linux/drivers/tty/serial/kgdboc.c
Linus Torvalds 6c536a17fa KGDB/KDB fixes and cleanups
Cleanups
    Clean up compile warnings in kgdboc.c and x86/kernel/kgdb.c
    Add module event hooks for simplified debugging with gdb
  Fixes
    Fix kdb to stop paging with 'q' on bta and dmesg
    Fix for data that scrolls off the vga console due to line wrapping
      when using the kdb pager
  New
    The debug core registers for kernel module events which allows a
      kernel aware gdb to automatically load symbols and break on entry
      to a kernel module
    Allow kgdboc=kdb to setup kdb on the vga console
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Merge tag 'for_linus-3.7' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb

Pull KGDB/KDB fixes and cleanups from Jason Wessel:
 "Cleanups
   - Clean up compile warnings in kgdboc.c and x86/kernel/kgdb.c
   - Add module event hooks for simplified debugging with gdb
 Fixes
   - Fix kdb to stop paging with 'q' on bta and dmesg
   - Fix for data that scrolls off the vga console due to line wrapping
     when using the kdb pager
 New
   - The debug core registers for kernel module events which allows a
     kernel aware gdb to automatically load symbols and break on entry
     to a kernel module
   - Allow kgdboc=kdb to setup kdb on the vga console"

* tag 'for_linus-3.7' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb:
  tty/console: fix warnings in drivers/tty/serial/kgdboc.c
  kdb,vt_console: Fix missed data due to pager overruns
  kdb: Fix dmesg/bta scroll to quit with 'q'
  kgdboc: Accept either kbd or kdb to activate the vga + keyboard kdb shell
  kgdb,x86: fix warning about unused variable
  mips,kgdb: fix recursive page fault with CONFIG_KPROBES
  kgdb: Add module event hooks
2012-10-13 11:16:58 +09:00

