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 36 static bool ReadData(int fd, off_t 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 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 (off_t page = static_cast<off_t>(start/pagesize); 75 page < static_cast<off_t>(end/pagesize); page++) { 76 uint64_t data; 77 if (ReadData(pagemap_fd, page, &data)) { 78 if (PAGEMAP_PRESENT(data) && !PAGEMAP_SWAPPED(data)) { 79 uint64_t count; 80 if (ReadData(pagecount_fd, static_cast<off_t>(PAGEMAP_PFN(data)), &count)) { 81 total_pss += (count >= 1) ? pagesize / count : 0; 82 } 83 } 84 } 85 } 86 } 87 88 fclose(maps); 89 90 close(pagecount_fd); 91 close(pagemap_fd); 92 93 return total_pss; 94 } 95
