debug: coredump: allow for coredump backends to be defined outside of tree

Move coredump_backend_api struct to public header so that custom backends
for coredump can be defined out of tree. Create simple backend in test
directory for verification.

Signed-off-by: Mark Holden <mholden@fb.com>

include/debug/coredump.h

@@ -128,6 +128,31 @@ struct coredump_mem_hdr_t {
 	uintptr_t	end;
 } __packed;
 
+typedef void (*coredump_backend_start_t)(void);
+typedef void (*coredump_backend_end_t)(void);
+typedef void (*coredump_backend_buffer_output_t)(uint8_t *buf, size_t buflen);
+typedef int (*coredump_backend_query_t)(enum coredump_query_id query_id,
+					void *arg);
+typedef int (*coredump_backend_cmd_t)(enum coredump_cmd_id cmd_id,
+				      void *arg);
+
+struct coredump_backend_api {
+	/* Signal to backend of the start of coredump. */
+	coredump_backend_start_t		start;
+
+	/* Signal to backend of the end of coredump. */
+	coredump_backend_end_t		end;
+
+	/* Raw buffer output */
+	coredump_backend_buffer_output_t	buffer_output;
+
+	/* Perform query on backend */
+	coredump_backend_query_t		query;
+
+	/* Perform command on backend */
+	coredump_backend_cmd_t			cmd;
+};
+
 void coredump(unsigned int reason, const z_arch_esf_t *esf,
 	      struct k_thread *thread);
 void coredump_memory_dump(uintptr_t start_addr, uintptr_t end_addr);

subsys/debug/coredump/Kconfig

@@ -28,6 +28,11 @@ config DEBUG_COREDUMP_BACKEND_FLASH_PARTITION
 	  Core dump is saved to a flash partition with DTS alias
 	  "coredump-partition".
 
+config DEBUG_COREDUMP_BACKEND_OTHER
+	bool "Backend subsystem for coredump defined out of tree"
+	help
+	  Core dump is done via custom mechanism defined out of tree
+
 endchoice
 
 choice

subsys/debug/coredump/coredump_backend_flash_partition.c

@@ -498,7 +498,7 @@ static int coredump_flash_backend_cmd(enum coredump_cmd_id cmd_id,
 }
 
 
-struct z_coredump_backend_api z_coredump_backend_flash_partition = {
+struct coredump_backend_api coredump_backend_flash_partition = {
 	.start = coredump_flash_backend_start,
 	.end = coredump_flash_backend_end,
 	.buffer_output = coredump_flash_backend_buffer_output,

subsys/debug/coredump/coredump_backend_logging.c

@@ -117,7 +117,7 @@ static int coredump_logging_backend_cmd(enum coredump_cmd_id cmd_id,
 }
 
 
-struct z_coredump_backend_api z_coredump_backend_logging = {
+struct coredump_backend_api coredump_backend_logging = {
 	.start = coredump_logging_backend_start,
 	.end = coredump_logging_backend_end,
 	.buffer_output = coredump_logging_backend_buffer_output,

subsys/debug/coredump/coredump_core.c

@@ -14,13 +14,17 @@
 #include "coredump_internal.h"
 
 #if defined(CONFIG_DEBUG_COREDUMP_BACKEND_LOGGING)
-extern struct z_coredump_backend_api z_coredump_backend_logging;
+extern struct coredump_backend_api coredump_backend_logging;
-static struct z_coredump_backend_api
+static struct coredump_backend_api
-	*backend_api = &z_coredump_backend_logging;
+	*backend_api = &coredump_backend_logging;
 #elif defined(CONFIG_DEBUG_COREDUMP_BACKEND_FLASH_PARTITION)
-extern struct z_coredump_backend_api z_coredump_backend_flash_partition;
+extern struct coredump_backend_api coredump_backend_flash_partition;
-static struct z_coredump_backend_api
+static struct coredump_backend_api
-	*backend_api = &z_coredump_backend_flash_partition;
+	*backend_api = &coredump_backend_flash_partition;
+#elif defined(CONFIG_DEBUG_COREDUMP_BACKEND_OTHER)
+extern struct coredump_backend_api coredump_backend_other;
+static struct coredump_backend_api
+	*backend_api = &coredump_backend_other;
 #else
 #error "Need to select a coredump backend"
 #endif

subsys/debug/coredump/coredump_internal.h

@@ -53,31 +53,6 @@ void z_coredump_start(void);
  */
 void z_coredump_end(void);
 
