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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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14
arch/x86/kernel/ftrace.c
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@@ -62,7 +62,6 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
unsigned char *new_code)
{
unsigned char replaced[MCOUNT_INSN_SIZE];
int ret;
/*
* Note: Due to modules and __init, code can
@@ -72,15 +71,16 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
* No real locking needed, this code is run through
* kstop_machine, or before SMP starts.
*/
if (__copy_from_user_inatomic(replaced, (char __user *)ip, MCOUNT_INSN_SIZE))
return 1;
if (__copy_from_user_inatomic(replaced, (char __user *)ip,
MCOUNT_INSN_SIZE))
return -EFAULT;
if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
return 2;
return -EINVAL;
ret = __copy_to_user_inatomic((char __user *)ip, new_code,
MCOUNT_INSN_SIZE);
WARN_ON_ONCE(ret);
if (__copy_to_user_inatomic((char __user *)ip, new_code,
MCOUNT_INSN_SIZE))
return -EPERM;
sync_core();