minix/test/test74.c

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/* Test 74 - mmap functionality & regression test.
*
* This test tests some basic functionality of mmap, and also some
* cases that are quite complex for the system to handle.
*
* Memory pages are generally made available on demand. Memory copying
* is done by the kernel. As the kernel may encounter pagefaults in
* legitimate memory ranges (e.g. pages that aren't mapped; pages that
* are mapped RO as they are COW), it cooperates with VM to make the
* mappings and let the copy succeed transparently.
*
* With file-mapped ranges this can result in a deadlock, if care is
* not taken, as the copy might be request by VFS or an FS. This test
* triggers as many of these states as possible to ensure they are
* successful or (where appropriate) fail gracefully, i.e. without
* deadlock.
*
* To do this, system calls are done with source or target buffers with
* missing or readonly mappings, both anonymous and file-mapped. The
* cache is flushed before mmap() so that we know the mappings should
* not be present on mmap() time. Then e.g. a read() or write() is
* executed with that buffer as target. This triggers a FS copying
* to or from a missing range that it itself is needed to map in first.
* VFS detects this, requests VM to map in the pages, which does so with
* the help of another VFS thread and the FS, and then re-issues the
* request to the FS.
*
* Another case is the VFS itself does such a copy. This is actually
* unusual as filenames are already faulted in by the requesting process
* in libc by strlen(). select() allows such a case, however, so this
* is tested too. We are satisfied if the call completes.
*/
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <sys/ioc_memory.h>
#include <sys/param.h>
#include <stdio.h>
#include <assert.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <dirent.h>
#include "common.h"
#include "testcache.h"
int max_error = 0; /* make all e()'s fatal */
int
dowriteblock(int b, int blocksize, u32_t seed, char *data)
{
u64_t offset;
int fd;
get_fd_offset(b, blocksize, &offset, &fd);
if(pwrite(fd, data, blocksize, offset) < blocksize) {
perror("pwrite");
return -1;
}
return blocksize;
}
int
readblock(int b, int blocksize, u32_t seed, char *data)
{
u64_t offset;
int fd;
char *mmapdata;
int pread_first = random() % 2;
get_fd_offset(b, blocksize, &offset, &fd);
if(pread_first) {
if(pread(fd, data, blocksize, offset) < blocksize) {
perror("pread");
return -1;
}
}
if((mmapdata = mmap(NULL, blocksize, PROT_READ, MAP_PRIVATE | MAP_FILE,
fd, offset)) == MAP_FAILED) {
perror("mmap");
return -1;
}
if(!pread_first) {
if(pread(fd, data, blocksize, offset) < blocksize) {
perror("pread");
return -1;
}
}
if(memcmp(mmapdata, data, blocksize)) {
fprintf(stderr, "readblock: mmap, pread mismatch\n");
return -1;
}
if(munmap(mmapdata, blocksize) < 0) {
perror("munmap");
return -1;
}
return blocksize;
}
void testend(void) { }
static void do_read(void *buf, int fd, int writable)
{
ssize_t ret;
size_t n = PAGE_SIZE;
struct stat sb;
if(fstat(fd, &sb) < 0) e(1);
if(S_ISDIR(sb.st_mode)) return;
ret = read(fd, buf, n);
/* if the buffer is writable, it should succeed */
