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authorRob Landley <rob@landley.net>2006-04-18 22:21:43 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-04-19 09:13:51 -0700
commit966a082f80a073af1564c5ed6313ef2f0587dde3 (patch)
treeda199abad4c035c60f04100b2759815655f46f31 /arch
parentf983c45ebedcaf686223afaecd8e681e8dcd15a9 (diff)
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[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>
Diffstat (limited to 'arch')
-rw-r--r--arch/um/os-Linux/mem.c118
-rw-r--r--arch/um/os-Linux/start_up.c24
2 files changed, 118 insertions, 24 deletions
diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c
index 71bb90a..c6432e7 100644
--- a/arch/um/os-Linux/mem.c
+++ b/arch/um/os-Linux/mem.c
@@ -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);
+}
diff --git a/arch/um/os-Linux/start_up.c b/arch/um/os-Linux/start_up.c
index 387e26a..5031485 100644
--- a/arch/um/os-Linux/start_up.c
+++ b/arch/um/os-Linux/start_up.c
@@ -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)
{