Add GDB support

include/sound/sof/ipc4/header.h

@@ -123,8 +123,9 @@ enum sof_ipc4_global_msg {
 	/* Notification (FW to SW driver) */
 	SOF_IPC4_GLB_NOTIFICATION,
 
-	/* 28 .. 31: RESERVED - do not use */
+	/* 28 .. 30: RESERVED - do not use */
 
+	SOF_IPC4_GLB_ENTER_GDB = 31,
 	SOF_IPC4_GLB_TYPE_LAST,
 };
 
@@ -540,16 +541,45 @@ struct sof_ipc4_notify_resource_data {
 	uint32_t data[6];
 } __packed __aligned(4);
 
-#define SOF_IPC4_DEBUG_DESCRIPTOR_SIZE		12 /* 3 x u32 */
-
 /*
- * The debug memory window is divided into 16 slots, and the
- * first slot is used as a recorder for the other 15 slots.
+ * The debug memory window contains up to 16 4kB large pages, where pages one to
+ * fifteen are used for user slots and page zero contains slot descriptors:
+ *
+ *	------------------------
+ *	| Page0  - descriptors |
+ *	------------------------
+ *	| Page1  - slot0       |
+ *	------------------------
+ *	| Page2  - slot1       |
+ *	------------------------
+ *	|         ...          |
+ *	------------------------
+ *	| Page14  - slot13     |
+ *	------------------------
+ *	| Page15  - slot14     |
+ *	------------------------
+ *
+ * The slot descriptor is:
+ * u32 res_id;
+ * u32 type;
+ * u32 vma;
  */
+
+#define SOF_IPC4_DEBUG_PAGE_SIZE		0x1000
+#define SOF_IPC4_DEBUG_SLOT_SIZE		SOF_IPC4_DEBUG_PAGE_SIZE
+#define SOF_IPC4_DEBUG_PAGE0_SLOT_OFFSET	1024
+
+/* Usable slots 0..14 (page 1..15) */
 #define SOF_IPC4_MAX_DEBUG_SLOTS		15
-#define SOF_IPC4_DEBUG_SLOT_SIZE		0x1000
 
-/* debug log slot types */
+/*
+ * Descriptor 0-14: slot 0-14 (page 1-15)
+ * Descriptor 15: partial slot at page 0 + 1024
+ */
+#define SOF_IPC4_MAX_DEBUG_DESCS		(SOF_IPC4_MAX_DEBUG_SLOTS + 1)
+#define SOF_IPC4_DEBUG_DESCRIPTOR_SIZE		12 /* 3 x u32 */
+
+/* Debug log slot types */
 #define SOF_IPC4_DEBUG_SLOT_UNUSED		0x00000000
 #define SOF_IPC4_DEBUG_SLOT_CRITICAL_LOG	0x54524300 /* byte 0: core ID */
 #define SOF_IPC4_DEBUG_SLOT_DEBUG_LOG		0x474f4c00 /* byte 0: core ID */

sound/soc/sof/Kconfig

@@ -258,6 +258,18 @@ config SND_SOC_SOF_DEBUG_IPC_KERNEL_INJECTOR
 	  Say Y if you want to enable the IPC kernel injector.
 	  If unsure, select "N".
 
+config SND_SOC_SOF_DEBUG_FW_GDB
+	tristate "SOF enable Firmware GDB debugging"
+	select SND_SOC_SOF_CLIENT
+	help
+	  This enables GDB debugging of the SOF firmware. If selected, this
+	  will make the kernel create a debugfs file, that can be used to
+	  communicate with the firmware GDB stub. When the file is opened, the
+	  kernel sends a command to the firmware to switch to the GDB mode and
+	  to wait for GDB commands. socat can be used to connect that file to a
+	  socket, to which GDB can then connect.
+	  If unsure, select "N".
+
 config SND_SOC_SOF_DEBUG_RETAIN_DSP_CONTEXT
 	bool "SOF retain DSP context on any FW exceptions"
 	help

sound/soc/sof/Makefile

@@ -35,6 +35,7 @@ endif
 ifneq ($(CONFIG_SND_SOC_SOF_IPC4),)
 snd-sof-probes-y += sof-client-probes-ipc4.o
 endif
+snd-sof-fw-gdb-objs := sof-client-fw-gdb.o
 
