From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: tglx@linutronix.de, linux-kernel@vger.kernel.org, x86@kernel.org
Subject: Re: [RFC][PATCH 15/16] objtool: Implement noinstr validation
Date: Mon, 16 Mar 2020 11:19:04 -0500 [thread overview]
Message-ID: <20200316161904.zouwkwup6vwsmxgp@treble> (raw)
In-Reply-To: <20200316132419.GF12521@hirez.programming.kicks-ass.net>
On Mon, Mar 16, 2020 at 02:24:19PM +0100, Peter Zijlstra wrote:
> > And "read_instr_hints" reads as "read_instruction_hints()".
> >
> > Can we come up with a more readable name? Why not just "notrace"?
> >
> > The trace begin/end annotations could be
> >
> > trace_allow_begin()
> > trace_allow_end()
>
> notrace already exists and we didn't want to confuse things further.
Um, why would it confuse things to call a section of notrace code
".notrace.text"???
> > Also -- what happens when a function belongs in both .notrace.text and
> > in one of the other special-purpose sections like .sched.text,
> > .meminit.text or .entry.text?
>
> Hasn't happened yet, initially we were thinking of using .entry.text for
> this as a whole, but decided against that due to how .entry.text is
> special for PTI (although exposing most of this code really wouldn't
> matter).
>
> The thing with .sched.text is that we really should never call into
> scheduling from these contexts anyway. We've not ran into meminit yet.
> (all this finicky entry code is ran with IRQs disabled).
>
> The one that could potentially interfere is .cpuidle.text.
>
> > Maybe storing pointers to the functions, like NOKPROBE_SYMBOL does,
> > would be better than putting the functions in a separate section.
>
> Thing is, I really _hate_ that annotation style.
I do too, but I get the feeling this "put everything in its own section"
thing is going to bite us.
> > Also, maybe we can just hard-code the fact that vmlinux.o is always
> > noinstr-only. Over time we'll probably need to move more per-.o
> > functionalities to vmlinux.o and I think we should avoid creating a
> > bunch of cmdline options.
>
> but you're ruining things here, see, for a regular x86_64 config, we'd
> run this with:
>
> objtool check -fail vmlinux.o
>
> And I was hoping to get vmlinux.o objtool clean, surprisingly there
> really aren't that many complaints. But the -i thing makes it run
> significantly faster without duplicating all the bits we've already
> checked.
My suggestion is that the "-i" option would be hard-coded (for now). So
nothing extra would get checked.
--
Josh
next prev parent reply other threads:[~2020-03-16 16:26 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-12 13:41 [RFC][PATCH 00/16] objtool: vmlinux.o and noinstr validation Peter Zijlstra
2020-03-12 13:41 ` [RFC][PATCH 01/16] objtool: Introduce validate_return() Peter Zijlstra
2020-03-12 13:41 ` [RFC][PATCH 02/16] objtool: Rename func_for_each_insn() Peter Zijlstra
2020-03-12 13:41 ` [RFC][PATCH 03/16] objtool: Rename func_for_each_insn_all() Peter Zijlstra
2020-03-12 13:41 ` [RFC][PATCH 04/16] objtool: Annotate identity_mapped() Peter Zijlstra
2020-03-13 14:34 ` Peter Zijlstra
2020-03-15 15:45 ` Josh Poimboeuf
2020-03-13 16:46 ` Brian Gerst
2020-03-13 17:22 ` Peter Zijlstra
2020-03-12 13:41 ` [RFC][PATCH 05/16] objtool: Optimize find_symbol_by_index() Peter Zijlstra
2020-03-15 16:09 ` Josh Poimboeuf
2020-03-15 16:18 ` Josh Poimboeuf
2020-03-15 16:10 ` Josh Poimboeuf
2020-03-17 11:55 ` Miroslav Benes
2020-03-17 14:08 ` Peter Zijlstra
2020-03-12 13:41 ` [RFC][PATCH 06/16] objtool: Add a statistics mode Peter Zijlstra
2020-03-15 16:20 ` Josh Poimboeuf
2020-03-12 13:41 ` [RFC][PATCH 07/16] objtool: Optimize find_section_by_index() Peter Zijlstra
2020-03-15 16:24 ` Josh Poimboeuf
2020-03-12 13:41 ` [RFC][PATCH 08/16] Optimize find_section_by_name() Peter Zijlstra
2020-03-15 16:25 ` Josh Poimboeuf
2020-03-17 12:22 ` Miroslav Benes
2020-03-17 14:10 ` Peter Zijlstra
2020-03-12 13:41 ` [RFC][PATCH 09/16] objtool: Optimize find_symbol_*() and read_symbols() Peter Zijlstra
2020-03-15 15:48 ` Josh Poimboeuf
2020-03-15 16:41 ` Josh Poimboeuf
2020-03-12 13:41 ` [RFC][PATCH 10/16] objtool: Resize insn_hash Peter Zijlstra
2020-03-12 13:41 ` [RFC][PATCH 11/16] objtool: Optimize find_symbol_by_name() Peter Zijlstra
2020-03-12 13:41 ` [RFC][PATCH 12/16] objtool: Optimize read_sections() Peter Zijlstra
2020-03-15 16:53 ` Josh Poimboeuf
2020-03-12 13:41 ` [RFC][PATCH 13/16] objtool: Delete cleanup() Peter Zijlstra
2020-03-12 13:41 ` [RFC][PATCH 14/16] objtool: Optimize find_rela_by_dest_range() Peter Zijlstra
2020-03-12 13:41 ` [RFC][PATCH 15/16] objtool: Implement noinstr validation Peter Zijlstra
2020-03-15 18:03 ` Josh Poimboeuf
2020-03-16 13:24 ` Peter Zijlstra
2020-03-16 16:19 ` Josh Poimboeuf [this message]
2020-03-16 16:21 ` Josh Poimboeuf
2020-03-16 16:46 ` Peter Zijlstra
2020-03-16 16:48 ` Peter Zijlstra
2020-03-16 19:20 ` Josh Poimboeuf
2020-03-12 13:41 ` [RFC][PATCH 16/16] objtool: Optimize !vmlinux.o again Peter Zijlstra
2020-03-12 21:57 ` [RFC][PATCH v2 " Peter Zijlstra
2020-03-12 16:23 ` [RFC][PATCH 00/16] objtool: vmlinux.o and noinstr validation Peter Zijlstra
2020-03-12 17:44 ` Josh Poimboeuf
2020-03-12 22:23 ` Peter Zijlstra
2020-03-17 0:56 ` Masami Hiramatsu
2020-03-17 9:26 ` Thomas Gleixner
2020-03-17 14:20 ` Masami Hiramatsu
2020-03-17 12:14 ` Peter Zijlstra
2020-03-15 18:12 ` Josh Poimboeuf
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