[PATCH 4.14 036/125] kgdb: Make "kgdbcon" work properly with "kgdb_earlycon"

Greg Kroah-Hartman
2020-11-03T21:09:59Z

From: Douglas Anderson <dianders@chromium.org>

[ Upstream commit b18b099e04f450cdc77bec72acefcde7042bd1f3 ]

On my system the kernel processes the "kgdb_earlycon" parameter before
the "kgdbcon" parameter. When we setup "kgdb_earlycon" we'll end up
in kgdb_register_callbacks() and "kgdb_use_con" won't have been set
yet so we'll never get around to starting "kgdbcon". Let's remedy
this by detecting that the IO module was already registered when
setting "kgdb_use_con" and registering the console then.

As part of this, to avoid pre-declaring things, move the handling of
the "kgdbcon" further down in the file.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20200630151422.1.I4aa062751ff5e281f5116655c976dff545c09a46@changeid
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/debug/debug_core.c | 22 ++++++++++++++--------
1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 694fcd0492827..4cf5697e72b18 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -95,14 +95,6 @@ int dbg_switch_cpu;
/* Use kdb or gdbserver mode */
int dbg_kdb_mode = 1;

-static int __init opt_kgdb_con(char *str)
-{
- kgdb_use_con = 1;
- return 0;
-}
-
-early_param("kgdbcon", opt_kgdb_con);
-
module_param(kgdb_use_con, int, 0644);
module_param(kgdbreboot, int, 0644);

@@ -816,6 +808,20 @@ static struct console kgdbcons = {
.index = -1,
};

+static int __init opt_kgdb_con(char *str)
+{
+ kgdb_use_con = 1;
+
+ if (kgdb_io_module_registered && !kgdb_con_registered) {
+ register_console(&kgdbcons);
+ kgdb_con_registered = 1;
+ }
+
+ return 0;
+}
+
+early_param("kgdbcon", opt_kgdb_con);
+
#ifdef CONFIG_MAGIC_SYSRQ
static void sysrq_handle_dbg(int key)
{
--
2.27.0