1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright 2016, Rashmica Gupta, IBM Corp.
4  *
5  * This traverses the kernel virtual memory and dumps the pages that are in
6  * the hash pagetable, along with their flags to
7  * /sys/kernel/debug/kernel_hash_pagetable.
8  *
9  * If radix is enabled then there is no hash page table and so no debugfs file
10  * is generated.
11  */
12 #include <linux/debugfs.h>
13 #include <linux/fs.h>
14 #include <linux/io.h>
15 #include <linux/mm.h>
16 #include <linux/sched.h>
17 #include <linux/seq_file.h>
18 #include <linux/const.h>
19 #include <asm/page.h>
20 #include <asm/pgalloc.h>
21 #include <asm/plpar_wrappers.h>
22 #include <linux/memblock.h>
23 #include <asm/firmware.h>
24 
25 struct pg_state {
26 	struct seq_file *seq;
27 	const struct addr_marker *marker;
28 	unsigned long start_address;
29 	unsigned int level;
30 	u64 current_flags;
31 };
32 
33 struct addr_marker {
34 	unsigned long start_address;
35 	const char *name;
36 };
37 
38 static struct addr_marker address_markers[] = {
39 	{ 0,	"Start of kernel VM" },
40 	{ 0,	"vmalloc() Area" },
41 	{ 0,	"vmalloc() End" },
42 	{ 0,	"isa I/O start" },
43 	{ 0,	"isa I/O end" },
44 	{ 0,	"phb I/O start" },
45 	{ 0,	"phb I/O end" },
46 	{ 0,	"I/O remap start" },
47 	{ 0,	"I/O remap end" },
48 	{ 0,	"vmemmap start" },
49 	{ -1,	NULL },
50 };
51 
52 struct flag_info {
53 	u64		mask;
54 	u64		val;
55 	const char	*set;
56 	const char	*clear;
57 	bool		is_val;
58 	int		shift;
59 };
60 
61 static const struct flag_info v_flag_array[] = {
62 	{
63 		.mask   = SLB_VSID_B,
64 		.val    = SLB_VSID_B_256M,
65 		.set    = "ssize: 256M",
66 		.clear  = "ssize: 1T  ",
67 	}, {
68 		.mask	= HPTE_V_SECONDARY,
69 		.val	= HPTE_V_SECONDARY,
70 		.set	= "secondary",
71 		.clear	= "primary  ",
72 	}, {
73 		.mask	= HPTE_V_VALID,
74 		.val	= HPTE_V_VALID,
75 		.set	= "valid  ",
76 		.clear	= "invalid",
77 	}, {
78 		.mask	= HPTE_V_BOLTED,
79 		.val	= HPTE_V_BOLTED,
80 		.set	= "bolted",
81 		.clear	= "",
82 	}
83 };
84 
85 static const struct flag_info r_flag_array[] = {
86 	{
87 		.mask	= HPTE_R_PP0 | HPTE_R_PP,
88 		.val	= PP_RWXX,
89 		.set	= "prot:RW--",
90 	}, {
91 		.mask	= HPTE_R_PP0 | HPTE_R_PP,
92 		.val	= PP_RWRX,
93 		.set	= "prot:RWR-",
94 	}, {
95 		.mask	= HPTE_R_PP0 | HPTE_R_PP,
96 		.val	= PP_RWRW,
97 		.set	= "prot:RWRW",
98 	}, {
99 		.mask	= HPTE_R_PP0 | HPTE_R_PP,
100 		.val	= PP_RXRX,
101 		.set	= "prot:R-R-",
102 	}, {
103 		.mask	= HPTE_R_PP0 | HPTE_R_PP,
104 		.val	= PP_RXXX,
105 		.set	= "prot:R---",
106 	}, {
107 		.mask	= HPTE_R_KEY_HI | HPTE_R_KEY_LO,
108 		.val	= HPTE_R_KEY_HI | HPTE_R_KEY_LO,
109 		.set	= "key",
110 		.clear	= "",
111 		.is_val = true,
112 	}, {
113 		.mask	= HPTE_R_R,
114 		.val	= HPTE_R_R,
115 		.set	= "ref",
116 		.clear	= "   ",
117 	}, {
118 		.mask	= HPTE_R_C,
119 		.val	= HPTE_R_C,
120 		.set	= "changed",
121 		.clear	= "       ",
122 	}, {
123 		.mask	= HPTE_R_N,
124 		.val	= HPTE_R_N,
125 		.set	= "no execute",
126 	}, {
127 		.mask	= HPTE_R_WIMG,
128 		.val	= HPTE_R_W,
129 		.set	= "writethru",
130 	}, {
131 		.mask	= HPTE_R_WIMG,
132 		.val	= HPTE_R_I,
133 		.set	= "no cache",