-typedef void (*z_coredump_backend_start_t)(void);
-typedef void (*z_coredump_backend_end_t)(void);
-typedef void (*z_coredump_backend_buffer_output_t)(uint8_t *buf, size_t buflen);
-typedef int (*coredump_backend_query_t)(enum coredump_query_id query_id,
-					void *arg);
-typedef int (*coredump_backend_cmd_t)(enum coredump_cmd_id cmd_id,
-				      void *arg);
-
-struct z_coredump_backend_api {
-	/* Signal to backend of the start of coredump. */
-	z_coredump_backend_start_t		start;
-
-	/* Signal to backend of the end of coredump. */
-	z_coredump_backend_end_t		end;
-
-	/* Raw buffer output */
-	z_coredump_backend_buffer_output_t	buffer_output;
-
-	/* Perform query on backend */
-	coredump_backend_query_t		query;
-
-	/* Perform command on backend */
-	coredump_backend_cmd_t			cmd;
-};
-
 /**
  * @endcond
  */

tests/subsys/debug/coredump_backends/CMakeLists.txt

@@ -6,3 +6,8 @@ find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
 project(hello_world)
 
 target_sources(app PRIVATE src/main.c)
+
+zephyr_library_sources_ifdef(
+  CONFIG_DEBUG_COREDUMP_BACKEND_OTHER
+  src/coredump_backend_empty.c
+  )

tests/subsys/debug/coredump_backends/prj_backend_other.conf

@@ -0,0 +1,6 @@
+CONFIG_ZTEST=y
+CONFIG_DEBUG_COREDUMP=y
+CONFIG_DEBUG_COREDUMP_BACKEND_OTHER=y
+CONFIG_MP_NUM_CPUS=1
+CONFIG_DEBUG_COREDUMP_MEMORY_DUMP_MIN=y
+CONFIG_DEBUG_COREDUMP_MEMORY_DUMP_LINKER_RAM=n

tests/subsys/debug/coredump_backends/src/coredump_backend_empty.c

@@ -0,0 +1,83 @@
+/*
+ * Copyright Meta Platforms, Inc. and its affiliates.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <errno.h>
+#include <debug/coredump.h>
+
+static int error;
+static bool is_valid;
+
+static void coredump_empty_backend_start(void)
+{
+	/* Reset error, is_valid */
+	error = 0;
+	is_valid = false;
+}
+
+static void coredump_empty_backend_end(void)
+{
+	is_valid = true;
+}
+
+static void coredump_empty_backend_buffer_output(uint8_t *buf, size_t buflen)
+{
+	/* no-op */
+}
+
+static int coredump_empty_backend_query(enum coredump_query_id query_id,
+					  void *arg)
+{
+	int ret;
+
+	switch (query_id) {
+	case COREDUMP_QUERY_GET_ERROR:
+		ret = error;
+		break;
+	case COREDUMP_QUERY_HAS_STORED_DUMP:
+		ret = 0;
+		if (is_valid) {
+			ret = 1;
+		}
+		break;
+	default:
+		ret = -ENOTSUP;
+		break;
+	}
+
+	return ret;
+}
+
+static int coredump_empty_backend_cmd(enum coredump_cmd_id cmd_id,
+					void *arg)
+{
+	int ret;
+
+	switch (cmd_id) {
+	case COREDUMP_CMD_CLEAR_ERROR:
+		error = 0;
+		ret = 0;
+		break;
+	case COREDUMP_CMD_VERIFY_STORED_DUMP:
+		ret = 0;
+		if (is_valid) {
+			ret = 1;
+		}
+		break;
+	default:
+		ret = -ENOTSUP;
+		break;
+	}
+
+	return ret;
+}
+
+struct coredump_backend_api coredump_backend_other = {
+	.start = coredump_empty_backend_start,
+	.end = coredump_empty_backend_end,
+	.buffer_output = coredump_empty_backend_buffer_output,
+	.query = coredump_empty_backend_query,
+	.cmd = coredump_empty_backend_cmd,
+};

tests/subsys/debug/coredump_backends/testcase.yaml

@@ -15,3 +15,8 @@ tests:
     filter: CONFIG_ARCH_SUPPORTS_COREDUMP
     extra_args: CONF_FILE=prj_flash_partition.conf
     platform_allow: qemu_x86
+  coredump.backends.other:
+    tags: ignore_faults ignore_qemu_crash
+    filter: CONFIG_ARCH_SUPPORTS_COREDUMP
+    extra_args: CONF_FILE=prj_backend_other.conf
+    platform_exclude: acrn_ehl_crb