if(writable) { if(ret != n) e(3); return; }
/* if the buffer is not writable, it should fail with EFAULT */
if(ret >= 0) e(4);
if(errno != EFAULT) e(5);
}
static void do_write(void *buf, int fd, int writable)
{
size_t n = PAGE_SIZE;
struct stat sb;
if(fstat(fd, &sb) < 0) e(1);
if(S_ISDIR(sb.st_mode)) return;
if(write(fd, buf, n) != n) e(3);
}
static void do_stat(void *buf, int fd, int writable)
{
int r;
struct stat sb;
r = fstat(fd, (struct stat *) buf);
/* should succeed if buf is writable */
if(writable) { if(r < 0) e(3); return; }
/* should fail with EFAULT if buf is not */
if(r >= 0) e(4);
if(errno != EFAULT) e(5);
}
static void do_getdents(void *buf, int fd, int writable)
{
struct stat sb;
int r;
if(fstat(fd, &sb) < 0) e(1);
if(!S_ISDIR(sb.st_mode)) return; /* OK */
r = getdents(fd, buf, PAGE_SIZE);
if(writable) { if(r < 0) e(3); return; }
/* should fail with EFAULT if buf is not */
if(r >= 0) e(4);
if(errno != EFAULT) e(5);
}
static void do_readlink1(void *buf, int fd, int writable)
{
char target[200];
/* the system call just has to fail gracefully */
readlink(buf, target, sizeof(target));
}
#define NODENAME "a"
#define TARGETNAME "b"
static void do_readlink2(void *buf, int fd, int writable)
{
ssize_t rl;
unlink(NODENAME);
if(symlink(TARGETNAME, NODENAME) < 0) e(1);
rl=readlink(NODENAME, buf, sizeof(buf));
/* if buf is writable, it should succeed, with a certain result */
if(writable) {
if(rl < 0) e(2);
((char *) buf)[rl] = '\0';
if(strcmp(buf, TARGETNAME)) {
fprintf(stderr, "readlink: expected %s, got %s\n",
TARGETNAME, buf);
e(3);
}
return;
}
/* if buf is not writable, it should fail with EFAULT */
if(rl >= 0) e(4);
if(errno != EFAULT) e(5);
}
static void do_symlink1(void *buf, int fd, int writable)
{
int r;
/* the system call just has to fail gracefully */
r = symlink(buf, NODENAME);
}
static void do_symlink2(void *buf, int fd, int writable)
{
int r;
/* the system call just has to fail gracefully */
r = symlink(NODENAME, buf);
}
static void do_open(void *buf, int fd, int writable)
{
int r;
/* the system call just has to fail gracefully */
r = open(buf, O_RDONLY);
if(r >= 0) close(r);
}
static void do_select1(void *buf, int fd, int writable)
{
int r;
struct timeval timeout = { 0, 200000 }; /* 0.2 sec */
/* the system call just has to fail gracefully */
r = select(1, buf, NULL, NULL, &timeout);
}
static void do_select2(void *buf, int fd, int writable)
{
int r;
struct timeval timeout = { 0, 200000 }; /* 1 sec */
/* the system call just has to fail gracefully */
r = select(1, NULL, buf, NULL, &timeout);
}
static void do_select3(void *buf, int fd, int writable)
{
int r;
struct timeval timeout = { 0, 200000 }; /* 1 sec */
/* the system call just has to fail gracefully */
r = select(1, NULL, NULL, buf, &timeout);
}
static void fillfile(int fd, int size)
{
char *buf = malloc(size);
if(size < 1 || size % PAGE_SIZE || !buf) { e(1); }
memset(buf, 'A', size);
buf[50] = '\0'; /* so it can be used as a filename arg */
buf[size-1] = '\0';
if(write(fd, buf, size) != size) { e(2); }
if(lseek(fd, SEEK_SET, 0) < 0) { e(3); }
free(buf);
}
static void make_buffers(int size,
int *ret_fd_rw, int *ret_fd_ro,
