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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

arch/um/os-Linux/mem.c

+117 −1
Original line number Diff line number Diff line
@@ -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);

}

arch/um/os-Linux/start_up.c

+1 −23
Original line number Diff line number Diff line
@@ -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)

{