system_safe_mode: Use common method for identifying critical tasks

Legacy EC uses tasks, Zephyr uses threads, so separate methods were used
to identify critical tasks/threads.

This change switches Zephyr EC to use task ids to identify critical
tasks. This allows some duplicate code to be removed and avoids the
CONFIG_THREAD_MONITOR dependency. This relies on the tasks shim for
mapping between task ids and thread ids.

BUG=b:266696987
BRANCH=None
TEST=Observe threads being disabled when safe mode runs

Change-Id: I87bcb7de87b0575cfc5d90bd12b21314ddeea093
Signed-off-by: Rob Barnes <robbarnes@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/4214562
Reviewed-by: Daisuke Nojiri <dnojiri@chromium.org>

5 files changed, 42 insertions, 52 deletions

diff --git a/common/system_safe_mode.c b/common/system_safe_mode.c
index e86aa5216f..bced1bd24e 100644
--- a/common/system_safe_mode.c
+++ b/common/system_safe_mode.c
@@ -26,17 +26,24 @@ static const int safe_mode_allowed_hostcmds[] = {
 	EC_CMD_GET_UPTIME_INFO
 };
 
-#ifndef CONFIG_ZEPHYR
-
-/* TODO: This function can be generalized for zephyr and legacy EC by
- * improving ec_tasks support in zephyr.
- */
-static bool task_is_safe_mode_critical(task_id_t task_id)
+bool is_task_safe_mode_critical(task_id_t task_id)
 {
 	const task_id_t safe_mode_critical_tasks[] = {
+#ifdef HAS_TASK_HOOK
 		TASK_ID_HOOKS,
+#endif
+#ifdef HAS_TASK_IDLE
 		TASK_ID_IDLE,
+#endif
+#ifdef HAS_TASK_HOSTCMD
 		TASK_ID_HOSTCMD,
+#endif
+#ifdef HAS_TASK_MAIN
+		TASK_ID_MAIN,
+#endif
+#ifdef HAS_TASK_SYSWORKQ
+		TASK_ID_SYSWORKQ,
+#endif
 	};
 	for (int i = 0; i < ARRAY_SIZE(safe_mode_critical_tasks); i++)
 		if (safe_mode_critical_tasks[i] == task_id)
@@ -44,15 +51,17 @@ static bool task_is_safe_mode_critical(task_id_t task_id)
 	return false;
 }
 
-bool current_task_is_safe_mode_critical(void)
+bool is_current_task_safe_mode_critical(void)
 {
-	return task_is_safe_mode_critical(task_get_current());
+	return is_task_safe_mode_critical(task_get_current());
 }
 
+#ifndef CONFIG_ZEPHYR
+
 int disable_non_safe_mode_critical_tasks(void)
 {
 	for (task_id_t task_id = 0; task_id < TASK_ID_COUNT; task_id++) {
-		if (!task_is_safe_mode_critical(task_id)) {
+		if (!is_task_safe_mode_critical(task_id)) {
 			task_disable_task(task_id);
 		}
 	}
@@ -108,7 +117,7 @@ int start_system_safe_mode(void)
 		return EC_ERROR_INVAL;
 	}
 
-	if (current_task_is_safe_mode_critical()) {
+	if (is_current_task_safe_mode_critical()) {
 		/* TODO: Restart critical tasks */
 		panic_printf(
 			"Fault in critical task, cannot enter system safe mode\n");
diff --git a/include/system_safe_mode.h b/include/system_safe_mode.h
index a8bf23d5b0..6c8909bf43 100644
--- a/include/system_safe_mode.h
+++ b/include/system_safe_mode.h
@@ -6,6 +6,8 @@
 #ifndef __CROS_EC_SYSTEM_SAFE_MODE_H
 #define __CROS_EC_SYSTEM_SAFE_MODE_H
 
+#include "task.h"
+
 /**
  * Checks if running in system safe mode
  *
@@ -21,11 +23,11 @@ bool system_is_in_safe_mode(void);
 bool command_is_allowed_in_safe_mode(int command);
 
 /**
- * Checks if current task critical for system safe mode
+ * Checks if a task is critical for system safe mode
  *
- * @return True if current task is safe mode critical
+ * @return True if task is safe mode critical
  */
-bool current_task_is_safe_mode_critical(void);
+bool is_task_safe_mode_critical(task_id_t task_id);
 
