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authorSteven Rostedt <srostedt@redhat.com>2008-05-12 21:20:43 +0200
committerThomas Gleixner <tglx@linutronix.de>2008-05-23 20:33:47 +0200
commitd61f82d06672f57fca410da6f7fffd15867db622 (patch)
tree62ef5573934eaa638c0d39a45d789691aecbd7d3 /include/linux/ftrace.h
parent3c1720f00bb619302ba19d55986ab565e74d06db (diff)
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ftrace: use dynamic patching for updating mcount calls
This patch replaces the indirect call to the mcount function pointer with a direct call that will be patched by the dynamic ftrace routines. On boot up, the mcount function calls the ftace_stub function. When the dynamic ftrace code is initialized, the ftrace_stub is replaced with a call to the ftrace_record_ip, which records the instruction pointers of the locations that call it. Later, the ftraced daemon will call kstop_machine and patch all the locations to nops. When a ftrace is enabled, the original calls to mcount will now be set top call ftrace_caller, which will do a direct call to the registered ftrace function. This direct call is also patched when the function that should be called is updated. All patching is performed by a kstop_machine routine to prevent any type of race conditions that is associated with modifying code on the fly. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'include/linux/ftrace.h')
-rw-r--r--include/linux/ftrace.h7
1 files changed, 6 insertions, 1 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index d509ad6c9cb8..b0dd0093058f 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -56,9 +56,14 @@ struct dyn_ftrace {
extern int ftrace_ip_converted(unsigned long ip);
extern unsigned char *ftrace_nop_replace(void);
extern unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr);
-extern int ftrace_dyn_arch_init(void);
+extern int ftrace_dyn_arch_init(void *data);
+extern int ftrace_mcount_set(unsigned long *data);
extern int ftrace_modify_code(unsigned long ip, unsigned char *old_code,
unsigned char *new_code);
+extern int ftrace_update_ftrace_func(ftrace_func_t func);
+extern void ftrace_caller(void);
+extern void ftrace_call(void);
+extern void mcount_call(void);
#endif
#ifdef CONFIG_FRAME_POINTER