[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: Rob Landley <rob@landley.net> Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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f983c45ebe
Коммит
966a082f80
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@ -8,6 +8,7 @@
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#include <fcntl.h>
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#include <sys/types.h>
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#include <sys/mman.h>
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#include <sys/statfs.h>
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#include "kern_util.h"
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#include "user.h"
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#include "user_util.h"
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@ -19,6 +20,7 @@
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#include <sys/param.h>
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static char *default_tmpdir = "/tmp";
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static char *tempdir = NULL;
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static void __init find_tempdir(void)
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@ -34,7 +36,7 @@ static void __init find_tempdir(void)
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break;
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}
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if((dir == NULL) || (*dir == '\0'))
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dir = "/tmp";
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dir = default_tmpdir;
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tempdir = malloc(strlen(dir) + 2);
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if(tempdir == NULL){
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@ -46,6 +48,96 @@ static void __init find_tempdir(void)
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strcat(tempdir, "/");
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}
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/* This will return 1, with the first character in buf being the
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* character following the next instance of c in the file. This will
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* read the file as needed. If there's an error, -errno is returned;
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* if the end of the file is reached, 0 is returned.
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*/
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static int next(int fd, char *buf, int size, char c)
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{
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int n;
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char *ptr;
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while((ptr = strchr(buf, c)) == NULL){
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n = read(fd, buf, size - 1);
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if(n == 0)
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return 0;
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else if(n < 0)
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return -errno;
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buf[n] = '\0';
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}
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ptr++;
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memmove(buf, ptr, strlen(ptr) + 1);
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return 1;
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}
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static int checked_tmpdir = 0;
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/* Look for a tmpfs mounted at /dev/shm. I couldn't find a cleaner
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* way to do this than to parse /proc/mounts. statfs will return the
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* same filesystem magic number and fs id for both /dev and /dev/shm
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* when they are both tmpfs, so you can't tell if they are different
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* filesystems. Also, there seems to be no other way of finding the
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* mount point of a filesystem from within it.
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*
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* If a /dev/shm tmpfs entry is found, then we switch to using it.
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* Otherwise, we stay with the default /tmp.
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*/
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static void which_tmpdir(void)
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{
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int fd, found;
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char buf[128] = { '\0' };
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if(checked_tmpdir)
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return;
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checked_tmpdir = 1;
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printf("Checking for tmpfs mount on /dev/shm...");
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fd = open("/proc/mounts", O_RDONLY);
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if(fd < 0){
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printf("failed to open /proc/mounts, errno = %d\n", errno);
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return;
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}
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while(1){
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found = next(fd, buf, sizeof(buf) / sizeof(buf[0]), ' ');
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if(found != 1)
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break;
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if(!strncmp(buf, "/dev/shm", strlen("/dev/shm")))
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goto found;
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found = next(fd, buf, sizeof(buf) / sizeof(buf[0]), '\n');
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if(found != 1)
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break;
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}
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err:
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if(found == 0)
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printf("nothing mounted on /dev/shm\n");
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else if(found < 0)
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printf("read returned errno %d\n", -found);
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return;
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found:
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found = next(fd, buf, sizeof(buf) / sizeof(buf[0]), ' ');
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if(found != 1)
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goto err;
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if(strncmp(buf, "tmpfs", strlen("tmpfs"))){
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printf("not tmpfs\n");
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return;
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}
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printf("OK\n");
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default_tmpdir = "/dev/shm";
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}
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/*
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* This proc still used in tt-mode
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* (file: kernel/tt/ptproxy/proxy.c, proc: start_debugger).
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@ -56,6 +148,7 @@ int make_tempfile(const char *template, char **out_tempname, int do_unlink)
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char *tempname;
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int fd;
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which_tmpdir();
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tempname = malloc(MAXPATHLEN);
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find_tempdir();
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@ -137,3 +230,26 @@ int create_mem_file(unsigned long long len)
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}
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return(fd);
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}
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void check_tmpexec(void)
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{
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void *addr;
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int err, fd = create_tmp_file(UM_KERN_PAGE_SIZE);
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addr = mmap(NULL, UM_KERN_PAGE_SIZE,
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PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, fd, 0);
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printf("Checking PROT_EXEC mmap in %s...",tempdir);
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fflush(stdout);
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if(addr == MAP_FAILED){
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err = errno;
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perror("failed");
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if(err == EPERM)
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printf("%s must be not mounted noexec\n",tempdir);
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exit(1);
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}
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printf("OK\n");
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munmap(addr, UM_KERN_PAGE_SIZE);
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close(fd);
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}
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@ -296,29 +296,7 @@ static void __init check_ptrace(void)
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check_sysemu();
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}
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extern int create_tmp_file(unsigned long long len);
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static void check_tmpexec(void)
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{
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void *addr;
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int err, fd = create_tmp_file(UM_KERN_PAGE_SIZE);
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addr = mmap(NULL, UM_KERN_PAGE_SIZE,
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PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, fd, 0);
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printf("Checking PROT_EXEC mmap in /tmp...");
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fflush(stdout);
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if(addr == MAP_FAILED){
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err = errno;
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perror("failed");
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if(err == EPERM)
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printf("/tmp must be not mounted noexec\n");
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exit(1);
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}
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printf("OK\n");
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munmap(addr, UM_KERN_PAGE_SIZE);
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close(fd);
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}
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extern void check_tmpexec(void);
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void os_early_checks(void)
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{
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