1#include <linux/bootmem.h>
2#include <linux/compiler.h>
3#include <linux/fs.h>
4#include <linux/init.h>
5#include <linux/ksm.h>
6#include <linux/mm.h>
7#include <linux/mmzone.h>
8#include <linux/huge_mm.h>
9#include <linux/proc_fs.h>
10#include <linux/seq_file.h>
11#include <linux/hugetlb.h>
12#include <linux/kernel-page-flags.h>
13#include <asm/uaccess.h>
14#include "internal.h"
15
16#define KPMSIZE sizeof(u64)
17#define KPMMASK (KPMSIZE - 1)
18
19/* /proc/kpagecount - an array exposing page counts
20 *
21 * Each entry is a u64 representing the corresponding
22 * physical page count.
23 */
24static ssize_t kpagecount_read(struct file *file, char __user *buf,
25			     size_t count, loff_t *ppos)
26{
27	u64 __user *out = (u64 __user *)buf;
28	struct page *ppage;
29	unsigned long src = *ppos;
30	unsigned long pfn;
31	ssize_t ret = 0;
32	u64 pcount;
33
34	pfn = src / KPMSIZE;
35	count = min_t(size_t, count, (max_pfn * KPMSIZE) - src);
36	if (src & KPMMASK || count & KPMMASK)
37		return -EINVAL;
38
39	while (count > 0) {
40		if (pfn_valid(pfn))
41			ppage = pfn_to_page(pfn);
42		else
43			ppage = NULL;
44		if (!ppage || PageSlab(ppage))
45			pcount = 0;
46		else
47			pcount = page_mapcount(ppage);
48
49		if (put_user(pcount, out)) {
50			ret = -EFAULT;
51			break;
52		}
53
54		pfn++;
55		out++;
56		count -= KPMSIZE;
57	}
58
59	*ppos += (char __user *)out - buf;
60	if (!ret)
61		ret = (char __user *)out - buf;
62	return ret;
63}
64
65static const struct file_operations proc_kpagecount_operations = {
66	.llseek = mem_lseek,
67	.read = kpagecount_read,
68};
69
70/* /proc/kpageflags - an array exposing page flags
71 *
72 * Each entry is a u64 representing the corresponding
73 * physical page flags.
74 */
75
76static inline u64 kpf_copy_bit(u64 kflags, int ubit, int kbit)
77{
78	return ((kflags >> kbit) & 1) << ubit;
79}
80
81u64 stable_page_flags(struct page *page)
82{
83	u64 k;
84	u64 u;
85
86	/*
87	 * pseudo flag: KPF_NOPAGE
88	 * it differentiates a memory hole from a page with no flags
89	 */
90	if (!page)
91		return 1 << KPF_NOPAGE;
92
93	k = page->flags;
94	u = 0;
95
96	/*
97	 * pseudo flags for the well known (anonymous) memory mapped pages
98	 *
99	 * Note that page->_mapcount is overloaded in SLOB/SLUB/SLQB, so the
100	 * simple test in page_mapped() is not enough.
101	 */
102	if (!PageSlab(page) && page_mapped(page))
103		u |= 1 << KPF_MMAP;
104	if (PageAnon(page))
105		u |= 1 << KPF_ANON;
106	if (PageKsm(page))
107		u |= 1 << KPF_KSM;
108
109	/*
110	 * compound pages: export both head/tail info
111	 * they together define a compound page's start/end pos and order
112	 */
113	if (PageHead(page))
114		u |= 1 << KPF_COMPOUND_HEAD;
115	if (PageTail(page))
116		u |= 1 << KPF_COMPOUND_TAIL;
117	if (PageHuge(page))
118		u |= 1 << KPF_HUGE;
119	/*
120	 * PageTransCompound can be true for non-huge compound pages (slab
121	 * pages or pages allocated by drivers with __GFP_COMP) because it
122	 * just checks PG_head/PG_tail, so we need to check PageLRU/PageAnon
123	 * to make sure a given page is a thp, not a non-huge compound page.
124	 */
125	else if (PageTransCompound(page)) {
126		struct page *head = compound_head(page);
127
128		if (PageLRU(head) || PageAnon(head))
129			u |= 1 << KPF_THP;
130		else if (is_huge_zero_page(head)) {
131			u |= 1 << KPF_ZERO_PAGE;
132			u |= 1 << KPF_THP;
133		}
134	} else if (is_zero_pfn(page_to_pfn(page)))
135		u |= 1 << KPF_ZERO_PAGE;
136
137
138	/*
139	 * Caveats on high order pages: page->_count will only be set
140	 * -1 on the head page; SLUB/SLQB do the same for PG_slab;
141	 * SLOB won't set PG_slab at all on compound pages.