134 	}, {
135 		.mask	= HPTE_R_WIMG,
136 		.val	= HPTE_R_G,
137 		.set	= "guarded",
138 	}
139 };
140 
141 static int calculate_pagesize(struct pg_state *st, int ps, char s[])
142 {
143 	static const char units[] = "BKMGTPE";
144 	const char *unit = units;
145 
146 	while (ps > 9 && unit[1]) {
147 		ps -= 10;
148 		unit++;
149 	}
150 	seq_printf(st->seq, "  %s_ps: %i%c\t", s, 1<<ps, *unit);
151 	return ps;
152 }
153 
154 static void dump_flag_info(struct pg_state *st, const struct flag_info
155 		*flag, u64 pte, int num)
156 {
157 	unsigned int i;
158 
159 	for (i = 0; i < num; i++, flag++) {
160 		const char *s = NULL;
161 		u64 val;
162 
163 		/* flag not defined so don't check it */
164 		if (flag->mask == 0)
165 			continue;
166 		/* Some 'flags' are actually values */
167 		if (flag->is_val) {
168 			val = pte & flag->val;
169 			if (flag->shift)
170 				val = val >> flag->shift;
171 			seq_printf(st->seq, "  %s:%llx", flag->set, val);
172 		} else {
173 			if ((pte & flag->mask) == flag->val)
174 				s = flag->set;
175 			else
176 				s = flag->clear;
177 			if (s)
178 				seq_printf(st->seq, "  %s", s);
179 		}
180 	}
181 }
182 
183 static void dump_hpte_info(struct pg_state *st, unsigned long ea, u64 v, u64 r,
184 		unsigned long rpn, int bps, int aps, unsigned long lp)
185 {
186 	int aps_index;
187 
188 	while (ea >= st->marker[1].start_address) {
189 		st->marker++;
190 		seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
191 	}
192 	seq_printf(st->seq, "0x%lx:\t", ea);
193 	seq_printf(st->seq, "AVPN:%llx\t", HPTE_V_AVPN_VAL(v));
194 	dump_flag_info(st, v_flag_array, v, ARRAY_SIZE(v_flag_array));
195 	seq_printf(st->seq, "  rpn: %lx\t", rpn);
196 	dump_flag_info(st, r_flag_array, r, ARRAY_SIZE(r_flag_array));
197 
198 	calculate_pagesize(st, bps, "base");
199 	aps_index = calculate_pagesize(st, aps, "actual");
200 	if (aps_index != 2)
201 		seq_printf(st->seq, "LP enc: %lx", lp);
202 	seq_putc(st->seq, '\n');
203 }
204 
205 
206 static int native_find(unsigned long ea, int psize, bool primary, u64 *v, u64
207 		*r)
208 {
209 	struct hash_pte *hptep;
210 	unsigned long hash, vsid, vpn, hpte_group, want_v, hpte_v;
211 	int i, ssize = mmu_kernel_ssize;
212 	unsigned long shift = mmu_psize_defs[psize].shift;
213 
214 	/* calculate hash */
215 	vsid = get_kernel_vsid(ea, ssize);
216 	vpn  = hpt_vpn(ea, vsid, ssize);
217 	hash = hpt_hash(vpn, shift, ssize);
218 	want_v = hpte_encode_avpn(vpn, psize, ssize);
219 
220 	/* to check in the secondary hash table, we invert the hash */
221 	if (!primary)
222 		hash = ~hash;
223 	hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP;
224 	for (i = 0; i < HPTES_PER_GROUP; i++) {
225 		hptep = htab_address + hpte_group;
226 		hpte_v = be64_to_cpu(hptep->v);
227 
228 		if (HPTE_V_COMPARE(hpte_v, want_v) && (hpte_v & HPTE_V_VALID)) {
229 			/* HPTE matches */
230 			*v = be64_to_cpu(hptep->v);
231 			*r = be64_to_cpu(hptep->r);
232 			return 0;
233 		}
234 		++hpte_group;
235 	}
236 	return -1;
237 }
238 
239 static int pseries_find(unsigned long ea, int psize, bool primary, u64 *v, u64 *r)
240 {
241 	struct hash_pte ptes[4];
