android_kernel_samsung_msm8976/arch/um/drivers/daemon_user.c
Jeff Dike 3d564047a5 uml: start fixing os_read_file and os_write_file
This patch starts the removal of a very old, very broken piece of code.  This
stems from the problem of passing a userspace buffer into read() or write() on
the host.  If that buffer had not yet been faulted in, read and write will
return -EFAULT.

To avoid this problem, the solution was to fault the buffer in before the
system call by touching the pages that hold the buffer by doing a copy-user of
a byte to each page.  This is obviously bogus, but it does usually work, in tt
mode, since the kernel and process are in the same address space and userspace
addresses can be accessed directly in the kernel.

In skas mode, where the kernel and process are in separate address spaces, it
is completely bogus because the userspace address, which is invalid in the
kernel, is passed into the system call instead of the corresponding physical
address, which would be valid.  Here, it appears that this code, on every host
read() or write(), tries to fault in a random process page.  This doesn't seem
to cause any correctness problems, but there is a performance impact.  This
patch, and the ones following, result in a 10-15% performance gain on a kernel
build.

This code can't be immediately tossed out because when it is, you can't log
in.  Apparently, there is some code in the console driver which depends on
this somehow.

However, we can start removing it by switching the code which does I/O using
kernel addresses to using plain read() and write().  This patch introduces
os_read_file_k and os_write_file_k for use with kernel buffers and converts
all call locations which use obvious kernel buffers to use them.  These
include I/O using buffers which are local variables which are on the stack or
kmalloc-ed.  Later patches will handle the less obvious cases, followed by a
mass conversion back to the original interface.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-07 12:13:03 -07:00

198 lines
4.2 KiB
C

/*
* Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org) and
* James Leu (jleu@mindspring.net).
* Copyright (C) 2001 by various other people who didn't put their name here.
* Licensed under the GPL.
*/
#include <errno.h>
#include <unistd.h>
#include <stdint.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/time.h>
#include "net_user.h"
#include "daemon.h"
#include "kern_util.h"
#include "user.h"
#include "os.h"
#include "um_malloc.h"
#define MAX_PACKET (ETH_MAX_PACKET + ETH_HEADER_OTHER)
enum request_type { REQ_NEW_CONTROL };
#define SWITCH_MAGIC 0xfeedface
struct request_v3 {
uint32_t magic;
uint32_t version;
enum request_type type;
struct sockaddr_un sock;
};
static struct sockaddr_un *new_addr(void *name, int len)
{
struct sockaddr_un *sun;
sun = um_kmalloc(sizeof(struct sockaddr_un));
if(sun == NULL){
printk("new_addr: allocation of sockaddr_un failed\n");
return NULL;
}
sun->sun_family = AF_UNIX;
memcpy(sun->sun_path, name, len);
return sun;
}
static int connect_to_switch(struct daemon_data *pri)
{
struct sockaddr_un *ctl_addr = pri->ctl_addr;
struct sockaddr_un *local_addr = pri->local_addr;
struct sockaddr_un *sun;
struct request_v3 req;
int fd, n, err;
pri->control = socket(AF_UNIX, SOCK_STREAM, 0);
if(pri->control < 0){
err = -errno;
printk("daemon_open : control socket failed, errno = %d\n",
-err);
return err;
}
if(connect(pri->control, (struct sockaddr *) ctl_addr,
sizeof(*ctl_addr)) < 0){
err = -errno;
printk("daemon_open : control connect failed, errno = %d\n",
-err);
goto out;
}
fd = socket(AF_UNIX, SOCK_DGRAM, 0);
if(fd < 0){
err = -errno;
printk("daemon_open : data socket failed, errno = %d\n",
-err);
goto out;
}
if(bind(fd, (struct sockaddr *) local_addr, sizeof(*local_addr)) < 0){
err = -errno;
printk("daemon_open : data bind failed, errno = %d\n",
-err);
goto out_close;
}
sun = um_kmalloc(sizeof(struct sockaddr_un));
if(sun == NULL){
printk("new_addr: allocation of sockaddr_un failed\n");
err = -ENOMEM;
goto out_close;
}
req.magic = SWITCH_MAGIC;
req.version = SWITCH_VERSION;
req.type = REQ_NEW_CONTROL;
req.sock = *local_addr;
n = os_write_file_k(pri->control, &req, sizeof(req));
if(n != sizeof(req)){
printk("daemon_open : control setup request failed, err = %d\n",
-n);
err = -ENOTCONN;
goto out_free;
}
n = os_read_file_k(pri->control, sun, sizeof(*sun));
if(n != sizeof(*sun)){
printk("daemon_open : read of data socket failed, err = %d\n",
-n);
err = -ENOTCONN;
goto out_free;
}
pri->data_addr = sun;
return fd;
out_free:
kfree(sun);
out_close:
os_close_file(fd);
out:
os_close_file(pri->control);
return err;
}
static int daemon_user_init(void *data, void *dev)
{
struct daemon_data *pri = data;
struct timeval tv;
struct {
char zero;
int pid;
int usecs;
} name;
if(!strcmp(pri->sock_type, "unix"))
pri->ctl_addr = new_addr(pri->ctl_sock,
strlen(pri->ctl_sock) + 1);
name.zero = 0;
name.pid = os_getpid();
gettimeofday(&tv, NULL);
name.usecs = tv.tv_usec;
pri->local_addr = new_addr(&name, sizeof(name));
pri->dev = dev;
pri->fd = connect_to_switch(pri);
if(pri->fd < 0){
kfree(pri->local_addr);
pri->local_addr = NULL;
return pri->fd;
}
return 0;
}
static int daemon_open(void *data)
{
struct daemon_data *pri = data;
return pri->fd;
}
static void daemon_remove(void *data)
{
struct daemon_data *pri = data;
os_close_file(pri->fd);
pri->fd = -1;
os_close_file(pri->control);
pri->control = -1;
kfree(pri->data_addr);
pri->data_addr = NULL;
kfree(pri->ctl_addr);
pri->ctl_addr = NULL;
kfree(pri->local_addr);
pri->local_addr = NULL;
}
int daemon_user_write(int fd, void *buf, int len, struct daemon_data *pri)
{
struct sockaddr_un *data_addr = pri->data_addr;
return net_sendto(fd, buf, len, data_addr, sizeof(*data_addr));
}
static int daemon_set_mtu(int mtu, void *data)
{
return mtu;
}
const struct net_user_info daemon_user_info = {
.init = daemon_user_init,
.open = daemon_open,
.close = NULL,
.remove = daemon_remove,
.set_mtu = daemon_set_mtu,
.add_address = NULL,
.delete_address = NULL,
.max_packet = MAX_PACKET - ETH_HEADER_OTHER
};