142	 */
143	if (PageBuddy(page))
144		u |= 1 << KPF_BUDDY;
145
146	if (PageBalloon(page))
147		u |= 1 << KPF_BALLOON;
148
149	u |= kpf_copy_bit(k, KPF_LOCKED,	PG_locked);
150
151	u |= kpf_copy_bit(k, KPF_SLAB,		PG_slab);
152
153	u |= kpf_copy_bit(k, KPF_ERROR,		PG_error);
154	u |= kpf_copy_bit(k, KPF_DIRTY,		PG_dirty);
155	u |= kpf_copy_bit(k, KPF_UPTODATE,	PG_uptodate);
156	u |= kpf_copy_bit(k, KPF_WRITEBACK,	PG_writeback);
157
158	u |= kpf_copy_bit(k, KPF_LRU,		PG_lru);
159	u |= kpf_copy_bit(k, KPF_REFERENCED,	PG_referenced);
160	u |= kpf_copy_bit(k, KPF_ACTIVE,	PG_active);
161	u |= kpf_copy_bit(k, KPF_RECLAIM,	PG_reclaim);
162
163	u |= kpf_copy_bit(k, KPF_SWAPCACHE,	PG_swapcache);
164	u |= kpf_copy_bit(k, KPF_SWAPBACKED,	PG_swapbacked);
165
166	u |= kpf_copy_bit(k, KPF_UNEVICTABLE,	PG_unevictable);
167	u |= kpf_copy_bit(k, KPF_MLOCKED,	PG_mlocked);
168
169#ifdef CONFIG_MEMORY_FAILURE
170	u |= kpf_copy_bit(k, KPF_HWPOISON,	PG_hwpoison);
171#endif
172
173#ifdef CONFIG_ARCH_USES_PG_UNCACHED
174	u |= kpf_copy_bit(k, KPF_UNCACHED,	PG_uncached);
175#endif
176
177	u |= kpf_copy_bit(k, KPF_RESERVED,	PG_reserved);
178	u |= kpf_copy_bit(k, KPF_MAPPEDTODISK,	PG_mappedtodisk);
179	u |= kpf_copy_bit(k, KPF_PRIVATE,	PG_private);
180	u |= kpf_copy_bit(k, KPF_PRIVATE_2,	PG_private_2);
181	u |= kpf_copy_bit(k, KPF_OWNER_PRIVATE,	PG_owner_priv_1);
182	u |= kpf_copy_bit(k, KPF_ARCH,		PG_arch_1);
183
184	return u;
185};
186
187static ssize_t kpageflags_read(struct file *file, char __user *buf,
188			     size_t count, loff_t *ppos)
189{
190	u64 __user *out = (u64 __user *)buf;
191	struct page *ppage;
192	unsigned long src = *ppos;
193	unsigned long pfn;
194	ssize_t ret = 0;
195
196	pfn = src / KPMSIZE;
197	count = min_t(unsigned long, count, (max_pfn * KPMSIZE) - src);
198	if (src & KPMMASK || count & KPMMASK)
199		return -EINVAL;
200
201	while (count > 0) {
202		if (pfn_valid(pfn))
203			ppage = pfn_to_page(pfn);
204		else
205			ppage = NULL;
206
207		if (put_user(stable_page_flags(ppage), out)) {
208			ret = -EFAULT;
209			break;
210		}
211
212		pfn++;
213		out++;
214		count -= KPMSIZE;
215	}
216
217	*ppos += (char __user *)out - buf;
218	if (!ret)
219		ret = (char __user *)out - buf;
220	return ret;
221}
222
223static const struct file_operations proc_kpageflags_operations = {
224	.llseek = mem_lseek,
225	.read = kpageflags_read,
226};
227
228static int __init proc_page_init(void)
229{
230	proc_create("kpagecount", S_IRUSR, NULL, &proc_kpagecount_operations);
231	proc_create("kpageflags", S_IRUSR, NULL, &proc_kpageflags_operations);
232	return 0;
233}
234fs_initcall(proc_page_init);
235