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authorJesse Barnes <jbarnes@virtuousgeek.org>2010-08-05 10:22:30 -0400
committerJason Wessel <jason.wessel@windriver.com>2010-08-05 10:22:30 -0400
commitb45cfba4e9005d64d419718e7ff7f7cab44c1994 (patch)
tree2d454a67c9a87ffc01579d958f9d95dd5e13170e /drivers/char/vt.c
parent3fa43aba08c5b5a4b407e402606fbe463239b14a (diff)
vt,console,kdb: implement atomic console enter/leave functions
These functions allow the kernel debugger to save and restore the state of the system console. Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org> Signed-off-by: Jason Wessel <jason.wessel@windriver.com> CC: David Airlie <airlied@linux.ie> CC: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'drivers/char/vt.c')
-rw-r--r--drivers/char/vt.c61
1 files changed, 61 insertions, 0 deletions
diff --git a/drivers/char/vt.c b/drivers/char/vt.c
index 7cdb6ee569cd..117ce99115dc 100644
--- a/drivers/char/vt.c
+++ b/drivers/char/vt.c
@@ -187,10 +187,15 @@ static DECLARE_WORK(console_work, console_callback);
187 * fg_console is the current virtual console, 187 * fg_console is the current virtual console,
188 * last_console is the last used one, 188 * last_console is the last used one,
189 * want_console is the console we want to switch to, 189 * want_console is the console we want to switch to,
190 * saved_* variants are for save/restore around kernel debugger enter/leave
190 */ 191 */
191int fg_console; 192int fg_console;
192int last_console; 193int last_console;
193int want_console = -1; 194int want_console = -1;
195int saved_fg_console;
196int saved_last_console;
197int saved_want_console;
198int saved_vc_mode;
194 199
195/* 200/*
196 * For each existing display, we have a pointer to console currently visible 201 * For each existing display, we have a pointer to console currently visible
@@ -3414,6 +3419,62 @@ int con_is_bound(const struct consw *csw)
3414EXPORT_SYMBOL(con_is_bound); 3419EXPORT_SYMBOL(con_is_bound);
3415 3420
3416/** 3421/**
3422 * con_debug_enter - prepare the console for the kernel debugger
3423 * @sw: console driver
3424 *
3425 * Called when the console is taken over by the kernel debugger, this
3426 * function needs to save the current console state, then put the console
3427 * into a state suitable for the kernel debugger.
3428 *
3429 * RETURNS:
3430 * Zero on success, nonzero if a failure occurred when trying to prepare
3431 * the console for the debugger.
3432 */
3433int con_debug_enter(struct vc_data *vc)
3434{
3435 int ret = 0;
3436
3437 saved_fg_console = fg_console;
3438 saved_last_console = last_console;
3439 saved_want_console = want_console;
3440 saved_vc_mode = vc->vc_mode;
3441 vc->vc_mode = KD_TEXT;
3442 console_blanked = 0;
3443 if (vc->vc_sw->con_debug_enter)
3444 ret = vc->vc_sw->con_debug_enter(vc);
3445 return ret;
3446}
3447EXPORT_SYMBOL_GPL(con_debug_enter);
3448
3449/**
3450 * con_debug_leave - restore console state
3451 * @sw: console driver
3452 *
3453 * Restore the console state to what it was before the kernel debugger
3454 * was invoked.
3455 *
3456 * RETURNS:
3457 * Zero on success, nonzero if a failure occurred when trying to restore
3458 * the console.
3459 */
3460int con_debug_leave(void)
3461{
3462 struct vc_data *vc;
3463 int ret = 0;
3464
3465 fg_console = saved_fg_console;
3466 last_console = saved_last_console;
3467 want_console = saved_want_console;
3468 vc_cons[fg_console].d->vc_mode = saved_vc_mode;
3469
3470 vc = vc_cons[fg_console].d;
3471 if (vc->vc_sw->con_debug_leave)
3472 ret = vc->vc_sw->con_debug_leave(vc);
3473 return ret;
3474}
3475EXPORT_SYMBOL_GPL(con_debug_leave);
3476
3477/**
3417 * register_con_driver - register console driver to console layer 3478 * register_con_driver - register console driver to console layer
3418 * @csw: console driver 3479 * @csw: console driver
3419 * @first: the first console to take over, minimum value is 0 3480 * @first: the first console to take over, minimum value is 0