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

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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: Jason Wessel <jason.wessel@windriver.com>
This commit is contained in:
Jason Wessel 2009-06-03 14:06:57 -05:00
parent 5dd11d5d47
commit 1cee5e35f1
2 changed files with 27 additions and 0 deletions
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1
include/linux/kgdb.h
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@ -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,

26
kernel/debug/debug_core.c
View file

@ -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;