xref: /openbmc/linux/fs/proc/page.c (revision fd589a8f)
1 #include <linux/bootmem.h>
2 #include <linux/compiler.h>
3 #include <linux/fs.h>
4 #include <linux/init.h>
5 #include <linux/mm.h>
6 #include <linux/mmzone.h>
7 #include <linux/proc_fs.h>
8 #include <linux/seq_file.h>
9 #include <linux/hugetlb.h>
10 #include <asm/uaccess.h>
11 #include "internal.h"
12 
13 #define KPMSIZE sizeof(u64)
14 #define KPMMASK (KPMSIZE - 1)
15 
16 /* /proc/kpagecount - an array exposing page counts
17  *
18  * Each entry is a u64 representing the corresponding
19  * physical page count.
20  */
21 static ssize_t kpagecount_read(struct file *file, char __user *buf,
22 			     size_t count, loff_t *ppos)
23 {
24 	u64 __user *out = (u64 __user *)buf;
25 	struct page *ppage;
26 	unsigned long src = *ppos;
27 	unsigned long pfn;
28 	ssize_t ret = 0;
29 	u64 pcount;
30 
31 	pfn = src / KPMSIZE;
32 	count = min_t(size_t, count, (max_pfn * KPMSIZE) - src);
33 	if (src & KPMMASK || count & KPMMASK)
34 		return -EINVAL;
35 
36 	while (count > 0) {
37 		if (pfn_valid(pfn))
38 			ppage = pfn_to_page(pfn);
39 		else
40 			ppage = NULL;
41 		if (!ppage)
42 			pcount = 0;
43 		else
44 			pcount = page_mapcount(ppage);
45 
46 		if (put_user(pcount, out)) {
47 			ret = -EFAULT;
48 			break;
49 		}
50 
51 		pfn++;
52 		out++;
53 		count -= KPMSIZE;
54 	}
55 
56 	*ppos += (char __user *)out - buf;
57 	if (!ret)
58 		ret = (char __user *)out - buf;
59 	return ret;
60 }
61 
62 static const struct file_operations proc_kpagecount_operations = {
63 	.llseek = mem_lseek,
64 	.read = kpagecount_read,
65 };
66 
67 /* /proc/kpageflags - an array exposing page flags
68  *
69  * Each entry is a u64 representing the corresponding
70  * physical page flags.
71  */
72 
73 /* These macros are used to decouple internal flags from exported ones */
74 
75 #define KPF_LOCKED		0
76 #define KPF_ERROR		1
77 #define KPF_REFERENCED		2
78 #define KPF_UPTODATE		3
79 #define KPF_DIRTY		4
80 #define KPF_LRU			5
81 #define KPF_ACTIVE		6
82 #define KPF_SLAB		7
83 #define KPF_WRITEBACK		8
84 #define KPF_RECLAIM		9
85 #define KPF_BUDDY		10
86 
87 /* 11-20: new additions in 2.6.31 */
88 #define KPF_MMAP		11
89 #define KPF_ANON		12
90 #define KPF_SWAPCACHE		13
91 #define KPF_SWAPBACKED		14
92 #define KPF_COMPOUND_HEAD	15
93 #define KPF_COMPOUND_TAIL	16
94 #define KPF_HUGE		17
95 #define KPF_UNEVICTABLE		18
96 #define KPF_NOPAGE		20
97 
98 /* kernel hacking assistances
99  * WARNING: subject to change, never rely on them!
100  */
101 #define KPF_RESERVED		32
102 #define KPF_MLOCKED		33
103 #define KPF_MAPPEDTODISK	34
104 #define KPF_PRIVATE		35
105 #define KPF_PRIVATE_2		36
106 #define KPF_OWNER_PRIVATE	37
107 #define KPF_ARCH		38
108 #define KPF_UNCACHED		39
109 
110 static inline u64 kpf_copy_bit(u64 kflags, int ubit, int kbit)
111 {
112 	return ((kflags >> kbit) & 1) << ubit;
113 }
114 
115 static u64 get_uflags(struct page *page)
116 {
117 	u64 k;
118 	u64 u;
119 
120 	/*
121 	 * pseudo flag: KPF_NOPAGE
122 	 * it differentiates a memory hole from a page with no flags
123 	 */
124 	if (!page)
125 		return 1 << KPF_NOPAGE;
126 
127 	k = page->flags;
128 	u = 0;
129 
130 	/*
131 	 * pseudo flags for the well known (anonymous) memory mapped pages
132 	 *
133 	 * Note that page->_mapcount is overloaded in SLOB/SLUB/SLQB, so the
134 	 * simple test in page_mapped() is not enough.
