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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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24
arch/x86/include/asm/thread_info.h
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@@ -20,6 +20,7 @@
struct task_struct;
struct exec_domain;
#include <asm/processor.h>
#include <asm/ftrace.h>
struct thread_info {
struct task_struct *task; /* main task structure */
@@ -38,8 +39,30 @@ struct thread_info {
*/
__u8 supervisor_stack[0];
#endif
#ifdef CONFIG_FUNCTION_RET_TRACER
/* Index of current stored adress in ret_stack */
int curr_ret_stack;
/* Stack of return addresses for return function tracing */
struct ftrace_ret_stack ret_stack[FTRACE_RET_STACK_SIZE];
#endif
};
#ifdef CONFIG_FUNCTION_RET_TRACER
#define INIT_THREAD_INFO(tsk) \
{ \
.task = &tsk, \
.exec_domain = &default_exec_domain, \
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
.curr_ret_stack = -1,\
}
#else
#define INIT_THREAD_INFO(tsk) \
{ \
.task = &tsk, \
@@ -52,6 +75,7 @@ struct thread_info {
.fn = do_no_restart_syscall, \
}, \
}
#endif
#define init_thread_info (init_thread_union.thread_info)
#define init_stack (init_thread_union.stack)