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tracing, x86: add low level support for ftrace return tracing

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Impact: add infrastructure for function-return tracing

Add low level support for ftrace return tracing.

This plug-in stores return addresses on the thread_info structure of
the current task.

The index of the current return address is initialized when the task
is the first one (init) and when a process forks (the child). It is
not needed when a task does a sys_execve because after this syscall,
it still needs to return on the kernel functions it called.

Note that the code of return_to_handler has been suggested by Steven
Rostedt as almost all of the ideas of improvements in this V3.

For purpose of security, arch/x86/kernel/process_32.c is not traced
because __switch_to() changes the current task during its execution.
That could cause inconsistency in the stored return address of this
function even if I didn't have any crash after testing with tracing on
this function enabled.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Frederic Weisbecker 2008-11-11 07:03:45 +01:00 • committed by Ingo Molnar
parent d844222a54
commit caf4b323b0
10 changed files with 301 additions and 9 deletions
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20
include/linux/ftrace.h
View file

@ -267,6 +267,26 @@ ftrace_init_module(unsigned long *start, unsigned long *end) { }
#endif
/*
* Structure that defines a return function trace.
*/
struct ftrace_retfunc {
unsigned long ret; /* Return address */
unsigned long func; /* Current function */
unsigned long long calltime;
unsigned long long rettime;
};
#ifdef CONFIG_FUNCTION_RET_TRACER
/* Type of a callback handler of tracing return function */
typedef void (*trace_function_return_t)(struct ftrace_retfunc *);
extern void register_ftrace_return(trace_function_return_t func);
/* The current handler in use */
extern trace_function_return_t ftrace_function_return;
extern void unregister_ftrace_return(void);
#endif
/*
* Structure which defines the trace of an initcall.
* You don't have to fill the func field since it is