debug: add parameters to prevent entering debug mode on errors

On non-developer devices kgdb prevents CONFIG_PANIC_TIMEOUT from
rebooting the device after a panic. Add module parameters
debug_core.break_on_exception and debug_core.break_on_panic to
allow skipping debug on panics and exceptions respectively.  Both
default to true to preserve existing behavior.

Change-Id: I75dce7263e96cee069a9750920cce83dc6f98e8c
Signed-off-by: Colin Cross <ccross@android.com>

diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 0506d447aed270867214c9da188b4ac8a22ebecf..2d4438b14b4230e9bd19fea15f2bd13f39bda81f 100644 (file)
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -86,6 +86,10 @@ static int kgdb_use_con;
 bool dbg_is_early = true;
 /* Next cpu to become the master debug core */
 int dbg_switch_cpu;
+/* Flag for entering kdb when a panic occurs */
+static bool break_on_panic = true;
+/* Flag for entering kdb when an exception occurs */
+static bool break_on_exception = true;
 
 /* Use kdb or gdbserver mode */
 int dbg_kdb_mode = 1;
@@ -100,6 +104,8 @@ early_param("kgdbcon", opt_kgdb_con);
 
 module_param(kgdb_use_con, int, 0644);
 module_param(kgdbreboot, int, 0644);
+module_param(break_on_panic, bool, 0644);
+module_param(break_on_exception, bool, 0644);
 
 /*
  * Holds information about breakpoints in a kernel. These breakpoints are
@@ -678,6 +684,9 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
        if (arch_kgdb_ops.enable_nmi)
                arch_kgdb_ops.enable_nmi(0);
 
+       if (unlikely(signo != SIGTRAP && !break_on_exception))
+               return 1;
+
        ks->cpu                 = raw_smp_processor_id();
        ks->ex_vector           = evector;
        ks->signo               = signo;
@@ -784,6 +793,9 @@ static int kgdb_panic_event(struct notifier_block *self,
                            unsigned long val,
                            void *data)
 {
+       if (!break_on_panic)
+               return NOTIFY_DONE;
+
        if (dbg_kdb_mode)
                kdb_printf("PANIC: %s\n", (char *)data);
        kgdb_breakpoint();