 /**
  * Disables tasks that are not critical for safe mode
diff --git a/zephyr/Kconfig.system b/zephyr/Kconfig.system
index 226832cb63..1db45ef2a8 100644
--- a/zephyr/Kconfig.system
+++ b/zephyr/Kconfig.system
@@ -85,7 +85,7 @@ config PLATFORM_EC_FW_RESET_VECTOR
 config PLATFORM_EC_SYSTEM_SAFE_MODE
 	bool "Enable System Safe Mode"
 	default n
-	depends on (CPU_CORTEX_M || ARCH_POSIX) && !TASK_HOSTCMD_THREAD_MAIN
+	depends on (CPU_CORTEX_M || ARCH_POSIX)
 	help
 	  This enables system safe mode for retrieving system state after
 	  a panic occurs. System safe mode only runs briefly after a panic.
diff --git a/zephyr/shim/src/system_safe_mode.c b/zephyr/shim/src/system_safe_mode.c
index ec52f210df..0acb5b270f 100644
--- a/zephyr/shim/src/system_safe_mode.c
+++ b/zephyr/shim/src/system_safe_mode.c
@@ -13,46 +13,24 @@
 #include <zephyr/kernel.h>
 #include <zephyr/kernel/thread.h>
 
-static bool thread_is_safe_mode_critical(const struct k_thread *thread)
-{
-	/* List of safe mode critical tasks */
-	static const char *safe_mode_critical_threads[] = {
-		"main",
-		"sysworkq",
-		"idle",
-		"HOSTCMD",
-	};
-	for (int i = 0; i < ARRAY_SIZE(safe_mode_critical_threads); i++)
-		if (strcmp(thread->name, safe_mode_critical_threads[i]) == 0)
-			return true;
-	return false;
-}
-
-__override bool current_task_is_safe_mode_critical(void)
-{
-	return thread_is_safe_mode_critical(k_current_get());
-}
-
-static void abort_non_critical_threads_cb(const struct k_thread *thread,
-					  void *user_data)
-{
-	ARG_UNUSED(user_data);
-
-	/*
-	 * Don't abort if thread is critical or current thread.
-	 * Current thread will be canceled automatically after returning from
-	 * exception handler.
-	 */
-	if (thread_is_safe_mode_critical(thread) || k_current_get() == thread)
-		return;
-
-	printk("Aborting thread %s\n", thread->name);
-	k_thread_abort((struct k_thread *)thread);
-}
-
 __override int disable_non_safe_mode_critical_tasks(void)
 {
-	k_thread_foreach(abort_non_critical_threads_cb, NULL);
+	for (task_id_t task_id = 0; task_id < TASK_ID_COUNT + EXTRA_TASK_COUNT;
+	     task_id++) {
+		k_tid_t thread_id = task_id_to_thread_id(task_id);
+
+		/* Don't abort the thread when:
+		 * 1) The task to thread lookup failed
+		 * 2) It's the current thread since it will be aborted
+		 *    automatically by the Zephyr kernel.
+		 * 3) The thread is safe mode critical
+		 */
+		if (thread_id == NULL || thread_id == k_current_get() ||
+		    is_task_safe_mode_critical(task_id)) {
+			continue;
+		}
+		k_thread_abort(thread_id);
+	}
 	return EC_SUCCESS;
 }
 
diff --git a/zephyr/test/system_safe_mode/prj.conf b/zephyr/test/system_safe_mode/prj.conf
index f7aeb4b776..6ecdbe1b16 100644
--- a/zephyr/test/system_safe_mode/prj.conf
+++ b/zephyr/test/system_safe_mode/prj.conf
@@ -12,6 +12,7 @@ CONFIG_PLATFORM_EC_SYSTEM_SAFE_MODE=y
 CONFIG_TASK_HOSTCMD_THREAD_DEDICATED=y
 CONFIG_PLATFORM_EC_HOSTCMD=y
 CONFIG_ASSERT_TEST=y
+CONFIG_SHIMMED_TASKS=y
 
 # Disable because not needed
 CONFIG_PLATFORM_EC_BACKLIGHT_LID=n