ | kasan |
363 * +- shadow start --+ | zero |
364 * | 1/8 addr space | | page |
365 * +- shadow end -+ | mapping |
366 * | ... gap ... |\ | (untracked) |
367 * +- vmalloc area -+ \ | |
368 * | vmalloc_size | \ | |
369 * +- modules vaddr -+ \ +----------------+
370 * | 2Gb | \| unmapped | allocated per module
371 * +-----------------+ +- shadow end ---+
372 *
373 * Current memory layout (KASAN_VMALLOC):
374 * +- 0 -------------+ +- shadow start -+
375 * | 1:1 ram mapping | /| 1/8 ram |
376 * | | / | |
377 * +- end of ram ----+ / +----------------+
378 * | ... gap ... | / | kasan |
379 * | |/ | zero |
380 * +- shadow start --+ | page |
381 * | 1/8 addr space | | mapping |
382 * +- shadow end -+ | (untracked) |
383 * | ... gap ... |\ | |
384 * +- vmalloc area -+ \ +- vmalloc area -+
385 * | vmalloc_size | \ |shallow populate|
386 * +- modules vaddr -+ \ +- modules area -+
387 * | 2Gb | \|shallow populate|
388 * +-----------------+ +- shadow end ---+
389 */
390 /* populate kasan shadow (for identity mapping and zero page mapping) */
391 kasan_early_vmemmap_populate(__sha(0), __sha(memsize), POPULATE_MAP);
392 if (IS_ENABLED(CONFIG_MODULES))
393 untracked_mem_end = kasan_vmax - MODULES_LEN;
394 if (IS_ENABLED(CONFIG_KASAN_VMALLOC)) {
395 untracked_mem_end = kasan_vmax - vmalloc_size - MODULES_LEN;
396 /* shallowly populate kasan shadow for vmalloc and modules */
397 kasan_early_vmemmap_populate(__sha(untracked_mem_end),
398 __sha(kasan_vmax), POPULATE_SHALLOW);
399 }
400 /* populate kasan shadow for untracked memory */
401 kasan_early_vmemmap_populate(__sha(max_physmem_end),
402 __sha(untracked_mem_end),
403 POPULATE_ZERO_SHADOW);
404 kasan_early_vmemmap_populate(__sha(kasan_vmax),
405 __sha(vmax_unlimited),
406 POPULATE_ZERO_SHADOW);
407 /* memory allocated for identity mapping structs will be freed later */
408 pgalloc_freeable = pgalloc_pos;
409 /* populate identity mapping */
410 kasan_early_vmemmap_populate(0, memsize, POPULATE_ONE2ONE);
411 kasan_set_pgd(early_pg_dir, asce_type);
412 kasan_enable_dat();
413 /* enable kasan */
414 init_task.kasan_depth = 0;
415 memblock_reserve(pgalloc_pos, memsize - pgalloc_pos);
416 sclp_early_printk("KernelAddressSanitizer initialized\n");
417 }
418
kasan_copy_shadow(pgd_t * pg_dir)419 void __init kasan_copy_shadow(pgd_t *pg_dir)
420 {
421 /*
422 * At this point we are still running on early pages setup early_pg_dir,
423 * while swapper_pg_dir has just been initialized with identity mapping.
424 * Carry over shadow memory region from early_pg_dir to swapper_pg_dir.
425 */
426
427 pgd_t *pg_dir_src;
428 pgd_t *pg_dir_dst;
429 p4d_t *p4_dir_src;
430 p4d_t *p4_dir_dst;
431 pud_t *pu_dir_src;
432 pud_t *pu_dir_dst;
433
434 pg_dir_src = pgd_offset_raw(early_pg_dir, KASAN_SHADOW_START);
435 pg_dir_dst = pgd_offset_raw(pg_dir, KASAN_SHADOW_START);
436 p4_dir_src = p4d_offset(pg_dir_src, KASAN_SHADOW_START);
437 p4_dir_dst = p4d_offset(pg_dir_dst, KASAN_SHADOW_START);
438 if (!p4d_folded(*p4_dir_src)) {
439 /* 4 level paging */
440 memcpy(p4_dir_dst, p4_dir_src,
441 (KASAN_SHADOW_SIZE >> P4D_SHIFT) * sizeof(p4d_t));
442 return;
443 }
444 /* 3 level paging */
445 pu_dir_src = pud_offset(p4_dir_src, KASAN_SHADOW_START);
446 pu_dir_dst = pud_offset(p4_dir_dst, KASAN_SHADOW_START);
447 memcpy(pu_dir_dst, pu_dir_src,
448 (KASAN_SHADOW_SIZE >> PUD_SHIFT) * sizeof(pud_t));
449 }
450
kasan_free_early_identity(void)451 void __init kasan_free_early_identity(void)
452 {
453 memblock_free(pgalloc_pos, pgalloc_freeable - pgalloc_pos);
454 }
455
