diff mbox

[v4,3/3] arm64/efi: isolate EFI stub from the kernel proper

Message ID CAKv+Gu-G1YS9Ha=-rtnPKJTOxBTrdSq6=Tqwq_GPW742JUE+2Q@mail.gmail.com
State New
Headers show

Commit Message

Ard Biesheuvel Oct. 27, 2015, 2:20 a.m. UTC 
On 27 October 2015 at 07:33, Jeremy Linton <jeremy.linton@arm.com> wrote:
> On 10/26/2015 05:26 PM, Jeremy Linton wrote:

>>

>> On 10/08/2015 02:02 PM, Ard Biesheuvel wrote:

>>>

>>> Since arm64 does not use a builtin decompressor, the EFI stub is built

>>> into the kernel proper. So far, this has been working fine, but actually,

>>> since the stub is in fact a PE/COFF relocatable binary that is executed

>>> at an unknown offset in the 1:1 mapping provided by the UEFI firmware, we

>>> should not be seamlessly sharing code with the kernel proper, which is a

>>> position dependent executable linked at a high virtual offset.

>>

>>

>> This patch appears to be causing a build break

>>

>>   STUBCPY drivers/firmware/efi/libstub/lib-sort.stub.o

>> 0000000000000000 R_AARCH64_ABS64   __efistub___crc_sort

>> drivers/firmware/efi/libstub/lib-sort.stub.o: absolute symbol references

>> not allowed in the EFI stub

>>

>> __kcrctab_sort:

>>      .xword    __crc_sort

>>      .weak    __crc_sort

>>      .text

>>

>>

>> Which is the EXPORT_SYMBOL() in sort.c combined with !CONFIG_MODVERSIONS.

>

>

>         Sorry, I that should be CONFIG_MODVERSIONS..

>


Hi Jeremy,

Thanks for the report. The following patch should fix it

-----------------8<----------------
From 1179099f89db54294f419493d152083fb8e5af3d Mon Sep 17 00:00:00 2001
From: Ard Biesheuvel <ard.biesheuvel@linaro.org>

Date: Tue, 27 Oct 2015 11:12:51 +0900
Subject: [PATCH] arm64/efi: fix libstub build under CONFIG_MODVERSIONS

Now that we strictly forbid absolute relocations in libstub code,
make sure that we don't emit any when CONFIG_MODVERSIONS is enabled,
by stripping the kcrctab sections from the object file. This fixes
a build problem under CONFIG_MODVERSIONS=y.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

---
 drivers/firmware/efi/libstub/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

-- 
2.1.4

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Comments

Ard Biesheuvel Oct. 30, 2015, 12:17 p.m. UTC | #1 
On 27 October 2015 at 23:44, Jeremy Linton <jeremy.linton@arm.com> wrote:
> On 10/26/2015 09:20 PM, Ard Biesheuvel wrote:

>>

>> Thanks for the report. The following patch should fix it

>

>

> Ard,

>

> Thanks, it does fix the build problem...

>

> Now to get the darn thing to boot (not related to this AFAIK).

>


Catalin,

Would you like me to resend this as a separate patch?

-- 
Ard.

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Mark Rutland Oct. 30, 2015, 2:35 p.m. UTC | #2 
[Adding Catalin to the To line]

On Fri, Oct 30, 2015 at 01:17:24PM +0100, Ard Biesheuvel wrote:
> On 27 October 2015 at 23:44, Jeremy Linton <jeremy.linton@arm.com> wrote:

> > On 10/26/2015 09:20 PM, Ard Biesheuvel wrote:

> >>

> >> Thanks for the report. The following patch should fix it

> >

> >

> > Ard,

> >

> > Thanks, it does fix the build problem...

> >

> > Now to get the darn thing to boot (not related to this AFAIK).

> >

> 

> Catalin,

> 

> Would you like me to resend this as a separate patch?


Ard's referring to the patch in a prior reply [1].

Mark.

[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2015-October/381074.html

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Catalin Marinas Oct. 30, 2015, 4:01 p.m. UTC | #3 
On Fri, Oct 30, 2015 at 01:17:24PM +0100, Ard Biesheuvel wrote:
> On 27 October 2015 at 23:44, Jeremy Linton <jeremy.linton@arm.com> wrote:

> > On 10/26/2015 09:20 PM, Ard Biesheuvel wrote:

> >>

> >> Thanks for the report. The following patch should fix it

> >

> >

> > Ard,

> >

> > Thanks, it does fix the build problem...

> >

> > Now to get the darn thing to boot (not related to this AFAIK).

> 

> Would you like me to resend this as a separate patch?


No need to but it would be good to get an Ack from Matt since it touches
drivers/firmware/efi/libstub/Makefile (the patch introducing
STUBCOPY_FLAGS was already acked).

-- 
Catalin

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diff mbox

Patch

diff --git a/drivers/firmware/efi/libstub/Makefile
b/drivers/firmware/efi/libstub/Makefile
index bca9a76cbd33..acc25d7c5da2 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -51,7 +51,7 @@  lib-$(CONFIG_EFI_ARMSTUB) += arm-stub.o fdt.o string.o \
 extra-$(CONFIG_EFI_ARMSTUB) := $(lib-y)
 lib-$(CONFIG_EFI_ARMSTUB) := $(patsubst %.o,%.stub.o,$(lib-y))

-STUBCOPY_FLAGS-y := -R .debug* -R *ksymtab*
+STUBCOPY_FLAGS-y := -R .debug* -R *ksymtab* -R *kcrctab*
 STUBCOPY_FLAGS-$(CONFIG_ARM64) += --prefix-alloc-sections=.init \
    --prefix-symbols=__efistub_
 STUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS