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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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26
arch/x86/include/asm/ftrace.h
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@@ -20,4 +20,30 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr)
#endif /* __ASSEMBLY__ */
#endif /* CONFIG_FUNCTION_TRACER */
#ifdef CONFIG_FUNCTION_RET_TRACER
#define FTRACE_RET_STACK_SIZE 20
#ifndef __ASSEMBLY__
/*
* Stack of return addresses for functions
* of a thread.
* Used in struct thread_info
*/
struct ftrace_ret_stack {
unsigned long ret;
unsigned long func;
unsigned long long calltime;
};
/*
* Primary handler of a function return.
* It relays on ftrace_return_to_handler.
* Defined in entry32.S
*/
extern void return_to_handler(void);
#endif /* __ASSEMBLY__ */
#endif /* CONFIG_FUNCTION_RET_TRACER */
#endif /* _ASM_X86_FTRACE_H */