void **filebuf_rw, void **filebuf_ro, void **anonbuf)
{
char fn_rw[] = "testfile_rw.XXXXXX", fn_ro[] = "testfile_ro.XXXXXX";
*ret_fd_rw = mkstemp(fn_rw);
*ret_fd_ro = mkstemp(fn_ro);
if(size < 1 || size % PAGE_SIZE) { e(2); }
if(*ret_fd_rw < 0) { e(1); }
if(*ret_fd_ro < 0) { e(1); }
fillfile(*ret_fd_rw, size);
fillfile(*ret_fd_ro, size);
if(fcntl(*ret_fd_rw, F_FLUSH_FS_CACHE) < 0) { e(4); }
if(fcntl(*ret_fd_ro, F_FLUSH_FS_CACHE) < 0) { e(4); }
if((*filebuf_rw = mmap(0, size, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_FILE, *ret_fd_rw, 0)) == MAP_FAILED) {
e(5);
quit();
}
if((*filebuf_ro = mmap(0, size, PROT_READ,
MAP_PRIVATE | MAP_FILE, *ret_fd_ro, 0)) == MAP_FAILED) {
e(5);
quit();
}
if((*anonbuf = mmap(0, size, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANON, -1, 0)) == MAP_FAILED) {
e(6);
quit();
}
if(unlink(fn_rw) < 0) { e(12); }
if(unlink(fn_ro) < 0) { e(12); }
}
static void forget_buffers(void *buf1, void *buf2, void *buf3, int fd1, int fd2, int size)
{
if(munmap(buf1, size) < 0) { e(1); }
if(munmap(buf2, size) < 0) { e(2); }
if(munmap(buf3, size) < 0) { e(2); }
if(fcntl(fd1, F_FLUSH_FS_CACHE) < 0) { e(3); }
if(fcntl(fd2, F_FLUSH_FS_CACHE) < 0) { e(3); }
if(close(fd1) < 0) { e(4); }
if(close(fd2) < 0) { e(4); }
}
#define NEXPERIMENTS 12
struct {
void (*do_operation)(void * buf, int fd, int writable);
} experiments[NEXPERIMENTS] = {
{ do_read },
{ do_write },
{ do_stat },
{ do_getdents },
{ do_readlink1 },
{ do_readlink2 },
{ do_symlink1 },
{ do_symlink2 },
{ do_open, },
{ do_select1 },
{ do_select2 },
{ do_select3 },
};
void test_memory_types_vs_operations(void)
{
#define NFDS 4
#define BUFSIZE (10 * PAGE_SIZE)
int exp, fds[NFDS];
int f = 0, size = BUFSIZE;
/* open some test fd's */
#define OPEN(fn, mode) { assert(f >= 0 && f < NFDS); \
fds[f] = open(fn, mode); if(fds[f] < 0) { e(2); } f++; }
OPEN("regular", O_RDWR | O_CREAT);
OPEN(".", O_RDONLY);
OPEN("/dev/ram", O_RDWR);
OPEN("/dev/zero", O_RDWR);
/* make sure the regular file has plenty of size to play with */
fillfile(fds[0], BUFSIZE);
/* and the ramdisk too */
if(ioctl(fds[2], MIOCRAMSIZE, &size) < 0) { e(3); }
for(exp = 0; exp < NEXPERIMENTS; exp++) {
for(f = 0; f < NFDS; f++) {
void *anonmem, *filemem_rw, *filemem_ro;
int buffd_rw, buffd_ro;
make_buffers(BUFSIZE, &buffd_rw, &buffd_ro,
&filemem_rw, &filemem_ro, &anonmem);
if(lseek(fds[f], 0, SEEK_SET) != 0) { e(10); }
experiments[exp].do_operation(anonmem, fds[f], 1);
if(lseek(fds[f], 0, SEEK_SET) != 0) { e(11); }
experiments[exp].do_operation(filemem_rw, fds[f], 1);
if(lseek(fds[f], 0, SEEK_SET) != 0) { e(12); }
experiments[exp].do_operation(filemem_ro, fds[f], 0);
forget_buffers(filemem_rw, filemem_ro, anonmem, buffd_rw, buffd_ro, BUFSIZE);
}
}
}
void basic_regression(void)
{
int fd, fd1, fd2;
ssize_t rb, wr;
char buf[PAGE_SIZE*2];
void *block, *block1, *block2;
#define BLOCKSIZE (PAGE_SIZE*10)
block = mmap(0, BLOCKSIZE, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANON, -1, 0);
if(block == MAP_FAILED) { e(1); }
memset(block, 0, BLOCKSIZE);
/* shrink from bottom */
munmap(block, PAGE_SIZE);
/* Next test: use a system call write() to access a block of
* unavailable file-mapped memory.
