From: Konrad Rzeszutek Wilk <konrad@kernel.org>
To: Jan Beulich <JBeulich@suse.com>
Cc: andrew.cooper3@citrix.com, julien.grall@arm.com,
sstabellini@kernel.org, xen-devel@lists.xenproject.org
Subject: Re: [PATCH v2 3/5] xen/livepatch/ARM32: Don't load and crash on livepatches loaded with wrong alignment.
Date: Wed, 20 Sep 2017 11:12:13 -0400 [thread overview]
Message-ID: <20170920151211.GA5508@localhost.localdomain> (raw)
In-Reply-To: <59C14E2C020000780017CF18@prv-mh.provo.novell.com>
On Tue, Sep 19, 2017 at 09:04:44AM -0600, Jan Beulich wrote:
> >>> On 18.09.17 at 21:37, <konrad.wilk@oracle.com> wrote:
> > On Tue, Sep 12, 2017 at 02:57:04AM -0600, Jan Beulich wrote:
> >> >>> On 12.09.17 at 02:22, <konrad@kernel.org> wrote:
> >> > If I compile the test-case under ARM32 it works OK (as the
> >> > .livepatch.depends ends up being aligned to four bytes).
> >>
> >> So why is that? What entity is creating this section (or the
> >> directive(s) to create it)?
> >
> > gcc
> >
> > Looking at the xen_bye_world.o produced by cross-compiler:
> >
> > xen_bye_world.o: file format elf32-littlearm
> >
> > Contents of section .rodata:
> > 0000 78656e5f 65787472 615f7665 7273696f xen_extra_versio
> > 0010 6e00 n.
> >
> > And native:
> >
> > xen_bye_world.o: file format elf32-littlearm
> >
> > Contents of section .rodata:
> > 0000 78656e5f 65787472 615f7665 7273696f xen_extra_versio
> > 0010 6e000000 n...
>
> This may rather be a gas than a gcc behavioral difference. What's
> the alignment of .rodata in both cases?
Cross:
* on the livepatch:
..snip..
[ 4] .rodata PROGBITS 00000000 000074 000012 00 A 0 0 4
[ 5] .rodata.str1.4 PROGBITS 00000000 000088 00000b 01 AMS 0 0 4
[ 6] .livepatch.depend PROGBITS 00000000 000093 000024 00 A 0 0 1
* on the .o file:
Section Headers:
[Nr] Name Type Addr Off Size ES Flg Lk Inf Al
.. snip..
[ 1] .text PROGBITS 00000000 000034 000000 00 AX 0 0 1
[ 2] .data PROGBITS 00000000 000034 000000 00 WA 0 0 1
[ 3] .bss NOBITS 00000000 000034 000000 00 WA 0 0 1
[ 4] .rodata PROGBITS 00000000 000034 000014 00 A 0 0 4
[ 5] .livepatch.funcs PROGBITS 00000000 000048 000034 00 WA 0 0 4
Native:
* on the livepatch:
..snip..
[ 4] .rodata PROGBITS 00000000 000074 000014 00 A 0 0 4
[ 5] .rodata.str1.4 PROGBITS 00000000 000088 00000c 01 AMS 0 0 4
[ 6] .livepatch.depend PROGBITS 00000000 000094 000024 00 A 0 0 1
* on the .o file:
..snip..
[ 1] .text PROGBITS 00000000 000034 000000 00 AX 0 0 1
[ 2] .data PROGBITS 00000000 000034 000000 00 WA 0 0 1
[ 3] .bss NOBITS 00000000 000034 000000 00 WA 0 0 1
[ 4] .rodata PROGBITS 00000000 000034 000012 00 A 0 0 4
[ 5] .livepatch.funcs PROGBITS 00000000 000048 000034 00 WA 0 0 4
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next prev parent reply other threads:[~2017-09-20 15:12 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-26 19:47 [PATCH v2] Livepatch fixes for v4.10 (v2) Konrad Rzeszutek Wilk
2017-07-26 19:47 ` [PATCH v2 1/5] livepatch: Tighten alignment checks Konrad Rzeszutek Wilk
2017-07-31 13:46 ` Jan Beulich
2017-07-26 19:47 ` [PATCH v2 2/5] livepatch: Include sizes when an mismatch occurs Konrad Rzeszutek Wilk
2017-07-31 13:51 ` Jan Beulich
2017-07-26 19:47 ` [PATCH v2 3/5] xen/livepatch/ARM32: Don't load and crash on livepatches loaded with wrong alignment Konrad Rzeszutek Wilk
2017-07-26 22:27 ` Andrew Cooper
2017-07-31 13:55 ` Jan Beulich
2017-07-31 16:04 ` Konrad Rzeszutek Wilk
2017-08-02 9:20 ` Jan Beulich
2017-09-07 17:36 ` Konrad Rzeszutek Wilk
2017-09-08 9:30 ` Jan Beulich
2017-09-09 12:05 ` Konrad Rzeszutek Wilk
2017-09-11 9:01 ` Jan Beulich
2017-09-12 0:22 ` Konrad Rzeszutek Wilk
2017-09-12 8:57 ` Jan Beulich
2017-09-18 19:37 ` Konrad Rzeszutek Wilk
2017-09-19 15:04 ` Jan Beulich
2017-09-20 15:12 ` Konrad Rzeszutek Wilk [this message]
2017-09-20 15:51 ` Jan Beulich
2017-07-26 19:47 ` [PATCH v2 4/5] alternative/x86/arm32: Align altinstructions (and altinstr_replacement) sections Konrad Rzeszutek Wilk
2017-07-31 14:01 ` Jan Beulich
2017-09-11 18:59 ` Konrad Rzeszutek Wilk
2017-07-26 19:47 ` [PATCH v2 5/5] livepatch: Declare live patching as a supported feature Konrad Rzeszutek Wilk
2017-07-31 14:03 ` Jan Beulich
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