diff --git a/[refs] b/[refs] index 242d2580e16d..e31bf7965729 100644 --- a/[refs] +++ b/[refs] @@ -1,2 +1,2 @@ --- -refs/heads/master: 593eb8a2d63e95772a5f22d746f18a997c5ee463 +refs/heads/master: 76aefee57657428fb77cbd8624119c1a440bee44 diff --git a/trunk/arch/x86/kernel/ftrace.c b/trunk/arch/x86/kernel/ftrace.c index 428291581cb2..783455454d78 100644 --- a/trunk/arch/x86/kernel/ftrace.c +++ b/trunk/arch/x86/kernel/ftrace.c @@ -66,18 +66,23 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code, /* * Note: Due to modules and __init, code can * disappear and change, we need to protect against faulting - * as well as code changing. + * as well as code changing. We do this by using the + * __copy_*_user functions. * * No real locking needed, this code is run through * kstop_machine, or before SMP starts. */ + + /* read the text we want to modify */ if (__copy_from_user_inatomic(replaced, (char __user *)ip, MCOUNT_INSN_SIZE)) return -EFAULT; + /* Make sure it is what we expect it to be */ if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0) return -EINVAL; + /* replace the text with the new text */ if (__copy_to_user_inatomic((char __user *)ip, new_code, MCOUNT_INSN_SIZE)) return -EPERM;