Commit 162bc7f5 authored by Douglas Anderson's avatar Douglas Anderson Committed by Daniel Thompson
Browse files

kdb: Don't back trace on a cpu that didn't round up 



If you have a CPU that fails to round up and then run 'btc' you'll end
up crashing in kdb becaue we dereferenced NULL.  Let's add a check.
It's wise to also set the task to NULL when leaving the debugger so
that if we fail to round up on a later entry into the debugger we
won't backtrace a stale task.

Signed-off-by: default avatarDouglas Anderson <dianders@chromium.org>
Acked-by: default avatarDaniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: default avatarDaniel Thompson <daniel.thompson@linaro.org>
parent 87b09592

kernel/debug/debug_core.c

+4 −0
Original line number Diff line number Diff line
@@ -592,6 +592,8 @@ return_normal: 
				arch_kgdb_ops.correct_hw_break();

			if (trace_on)

				tracing_on();

			kgdb_info[cpu].debuggerinfo = NULL;

			kgdb_info[cpu].task = NULL;

			kgdb_info[cpu].exception_state &=

				~(DCPU_WANT_MASTER | DCPU_IS_SLAVE);

			kgdb_info[cpu].enter_kgdb--;
@@ -724,6 +726,8 @@ kgdb_restore: 
	if (trace_on)

		tracing_on();



	kgdb_info[cpu].debuggerinfo = NULL;

	kgdb_info[cpu].task = NULL;

	kgdb_info[cpu].exception_state &=

		~(DCPU_WANT_MASTER | DCPU_IS_SLAVE);

	kgdb_info[cpu].enter_kgdb--;

kernel/debug/kdb/kdb_bt.c

+10 −1
Original line number Diff line number Diff line
@@ -186,7 +186,16 @@ kdb_bt(int argc, const char **argv) 
		kdb_printf("btc: cpu status: ");

		kdb_parse("cpu\n");

		for_each_online_cpu(cpu) {

			sprintf(buf, "btt 0x%px\n", KDB_TSK(cpu));

			void *kdb_tsk = KDB_TSK(cpu);



			/* If a CPU failed to round up we could be here */

			if (!kdb_tsk) {

				kdb_printf("WARNING: no task for cpu %ld\n",

					   cpu);

				continue;

			}



			sprintf(buf, "btt 0x%px\n", kdb_tsk);

			kdb_parse(buf);

			touch_nmi_watchdog();

		}

kernel/debug/kdb/kdb_debugger.c

+0 −7
Original line number Diff line number Diff line
@@ -118,13 +118,6 @@ int kdb_stub(struct kgdb_state *ks) 
	kdb_bp_remove();

	KDB_STATE_CLEAR(DOING_SS);

	KDB_STATE_SET(PAGER);

	/* zero out any offline cpu data */

	for_each_present_cpu(i) {

		if (!cpu_online(i)) {

			kgdb_info[i].debuggerinfo = NULL;

			kgdb_info[i].task = NULL;

		}

	}

	if (ks->err_code == DIE_OOPS || reason == KDB_REASON_OOPS) {

		ks->pass_exception = 1;

		KDB_FLAG_SET(CATASTROPHIC);

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