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From: Arvind Sankar <nivedita@alum.mit.edu>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: Arvind Sankar <nivedita@alum.mit.edu>,
	Mike Lothian <mike@fireburn.co.uk>,
	linux-efi <linux-efi@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	X86 ML <x86@kernel.org>
Subject: Re: [PATCH v2 4/5] efi/x86: Remove extra headroom for setup block
Date: Mon, 11 May 2020 18:53:24 -0400	[thread overview]
Message-ID: <20200511225324.GA1307788@rani.riverdale.lan> (raw)
In-Reply-To: <CAMj1kXEmJRpVyWDVkBn9eL0y0J4iVrUkYZd_pk_oKOeQPH661g@mail.gmail.com>

On Mon, May 11, 2020 at 11:13:00PM +0200, Ard Biesheuvel wrote:
> On Mon, 11 May 2020 at 20:36, Arvind Sankar <nivedita@alum.mit.edu> wrote:
> >
> > On Mon, May 11, 2020 at 06:01:49PM +0100, Mike Lothian wrote:
> > > Hi
> > >
> > > This patch has been causing issues for me since switching to GCC 10.1:
> > >
> > >   CALL    scripts/checksyscalls.sh
> > >   CALL    scripts/atomic/check-atomics.sh
> > >   DESCEND  objtool
> > >   CHK     include/generated/compile.h
> > >   HOSTCC  arch/x86/boot/tools/build
> > > /usr/lib/gcc/x86_64-pc-linux-gnu/10.1.0/../../../../x86_64-pc-linux-gnu/bin/ld: error: linker defined: multiple definition of '_end'
> > > /usr/lib/gcc/x86_64-pc-linux-gnu/10.1.0/../../../../x86_64-pc-linux-gnu/bin/ld: /tmp/ccEkW0jM.o: previous definition here
> > > collect2: error: ld returned 1 exit status
> > > make[1]: *** [scripts/Makefile.host:103: arch/x86/boot/tools/build] Error 1
> > > make: *** [arch/x86/Makefile:303: bzImage] Error 2
> > >
> > > Cheers
> > >
> > > Mike
> >
> > I'm not getting an error even with gcc 10 for some reason, but I can see
> > that it is busted. It's using the linker-defined _end symbol which is
> > just pass the end of the .bss.
> >
> > Does adding "static" to the declaration of _end fix your error?
> 
> This is in a host tool, so it depends on the builtin linker script the
> toolchain decides to use. This is risky, though, as it may be using
> PROVIDE() for _end, which means that in cases where it doesn't break,
> other references to _end that may exist will be linked to the wrong
> symbol. I don't think 'build' should be expected to do anything
> interesting with its own representation in memory, but better fix it
> nonetheless.

Right, _end _is_ getting redefined in my system linker script too: I can
see with objdump that the final _end symbol in my version of build is
actually pointing beyond the .bss. But my toolchain doesn't report an
error for some reason.

> 
> Arvind: mind sending a fix for this, please?

Yeah, I have one ready -- was just waiting to hear back if "static" did
fix it, but I can send it out now.

  reply	other threads:[~2020-05-11 22:53 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-01 23:05 [PATCH 0/5] Minimize the need to move the kernel in the EFI stub Arvind Sankar
2020-03-01 23:05 ` [PATCH 1/5] x86/boot/compressed/32: Save the output address instead of recalculating it Arvind Sankar
2020-03-03 19:10   ` Ard Biesheuvel
2020-03-01 23:05 ` [PATCH 2/5] efi/x86: Decompress at start of PE image load address Arvind Sankar
2020-03-03  6:28   ` Mika Penttilä
2020-03-03 13:45     ` Arvind Sankar
2020-03-03 19:08   ` Ard Biesheuvel
2020-03-01 23:05 ` [PATCH 3/5] efi/x86: Add kernel preferred address to PE header Arvind Sankar
2020-03-03 19:11   ` Ard Biesheuvel
2020-03-01 23:05 ` [PATCH 4/5] efi/x86: Remove extra headroom for setup block Arvind Sankar
2020-03-02  4:21   ` Mika Penttilä
2020-03-03  4:14     ` Arvind Sankar
2020-03-01 23:05 ` [PATCH 5/5] efi/x86: Don't relocate the kernel unless necessary Arvind Sankar
2020-03-03 19:15   ` Ard Biesheuvel
2020-03-03 22:12 ` [PATCH v2 0/5] Minimize the need to move the kernel in the EFI stub Arvind Sankar
2020-03-03 22:12   ` [PATCH v2 1/5] x86/boot/compressed/32: Save the output address instead of recalculating it Arvind Sankar
2020-03-03 22:12   ` [PATCH v2 2/5] efi/x86: Decompress at start of PE image load address Arvind Sankar
2020-03-03 22:12   ` [PATCH v2 3/5] efi/x86: Add kernel preferred address to PE header Arvind Sankar
2020-03-03 22:12   ` [PATCH v2 4/5] efi/x86: Remove extra headroom for setup block Arvind Sankar
2020-05-11 17:01     ` Mike Lothian
2020-05-11 18:36       ` Arvind Sankar
2020-05-11 21:13         ` Ard Biesheuvel
2020-05-11 22:53           ` Arvind Sankar [this message]
2020-05-11 22:58             ` [PATCH] x86/boot: Mark global variables as static Arvind Sankar
2020-05-11 23:12               ` Mike Lothian
2020-05-12 11:05                 ` Ard Biesheuvel
2020-03-03 22:12   ` [PATCH v2 5/5] efi/x86: Don't relocate the kernel unless necessary Arvind Sankar
2020-03-03 23:08     ` Ard Biesheuvel
2020-03-03 23:34       ` Arvind Sankar
2020-03-04  7:30         ` Ard Biesheuvel
2020-03-03 22:26   ` [PATCH v2 0/5] Minimize the need to move the kernel in the EFI stub Ard Biesheuvel

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