135 	 */
136 	if (!PageSlab(page) && page_mapped(page))
137 		u |= 1 << KPF_MMAP;
138 	if (PageAnon(page))
139 		u |= 1 << KPF_ANON;
140 
141 	/*
142 	 * compound pages: export both head/tail info
143 	 * they together define a compound page's start/end pos and order
144 	 */
145 	if (PageHead(page))
146 		u |= 1 << KPF_COMPOUND_HEAD;
147 	if (PageTail(page))
148 		u |= 1 << KPF_COMPOUND_TAIL;
149 	if (PageHuge(page))
150 		u |= 1 << KPF_HUGE;
151 
152 	u |= kpf_copy_bit(k, KPF_LOCKED,	PG_locked);
153 
154 	/*
155 	 * Caveats on high order pages:
156 	 * PG_buddy will only be set on the head page; SLUB/SLQB do the same
157 	 * for PG_slab; SLOB won't set PG_slab at all on compound pages.
158 	 */
159 	u |= kpf_copy_bit(k, KPF_SLAB,		PG_slab);
160 	u |= kpf_copy_bit(k, KPF_BUDDY,		PG_buddy);
161 
162 	u |= kpf_copy_bit(k, KPF_ERROR,		PG_error);
163 	u |= kpf_copy_bit(k, KPF_DIRTY,		PG_dirty);
164 	u |= kpf_copy_bit(k, KPF_UPTODATE,	PG_uptodate);
165 	u |= kpf_copy_bit(k, KPF_WRITEBACK,	PG_writeback);
166 
167 	u |= kpf_copy_bit(k, KPF_LRU,		PG_lru);
168 	u |= kpf_copy_bit(k, KPF_REFERENCED,	PG_referenced);
169 	u |= kpf_copy_bit(k, KPF_ACTIVE,	PG_active);
170 	u |= kpf_copy_bit(k, KPF_RECLAIM,	PG_reclaim);
171 
172 	u |= kpf_copy_bit(k, KPF_SWAPCACHE,	PG_swapcache);
173 	u |= kpf_copy_bit(k, KPF_SWAPBACKED,	PG_swapbacked);
174 
175 	u |= kpf_copy_bit(k, KPF_UNEVICTABLE,	PG_unevictable);
176 	u |= kpf_copy_bit(k, KPF_MLOCKED,	PG_mlocked);
177 
178 #ifdef CONFIG_IA64_UNCACHED_ALLOCATOR
179 	u |= kpf_copy_bit(k, KPF_UNCACHED,	PG_uncached);
180 #endif
181 
182 	u |= kpf_copy_bit(k, KPF_RESERVED,	PG_reserved);
183 	u |= kpf_copy_bit(k, KPF_MAPPEDTODISK,	PG_mappedtodisk);
184 	u |= kpf_copy_bit(k, KPF_PRIVATE,	PG_private);
185 	u |= kpf_copy_bit(k, KPF_PRIVATE_2,	PG_private_2);
186 	u |= kpf_copy_bit(k, KPF_OWNER_PRIVATE,	PG_owner_priv_1);
187 	u |= kpf_copy_bit(k, KPF_ARCH,		PG_arch_1);
188 
189 	return u;
190 };
191 
192 static ssize_t kpageflags_read(struct file *file, char __user *buf,
193 			     size_t count, loff_t *ppos)
194 {
195 	u64 __user *out = (u64 __user *)buf;
196 	struct page *ppage;
197 	unsigned long src = *ppos;
198 	unsigned long pfn;
199 	ssize_t ret = 0;
200 
201 	pfn = src / KPMSIZE;
202 	count = min_t(unsigned long, count, (max_pfn * KPMSIZE) - src);
203 	if (src & KPMMASK || count & KPMMASK)
204 		return -EINVAL;
205 
206 	while (count > 0) {
207 		if (pfn_valid(pfn))
208 			ppage = pfn_to_page(pfn);
209 		else
210 			ppage = NULL;
211 
212 		if (put_user(get_uflags(ppage), out)) {
213 			ret = -EFAULT;
214 			break;
215 		}
216 
217 		pfn++;
218 		out++;
219 		count -= KPMSIZE;
220 	}
221 
222 	*ppos += (char __user *)out - buf;
223 	if (!ret)
224 		ret = (char __user *)out - buf;
225 	return ret;
226 }
227 
228 static const struct file_operations proc_kpageflags_operations = {
229 	.llseek = mem_lseek,
230 	.read = kpageflags_read,
231 };
232 
233 static int __init proc_page_init(void)
234 {
235 	proc_create("kpagecount", S_IRUSR, NULL, &proc_kpagecount_operations);
236 	proc_create("kpageflags", S_IRUSR, NULL, &proc_kpageflags_operations);
237 	return 0;
238 }
239 module_init(proc_page_init);
240