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