mk-rootfs.sh

hc

2023-12-11 072de836f53be56a70cecf70b43ae43b7ce17376

 kernel/include/linux/tracepoint-defs.h
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@@ -11,6 +11,8 @@
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 #include <linux/atomic.h>
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 #include <linux/static_key.h>
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13
 
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+struct static_call_key;
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+
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 struct trace_print_flags {
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 	unsigned long		mask;
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 	const char		*name;
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@@ -30,6 +32,9 @@
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 struct tracepoint {
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 	const char *name;		/* Tracepoint name */
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 	struct static_key key;
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+	struct static_call_key *static_call_key;
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+	void *static_call_tramp;
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+	void *iterator;
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 	int (*regfunc)(void);
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 	void (*unregfunc)(void);
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 	struct tracepoint_func __rcu *funcs;
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@@ -45,6 +50,41 @@
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 	struct tracepoint	*tp;
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 	void			*bpf_func;
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 	u32			num_args;
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+	u32			writable_size;
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 } __aligned(32);
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+/*
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+ * If a tracepoint needs to be called from a header file, it is not
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+ * recommended to call it directly, as tracepoints in header files
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+ * may cause side-effects and bloat the kernel. Instead, use
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+ * tracepoint_enabled() to test if the tracepoint is enabled, then if
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+ * it is, call a wrapper function defined in a C file that will then
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+ * call the tracepoint.
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+ *
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+ * For "trace_foo_bar()", you would need to create a wrapper function
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+ * in a C file to call trace_foo_bar():
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+ *   void do_trace_foo_bar(args) { trace_foo_bar(args); }
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+ * Then in the header file, declare the tracepoint:
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+ *   DECLARE_TRACEPOINT(foo_bar);
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+ * And call your wrapper:
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+ *   static inline void some_inlined_function() {
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+ *            [..]
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+ *            if (tracepoint_enabled(foo_bar))
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+ *                    do_trace_foo_bar(args);
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+ *            [..]
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+ *   }
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+ *
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+ * Note: tracepoint_enabled(foo_bar) is equivalent to trace_foo_bar_enabled()
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+ *   but is safe to have in headers, where trace_foo_bar_enabled() is not.
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+ */
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+#define DECLARE_TRACEPOINT(tp) \
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+	extern struct tracepoint __tracepoint_##tp
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+
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+#ifdef CONFIG_TRACEPOINTS
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+# define tracepoint_enabled(tp) \
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+	static_key_false(&(__tracepoint_##tp).key)
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+#else
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+# define tracepoint_enabled(tracepoint) false
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+#endif
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+
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 #endif