340 lines
7.4 KiB
C

/*
* Based on the same principle as kgdboe using the NETPOLL api, this
* driver uses a console polling api to implement a gdb serial inteface
* which is multiplexed on a console port.
*
* Maintainer: Jason Wessel <jason.wessel@windriver.com>
*
* 2007-2008 (c) Jason Wessel - Wind River Systems, Inc.
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*/
#include <linux/kernel.h>
#include <linux/ctype.h>
#include <linux/kgdb.h>
#include <linux/kdb.h>
#include <linux/tty.h>
#include <linux/console.h>
#include <linux/vt_kern.h>
#include <linux/input.h>
#include <linux/module.h>
#define MAX_CONFIG_LEN 40
static struct kgdb_io kgdboc_io_ops;
/* -1 = init not run yet, 0 = unconfigured, 1 = configured. */
static int configured = -1;
static char config[MAX_CONFIG_LEN];
static struct kparam_string kps = {
.string = config,
.maxlen = MAX_CONFIG_LEN,
};
static int kgdboc_use_kms; /* 1 if we use kernel mode switching */
static struct tty_driver *kgdb_tty_driver;
static int kgdb_tty_line;
#ifdef CONFIG_KDB_KEYBOARD
static int kgdboc_reset_connect(struct input_handler *handler,
struct input_dev *dev,
const struct input_device_id *id)
{
input_reset_device(dev);
/* Retrun an error - we do not want to bind, just to reset */
return -ENODEV;
}
static void kgdboc_reset_disconnect(struct input_handle *handle)
{
/* We do not expect anyone to actually bind to us */
BUG();
}
static const struct input_device_id kgdboc_reset_ids[] = {
{
.flags = INPUT_DEVICE_ID_MATCH_EVBIT,
.evbit = { BIT_MASK(EV_KEY) },
},
{ }
};
static struct input_handler kgdboc_reset_handler = {
.connect = kgdboc_reset_connect,
.disconnect = kgdboc_reset_disconnect,
.name = "kgdboc_reset",
.id_table = kgdboc_reset_ids,
};
static DEFINE_MUTEX(kgdboc_reset_mutex);
static void kgdboc_restore_input_helper(struct work_struct *dummy)
{
/*
* We need to take a mutex to prevent several instances of
* this work running on different CPUs so they don't try
* to register again already registered handler.
*/
mutex_lock(&kgdboc_reset_mutex);
if (input_register_handler(&kgdboc_reset_handler) == 0)
input_unregister_handler(&kgdboc_reset_handler);
mutex_unlock(&kgdboc_reset_mutex);
}
static DECLARE_WORK(kgdboc_restore_input_work, kgdboc_restore_input_helper);
static void kgdboc_restore_input(void)
{
if (likely(system_state == SYSTEM_RUNNING))
schedule_work(&kgdboc_restore_input_work);
}
static int kgdboc_register_kbd(char **cptr)
{
if (strncmp(*cptr, "kbd", 3) == 0 ||
strncmp(*cptr, "kdb", 3) == 0) {
if (kdb_poll_idx < KDB_POLL_FUNC_MAX) {
kdb_poll_funcs[kdb_poll_idx] = kdb_get_kbd_char;
kdb_poll_idx++;
if (cptr[0][3] == ',')
*cptr += 4;
else
return 1;
}
}
return 0;
}
static void kgdboc_unregister_kbd(void)
{
int i;
for (i = 0; i < kdb_poll_idx; i++) {
if (kdb_poll_funcs[i] == kdb_get_kbd_char) {
kdb_poll_idx--;
kdb_poll_funcs[i] = kdb_poll_funcs[kdb_poll_idx];
kdb_poll_funcs[kdb_poll_idx] = NULL;
i--;
}
}
flush_work(&kgdboc_restore_input_work);
}
#else /* ! CONFIG_KDB_KEYBOARD */
#define kgdboc_register_kbd(x) 0
#define kgdboc_unregister_kbd()
#define kgdboc_restore_input()
#endif /* ! CONFIG_KDB_KEYBOARD */
static int kgdboc_option_setup(char *opt)
{
if (strlen(opt) >= MAX_CONFIG_LEN) {
printk(KERN_ERR "kgdboc: config string too long\n");
return -ENOSPC;
}
strcpy(config, opt);
return 0;
}
__setup("kgdboc=", kgdboc_option_setup);
static void cleanup_kgdboc(void)
{
if (kgdb_unregister_nmi_console())
return;
kgdboc_unregister_kbd();
if (configured == 1)
kgdb_unregister_io_module(&kgdboc_io_ops);
}
static int configure_kgdboc(void)
{
struct tty_driver *p;
int tty_line = 0;
int err;
char *cptr = config;
struct console *cons;
err = kgdboc_option_setup(config);
if (err || !strlen(config) || isspace(config[0]))
goto noconfig;
err = -ENODEV;
kgdboc_io_ops.is_console = 0;
kgdb_tty_driver = NULL;
kgdboc_use_kms = 0;
if (strncmp(cptr, "kms,", 4) == 0) {
cptr += 4;
kgdboc_use_kms = 1;
}
if (kgdboc_register_kbd(&cptr))
goto do_register;
p = tty_find_polling_driver(cptr, &tty_line);
if (!p)
goto noconfig;
cons = console_drivers;
while (cons) {
int idx;
if (cons->device && cons->device(cons, &idx) == p &&
idx == tty_line) {
kgdboc_io_ops.is_console = 1;
break;
}
cons = cons->next;
}
kgdb_tty_driver = p;
kgdb_tty_line = tty_line;
do_register:
err = kgdb_register_io_module(&kgdboc_io_ops);
if (err)
goto noconfig;
err = kgdb_register_nmi_console();
if (err)
goto nmi_con_failed;
configured = 1;
return 0;
nmi_con_failed:
kgdb_unregister_io_module(&kgdboc_io_ops);
noconfig:
kgdboc_unregister_kbd();
config[0] = 0;
configured = 0;
cleanup_kgdboc();
return err;
}
static int __init init_kgdboc(void)
{
/* Already configured? */
if (configured == 1)
return 0;
return configure_kgdboc();
}
static int kgdboc_get_char(void)
{
if (!kgdb_tty_driver)
return -1;
return kgdb_tty_driver->ops->poll_get_char(kgdb_tty_driver,
kgdb_tty_line);
}
static void kgdboc_put_char(u8 chr)
{
if (!kgdb_tty_driver)
return;
kgdb_tty_driver->ops->poll_put_char(kgdb_tty_driver,
kgdb_tty_line, chr);
}
static int param_set_kgdboc_var(const char *kmessage, struct kernel_param *kp)
{
int len = strlen(kmessage);
if (len >= MAX_CONFIG_LEN) {
printk(KERN_ERR "kgdboc: config string too long\n");
return -ENOSPC;
}
/* Only copy in the string if the init function has not run yet */
if (configured < 0) {
strcpy(config, kmessage);
return 0;
}
if (kgdb_connected) {
printk(KERN_ERR
"kgdboc: Cannot reconfigure while KGDB is connected.\n");
return -EBUSY;
}
strcpy(config, kmessage);
/* Chop out \n char as a result of echo */
if (config[len - 1] == '\n')
config[len - 1] = '\0';
if (configured == 1)
cleanup_kgdboc();
/* Go and configure with the new params. */
return configure_kgdboc();
}
static int dbg_restore_graphics;
static void kgdboc_pre_exp_handler(void)
{
if (!dbg_restore_graphics && kgdboc_use_kms) {
dbg_restore_graphics = 1;
con_debug_enter(vc_cons[fg_console].d);
}
/* Increment the module count when the debugger is active */
if (!kgdb_connected)
try_module_get(THIS_MODULE);
}
static void kgdboc_post_exp_handler(void)
{
/* decrement the module count when the debugger detaches */
if (!kgdb_connected)
module_put(THIS_MODULE);
if (kgdboc_use_kms && dbg_restore_graphics) {
dbg_restore_graphics = 0;
con_debug_leave();
}
kgdboc_restore_input();
}
static struct kgdb_io kgdboc_io_ops = {
.name = "kgdboc",
.read_char = kgdboc_get_char,
.write_char = kgdboc_put_char,
.pre_exception = kgdboc_pre_exp_handler,
.post_exception = kgdboc_post_exp_handler,
};
#ifdef CONFIG_KGDB_SERIAL_CONSOLE
/* This is only available if kgdboc is a built in for early debugging */
static int __init kgdboc_early_init(char *opt)
{
/* save the first character of the config string because the
* init routine can destroy it.
*/
char save_ch;
kgdboc_option_setup(opt);
save_ch = config[0];
init_kgdboc();
config[0] = save_ch;
return 0;
}
early_param("ekgdboc", kgdboc_early_init);
#endif /* CONFIG_KGDB_SERIAL_CONSOLE */
module_init(init_kgdboc);
module_exit(cleanup_kgdboc);
module_param_call(kgdboc, param_set_kgdboc_var, param_get_string, &kps, 0644);
MODULE_PARM_DESC(kgdboc, "<serial_device>[,baud]");
MODULE_DESCRIPTION("KGDB Console TTY Driver");
MODULE_LICENSE("GPL");