*
* This is a thorny corner case to make succeed transparently
* because
* (1) it is a filesystem that is doing the memory access
* (copy from the constblock1 range in this process to the
* FS) but is also the FS needed to satisfy the range if it
* isn't in the cache.
* (2) there are two separate memory regions involved, requiring
* separate VFS requests from VM to properly satisfy, requiring
* some complex state to be kept.
*/
fd1 = open("../testsh1", O_RDONLY);
fd2 = open("../testsh2", O_RDONLY);
if(fd1 < 0 || fd2 < 0) { e(2); }
/* just check that we can't mmap() a file writable */
if(mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_FILE, fd1, 0) != MAP_FAILED) {
e(1);
}
/* check that we can mmap() a file MAP_SHARED readonly */
if(mmap(NULL, PAGE_SIZE, PROT_READ, MAP_SHARED | MAP_FILE, fd1, 0) == MAP_FAILED) {
e(1);
}
/* clear cache of files before mmap so pages won't be present already */
if(fcntl(fd1, F_FLUSH_FS_CACHE) < 0) { e(1); }
if(fcntl(fd2, F_FLUSH_FS_CACHE) < 0) { e(1); }
#define LOCATION1 (void *) 0x90000000
#define LOCATION2 (LOCATION1 + PAGE_SIZE)
block1 = mmap(LOCATION1, PAGE_SIZE, PROT_READ, MAP_PRIVATE | MAP_FILE, fd1, 0);
if(block1 == MAP_FAILED) { e(4); }
if(block1 != LOCATION1) { e(5); }
block2 = mmap(LOCATION2, PAGE_SIZE, PROT_READ, MAP_PRIVATE | MAP_FILE, fd2, 0);
if(block2 == MAP_FAILED) { e(10); }
if(block2 != LOCATION2) { e(11); }
unlink("testfile");
fd = open("testfile", O_CREAT | O_RDWR);
if(fd < 0) { e(15); }
/* write() using the mmap()ped memory as buffer */
if((wr=write(fd, LOCATION1, sizeof(buf))) != sizeof(buf)) {
fprintf(stderr, "wrote %zd bytes instead of %zd\n",
wr, sizeof(buf));
e(20);
quit();
}
/* verify written contents */
if((rb=pread(fd, buf, sizeof(buf), 0)) != sizeof(buf)) {
if(rb < 0) perror("pread");
fprintf(stderr, "wrote %zd bytes\n", wr);
fprintf(stderr, "read %zd bytes instead of %zd\n",
rb, sizeof(buf));
e(21);
quit();
}
if(memcmp(buf, LOCATION1, sizeof(buf))) {
e(22);
quit();
}
close(fd);
close(fd1);
close(fd2);
}
int
main(int argc, char *argv[])
{
int iter = 2;
start(74);
basic_regression();
test_memory_types_vs_operations();
makefiles(MAXFILES);
cachequiet(!bigflag);
if(bigflag) iter = 3;
/* Try various combinations working set sizes
* and block sizes in order to specifically
* target the primary cache, then primary+secondary
* cache, then primary+secondary cache+secondary
* cache eviction.
*/
if(dotest(PAGE_SIZE, 100, iter)) e(5);
if(dotest(PAGE_SIZE*2, 100, iter)) e(2);
if(dotest(PAGE_SIZE*3, 100, iter)) e(3);
if(dotest(PAGE_SIZE, 20000, iter)) e(5);
if(bigflag) {
u32_t totalmem, freemem, cachedmem;
if(dotest(PAGE_SIZE, 150000, iter)) e(5);
getmem(&totalmem, &freemem, &cachedmem);
if(dotest(PAGE_SIZE, totalmem*1.5, iter)) e(6);
}
quit();
return 0;
}