// SPDX-License-Identifier: GPL-2.0
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/*
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* Test that MAP_FIXED_NOREPLACE works.
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*
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* Copyright 2018, Jann Horn <jannh@google.com>
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* Copyright 2018, Michael Ellerman, IBM Corporation.
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*/
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#include <sys/mman.h>
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#ifndef MAP_FIXED_NOREPLACE
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#define MAP_FIXED_NOREPLACE 0x100000
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#endif
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static void dump_maps(void)
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{
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char cmd[32];
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snprintf(cmd, sizeof(cmd), "cat /proc/%d/maps", getpid());
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system(cmd);
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}
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static unsigned long find_base_addr(unsigned long size)
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{
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void *addr;
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unsigned long flags;
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flags = MAP_PRIVATE | MAP_ANONYMOUS;
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addr = mmap(NULL, size, PROT_NONE, flags, -1, 0);
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if (addr == MAP_FAILED) {
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printf("Error: couldn't map the space we need for the test\n");
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return 0;
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}
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if (munmap(addr, size) != 0) {
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printf("Error: couldn't map the space we need for the test\n");
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return 0;
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}
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return (unsigned long)addr;
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}
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int main(void)
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{
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unsigned long base_addr;
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unsigned long flags, addr, size, page_size;
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char *p;
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page_size = sysconf(_SC_PAGE_SIZE);
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//let's find a base addr that is free before we start the tests
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size = 5 * page_size;
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base_addr = find_base_addr(size);
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if (!base_addr) {
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printf("Error: couldn't map the space we need for the test\n");
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return 1;
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}
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flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED_NOREPLACE;
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// Check we can map all the areas we need below
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errno = 0;
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addr = base_addr;
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size = 5 * page_size;
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p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
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printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
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if (p == MAP_FAILED) {
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dump_maps();
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printf("Error: couldn't map the space we need for the test\n");
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return 1;
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}
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errno = 0;
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if (munmap((void *)addr, 5 * page_size) != 0) {
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dump_maps();
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printf("Error: munmap failed!?\n");
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return 1;
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}
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printf("unmap() successful\n");
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errno = 0;
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addr = base_addr + page_size;
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size = 3 * page_size;
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p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
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printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
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if (p == MAP_FAILED) {
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dump_maps();
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printf("Error: first mmap() failed unexpectedly\n");
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return 1;
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}
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/*
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* Exact same mapping again:
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* base | free | new
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* +1 | mapped | new
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* +2 | mapped | new
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* +3 | mapped | new
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* +4 | free | new
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*/
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errno = 0;
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addr = base_addr;
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size = 5 * page_size;
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p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
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printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
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if (p != MAP_FAILED) {
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dump_maps();
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printf("Error:1: mmap() succeeded when it shouldn't have\n");
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return 1;
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}
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/*
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* Second mapping contained within first:
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*
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* base | free |
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* +1 | mapped |
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* +2 | mapped | new
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* +3 | mapped |
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* +4 | free |
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*/
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errno = 0;
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addr = base_addr + (2 * page_size);
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size = page_size;
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p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
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printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
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if (p != MAP_FAILED) {
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dump_maps();
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printf("Error:2: mmap() succeeded when it shouldn't have\n");
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return 1;
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}
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/*
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* Overlap end of existing mapping:
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* base | free |
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* +1 | mapped |
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* +2 | mapped |
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* +3 | mapped | new
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* +4 | free | new
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*/
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errno = 0;
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addr = base_addr + (3 * page_size);
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size = 2 * page_size;
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p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
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printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
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if (p != MAP_FAILED) {
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dump_maps();
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printf("Error:3: mmap() succeeded when it shouldn't have\n");
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return 1;
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}
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/*
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* Overlap start of existing mapping:
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* base | free | new
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* +1 | mapped | new
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* +2 | mapped |
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* +3 | mapped |
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* +4 | free |
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*/
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errno = 0;
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addr = base_addr;
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size = 2 * page_size;
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p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
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printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
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if (p != MAP_FAILED) {
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dump_maps();
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printf("Error:4: mmap() succeeded when it shouldn't have\n");
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return 1;
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}
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/*
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* Adjacent to start of existing mapping:
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* base | free | new
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* +1 | mapped |
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* +2 | mapped |
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* +3 | mapped |
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* +4 | free |
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*/
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errno = 0;
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addr = base_addr;
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size = page_size;
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p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
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printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
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if (p == MAP_FAILED) {
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dump_maps();
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printf("Error:5: mmap() failed when it shouldn't have\n");
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return 1;
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}
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/*
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* Adjacent to end of existing mapping:
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* base | free |
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* +1 | mapped |
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* +2 | mapped |
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* +3 | mapped |
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* +4 | free | new
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*/
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errno = 0;
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addr = base_addr + (4 * page_size);
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size = page_size;
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p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
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printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
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if (p == MAP_FAILED) {
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dump_maps();
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printf("Error:6: mmap() failed when it shouldn't have\n");
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return 1;
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}
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addr = base_addr;
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size = 5 * page_size;
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if (munmap((void *)addr, size) != 0) {
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dump_maps();
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printf("Error: munmap failed!?\n");
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return 1;
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}
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printf("unmap() successful\n");
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printf("OK\n");
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return 0;
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}
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