From f308299ca284ebcc2f81633ba339a4356ca5a2be Mon Sep 17 00:00:00 2001
From: Dmitrii Golovanov <dmitrii.golovanov@intel.com>
Date: Tue, 3 Oct 2023 17:55:46 +0200
Subject: [PATCH] debug: gdbstub: kconfig: Add GDBSTUB_TRACE config option

Add GDBSTUB_TRACE config option to extend GDB backend debug logging
for remote commands received and to debug the GDB stub itself.

Signed-off-by: Dmitrii Golovanov <dmitrii.golovanov@intel.com>
---
 arch/x86/core/ia32/gdbstub.c                  | 24 +++++++++++++++++++
 subsys/debug/Kconfig                          |  6 +++++
 subsys/debug/gdbstub.c                        | 16 ++++++++++++-
 subsys/debug/gdbstub/gdbstub_backend_serial.c |  7 ++++++
 4 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/arch/x86/core/ia32/gdbstub.c b/arch/x86/core/ia32/gdbstub.c
index afda9b5a7e2..41b6a4500ff 100644
--- a/arch/x86/core/ia32/gdbstub.c
+++ b/arch/x86/core/ia32/gdbstub.c
@@ -218,17 +218,41 @@ size_t arch_gdb_reg_writeone(struct gdb_ctx *ctx, uint8_t *hex, size_t hexlen,
 
 static __used void z_gdb_debug_isr(z_arch_esf_t *esf)
 {
+#ifdef CONFIG_GDBSTUB_TRACE
+	printk("gdbstub:enter %s (IV_DEBUG)\n", __func__);
+#endif
+
 	z_gdb_interrupt(IV_DEBUG, esf);
+
+#ifdef CONFIG_GDBSTUB_TRACE
+	printk("gdbstub:exit %s (IV_DEBUG)\n", __func__);
+#endif
 }
 
 static __used void z_gdb_break_isr(z_arch_esf_t *esf)
 {
+#ifdef CONFIG_GDBSTUB_TRACE
+	printk("gdbstub:enter %s (IV_BREAKPOINT)\n", __func__);
+#endif
+
 	z_gdb_interrupt(IV_BREAKPOINT, esf);
+
+#ifdef CONFIG_GDBSTUB_TRACE
+	printk("gdbstub:exit %s (IV_BREAKPOINT)\n", __func__);
+#endif
 }
 
 void arch_gdb_init(void)
 {
+#ifdef CONFIG_GDBSTUB_TRACE
+	printk("gdbstub:%s awaits GDB connection\n", __func__);
+#endif
+
 	__asm__ volatile ("int3");
+
+#ifdef CONFIG_GDBSTUB_TRACE
+	printk("gdbstub:%s GDB is connected\n", __func__);
+#endif
 }
 
 /* Hook current IDT. */
diff --git a/subsys/debug/Kconfig b/subsys/debug/Kconfig
index 54d83f18ff6..7da4440c010 100644
--- a/subsys/debug/Kconfig
+++ b/subsys/debug/Kconfig
@@ -424,6 +424,12 @@ config GDBSTUB_BUF_SZ
 	  for GDB backend. This needs to be big enough to hold one
 	  full GDB packet at a time.
 
+config GDBSTUB_TRACE
+	bool "GDB backend extra logging"
+	help
+	  Enable extra debug logging for the GDB backend, including
+	  breakpoint interrupts and remote commands it receives.
+
 endif
 
 config SEGGER_DEBUGMON
diff --git a/subsys/debug/gdbstub.c b/subsys/debug/gdbstub.c
index 3cced7b0310..e632ff8abf4 100644
--- a/subsys/debug/gdbstub.c
+++ b/subsys/debug/gdbstub.c
@@ -559,6 +559,10 @@ static int gdb_send_exception(uint8_t *buf, size_t len, uint8_t exception)
 {
 	size_t size;
 
+#ifdef CONFIG_GDBSTUB_TRACE
+	printk("gdbstub:%s exception=0x%x\n", __func__, exception);
+#endif
+
 	*buf = 'T';
 	size = gdb_bin2hex(&exception, 1, buf + 1, len - 1);
 	if (size == 0) {
@@ -644,6 +648,10 @@ int z_gdb_main_loop(struct gdb_ctx *ctx)
 
 		ptr = buf;
 
+#ifdef CONFIG_GDBSTUB_TRACE
+		printk("gdbstub:%s got '%c'(0x%x) command\n", __func__, *ptr, *ptr);
+#endif
+
 		switch (*ptr++) {
 
 		/**
@@ -823,13 +831,19 @@ int z_gdb_main_loop(struct gdb_ctx *ctx)
 
 int gdb_init(void)
 {
-
+#ifdef CONFIG_GDBSTUB_TRACE
+	printk("gdbstub:%s enter\n", __func__);
+#endif
 	if (z_gdb_backend_init() == -1) {
 		LOG_ERR("Could not initialize gdbstub backend.");
 		return -1;
 	}
 
 	arch_gdb_init();
+
+#ifdef CONFIG_GDBSTUB_TRACE
+	printk("gdbstub:%s exit\n", __func__);
+#endif
 	return 0;
 }
 
diff --git a/subsys/debug/gdbstub/gdbstub_backend_serial.c b/subsys/debug/gdbstub/gdbstub_backend_serial.c
index e9c6c6f9152..c5806cd4e02 100644
--- a/subsys/debug/gdbstub/gdbstub_backend_serial.c
+++ b/subsys/debug/gdbstub/gdbstub_backend_serial.c
@@ -21,6 +21,10 @@ int z_gdb_backend_init(void)
 		.flow_ctrl = UART_CFG_FLOW_CTRL_NONE
 	};
 
+#ifdef CONFIG_GDBSTUB_TRACE
+	printk("gdbstub_serial:%s enter\n", __func__);
+#endif
+
 	if (uart_dev == NULL) {
 		uart_dev = DEVICE_DT_GET(DT_CHOSEN(zephyr_gdbstub_uart));
 
@@ -30,6 +34,9 @@ int z_gdb_backend_init(void)
 		__ASSERT(ret == 0, "Could not configure uart device");
 	}
 
+#ifdef CONFIG_GDBSTUB_TRACE
+	printk("gdbstub_serial:%s exit\n", __func__);
+#endif
 	return ret;
 }