Re: [PATCH v2 12/39] x86/ibt,ftrace: Search for __fentry__ location

From: Steven Rostedt
Date: Tue Mar 01 2022 - 14:20:25 EST


On Wed, 02 Mar 2022 00:27:51 +0530
"Naveen N. Rao" <naveen.n.rao@xxxxxxxxxxxxxxxxxx> wrote:

> Won't this cause issues with ftrace_set_filter_ip() and others? If the
> passed-in ip points to func+0 when the actual ftrace location is at some
> offset, the ftrace location check in ftrace_match_addr() will now pass,
> resulting in adding func+0 to the hash. Should we also update
> ftrace_match_addr() to use the ip returned by ftrace_location()?
>

Yes, ftrace_match_addr() would need to be updated, or at least
ftrace_set_filter_ip() which is the only user ftrace_match_addr(), and is
currently only used by kprobes, live kernel patching and the direct
trampoline example code.

-- Steve