From: linux@armlinux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] ARM: compressed: discard ksym/kcrctab input section
Date: Wed, 4 Oct 2017 13:43:20 +0100 [thread overview]
Message-ID: <20171004124320.GP20805@n2100.armlinux.org.uk> (raw)
In-Reply-To: <CAKv+Gu_pGeDxK_vD9iGUO486VgLsntMQwVs9wGKa79pkx7paMQ@mail.gmail.com>
On Wed, Oct 04, 2017 at 01:20:26PM +0100, Ard Biesheuvel wrote:
> On 4 October 2017 at 13:16, Gregory CLEMENT
> <gregory.clement@free-electrons.com> wrote:
> > Hi Ard,
> >
> > On ven., sept. 08 2017, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:
> >
> >> As it turns out, building the ARM kernel with EFI support pulls in
> >> a couple of sections that we don't really need in the decompressor.
> >> This is due to the fact the the UEFI stub uses sort() to sort the UEFI
> >> memory map, which is an exported symbol pulled in from lib/sort.c.
> >>
> >> Before commit e4bae4d0b5f3 ("arm/efi: Split zImage code and data into
> >> separate PE/COFF sections"), this resulted in the following layout
> >> for the decompressor ELF binary.
> >>
> >> [Nr] Name Type Addr Off Size ES Flg Lk Inf Al
> >> [ 0] NULL 00000000 000000 000000 00 0 0 0
> >> [ 1] .text PROGBITS 00000000 010000 009b3c 00 AX 0 0 512
> >> [ 2] .rodata PROGBITS 00009b3c 019b3c 001684 00 A 0 0 4
> >> [ 3] __ksymtab_strings PROGBITS 0000b1c0 01b1c0 000005 00 A 0 0 1
> >> [ 4] .data PROGBITS 0000b1c8 01b1c8 000020 00 WA 0 0 8
> >> [ 5] ___ksymtab+sort PROGBITS 0000b1e8 01b1e8 000008 00 WA 0 0 4
> >> [ 6] .piggydata PROGBITS 0000b1f0 01b1f0 77ac38 00 A 0 0 1
> >> [ 7] .got.plt PROGBITS 00785e28 795e28 00000c 04 WA 0 0 4
> >> [ 8] .got PROGBITS 00785e34 795e34 000028 00 WA 0 0 4
> >> [ 9] .pad PROGBITS 00785e5c 795e5c 000004 00 WA 0 0 1
> >> [10] .bss NOBITS 00785e60 795e60 00001c 00 WA 0 0 4
> >> [11] .stack NOBITS 00785e80 795e60 001000 00 WA 0 0 1
> >>
> >> Commit e4bae4d0b5f3 made some changes to the linker script to allow the
> >> UEFI firmware to map the decompressor with strict R-X/RW- permissions
> >> before invoking it. Unfortunately, this turns out to break the boot on
> >> some systems, because the linker now also moves the ksymtab/kcrctab
> >> sections around, resulting in .piggydata to appear misaligned.
> >>
> >> [Nr] Name Type Addr Off Size ES Flg Lk Inf Al
> >> [ 0] NULL 00000000 000000 000000 00 0 0 0
> >> [ 1] .text PROGBITS 00000000 010000 00a93c 00 AX 0 0 4096
> >> [ 2] .rodata PROGBITS 0000a93c 01a93c 001684 00 A 0 0 4
> >> [ 3] __ksymtab_strings PROGBITS 0000bfc0 01bfc0 000005 00 A 0 0 1
> >> [ 4] .piggydata PROGBITS 0000bfc5 01bfc5 77ac47 00 A 0 0 1
> >> [ 5] .got.plt PROGBITS 00786c0c 796c0c 00000c 04 WA 0 0 4
> >> [ 6] .got PROGBITS 00786c18 796c18 000028 00 WA 0 0 4
> >> [ 7] .pad PROGBITS 00786c40 796c40 000008 00 WA 0 0 1
> >> [ 8] .data PROGBITS 00787000 797000 000200 00 WA 0 0 4096
> >> [ 9] ___ksymtab+sort PROGBITS 00787200 797200 000008 00 WA 0 0 4
> >> [10] .bss NOBITS 00787208 797208 00001c 00 WA 0 0 4
> >> [11] .stack NOBITS 00787228 797208 001000 00 WA 0 0 1
> >>
> >> So let's align piggydata explicitly, and discard these sections from the
> >> binary.
> >>
> >> Cc: Russell King <linux@armlinux.org.uk>
> >> Fixes: e4bae4d0b5f3 ("arm/efi: Split zImage code and data into separate ...")
> >> Tested-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
> >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> >
> > Any new for this patch?
> >
> > It is not yet in v4.14-rc whereas "arm/efi: Split zImage code and data
> > into separate ..." was already merged. So currently I have many boards
> > which still does not boot in v4.14-rc3.
> >
>
> Russell, any objections?
It would be nice if there was something in the commit log that described
why we need to align data that is basically a byte stream, and which
decompressor methods it affects. Maybe the decompressors should cope
with a misaligned byte stream - what if (for example) someone supplies
the kernel with a compressed initramfs image that is not word aligned?
We already have people using non-page aligned compressed initramfs
images.
--
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
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next prev parent reply other threads:[~2017-10-04 12:43 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-08 15:31 [PATCH] ARM: compressed: discard ksym/kcrctab input section Ard Biesheuvel
2017-09-08 15:39 ` Gregory CLEMENT
2017-09-08 15:41 ` Ard Biesheuvel
2017-10-04 12:16 ` Gregory CLEMENT
2017-10-04 12:20 ` Ard Biesheuvel
2017-10-04 12:43 ` Russell King - ARM Linux [this message]
2017-10-09 12:39 ` Ard Biesheuvel
2017-10-12 9:24 ` Gregory CLEMENT
2017-10-12 9:45 ` Russell King - ARM Linux
2017-10-12 19:03 ` Ard Biesheuvel
2017-10-20 15:25 ` Gregory CLEMENT
2017-10-20 15:28 ` Ard Biesheuvel
2017-10-20 16:11 ` Russell King - ARM Linux
2017-10-20 16:20 ` Ard Biesheuvel
2017-10-20 16:32 ` Russell King - ARM Linux
2017-10-20 16:36 ` Ard Biesheuvel
2017-10-20 16:54 ` Russell King - ARM Linux
2017-10-20 17:12 ` Ard Biesheuvel
2017-10-21 7:56 ` Matthias Brugger
2017-10-21 8:14 ` Ard Biesheuvel
2017-10-22 22:00 ` Matthias Brugger
2017-10-23 9:29 ` Russell King - ARM Linux
2017-10-23 11:48 ` Russell King - ARM Linux
2017-10-23 21:17 ` Matthias Brugger
2017-10-23 22:19 ` Russell King - ARM Linux
2017-10-24 6:51 ` Matthias Brugger
2017-10-23 21:15 ` Matthias Brugger
2017-10-23 21:32 ` Matthias Brugger
2017-10-23 22:29 ` Russell King - ARM Linux
2017-10-24 8:36 ` Andrea Adami
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