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/plpar_wrappers.h>
21#include <linux/memblock.h>
22#include <asm/firmware.h>
23#include <asm/pgalloc.h>
24
25struct 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
33struct addr_marker {
34	unsigned long start_address;
35	const char *name;
36};
37
38static 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
52struct 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
61static 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
85static 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
141static 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
154static 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
183static 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
206static 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
239static 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)
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
276static 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
313static 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
322static 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
371static 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
405static 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
419static 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
433static 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
447static 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
466static 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
481static 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
498static 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
512static 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
529static int ptdump_open(struct inode *inode, struct file *file)
530{
531	return single_open(file, ptdump_show, NULL);
532}
533
534static const struct file_operations ptdump_fops = {
535	.open		= ptdump_open,
536	.read		= seq_read,
537	.llseek		= seq_lseek,
538	.release	= single_release,
539};
540
541static 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}
550device_initcall(ptdump_init);
551