From: Nick Desaulniers <ndesaulniers@google.com>
To: bp@alien8.de
Cc: luto@kernel.org, Fangrui Song <maskray@google.com>,
Andi Kleen <ak@linux.intel.com>,
andi@firstfloor.org, Dmitry Golovin <dima@golovin.in>,
Bill Wendling <morbo@google.com>, Rui Ueyama <ruiu@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
mingo@redhat.com, hpa@zytor.com, x86@kernel.org,
LKML <linux-kernel@vger.kernel.org>,
rafael@espindo.la, Stephen Hines <srhines@google.com>,
Greg KH <gregkh@linuxfoundation.org>
Subject: Re: [PATCH] x86/vdso: drop implicit common-page-size linker flag
Date: Fri, 7 Dec 2018 09:45:42 -0800 [thread overview]
Message-ID: <CAKwvOd=75MRjaDbEjHRaMTm1MSC1wkLxPKhH_S3KXreP8yU9Uw@mail.gmail.com> (raw)
In-Reply-To: <20181207101814.GA9385@zn.tnic>
On Fri, Dec 7, 2018 at 2:18 AM Borislav Petkov <bp@alien8.de> wrote:
>
> On Thu, Dec 06, 2018 at 11:12:31AM -0800, ndesaulniers@google.com wrote:
> > These are implied by the target architecture and for x86_64 match the
> > max-page-size. The default for non-NaCl x86_64 is 0x1000 (4096).
> >
> > In bfd the common page size is defined as 0x1000 (4096) for non-NaCl
>
> Sodium Chloride?
Google's Native Client, a technology for running native code in a web
browser. It's since been superseded by Portable Native Client (pNaCl)
and to an extent Web Assembly. It seems that BFD still contains code
for NaCl.
>
> > x86_64 targets:
> >
> > bfd/elf64-x86-64.c:
> > 4998:#define ELF_COMMONPAGESIZE 0x1000
> >
> > For gold, the common page size is defined as 0x1000 (4096) for non-NaCl
> > x86_64 targets:
> >
> > gold/x86_64.cc:
> > 1413: 0x1000, // common_pagesize (overridable by -z common-page-size)
> > 1442: 0x1000, // common_pagesize (overridable by -z common-page-size)
> >
> > (ELF_COMMONPAGESIZE also defaults to ELF_MAXPAGESIZE when not set
> > explicitly for a target architecture in bfd/elfxx-target.h, but that's
> > not relevant for x86_64).
> >
> > Because it's implied by the target architecture, it's of questionable
> > use to implement in LLD. This patch resolves one of the issues towards
> > using LLD to link an x86_64 kernel.
>
> LLD?
LLD is LLVM's linker.
https://lld.llvm.org/
>
> I can only guess what this commit message is about and have to look at
> the patch itself and then look at the LD(1) man page and rhyme up what
> it is aiming to do.
>
> How about rewriting it for mere mortals?
How does this sound:
TL;DR
-z common-page-size's default value is based on the target
architecture. arch/x86/entry/vdso/Makefile sets it to the
architecture default, which is implicit and redundant. Drop it.
--
Thanks,
~Nick Desaulniers
next prev parent reply other threads:[~2018-12-07 17:45 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-06 19:12 [PATCH] x86/vdso: drop implicit common-page-size linker flag ndesaulniers
2018-12-06 20:29 ` Andy Lutomirski
2018-12-07 10:18 ` Borislav Petkov
2018-12-07 17:45 ` Nick Desaulniers [this message]
2018-12-07 17:52 ` Borislav Petkov
2018-12-07 18:00 ` Nick Desaulniers
2018-12-07 18:33 ` [tip:x86/urgent] x86/vdso: Drop " tip-bot for Nick Desaulniers
2018-12-11 13:12 ` [tip:x86/build] x86/um/vdso: " tip-bot for ndesaulniers@google.com
2018-12-11 17:39 ` Nick Desaulniers
2018-12-11 17:43 ` Richard Weinberger
2018-12-11 17:46 ` Borislav Petkov
2018-12-11 17:53 ` Nick Desaulniers
2018-12-11 18:05 ` Borislav Petkov
2018-12-11 19:08 ` Nick Desaulniers
2018-12-11 20:14 ` Richard Weinberger
2018-12-11 20:53 ` Borislav Petkov
2018-12-11 13:25 ` tip-bot for Nick Desaulniers
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