Commit 966a082f authored by Rob Landley's avatar Rob Landley Committed by Linus Torvalds
Browse files

[PATCH] uml: physical memory map file fixes



UML really wants shared memory semantics form its physical memory map file,
and the place for that is /dev/shm.  So move the default, and fix the error
messages to recognize that this value can be overridden.
Signed-off-by: default avatarRob Landley <rob@landley.net>
Signed-off-by: default avatarJeff Dike <jdike@addtoit.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent f983c45e
......@@ -8,6 +8,7 @@
#include <fcntl.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/statfs.h>
#include "kern_util.h"
#include "user.h"
#include "user_util.h"
......@@ -19,6 +20,7 @@
#include <sys/param.h>
static char *default_tmpdir = "/tmp";
static char *tempdir = NULL;
static void __init find_tempdir(void)
......@@ -34,7 +36,7 @@ static void __init find_tempdir(void)
break;
}
if((dir == NULL) || (*dir == '\0'))
dir = "/tmp";
dir = default_tmpdir;
tempdir = malloc(strlen(dir) + 2);
if(tempdir == NULL){
......@@ -46,6 +48,96 @@ static void __init find_tempdir(void)
strcat(tempdir, "/");
}
/* This will return 1, with the first character in buf being the
* character following the next instance of c in the file. This will
* read the file as needed. If there's an error, -errno is returned;
* if the end of the file is reached, 0 is returned.
*/
static int next(int fd, char *buf, int size, char c)
{
int n;
char *ptr;
while((ptr = strchr(buf, c)) == NULL){
n = read(fd, buf, size - 1);
if(n == 0)
return 0;
else if(n < 0)
return -errno;
buf[n] = '\0';
}
ptr++;
memmove(buf, ptr, strlen(ptr) + 1);
return 1;
}
static int checked_tmpdir = 0;
/* Look for a tmpfs mounted at /dev/shm. I couldn't find a cleaner
* way to do this than to parse /proc/mounts. statfs will return the
* same filesystem magic number and fs id for both /dev and /dev/shm
* when they are both tmpfs, so you can't tell if they are different
* filesystems. Also, there seems to be no other way of finding the
* mount point of a filesystem from within it.
*
* If a /dev/shm tmpfs entry is found, then we switch to using it.
* Otherwise, we stay with the default /tmp.
*/
static void which_tmpdir(void)
{
int fd, found;
char buf[128] = { '\0' };
if(checked_tmpdir)
return;
checked_tmpdir = 1;
printf("Checking for tmpfs mount on /dev/shm...");
fd = open("/proc/mounts", O_RDONLY);
if(fd < 0){
printf("failed to open /proc/mounts, errno = %d\n", errno);
return;
}
while(1){
found = next(fd, buf, sizeof(buf) / sizeof(buf[0]), ' ');
if(found != 1)
break;
if(!strncmp(buf, "/dev/shm", strlen("/dev/shm")))
goto found;
found = next(fd, buf, sizeof(buf) / sizeof(buf[0]), '\n');
if(found != 1)
break;
}
err:
if(found == 0)
printf("nothing mounted on /dev/shm\n");
else if(found < 0)
printf("read returned errno %d\n", -found);
return;
found:
found = next(fd, buf, sizeof(buf) / sizeof(buf[0]), ' ');
if(found != 1)
goto err;
if(strncmp(buf, "tmpfs", strlen("tmpfs"))){
printf("not tmpfs\n");
return;
}
printf("OK\n");
default_tmpdir = "/dev/shm";
}
/*
* This proc still used in tt-mode
* (file: kernel/tt/ptproxy/proxy.c, proc: start_debugger).
......@@ -56,6 +148,7 @@ int make_tempfile(const char *template, char **out_tempname, int do_unlink)
char *tempname;
int fd;
which_tmpdir();
tempname = malloc(MAXPATHLEN);
find_tempdir();
......@@ -137,3 +230,26 @@ int create_mem_file(unsigned long long len)
}
return(fd);
}
void check_tmpexec(void)
{
void *addr;
int err, fd = create_tmp_file(UM_KERN_PAGE_SIZE);
addr = mmap(NULL, UM_KERN_PAGE_SIZE,
PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, fd, 0);
printf("Checking PROT_EXEC mmap in %s...",tempdir);
fflush(stdout);
if(addr == MAP_FAILED){
err = errno;
perror("failed");
if(err == EPERM)
printf("%s must be not mounted noexec\n",tempdir);
exit(1);
}
printf("OK\n");
munmap(addr, UM_KERN_PAGE_SIZE);
close(fd);
}
......@@ -296,29 +296,7 @@ static void __init check_ptrace(void)
check_sysemu();
}
extern int create_tmp_file(unsigned long long len);
static void check_tmpexec(void)
{
void *addr;
int err, fd = create_tmp_file(UM_KERN_PAGE_SIZE);
addr = mmap(NULL, UM_KERN_PAGE_SIZE,
PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, fd, 0);
printf("Checking PROT_EXEC mmap in /tmp...");
fflush(stdout);
if(addr == MAP_FAILED){
err = errno;
perror("failed");
if(err == EPERM)
printf("/tmp must be not mounted noexec\n");
exit(1);
}
printf("OK\n");
munmap(addr, UM_KERN_PAGE_SIZE);
close(fd);
}
extern void check_tmpexec(void);
void os_early_checks(void)
{
......
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