From 87276f721a9407a4a152b09265dc079f37674672 Mon Sep 17 00:00:00 2001 From: Paolo 'Blaisorblade' Giarrusso Date: Mon, 10 Apr 2006 22:53:39 -0700 Subject: [PATCH] uml: fix big stack user Switch this proc from storing 4k of data (a whole path) on the stack to keeping it on the heap. Maybe it's not called in process context but only in early boot context (where in UML you have a normal process stack on the host) but just to be safe, fix it. While at it some little readability simplifications. Signed-off-by: Paolo 'Blaisorblade' Giarrusso Cc: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/um/os-Linux/mem.c | 23 +++++++++++++---------- 1 file changed, 13 insertions(+), 10 deletions(-) (limited to 'arch/um/os-Linux/mem.c') diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c index 6ab372da965..71bb90a7606 100644 --- a/arch/um/os-Linux/mem.c +++ b/arch/um/os-Linux/mem.c @@ -53,33 +53,36 @@ static void __init find_tempdir(void) */ int make_tempfile(const char *template, char **out_tempname, int do_unlink) { - char tempname[MAXPATHLEN]; + char *tempname; int fd; + tempname = malloc(MAXPATHLEN); + find_tempdir(); - if (*template != '/') + if (template[0] != '/') strcpy(tempname, tempdir); else - *tempname = 0; + tempname[0] = '\0'; strcat(tempname, template); fd = mkstemp(tempname); if(fd < 0){ fprintf(stderr, "open - cannot create %s: %s\n", tempname, strerror(errno)); - return -1; + goto out; } if(do_unlink && (unlink(tempname) < 0)){ perror("unlink"); - return -1; + goto out; } if(out_tempname){ - *out_tempname = strdup(tempname); - if(*out_tempname == NULL){ - perror("strdup"); - return -1; - } + *out_tempname = tempname; + } else { + free(tempname); } return(fd); +out: + free(tempname); + return -1; } #define TEMPNAME_TEMPLATE "vm_file-XXXXXX" -- cgit v1.2.3 From 966a082f80a073af1564c5ed6313ef2f0587dde3 Mon Sep 17 00:00:00 2001 From: Rob Landley Date: Tue, 18 Apr 2006 22:21:43 -0700 Subject: [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 Signed-off-by: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/um/os-Linux/mem.c | 118 ++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 117 insertions(+), 1 deletion(-) (limited to 'arch/um/os-Linux/mem.c') diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c index 71bb90a7606..c6432e72924 100644 --- a/arch/um/os-Linux/mem.c +++ b/arch/um/os-Linux/mem.c @@ -8,6 +8,7 @@ #include #include #include +#include #include "kern_util.h" #include "user.h" #include "user_util.h" @@ -19,6 +20,7 @@ #include +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); +} -- cgit v1.2.3