From: Peter Zijlstra <peterz@infradead.org>
To: Jiri Slaby <jslaby@suse.cz>
Cc: Vegard Nossum <vegard.nossum@oracle.com>,
linux-kernel@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
"Luis R . Rodriguez" <mcgrof@kernel.org>,
stable@vger.kernel.org, Ming Lei <ming.lei@canonical.com>,
Steven Rostedt <srostedt@redhat.com>
Subject: Re: [PATCH 01/12] extarray: define helpers for arrays defined in linker scripts
Date: Mon, 17 Oct 2016 11:09:30 +0200 [thread overview]
Message-ID: <20161017090930.GT3142@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <186f8242-3f8d-31cd-a8e8-9743bbc1c1fd@suse.cz>
On Mon, Oct 17, 2016 at 11:01:13AM +0200, Jiri Slaby wrote:
> On 10/17/2016, 10:33 AM, Peter Zijlstra wrote:
> > On Sun, Oct 16, 2016 at 05:16:05PM +0200, Vegard Nossum wrote:
> >> The test in this loop:
> >>
> >> for (b_fw = __start_builtin_fw; b_fw != __end_builtin_fw; b_fw++) {
> >>
> >> was getting completely compiled out by my gcc, 7.0.0 20160520. The result
> >> was that the loop was going beyond the end of the builtin_fw array and
> >> giving me a page fault when trying to dereference b_fw->name.
> >>
> >> This is because __start_builtin_fw and __end_builtin_fw are both declared
> >> as (separate) arrays, and so gcc conludes that b_fw can never point to
> >> __end_builtin_fw.
> >>
> >
> > Urgh, isn't that the kind of 'optimizations' we should shoot in the head
> > for the kernel? Just like the -fno-strict-aliassing crap?
>
> Unfortunately, there is no such switch for this optimization.
Should we get one?
> On the top of that, it's incorrect C according to the standard.
According to the standard non of the kernel has any chance in hell of
working, so don't pretend you care about that :-)
next prev parent reply other threads:[~2016-10-17 9:09 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-16 15:16 [PATCH 00/12] external array access helpers Vegard Nossum
2016-10-16 15:16 ` [PATCH 01/12] extarray: define helpers for arrays defined in linker scripts Vegard Nossum
2016-10-17 7:04 ` Greg Kroah-Hartman
2016-10-17 8:33 ` Peter Zijlstra
2016-10-17 9:01 ` Jiri Slaby
2016-10-17 9:09 ` Peter Zijlstra [this message]
2016-10-17 11:27 ` Vegard Nossum
2016-10-17 11:45 ` Peter Zijlstra
2016-10-18 8:08 ` Vegard Nossum
2016-10-18 21:18 ` Luis R. Rodriguez
2016-10-19 8:18 ` Richard Biener
2016-10-19 9:13 ` Peter Zijlstra
2016-10-19 9:33 ` Richard Biener
2016-10-19 10:25 ` Peter Zijlstra
2016-10-19 11:11 ` Richard Biener
2016-10-19 11:31 ` Peter Zijlstra
2016-11-02 12:11 ` Markus Trippelsdorf
2016-11-02 12:14 ` Richard Biener
2016-11-02 15:02 ` Linus Torvalds
2016-10-19 7:16 ` Jiri Slaby
2016-10-16 15:16 ` [PATCH 02/12] firmware: declare {__start,__end}_builtin_fw as external array Vegard Nossum
2016-10-16 15:16 ` [PATCH 03/12] ftrace: declare __{start,stop}_mcount_loc " Vegard Nossum
2016-10-16 15:16 ` [PATCH 04/12] tracing: declare __{start,stop}_{annotated_,}branch_profile " Vegard Nossum
2016-10-16 15:16 ` [PATCH 05/12] kprobes: declare __{start,stop}_kprobe_blacklist " Vegard Nossum
2016-10-17 5:53 ` Masami Hiramatsu
2016-10-16 15:16 ` [PATCH 06/12] tracing: declare __{start,stop}_ftrace_events " Vegard Nossum
2016-10-16 15:16 ` [PATCH 07/12] tracing: declare __{start,stop}_ftrace_enum_maps " Vegard Nossum
2016-10-16 15:16 ` [PATCH 08/12] tracing: declare __trace_bprintk_fmt/__tracepoint_str as external arrays Vegard Nossum
2016-10-16 15:16 ` [PATCH 09/12] tracing: declare __{start,stop}_syscalls_metadata as external array Vegard Nossum
2016-10-16 15:16 ` [PATCH 10/12] serial_core: declare __earlycon_table{,_end} " Vegard Nossum
2016-10-16 15:16 ` [PATCH 11/12] jump_label: declare jump table " Vegard Nossum
2016-10-16 16:25 ` Peter Zijlstra
2016-10-16 16:50 ` Vegard Nossum
2016-10-16 17:44 ` Peter Zijlstra
2016-10-17 21:33 ` Steven Rostedt
2016-10-16 15:16 ` [PATCH 12/12] dynamic debug: declare " Vegard Nossum
2016-10-16 16:14 ` [PATCH 00/12] external array access helpers Greg Kroah-Hartman
2016-10-16 17:05 ` Vegard Nossum
2016-10-17 7:02 ` Greg Kroah-Hartman
2016-10-17 6:26 ` Jiri Slaby
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20161017090930.GT3142@twins.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=gregkh@linuxfoundation.org \
--cc=jslaby@suse.cz \
--cc=linux-kernel@vger.kernel.org \
--cc=mcgrof@kernel.org \
--cc=ming.lei@canonical.com \
--cc=srostedt@redhat.com \
--cc=stable@vger.kernel.org \
--cc=torvalds@linux-foundation.org \
--cc=vegard.nossum@oracle.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
Powered by JetHome