From: Mark Salter <msalter@redhat.com>
To: Will Deacon <will.deacon@arm.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Catalin Marinas <Catalin.Marinas@arm.com>
Subject: Re: [PATCH] arm64: add PAGE_ALIGNED_DATA to linker script
Date: Wed, 09 Oct 2013 13:31:45 -0400 [thread overview]
Message-ID: <1381339905.8305.31.camel@deneb.redhat.com> (raw)
In-Reply-To: <20131009101447.GC5985@mudshark.cambridge.arm.com>
On Wed, 2013-10-09 at 11:14 +0100, Will Deacon wrote:
> On Tue, Oct 08, 2013 at 09:37:39PM +0100, Mark Salter wrote:
> > The arm64 linker script doesn't use the PAGE_ALIGNED_DATA macro which
> > leads to a ".data..page_aligned" section being placed between the end
> > of .data and start of .bss:
> >
> > % readelf -e vmlinux
> > ...
> > Section to Segment mapping:
> > Segment Sections...
> > 00 .head.text .text .text.init .rodata __ksymtab __ksymtab_gpl \
> > __ksymtab_strings __param __modver __ex_table .notes \
> > .init.text .init.data .data..percpu .data .data..page_aligned .bss
> >
> > This causes problems for the EFI stub which may have to relocate the
> > kernel image based on stext and _edata symbols.
> >
> > This patch adds PAGE_ALIGNED_DATA() to the linker script inside the
> > the .data section.
> >
> > Signed-off-by: Mark Salter <msalter@redhat.com>
> > ---
> > arch/arm64/kernel/vmlinux.lds.S | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
> > index f8ab9d8..e441556 100644
> > --- a/arch/arm64/kernel/vmlinux.lds.S
> > +++ b/arch/arm64/kernel/vmlinux.lds.S
> > @@ -110,6 +110,7 @@ SECTIONS
> > */
> > INIT_TASK_DATA(THREAD_SIZE)
> > NOSAVE_DATA
> > + PAGE_ALIGNED_DATA(PAGE_SIZE)
> > CACHELINE_ALIGNED_DATA(64)
> > READ_MOSTLY_DATA(64)
>
> Can we just replace this chunk with RW_DATA_SECTION(64, PAGE_SIZE,
> THREAD_SIZE) instead?
Possibly. The layout of the included macros is the same. The only
difference being the placement of _data, _sdata, and _edata inside
.data and the use of __data_loc.
--Mark
next prev parent reply other threads:[~2013-10-09 17:31 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-08 20:37 [PATCH] arm64: add PAGE_ALIGNED_DATA to linker script Mark Salter
2013-10-09 10:14 ` Will Deacon
2013-10-09 17:31 ` Mark Salter [this message]
2013-10-11 12:18 ` Mark Salter
2013-11-01 15:01 ` Mark Salter
2013-11-01 16:17 ` Will Deacon
2013-11-04 11:28 ` Catalin Marinas
2013-11-04 16:38 ` [PATCH] arm64: use generic RW_DATA_SECTION macro in " Mark Salter
2013-11-04 17:20 ` Will Deacon
2013-11-04 18:19 ` Catalin Marinas
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