 snd-sof-nocodec-y := nocodec.o
 
@@ -53,6 +54,7 @@ obj-$(CONFIG_SND_SOC_SOF_DEBUG_IPC_FLOOD_TEST) += snd-sof-ipc-flood-test.o
 obj-$(CONFIG_SND_SOC_SOF_DEBUG_IPC_MSG_INJECTOR) += snd-sof-ipc-msg-injector.o
 obj-$(CONFIG_SND_SOC_SOF_DEBUG_IPC_KERNEL_INJECTOR) += snd-sof-ipc-kernel-injector.o
 obj-$(CONFIG_SND_SOC_SOF_DEBUG_PROBES) += snd-sof-probes.o
+obj-$(CONFIG_SND_SOC_SOF_DEBUG_FW_GDB) += snd-sof-fw-gdb.o
 
 obj-$(CONFIG_SND_SOC_SOF_INTEL_TOPLEVEL) += intel/
 obj-$(CONFIG_SND_SOC_SOF_IMX_TOPLEVEL) += imx/

sound/soc/sof/ipc4-mtrace.c

@@ -10,31 +10,7 @@
 #include "ipc4-priv.h"
 
 /*
- * debug info window is organized in 16 (equal sized) pages:
- *
- *	------------------------
- *	| Page0  - descriptors |
- *	------------------------
- *	| Page1  - slot0       |
- *	------------------------
- *	| Page2  - slot1       |
- *	------------------------
- *	|         ...          |
- *	------------------------
- *	| Page14  - slot13     |
- *	------------------------
- *	| Page15  - slot14     |
- *	------------------------
- *
- * The slot size == page size
- *
- * The first page contains descriptors for the remaining 15 cores
- * The slot descriptor is:
- * u32 res_id;
- * u32 type;
- * u32 vma;
- *
- * Log buffer slots have the following layout:
+ * Log buffer debug window slots have the following layout:
  * u32 host_read_ptr;
  * u32 dsp_write_ptr;
  * u8 buffer[];

sound/soc/sof/ipc4.c

@@ -164,6 +164,7 @@ static const char * const ipc4_dbg_glb_msg_type[] = {
 	DBG_IPC4_MSG_TYPE_ENTRY(GLB_LOAD_LIBRARY_PREPARE),
 	DBG_IPC4_MSG_TYPE_ENTRY(GLB_INTERNAL_MESSAGE),
 	DBG_IPC4_MSG_TYPE_ENTRY(GLB_NOTIFICATION),
+	DBG_IPC4_MSG_TYPE_ENTRY(GLB_ENTER_GDB),
 };
 
 #define DBG_IPC4_NOTIFICATION_TYPE_ENTRY(type)	[SOF_IPC4_NOTIFY_##type] = #type
@@ -585,11 +586,16 @@ size_t sof_ipc4_find_debug_slot_offset_by_type(struct snd_sof_dev *sdev,
 
 	/* The type is the second u32 in the slot descriptor */
 	slot_desc_type_offset = sdev->debug_box.offset + sizeof(u32);
-	for (i = 0; i < SOF_IPC4_MAX_DEBUG_SLOTS; i++) {
+	for (i = 0; i < SOF_IPC4_MAX_DEBUG_DESCS; i++) {
 		sof_mailbox_read(sdev, slot_desc_type_offset, &type, sizeof(type));
 
-		if (type == slot_type)
+		if (type == slot_type) {
+			if (i == SOF_IPC4_MAX_DEBUG_DESCS - 1)
+				/* Desc 15: see comment on SOF_IPC4_MAX_DEBUG_DESCS in header.h */
+				return sdev->debug_box.offset + SOF_IPC4_DEBUG_PAGE0_SLOT_OFFSET;
+
 			return sdev->debug_box.offset + (i + 1) * SOF_IPC4_DEBUG_SLOT_SIZE;
+		}
 
 		slot_desc_type_offset += SOF_IPC4_DEBUG_DESCRIPTOR_SIZE;
 	}