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ftrace: return error on failed modified text.

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Have the ftrace_modify_code return error values:

  -EFAULT on error of reading the address

  -EINVAL if what is read does not match what it expected

  -EPERM  if the write fails to update after a successful match.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Steven Rostedt 2008-10-23 09:32:59 -04:00 • committed by Ingo Molnar
parent 34698bcbdf
commit 593eb8a2d6
3 changed files with 44 additions and 15 deletions
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24
include/linux/ftrace.h
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@ -72,13 +72,33 @@ 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 *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);
/**
* ftrace_modify_code - modify code segment
* @ip: the address of the code segment
* @old_code: the contents of what is expected to be there
* @new_code: the code to patch in
*
* This is a very sensitive operation and great care needs
* to be taken by the arch. The operation should carefully
* read the location, check to see if what is read is indeed
* what we expect it to be, and then on success of the compare,
* it should write to the location.
*
* Return must be:
* 0 on success
* -EFAULT on error reading the location
* -EINVAL on a failed compare of the contents
* -EPERM on error writing to the location
* Any other value will be considered a failure.
*/
extern int ftrace_modify_code(unsigned long ip, unsigned char *old_code,
unsigned char *new_code);
extern int skip_trace(unsigned long ip);
extern void ftrace_release(void *start, unsigned long size);