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 <inttypes.h>
18 #include <stdint.h>
19 #include <stdio.h>
20 #include <stdlib.h>
21 #include <sys/types.h>
22 #include <unistd.h>
23 #include <fcntl.h>
24
25 // This is an extremely simplified version of libpagemap.
26
27 #define _BITS(x, offset, bits) (((x) >> offset) & ((1LL << (bits)) - 1))
28
29 #define PAGEMAP_PRESENT(x) (_BITS(x, 63, 1))
30 #define PAGEMAP_SWAPPED(x) (_BITS(x, 62, 1))
31 #define PAGEMAP_SHIFT(x) (_BITS(x, 55, 6))
32 #define PAGEMAP_PFN(x) (_BITS(x, 0, 55))
33 #define PAGEMAP_SWAP_OFFSET(x) (_BITS(x, 5, 50))
34 #define PAGEMAP_SWAP_TYPE(x) (_BITS(x, 0, 5))
35
ReadData(int fd,unsigned long place,uint64_t * data)36 static bool ReadData(int fd, unsigned long place, uint64_t *data) {
37 if (lseek(fd, place * sizeof(uint64_t), SEEK_SET) < 0) {
38 return false;
39 }
40 if (read(fd, (void*)data, sizeof(uint64_t)) != (ssize_t)sizeof(uint64_t)) {
41 return false;
42 }
43 return true;
44 }
45
GetPssBytes()46 size_t GetPssBytes() {
47 FILE* maps = fopen("/proc/self/maps", "r");
48 if (maps == nullptr) {
49 return 0;
50 }
51
52 int pagecount_fd = open("/proc/kpagecount", O_RDONLY);
53 if (pagecount_fd == -1) {
54 fclose(maps);
55 return 0;
56 }
57
58 int pagemap_fd = open("/proc/self/pagemap", O_RDONLY);
59 if (pagemap_fd == -1) {
60 fclose(maps);
61 close(pagecount_fd);
62 return 0;
63 }
64
65 char line[4096];
66 size_t total_pss = 0;
67 int pagesize = getpagesize();
68 while (fgets(line, sizeof(line), maps)) {
69 uintptr_t start, end;
70 if (sscanf(line, "%" SCNxPTR "-%" SCNxPTR " ", &start, &end) != 2) {
71 total_pss = 0;
72 break;
73 }
74 for (size_t page = start/pagesize; page < end/pagesize; page++) {
75 uint64_t data;
76 if (ReadData(pagemap_fd, page, &data)) {
77 if (PAGEMAP_PRESENT(data) && !PAGEMAP_SWAPPED(data)) {
78 uint64_t count;
79 if (ReadData(pagecount_fd, PAGEMAP_PFN(data), &count)) {
80 total_pss += (count >= 1) ? pagesize / count : 0;
81 }
82 }
83 }
84 }
85 }
86
87 fclose(maps);
88
89 close(pagecount_fd);
90 close(pagemap_fd);
91
92 return total_pss;
93 }
94