linux-kernel - Re: [PATCH v2 12/39] x86/ibt,ftrace: Search for __fentry_

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Date:   Wed, 2 Mar 2022 15:48:03 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        alexei.starovoitov@...il.com, alyssa.milburn@...el.com,
        andrew.cooper3@...rix.com, hjl.tools@...il.com,
        joao@...rdrivepizza.com, jpoimboe@...hat.com,
        keescook@...omium.org, linux-kernel@...r.kernel.org,
        mark.rutland@....com, mbenes@...e.cz, ndesaulniers@...gle.com,
        samitolvanen@...gle.com, x86@...nel.org
Subject: Re: [PATCH v2 12/39] x86/ibt,ftrace: Search for __fentry__ location

On Wed, 2 Mar 2022 14:47:16 -0500
Steven Rostedt <rostedt@...dmis.org> wrote:

> Note, I just pulled this patch, and I hit this warning:
> 
> WARNING: CPU: 0 PID: 6965 at arch/x86/kernel/kprobes/core.c:205 recover_probed_instruction+0x8f/0xa0

As we discussed on IRC (but I want an email record of this), it appears that
with some debugging, the ftrace_location() could return the function right
after the current function because lookup_rec() has an inclusive "end"
argument.

Testing:

	rec = lookup_rec(ip - offset, (ip - offset) + size - 1);

Appears to fix the issue.

-- Steve