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/*
* Copyright (C) 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <inttypes.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
// This is an extremely simplified version of libpagemap.
#define _BITS(x, offset, bits) (((x) >> (offset)) & ((1LL << (bits)) - 1))
#define PAGEMAP_PRESENT(x) (_BITS(x, 63, 1))
#define PAGEMAP_SWAPPED(x) (_BITS(x, 62, 1))
#define PAGEMAP_SHIFT(x) (_BITS(x, 55, 6))
#define PAGEMAP_PFN(x) (_BITS(x, 0, 55))
#define PAGEMAP_SWAP_OFFSET(x) (_BITS(x, 5, 50))
#define PAGEMAP_SWAP_TYPE(x) (_BITS(x, 0, 5))
static bool ReadData(int fd, off_t place, uint64_t *data) {
if (lseek(fd, place * sizeof(uint64_t), SEEK_SET) < 0) {
return false;
}
if (read(fd, (void*)data, sizeof(uint64_t)) != (ssize_t)sizeof(uint64_t)) {
return false;
}
return true;
}
size_t GetPssBytes() {
FILE* maps = fopen("/proc/self/maps", "r");
if (maps == nullptr) {
return 0;
}
int pagecount_fd = open("/proc/kpagecount", O_RDONLY);
if (pagecount_fd == -1) {
fclose(maps);
return 0;
}
int pagemap_fd = open("/proc/self/pagemap", O_RDONLY);
if (pagemap_fd == -1) {
fclose(maps);
close(pagecount_fd);
return 0;
}
char line[4096];
size_t total_pss = 0;
int pagesize = getpagesize();
while (fgets(line, sizeof(line), maps)) {
uintptr_t start, end;
if (sscanf(line, "%" SCNxPTR "-%" SCNxPTR " ", &start, &end) != 2) {
total_pss = 0;
break;
}
for (off_t page = static_cast<off_t>(start/pagesize);
page < static_cast<off_t>(end/pagesize); page++) {
uint64_t data;
if (ReadData(pagemap_fd, page, &data)) {
if (PAGEMAP_PRESENT(data) && !PAGEMAP_SWAPPED(data)) {
uint64_t count;
if (ReadData(pagecount_fd, static_cast<off_t>(PAGEMAP_PFN(data)), &count)) {
total_pss += (count >= 1) ? pagesize / count : 0;
}
}
}
}
}
fclose(maps);
close(pagecount_fd);
close(pagemap_fd);
return total_pss;
}
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