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-rw-r--r--kernel/debug/debug_core.c34
-rw-r--r--kernel/debug/debug_core.h2
-rw-r--r--kernel/debug/kdb/kdb_bt.c19
3 files changed, 43 insertions, 12 deletions
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index f76d6f77dd5e..70e86b4b4932 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -441,6 +441,37 @@ setundefined:
return 0;
}
+#ifdef CONFIG_KGDB_KDB
+void kdb_dump_stack_on_cpu(int cpu)
+{
+ if (cpu == raw_smp_processor_id()) {
+ dump_stack();
+ return;
+ }
+
+ if (!(kgdb_info[cpu].exception_state & DCPU_IS_SLAVE)) {
+ kdb_printf("ERROR: Task on cpu %d didn't stop in the debugger\n",
+ cpu);
+ return;
+ }
+
+ /*
+ * In general, architectures don't support dumping the stack of a
+ * "running" process that's not the current one. From the point of
+ * view of the Linux, kernel processes that are looping in the kgdb
+ * slave loop are still "running". There's also no API (that actually
+ * works across all architectures) that can do a stack crawl based
+ * on registers passed as a parameter.
+ *
+ * Solve this conundrum by asking slave CPUs to do the backtrace
+ * themselves.
+ */
+ kgdb_info[cpu].exception_state |= DCPU_WANT_BT;
+ while (kgdb_info[cpu].exception_state & DCPU_WANT_BT)
+ cpu_relax();
+}
+#endif
+
/*
* Return true if there is a valid kgdb I/O module. Also if no
* debugger is attached a message can be printed to the console about
@@ -580,6 +611,9 @@ cpu_loop:
atomic_xchg(&kgdb_active, cpu);
break;
}
+ } else if (kgdb_info[cpu].exception_state & DCPU_WANT_BT) {
+ dump_stack();
+ kgdb_info[cpu].exception_state &= ~DCPU_WANT_BT;
} else if (kgdb_info[cpu].exception_state & DCPU_IS_SLAVE) {
if (!raw_spin_is_locked(&dbg_slave_lock))
goto return_normal;
diff --git a/kernel/debug/debug_core.h b/kernel/debug/debug_core.h
index 804b0fe5a0ba..cd22b5f68831 100644
--- a/kernel/debug/debug_core.h
+++ b/kernel/debug/debug_core.h
@@ -33,6 +33,7 @@ struct kgdb_state {
#define DCPU_WANT_MASTER 0x1 /* Waiting to become a master kgdb cpu */
#define DCPU_NEXT_MASTER 0x2 /* Transition from one master cpu to another */
#define DCPU_IS_SLAVE 0x4 /* Slave cpu enter exception */
+#define DCPU_WANT_BT 0x8 /* Slave cpu should backtrace then clear flag */
struct debuggerinfo_struct {
void *debuggerinfo;
@@ -75,6 +76,7 @@ extern int kdb_stub(struct kgdb_state *ks);
extern int kdb_parse(const char *cmdstr);
extern int kdb_common_init_state(struct kgdb_state *ks);
extern int kdb_common_deinit_state(void);
+extern void kdb_dump_stack_on_cpu(int cpu);
#else /* ! CONFIG_KGDB_KDB */
static inline int kdb_stub(struct kgdb_state *ks)
{
diff --git a/kernel/debug/kdb/kdb_bt.c b/kernel/debug/kdb/kdb_bt.c
index d9af139f9a31..0e94efe07b72 100644
--- a/kernel/debug/kdb/kdb_bt.c
+++ b/kernel/debug/kdb/kdb_bt.c
@@ -22,20 +22,15 @@
static void kdb_show_stack(struct task_struct *p, void *addr)
{
int old_lvl = console_loglevel;
+
console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH;
kdb_trap_printk++;
- kdb_set_current_task(p);
- if (addr) {
- show_stack((struct task_struct *)p, addr);
- } else if (kdb_current_regs) {
-#ifdef CONFIG_X86
- show_stack(p, &kdb_current_regs->sp);
-#else
- show_stack(p, NULL);
-#endif
- } else {
- show_stack(p, NULL);
- }
+
+ if (!addr && kdb_task_has_cpu(p))
+ kdb_dump_stack_on_cpu(kdb_process_cpu(p));
+ else
+ show_stack(p, addr);
+
console_loglevel = old_lvl;
kdb_trap_printk--;
}