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Commit 1cee5e35 authored by Jason Wessel's avatar Jason Wessel
Browse files

kgdb: Add the ability to schedule a breakpoint via a tasklet 



Some kgdb I/O modules require the ability to create a breakpoint
tasklet, such as kgdboc and external modules such as kgdboe.  The
breakpoint tasklet is used as an asynchronous entry point into the
debugger which will have a different function scope than the current
execution path where it might not be safe to have an inline
breakpoint.  This is true of some of the kgdb I/O drivers which share
code with kgdb and rest of the kernel users.

Signed-off-by: default avatarJason Wessel <jason.wessel@windriver.com>
parent 5dd11d5d

include/linux/kgdb.h

+1 −0
Original line number Diff line number Diff line
@@ -271,6 +271,7 @@ extern int kgdb_mem2hex(char *mem, char *buf, int count); 
extern int kgdb_hex2mem(char *buf, char *mem, int count);



extern int kgdb_isremovedbreak(unsigned long addr);

extern void kgdb_schedule_breakpoint(void);



extern int

kgdb_handle_exception(int ex_vector, int signo, int err_code,

kernel/debug/debug_core.c

+26 −0
Original line number Diff line number Diff line
@@ -114,6 +114,7 @@ EXPORT_SYMBOL_GPL(kgdb_active); 
 */

static atomic_t			passive_cpu_wait[NR_CPUS];

static atomic_t			cpu_in_kgdb[NR_CPUS];

static atomic_t			kgdb_break_tasklet_var;

atomic_t			kgdb_setting_breakpoint;



struct task_struct		*kgdb_usethread;
@@ -789,6 +790,31 @@ static void kgdb_unregister_callbacks(void) 
	}

}



/*

 * There are times a tasklet needs to be used vs a compiled in

 * break point so as to cause an exception outside a kgdb I/O module,

 * such as is the case with kgdboe, where calling a breakpoint in the

 * I/O driver itself would be fatal.

 */

static void kgdb_tasklet_bpt(unsigned long ing)

{

	kgdb_breakpoint();

	atomic_set(&kgdb_break_tasklet_var, 0);

}



static DECLARE_TASKLET(kgdb_tasklet_breakpoint, kgdb_tasklet_bpt, 0);



void kgdb_schedule_breakpoint(void)

{

	if (atomic_read(&kgdb_break_tasklet_var) ||

		atomic_read(&kgdb_active) != -1 ||

		atomic_read(&kgdb_setting_breakpoint))

		return;

	atomic_inc(&kgdb_break_tasklet_var);

	tasklet_schedule(&kgdb_tasklet_breakpoint);

}

EXPORT_SYMBOL_GPL(kgdb_schedule_breakpoint);



static void kgdb_initial_breakpoint(void)

{

	kgdb_break_asap = 0;