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-rw-r--r--include/linux/compiler.h84
1 files changed, 82 insertions, 2 deletions
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 98115d9..ea7c6be 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -59,8 +59,88 @@ extern void __chk_io_ptr(const volatile void __iomem *);
* specific implementations come from the above header files
*/
-#define likely(x) __builtin_expect(!!(x), 1)
-#define unlikely(x) __builtin_expect(!!(x), 0)
+struct ftrace_branch_data {
+ const char *func;
+ const char *file;
+ unsigned line;
+ union {
+ struct {
+ unsigned long correct;
+ unsigned long incorrect;
+ };
+ struct {
+ unsigned long miss;
+ unsigned long hit;
+ };
+ };
+};
+
+/*
+ * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
+ * to disable branch tracing on a per file basis.
+ */
+#if defined(CONFIG_TRACE_BRANCH_PROFILING) && !defined(DISABLE_BRANCH_PROFILING)
+void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
+
+#define likely_notrace(x) __builtin_expect(!!(x), 1)
+#define unlikely_notrace(x) __builtin_expect(!!(x), 0)
+
+#define __branch_check__(x, expect) ({ \
+ int ______r; \
+ static struct ftrace_branch_data \
+ __attribute__((__aligned__(4))) \
+ __attribute__((section("_ftrace_annotated_branch"))) \
+ ______f = { \
+ .func = __func__, \
+ .file = __FILE__, \
+ .line = __LINE__, \
+ }; \
+ ______r = likely_notrace(x); \
+ ftrace_likely_update(&______f, ______r, expect); \
+ ______r; \
+ })
+
+/*
+ * Using __builtin_constant_p(x) to ignore cases where the return
+ * value is always the same. This idea is taken from a similar patch
+ * written by Daniel Walker.
+ */
+# ifndef likely
+# define likely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1))
+# endif
+# ifndef unlikely
+# define unlikely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
+# endif
+
+#ifdef CONFIG_PROFILE_ALL_BRANCHES
+/*
+ * "Define 'is'", Bill Clinton
+ * "Define 'if'", Steven Rostedt
+ */
+#define if(cond) if (__builtin_constant_p((cond)) ? !!(cond) : \
+ ({ \
+ int ______r; \
+ static struct ftrace_branch_data \
+ __attribute__((__aligned__(4))) \
+ __attribute__((section("_ftrace_branch"))) \
+ ______f = { \
+ .func = __func__, \
+ .file = __FILE__, \
+ .line = __LINE__, \
+ }; \
+ ______r = !!(cond); \
+ if (______r) \
+ ______f.hit++; \
+ else \
+ ______f.miss++; \
+ ______r; \
+ }))
+#endif /* CONFIG_PROFILE_ALL_BRANCHES */
+
+#else
+# define likely(x) __builtin_expect(!!(x), 1)
+# define unlikely(x) __builtin_expect(!!(x), 0)
+#endif
/* Optimization barrier */
#ifndef barrier
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