From b45cfba4e9005d64d419718e7ff7f7cab44c1994 Mon Sep 17 00:00:00 2001 From: Jesse Barnes Date: Thu, 5 Aug 2010 09:22:30 -0500 Subject: 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 Signed-off-by: Jason Wessel CC: David Airlie CC: Andrew Morton --- drivers/char/vt.c | 61 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 61 insertions(+) (limited to 'drivers/char') 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); * fg_console is the current virtual console, * last_console is the last used one, * want_console is the console we want to switch to, + * saved_* variants are for save/restore around kernel debugger enter/leave */ int fg_console; int last_console; int want_console = -1; +int saved_fg_console; +int saved_last_console; +int saved_want_console; +int saved_vc_mode; /* * For each existing display, we have a pointer to console currently visible @@ -3413,6 +3418,62 @@ int con_is_bound(const struct consw *csw) } EXPORT_SYMBOL(con_is_bound); +/** + * con_debug_enter - prepare the console for the kernel debugger + * @sw: console driver + * + * Called when the console is taken over by the kernel debugger, this + * function needs to save the current console state, then put the console + * into a state suitable for the kernel debugger. + * + * RETURNS: + * Zero on success, nonzero if a failure occurred when trying to prepare + * the console for the debugger. + */ +int con_debug_enter(struct vc_data *vc) +{ + int ret = 0; + + saved_fg_console = fg_console; + saved_last_console = last_console; + saved_want_console = want_console; + saved_vc_mode = vc->vc_mode; + vc->vc_mode = KD_TEXT; + console_blanked = 0; + if (vc->vc_sw->con_debug_enter) + ret = vc->vc_sw->con_debug_enter(vc); + return ret; +} +EXPORT_SYMBOL_GPL(con_debug_enter); + +/** + * con_debug_leave - restore console state + * @sw: console driver + * + * Restore the console state to what it was before the kernel debugger + * was invoked. + * + * RETURNS: + * Zero on success, nonzero if a failure occurred when trying to restore + * the console. + */ +int con_debug_leave(void) +{ + struct vc_data *vc; + int ret = 0; + + fg_console = saved_fg_console; + last_console = saved_last_console; + want_console = saved_want_console; + vc_cons[fg_console].d->vc_mode = saved_vc_mode; + + vc = vc_cons[fg_console].d; + if (vc->vc_sw->con_debug_leave) + ret = vc->vc_sw->con_debug_leave(vc); + return ret; +} +EXPORT_SYMBOL_GPL(con_debug_leave); + /** * register_con_driver - register console driver to console layer * @csw: console driver -- cgit v1.2.2