1 /*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include <assert.h>
18 #include <inttypes.h>
19 #include <stdio.h>
20 #include <stdlib.h>
21 #include <stdint.h>
22 #include <sys/types.h>
23 #include <unistd.h>
24 #include <fcntl.h>
25
26 // This is an extremely simplified version of libpagemap.
27
28 #define _BITS(x, offset, bits) (((x) >> offset) & ((1LL << (bits)) - 1))
29
30 #define PAGEMAP_PRESENT(x) (_BITS(x, 63, 1))
31 #define PAGEMAP_SWAPPED(x) (_BITS(x, 62, 1))
32 #define PAGEMAP_SHIFT(x) (_BITS(x, 55, 6))
33 #define PAGEMAP_PFN(x) (_BITS(x, 0, 55))
34 #define PAGEMAP_SWAP_OFFSET(x) (_BITS(x, 5, 50))
35 #define PAGEMAP_SWAP_TYPE(x) (_BITS(x, 0, 5))
36
ReadData(int fd,unsigned long place,uint64_t * data)37 static bool ReadData(int fd, unsigned long place, uint64_t *data) {
38 if (lseek(fd, place * sizeof(uint64_t), SEEK_SET) < 0) {
39 return false;
40 }
41 if (read(fd, (void*)data, sizeof(uint64_t)) != (ssize_t)sizeof(uint64_t)) {
42 return false;
43 }
44 return true;
45 }
46
GetPssBytes()47 size_t GetPssBytes() {
48 FILE* maps = fopen("/proc/self/maps", "r");
49 assert(maps != NULL);
50
51 int pagecount_fd = open("/proc/kpagecount", O_RDONLY);
52 assert(pagecount_fd >= 0);
53
54 int pagemap_fd = open("/proc/self/pagemap", O_RDONLY);
55 assert(pagemap_fd >= 0);
56
57 char line[4096];
58 size_t total_pss = 0;
59 int pagesize = getpagesize();
60 while (fgets(line, sizeof(line), maps)) {
61 uintptr_t start, end;
62 if (sscanf(line, "%" SCNxPTR "-%" SCNxPTR " ", &start, &end) != 2) {
63 total_pss = 0;
64 break;
65 }
66 for (size_t page = start/pagesize; page < end/pagesize; page++) {
67 uint64_t data;
68 if (ReadData(pagemap_fd, page, &data)) {
69 if (PAGEMAP_PRESENT(data) && !PAGEMAP_SWAPPED(data)) {
70 uint64_t count;
71 if (ReadData(pagecount_fd, PAGEMAP_PFN(data), &count)) {
72 total_pss += (count >= 1) ? pagesize / count : 0;
73 }
74 }
75 }
76 }
77 }
78
79 fclose(maps);
80
81 close(pagecount_fd);
82 close(pagemap_fd);
83
84 return total_pss;
85 }
86