ANDROID: ARM: fiq_debugger: add support for kgdb
Adds polling tty ops to the fiq debugger console tty, which allows
kgdb to run against an fiq debugger console.
Add a check in do_sysrq to prevent enabling kgdb from the fiq
debugger unless a flag (writable only by root) has been set. This
should make it safe to enable KGDB on a production device.
Also add a shortcut to enable the console and kgdb together, to
allow kgdb to be enabled when the shell on the console is not
responding.
Change-Id: Ifc65239ca96c9887431a6a36b9b44a539002f544
Signed-off-by: Colin Cross <ccross@android.com>
diff --git a/arch/arm/common/fiq_debugger.c b/arch/arm/common/fiq_debugger.c
index 909ef56..1f64d7d 100644
--- a/arch/arm/common/fiq_debugger.c
+++ b/arch/arm/common/fiq_debugger.c
@@ -106,9 +106,12 @@
static bool initial_console_enable;
#endif
+static bool fiq_kgdb_enable;
+
module_param_named(no_sleep, initial_no_sleep, bool, 0644);
module_param_named(debug_enable, initial_debug_enable, bool, 0644);
module_param_named(console_enable, initial_console_enable, bool, 0644);
+module_param_named(kgdb_enable, fiq_kgdb_enable, bool, 0644);
#ifdef CONFIG_FIQ_DEBUGGER_WAKEUP_IRQ_ALWAYS_ON
static inline void enable_wakeup_irq(struct fiq_debugger_state *state) {}
@@ -526,11 +529,29 @@
static void do_sysrq(struct fiq_debugger_state *state, char rq)
{
+ if ((rq == 'g' || rq == 'G') && !fiq_kgdb_enable) {
+ debug_printf(state, "sysrq-g blocked\n");
+ return;
+ }
begin_syslog_dump(state);
handle_sysrq(rq);
end_syslog_dump(state);
}
+#ifdef CONFIG_KGDB
+static void do_kgdb(struct fiq_debugger_state *state)
+{
+ if (!fiq_kgdb_enable) {
+ debug_printf(state, "kgdb through fiq debugger not enabled\n");
+ return;
+ }
+
+ debug_printf(state, "enabling console and triggering kgdb\n");
+ state->console_enable = true;
+ handle_sysrq('g');
+}
+#endif
+
/* This function CANNOT be called in FIQ context */
static void debug_irq_exec(struct fiq_debugger_state *state, char *cmd)
{
@@ -540,6 +561,10 @@
do_sysrq(state, 'h');
if (!strncmp(cmd, "sysrq ", 6))
do_sysrq(state, cmd[6]);
+#ifdef CONFIG_KGDB
+ if (!strcmp(cmd, "kgdb"))
+ do_kgdb(state);
+#endif
}
static void debug_help(struct fiq_debugger_state *state)
@@ -561,6 +586,9 @@
debug_printf(state, " ps Process list\n"
" sysrq sysrq options\n"
" sysrq <param> Execute sysrq with <param>\n");
+#ifdef CONFIG_KGDB
+ debug_printf(state, " kgdb Enter kernel debugger\n");
+#endif
}
static void take_affinity(void *info)
@@ -724,7 +752,8 @@
#endif
if (state->debug_busy) {
debug_irq_exec(state, state->debug_cmd);
- debug_prompt(state);
+ if (!state->console_enable)
+ debug_prompt(state);
state->debug_busy = 0;
}
}
@@ -957,11 +986,53 @@
return 1024;
}
+#ifdef CONFIG_CONSOLE_POLL
+static int fiq_tty_poll_init(struct tty_driver *driver, int line, char *options)
+{
+ return 0;
+}
+
+static int fiq_tty_poll_get_char(struct tty_driver *driver, int line)
+{
+ struct fiq_debugger_state *state = driver->ttys[line]->driver_data;
+ int c = NO_POLL_CHAR;
+
+ debug_uart_enable(state);
+ if (debug_have_fiq(state)) {
+ int count = fiq_debugger_ringbuf_level(state->tty_rbuf);
+ if (count > 0) {
+ c = fiq_debugger_ringbuf_peek(state->tty_rbuf, 0);
+ fiq_debugger_ringbuf_consume(state->tty_rbuf, 1);
+ }
+ } else {
+ c = debug_getc(state);
+ if (c == FIQ_DEBUGGER_NO_CHAR)
+ c = NO_POLL_CHAR;
+ }
+ debug_uart_disable(state);
+
+ return c;
+}
+
+static void fiq_tty_poll_put_char(struct tty_driver *driver, int line, char ch)
+{
+ struct fiq_debugger_state *state = driver->ttys[line]->driver_data;
+ debug_uart_enable(state);
+ debug_putc(state, ch);
+ debug_uart_disable(state);
+}
+#endif
+
static const struct tty_operations fiq_tty_driver_ops = {
.write = fiq_tty_write,
.write_room = fiq_tty_write_room,
.open = fiq_tty_open,
.close = fiq_tty_close,
+#ifdef CONFIG_CONSOLE_POLL
+ .poll_init = fiq_tty_poll_init,
+ .poll_get_char = fiq_tty_poll_get_char,
+ .poll_put_char = fiq_tty_poll_put_char,
+#endif
};
static int fiq_debugger_tty_init(struct fiq_debugger_state *state)