242 	unsigned long vsid, vpn, hash, hpte_group, want_v;
243 	int i, j, ssize = mmu_kernel_ssize;
244 	long lpar_rc = 0;
245 	unsigned long shift = mmu_psize_defs[psize].shift;
246 
247 	/* calculate hash */
248 	vsid = get_kernel_vsid(ea, ssize);
249 	vpn  = hpt_vpn(ea, vsid, ssize);
250 	hash = hpt_hash(vpn, shift, ssize);
251 	want_v = hpte_encode_avpn(vpn, psize, ssize);
252 
253 	/* to check in the secondary hash table, we invert the hash */
254 	if (!primary)
255 		hash = ~hash;
256 	hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP;
257 	/* see if we can find an entry in the hpte with this hash */
258 	for (i = 0; i < HPTES_PER_GROUP; i += 4, hpte_group += 4) {
259 		lpar_rc = plpar_pte_read_4(0, hpte_group, (void *)ptes);
260 
261 		if (lpar_rc != H_SUCCESS)
262 			continue;
263 		for (j = 0; j < 4; j++) {
264 			if (HPTE_V_COMPARE(ptes[j].v, want_v) &&
265 					(ptes[j].v & HPTE_V_VALID)) {
266 				/* HPTE matches */
267 				*v = ptes[j].v;
268 				*r = ptes[j].r;
269 				return 0;
270 			}
271 		}
272 	}
273 	return -1;
274 }
275 
276 static void decode_r(int bps, unsigned long r, unsigned long *rpn, int *aps,
277 		unsigned long *lp_bits)
278 {
279 	struct mmu_psize_def entry;
280 	unsigned long arpn, mask, lp;
281 	int penc = -2, idx = 0, shift;
282 
283 	/*.
284 	 * The LP field has 8 bits. Depending on the actual page size, some of
285 	 * these bits are concatenated with the APRN to get the RPN. The rest
286 	 * of the bits in the LP field is the LP value and is an encoding for
287 	 * the base page size and the actual page size.
288 	 *
289 	 *  -	find the mmu entry for our base page size
290 	 *  -	go through all page encodings and use the associated mask to
291 	 *	find an encoding that matches our encoding in the LP field.
292 	 */
293 	arpn = (r & HPTE_R_RPN) >> HPTE_R_RPN_SHIFT;
294 	lp = arpn & 0xff;
295 
296 	entry = mmu_psize_defs[bps];
297 	while (idx < MMU_PAGE_COUNT) {
298 		penc = entry.penc[idx];
299 		if ((penc != -1) && (mmu_psize_defs[idx].shift)) {
300 			shift = mmu_psize_defs[idx].shift -  HPTE_R_RPN_SHIFT;
301 			mask = (0x1 << (shift)) - 1;
302 			if ((lp & mask) == penc) {
303 				*aps = mmu_psize_to_shift(idx);
304 				*lp_bits = lp & mask;
305 				*rpn = arpn >> shift;
306 				return;
307 			}
308 		}
309 		idx++;
310 	}
311 }
312 
313 static int base_hpte_find(unsigned long ea, int psize, bool primary, u64 *v,
314 			  u64 *r)
315 {
316 	if (IS_ENABLED(CONFIG_PPC_PSERIES) && firmware_has_feature(FW_FEATURE_LPAR))
317 		return pseries_find(ea, psize, primary, v, r);
318 
319 	return native_find(ea, psize, primary, v, r);
320 }
321 
322 static unsigned long hpte_find(struct pg_state *st, unsigned long ea, int psize)
323 {
324 	unsigned long slot;
325 	u64 v  = 0, r = 0;
326 	unsigned long rpn, lp_bits;
327 	int base_psize = 0, actual_psize = 0;
328 
329 	if (ea < PAGE_OFFSET)
330 		return -1;
331 
332 	/* Look in primary table */
333 	slot = base_hpte_find(ea, psize, true, &v, &r);
334 
335 	/* Look in secondary table */
336 	if (slot == -1)
337 		slot = base_hpte_find(ea, psize, false, &v, &r);
338 
339 	/* No entry found */
340 	if (slot == -1)
341 		return -1;
342 
343 	/*
344 	 * We found an entry in the hash page table:
345 	 *  - check that this has the same base page
346 	 *  - find the actual page size
347 	 *  - find the RPN
348 	 */
349 	base_psize = mmu_psize_to_shift(psize);
350 
351 	if ((v & HPTE_V_LARGE) == HPTE_V_LARGE) {
352 		decode_r(psize, r, &rpn, &actual_psize, &lp_bits);
353 	} else {
354 		/* 4K actual page size */
355 		actual_psize = 12;
356 		rpn = (r & HPTE_R_RPN) >> HPTE_R_RPN_SHIFT;
357 		/* In this case there are no LP bits */
358 		lp_bits = -1;
359 	}
360 	/*
361 	 * We didn't find a matching encoding, so the PTE we found isn't for
362 	 * this address.
363 	 */
364 	if (actual_psize == -1)
365 		return -1;
366 
367 	dump_hpte_info(st, ea, v, r, rpn, base_psize, actual_psize, lp_bits);
368 	return 0;
369 }
370 
371 static void walk_pte(struct pg_state *st, pmd_t *pmd, unsigned long start)
372 {
373 	pte_t *pte = pte_offset_kernel(pmd, 0);
374 	unsigned long addr, pteval, psize;
375 	int i, status;
376 
377 	for (i = 0; i < PTRS_PER_PTE; i++, pte++) {
378 		addr = start + i * PAGE_SIZE;
379 		pteval = pte_val(*pte);
380 
381 		if (addr < VMALLOC_END)
382 			psize = mmu_vmalloc_psize;
383 		else
384 			psize = mmu_io_psize;
385 
386 		/* check for secret 4K mappings */
387 		if (IS_ENABLED(CONFIG_PPC_64K_PAGES) &&
388 		    ((pteval & H_PAGE_COMBO) == H_PAGE_COMBO ||
389 		     (pteval & H_PAGE_4K_PFN) == H_PAGE_4K_PFN))
390 			psize = mmu_io_psize;
391 
392 		/* check for hashpte */
393 		status = hpte_find(st, addr, psize);
394 
395 		if (((pteval & H_PAGE_HASHPTE) != H_PAGE_HASHPTE)
396 				&& (status != -1)) {
397 		/* found a hpte that is not in the linux page tables */
398 			seq_printf(st->seq, "page probably bolted before linux"
399 				" pagetables were set: addr:%lx, pteval:%lx\n",
400 				addr, pteval);
401 		}
402 	}
403 }
404 
405 static void walk_pmd(struct pg_state *st, pud_t *pud, unsigned long start)
406 {
407 	pmd_t *pmd = pmd_offset(pud, 0);
408 	unsigned long addr;
409 	unsigned int i;
410 
411 	for (i = 0; i < PTRS_PER_PMD; i++, pmd++) {
412 		addr = start + i * PMD_SIZE;
413 		if (!pmd_none(*pmd))
414 			/* pmd exists */
415 			walk_pte(st, pmd, addr);
416 	}
417 }
418 
419 static void walk_pud(struct pg_state *st, p4d_t *p4d, unsigned long start)
420 {
421 	pud_t *pud = pud_offset(p4d, 0);
422 	unsigned long addr;
423 	unsigned int i;
424 
425 	for (i = 0; i < PTRS_PER_PUD; i++, pud++) {
426 		addr = start + i * PUD_SIZE;
427 		if (!pud_none(*pud))
428 			/* pud exists */
429 			walk_pmd(st, pud, addr);
430 	}
431 }
432 
433 static void walk_p4d(struct pg_state *st, pgd_t *pgd, unsigned long start)
434 {
435 	p4d_t *p4d = p4d_offset(pgd, 0);
436 	unsigned long addr;
437 	unsigned int i;
438 
439 	for (i = 0; i < PTRS_PER_P4D; i++, p4d++) {
440 		addr = start + i * P4D_SIZE;
441 		if (!p4d_none(*p4d))
442 			/* p4d exists */
443 			walk_pud(st, p4d, addr);
444 	}
445 }
446 
447 static void walk_pagetables(struct pg_state *st)
448 {
449 	pgd_t *pgd = pgd_offset_k(0UL);
450 	unsigned int i;
451 	unsigned long addr;
452 
453 	/*
454 	 * Traverse the linux pagetable structure and dump pages that are in
455 	 * the hash pagetable.
