From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Andy Lutomirski <luto@amacapital.net>,
Peter Zijlstra <peterz@infradead.org>,
LKML <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Masami Hiramatsu <mhiramat@kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Matthew Helsley <mhelsley@vmware.com>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
David Woodhouse <dwmw2@infradead.org>,
Paolo Bonzini <pbonzini@redhat.com>,
Jason Baron <jbaron@akamai.com>, Jiri Kosina <jkosina@suse.cz>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Andrew Lutomirski <luto@kernel.org>
Subject: Re: [POC][RFC][PATCH 1/2] jump_function: Addition of new feature "jump_function"
Date: Wed, 10 Oct 2018 15:16:09 -0500 [thread overview]
Message-ID: <20181010201609.3zwvzpr3ulredpek@treble> (raw)
In-Reply-To: <20181010145608.2094d254@gandalf.local.home>
On Wed, Oct 10, 2018 at 02:56:08PM -0400, Steven Rostedt wrote:
> On Wed, 10 Oct 2018 13:33:30 -0500
> Josh Poimboeuf <jpoimboe@redhat.com> wrote:
>
> > Re-reading your suggestion, I may have misunderstood what you're
> > suggesting here, but I'm thinking about doing something like what you
> > proposed earlier:
> >
> > GLOBAL(tramp)
> > jmp *current_func(%rip)
> > ENDPROC(tramp)
> >
> > That is, doing an indirect jump instead of the above direct jump, so
> > that any previous references to the trampoline would still work (and it
> > would also work during early boot).
> >
> > Though it should probably be a retpoline instead of an indirect jump.
>
> But do we care, as it only takes place during text_poke_bp() right?
>
> I don't think we need to worry about training trampoline branch
> prediction that can only be hit when something enables the jump.
Yeah, I guess it depends on if we'd expect anybody (or gcc) to get a
function pointer to the trampoline itself. I can just create a warning
for that in objtool.
--
Josh
next prev parent reply other threads:[~2018-10-10 20:16 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-06 1:51 [POC][RFC][PATCH 0/2] PROOF OF CONCEPT: Dynamic Functions (jump functions) Steven Rostedt
2018-10-06 1:51 ` [POC][RFC][PATCH 1/2] jump_function: Addition of new feature "jump_function" Steven Rostedt
2018-10-06 2:00 ` Steven Rostedt
2018-10-06 2:02 ` Steven Rostedt
2018-10-06 2:03 ` Steven Rostedt
2018-10-06 15:15 ` Steven Rostedt
2018-10-06 12:12 ` Peter Zijlstra
2018-10-06 13:39 ` Steven Rostedt
2018-10-06 15:13 ` Andy Lutomirski
2018-10-06 15:16 ` Steven Rostedt
2018-10-08 7:21 ` Peter Zijlstra
2018-10-08 8:33 ` Andy Lutomirski
2018-10-08 15:57 ` Peter Zijlstra
2018-10-08 16:29 ` Andy Lutomirski
2018-10-08 16:39 ` Steven Rostedt
2018-10-08 16:39 ` Peter Zijlstra
2018-10-08 17:25 ` Andy Lutomirski
2018-10-08 17:30 ` Ard Biesheuvel
2018-10-08 17:42 ` Andy Lutomirski
2018-10-08 17:44 ` Jiri Kosina
2018-10-08 17:45 ` Ard Biesheuvel
2018-10-08 17:47 ` Andy Lutomirski
2018-10-09 2:17 ` Josh Poimboeuf
2018-10-09 3:57 ` Steven Rostedt
2018-10-10 17:52 ` Josh Poimboeuf
2018-10-10 18:03 ` Andy Lutomirski
2018-10-10 18:16 ` Josh Poimboeuf
2018-10-10 18:17 ` Josh Poimboeuf
2018-10-10 21:13 ` Andy Lutomirski
2018-10-11 3:07 ` Josh Poimboeuf
2018-10-11 12:52 ` Josh Poimboeuf
2018-10-11 16:20 ` Andy Lutomirski
2018-10-10 18:33 ` Josh Poimboeuf
2018-10-10 18:56 ` Steven Rostedt
2018-10-10 20:16 ` Josh Poimboeuf [this message]
2018-10-10 20:57 ` Andy Lutomirski
2018-10-08 16:31 ` Steven Rostedt
2018-10-08 11:30 ` Ard Biesheuvel
2018-10-09 3:44 ` Masami Hiramatsu
2018-10-09 3:55 ` Steven Rostedt
2018-10-09 16:04 ` Masami Hiramatsu
2018-10-09 8:59 ` David Laight
2018-10-06 1:51 ` [POC][RFC][PATCH 2/2] tracepoints: Implement it with dynamic functions Steven Rostedt
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