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