456 	 */
457 	for (i = 0; i < PTRS_PER_PGD; i++, pgd++) {
458 		addr = KERN_VIRT_START + i * PGDIR_SIZE;
459 		if (!pgd_none(*pgd))
460 			/* pgd exists */
461 			walk_p4d(st, pgd, addr);
462 	}
463 }
464 
465 
466 static void walk_linearmapping(struct pg_state *st)
467 {
468 	unsigned long addr;
469 
470 	/*
471 	 * Traverse the linear mapping section of virtual memory and dump pages
472 	 * that are in the hash pagetable.
473 	 */
474 	unsigned long psize = 1 << mmu_psize_defs[mmu_linear_psize].shift;
475 
476 	for (addr = PAGE_OFFSET; addr < PAGE_OFFSET +
477 			memblock_end_of_DRAM(); addr += psize)
478 		hpte_find(st, addr, mmu_linear_psize);
479 }
480 
481 static void walk_vmemmap(struct pg_state *st)
482 {
483 	struct vmemmap_backing *ptr = vmemmap_list;
484 
485 	if (!IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP))
486 		return;
487 	/*
488 	 * Traverse the vmemmaped memory and dump pages that are in the hash
489 	 * pagetable.
490 	 */
491 	while (ptr->list) {
492 		hpte_find(st, ptr->virt_addr, mmu_vmemmap_psize);
493 		ptr = ptr->list;
494 	}
495 	seq_puts(st->seq, "---[ vmemmap end ]---\n");
496 }
497 
498 static void populate_markers(void)
499 {
500 	address_markers[0].start_address = PAGE_OFFSET;
501 	address_markers[1].start_address = VMALLOC_START;
502 	address_markers[2].start_address = VMALLOC_END;
503 	address_markers[3].start_address = ISA_IO_BASE;
504 	address_markers[4].start_address = ISA_IO_END;
505 	address_markers[5].start_address = PHB_IO_BASE;
506 	address_markers[6].start_address = PHB_IO_END;
507 	address_markers[7].start_address = IOREMAP_BASE;
508 	address_markers[8].start_address = IOREMAP_END;
509 	address_markers[9].start_address =  H_VMEMMAP_START;
510 }
511 
512 static int ptdump_show(struct seq_file *m, void *v)
513 {
514 	struct pg_state st = {
515 		.seq = m,
516 		.start_address = PAGE_OFFSET,
517 		.marker = address_markers,
518 	};
519 	/*
520 	 * Traverse the 0xc, 0xd and 0xf areas of the kernel virtual memory and
521 	 * dump pages that are in the hash pagetable.
522 	 */
523 	walk_linearmapping(&st);
524 	walk_pagetables(&st);
525 	walk_vmemmap(&st);
526 	return 0;
527 }
528 
529 static int ptdump_open(struct inode *inode, struct file *file)
530 {
531 	return single_open(file, ptdump_show, NULL);
532 }
533 
534 static const struct file_operations ptdump_fops = {
535 	.open		= ptdump_open,
536 	.read		= seq_read,
537 	.llseek		= seq_lseek,
538 	.release	= single_release,
539 };
540 
541 static int ptdump_init(void)
542 {
543 	if (!radix_enabled()) {
544 		populate_markers();
545 		debugfs_create_file("kernel_hash_pagetable", 0400, NULL, NULL,
546 				    &ptdump_fops);
547 	}
548 	return 0;
549 }
550 device_initcall(ptdump_init);
551