write in 30M

hc

2024-02-20 ea08eeccae9297f7aabd2ef7f0c2517ac4549acc

 kernel/kernel/context_tracking.c
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@@ -1,3 +1,4 @@
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+// SPDX-License-Identifier: GPL-2.0-only
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 /*
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  * Context tracking: Probe on high level context boundaries such as kernel
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  * and userspace. This includes syscalls and exceptions entry/exit.
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@@ -24,13 +25,13 @@
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 #define CREATE_TRACE_POINTS
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 #include <trace/events/context_tracking.h>
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-DEFINE_STATIC_KEY_FALSE(context_tracking_enabled);
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-EXPORT_SYMBOL_GPL(context_tracking_enabled);
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+DEFINE_STATIC_KEY_FALSE(context_tracking_key);
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+EXPORT_SYMBOL_GPL(context_tracking_key);
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 DEFINE_PER_CPU(struct context_tracking, context_tracking);
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 EXPORT_SYMBOL_GPL(context_tracking);
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-static bool context_tracking_recursion_enter(void)
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+static noinstr bool context_tracking_recursion_enter(void)
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 {
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 	int recursion;
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@@ -44,7 +45,7 @@
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 	return false;
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 }
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-static void context_tracking_recursion_exit(void)
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+static __always_inline void context_tracking_recursion_exit(void)
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 {
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 	__this_cpu_dec(context_tracking.recursion);
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 }
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@@ -58,7 +59,7 @@
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  * instructions to execute won't use any RCU read side critical section
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  * because this function sets RCU in extended quiescent state.
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  */
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-void __context_tracking_enter(enum ctx_state state)
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+void noinstr __context_tracking_enter(enum ctx_state state)
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 {
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 	/* Kernel threads aren't supposed to go to userspace */
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 	WARN_ON_ONCE(!current->mm);
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@@ -76,8 +77,10 @@
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 			 * on the tick.
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 			 */
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 			if (state == CONTEXT_USER) {
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+				instrumentation_begin();
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 				trace_user_enter(0);
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 				vtime_user_enter(current);
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+				instrumentation_end();
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 			}
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 			rcu_user_enter();
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 		}
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@@ -98,7 +101,6 @@
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 	}
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 	context_tracking_recursion_exit();
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 }
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-NOKPROBE_SYMBOL(__context_tracking_enter);
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 EXPORT_SYMBOL_GPL(__context_tracking_enter);
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 void context_tracking_enter(enum ctx_state state)
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@@ -141,7 +143,7 @@
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  * This call supports re-entrancy. This way it can be called from any exception
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  * handler without needing to know if we came from userspace or not.
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  */
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-void __context_tracking_exit(enum ctx_state state)
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+void noinstr __context_tracking_exit(enum ctx_state state)
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 {
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 	if (!context_tracking_recursion_enter())
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 		return;
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@@ -154,15 +156,16 @@
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 			 */
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 			rcu_user_exit();
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 			if (state == CONTEXT_USER) {
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+				instrumentation_begin();
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 				vtime_user_exit(current);
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 				trace_user_exit(0);
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+				instrumentation_end();
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 			}
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 		}
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 		__this_cpu_write(context_tracking.state, CONTEXT_KERNEL);
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 	}
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 	context_tracking_recursion_exit();
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 }
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-NOKPROBE_SYMBOL(__context_tracking_exit);
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 EXPORT_SYMBOL_GPL(__context_tracking_exit);
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 void context_tracking_exit(enum ctx_state state)
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@@ -191,17 +194,19 @@
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 	if (!per_cpu(context_tracking.active, cpu)) {
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 		per_cpu(context_tracking.active, cpu) = true;
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-		static_branch_inc(&context_tracking_enabled);
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+		static_branch_inc(&context_tracking_key);
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 	}
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 	if (initialized)
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 		return;
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+#ifdef CONFIG_HAVE_TIF_NOHZ
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 	/*
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 	 * Set TIF_NOHZ to init/0 and let it propagate to all tasks through fork
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 	 * This assumes that init is the only task at this early boot stage.
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 	 */
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 	set_tsk_thread_flag(&init_task, TIF_NOHZ);
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+#endif
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 	WARN_ON_ONCE(!tasklist_empty());
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 	initialized = true;