Commit e9b349f0 authored by Li Bin's avatar Li Bin Committed by Steven Rostedt

metag: ftrace: Fix the comments for ftrace_modify_code

There is no need to worry about module and __init text disappearing
case, because that ftrace has a module notifier that is called when
a module is being unloaded and before the text goes away and this
code grabs the ftrace_lock mutex and removes the module functions
from the ftrace list, such that it will no longer do any
modifications to that module's text, the update to make functions
be traced or not is done under the ftrace_lock mutex as well.
And by now, __init section codes should not been modified
by ftrace, because it is black listed in recordmcount.c and
ignored by ftrace.

Link: http://lkml.kernel.org/r/1449367378-29430-3-git-send-email-huawei.libin@huawei.com

Cc: linux-metag@vger.kernel.org
Acked-by: default avatarJames Hogan <james.hogan@imgtec.com>
Suggested-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarLi Bin <huawei.libin@huawei.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 5243238a
...@@ -54,12 +54,11 @@ static int ftrace_modify_code(unsigned long pc, unsigned char *old_code, ...@@ -54,12 +54,11 @@ static int ftrace_modify_code(unsigned long pc, unsigned char *old_code,
unsigned char replaced[MCOUNT_INSN_SIZE]; unsigned char replaced[MCOUNT_INSN_SIZE];
/* /*
* Note: Due to modules and __init, code can * Note:
* disappear and change, we need to protect against faulting * We are paranoid about modifying text, as if a bug was to happen, it
* as well as code changing. * could cause us to read or write to someplace that could cause harm.
* * Carefully read and modify the code with probe_kernel_*(), and make
* No real locking needed, this code is run through * sure what we read is what we expected it to be before modifying it.
* kstop_machine.
*/ */
/* read the text we want to modify */ /* read the text we want to modify */
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment