From: ludo@gnu.org (Ludovic Courtès)
To: Alex Vong <alexvong1995@gmail.com>
Cc: 30111@debbugs.gnu.org
Subject: [bug#30111] [PATCH] gnu: gcc@7: Use retpoline options when building itself.
Date: Tue, 27 Feb 2018 10:37:10 +0100 [thread overview]
Message-ID: <87r2p64vuh.fsf@gnu.org> (raw)
In-Reply-To: <87lggkt2ck.fsf@gmail.com> (Alex Vong's message of "Sat, 27 Jan 2018 11:19:55 +0800")
Hi Alex,
Sorry for the delay.
Alex Vong <alexvong1995@gmail.com> skribis:
> This patch makes gcc use retpoline options when building itself. My last
> attempt to build it was successful. But after that I have changed
> something, I hope it wouldn't make it fail to build. (It shouldn't,
> since the options passed aren't changed.)
Any idea what upstream thinks of compiling GCC itself with these
options? Do they offer a configure flag or something to help with that?
> Are we going to add these options to other natively compiled programs as
> well?
I don’t have a good answer. Clearly we’ll want that in key packages,
but then where do we draw the line, and also how do we make sure we
don’t repeat ourselves?
Thoughts?
>>From f6b9caae6e13936be65550c871208a3425fe4ce4 Mon Sep 17 00:00:00 2001
> From: Alex Vong <alexvong1995@gmail.com>
> Date: Thu, 25 Jan 2018 23:24:24 +0800
> Subject: [PATCH] gnu: gcc@7: Use retpoline options when building itself.
>
> * gnu/packages/gcc.scm (gcc@7)[arguments]: Add retpoline options
> to #:make-flags.
[...]
> + (arguments
> + (substitute-keyword-arguments `(#:modules ((guix build gnu-build-system)
> + (guix build utils)
> + (ice-9 regex)
> + (srfi srfi-1)
> + (srfi srfi-26))
> + ,@(package-arguments gcc-6))
> + ;; Use retpoline options when building itself.
> + ((#:make-flags flags)
> + `(let* ((cross-compiling? ,(%current-target-system))
> + (system (if cross-compiling?
> + ,(%current-target-system)
> + ,(%current-system)))
> + (retpoline-opts '("-mindirect-branch=thunk"
> + "-mfunction-return=thunk"
> + "-mindirect-branch-register"))
> + (append-flag
> + (lambda (flag)
> + (if (string-match "^((BOOT_)?CFLAGS|C(XX)?FLAGS_FOR_TARGET)="
> + flag)
> + (string-join (cons flag retpoline-opts))
> + flag)))
> + (add-flag
> + (lambda (prefix flags)
> + (if (any (cut string-prefix? prefix <>) flags)
> + flags
> + (cons (string-append prefix
> + (string-join retpoline-opts))
> + flags))))
> + (add-gcc-flag (cut add-flag
> + (if cross-compiling? "CFLAGS=" "BOOT_CFLAGS=")
> + <>))
> + (add-c-lib-flag (cut add-flag "CFLAGS_FOR_TARGET=" <>))
> + (add-c++-lib-flag (cut add-flag "CXXFLAGS_FOR_TARGET=" <>)))
> + ;; Right now, the retpoline options are x86-specific.
> + (if (any (cut string-prefix? <> system) '("x86_64" "i686"))
> + (add-gcc-flag (add-c-lib-flag (add-c++-lib-flag (map append-flag
> + ,flags))))
> + ,flags)))))
I’m a bit concerned by the apparent complexity and the extra maintenance
burden it may entail. I don’t have any concrete suggestions though. I
suppose we should somehow abstract GCC compilation to make it easier to
pass new flags?
Thanks,
Ludo’.
next prev parent reply other threads:[~2018-02-27 9:38 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-14 13:07 [bug#30111] gnu: gcc@7: Apply the 'retpoline' mitigation technique Alex Vong
2018-01-15 14:29 ` Alex Vong
2018-01-16 13:14 ` Alex Vong
2018-01-16 14:33 ` Ludovic Courtès
2018-01-16 15:24 ` Alex Vong
2018-01-17 13:11 ` Ludovic Courtès
2018-01-17 23:31 ` Leo Famulari
2018-01-27 3:19 ` [bug#30111] [PATCH] gnu: gcc@7: Use retpoline options when building itself Alex Vong
2018-02-27 9:37 ` Ludovic Courtès [this message]
2018-06-22 20:07 ` [bug#30111] gnu: gcc@7: Use retpoline options when building itself. Previous Next Gábor Boskovits
2020-12-18 23:22 ` [bug#30111] gnu: gcc@7: Apply the 'retpoline' mitigation technique zimoun
2021-01-11 15:43 ` zimoun
2021-01-11 20:03 ` Efraim Flashner
2021-02-09 1:07 ` bug#30111: " zimoun
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