From ed926f9b35cda0988234c356e16a7cb30f4e5338 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Tue, 3 May 2011 13:25:24 -0400 Subject: ftrace: Use counters to enable functions to trace Every function has its own record that stores the instruction pointer and flags for the function to be traced. There are only two flags: enabled and free. The enabled flag states that tracing for the function has been enabled (actively traced), and the free flag states that the record no longer points to a function and can be used by new functions (loaded modules). These flags are now moved to the MSB of the flags (actually just the top 32bits). The rest of the bits (30 bits) are now used as a ref counter. Everytime a tracer register functions to trace, those functions will have its counter incremented. When tracing is enabled, to determine if a function should be traced, the counter is examined, and if it is non-zero it is set to trace. When a ftrace_ops is registered to trace functions, its hashes are examined. If the ftrace_ops filter_hash count is zero, then all functions are set to be traced, otherwise only the functions in the hash are to be traced. The exception to this is if a function is also in the ftrace_ops notrace_hash. Then that function's counter is not incremented for this ftrace_ops. Signed-off-by: Steven Rostedt --- include/linux/ftrace.h | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'include/linux/ftrace.h') diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 6658a51390fe..ab1c46e70bb6 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -37,6 +37,7 @@ struct ftrace_ops { #ifdef CONFIG_DYNAMIC_FTRACE struct ftrace_hash *notrace_hash; struct ftrace_hash *filter_hash; + unsigned long flags; #endif }; @@ -152,10 +153,13 @@ extern void unregister_ftrace_function_probe_all(char *glob); extern int ftrace_text_reserved(void *start, void *end); enum { - FTRACE_FL_FREE = (1 << 0), - FTRACE_FL_ENABLED = (1 << 1), + FTRACE_FL_ENABLED = (1 << 30), + FTRACE_FL_FREE = (1 << 31), }; +#define FTRACE_FL_MASK (0x3UL << 30) +#define FTRACE_REF_MAX ((1 << 30) - 1) + struct dyn_ftrace { union { unsigned long ip; /* address of mcount call-site */ -- cgit v1.2.3-59-g8ed1b