[Buildroot] GNU Binutils 2.33.1 has been released.

Hi Tamar,

Le 15/10/2019 ? 15:38, Tamar Christina a ?crit?:

Hi Romain,

Thanks I was able to reproduce the segfault using that config.

I believe this is a bug in elf2flt.  Particularly the segfault happens here https://github.com/uclinux-dev/elf2flt/blob/master/elf2flt.c#L1464 
when dereferencing r_mem. 

r_mem is invalid because of https://github.com/uclinux-dev/elf2flt/blob/master/elf2flt.c#L532 which does

r_mem = sectionp + q->address;

here sectionp is invalid because of this code https://github.com/uclinux-dev/elf2flt/blob/master/elf2flt.c#L424

The section this is failing on is 

$26 = {
  name = 0x55a717912241 ".ARM.exidx"
  
.ARM.exidx is a RO data section which will get placed in the same segment as the text section and BFD usually places it after the text section, however the code in elf2flt.c does

if ((!pic_with_got || ALWAYS_RELOC_TEXT) && (a->flags & SEC_CODE))
	sectionp = text + (a->vma - text_vma);
else if (a->flags & SEC_DATA)
	sectionp = data + (a->vma - data_vma);

Which will incorrectly map it to data. Essentially it's overriding a random point in the data section.  Changing that code to map SEC_READONLY | SEC_DATA to text makes it compile and generate an image as expected.  I did not try running it.

Thanks for the investigation, I did the change you suggested and indeed busybox
build correctly and the image is generated as expected.
But I don't have the hardware to test it.

The best I can do is building for all architectures supported by Buildroot and
do a runtime test on the target I have (x86, ARM, aarch64).
The toolchain-builder project is testing with Qemu when a target emulation is
available.

But for this specific case, we don't have such Qemu support.

I think this was broken before already, but you wouldn't really notice it unless you actually had some stack traces to print.

Ok, I'll create an issue on elf2flt github.

Best regards,
Romain

Regards,
Tamar

quoted

-----Original Message-----
From: Romain Naour <redacted>
Sent: Monday, October 14, 2019 4:12 PM
To: Tamar Christina <redacted>; nickc at redhat.com
Cc: binutils at sourceware.org; buildroot <redacted>; nd
[off-list ref]
Subject: Re: GNU Binutils 2.33.1 has been released.

Hi Tamar, Nick,

Le 14/10/2019 ? 15:27, Tamar Christina a ?crit?:

quoted

Hi Romain,

What's the easiest way for me to reproduce this?

I've tried

    git clone https://github.com/RomainNaour/buildroot.git buildroot
    cd buildroot
    git checkout binutils-2.33.1

This is the correct way to reproduce it :)

quoted

    curl
https://toolchains.bootlin.com/downloads/releases/toolchains/armv7-eab
ihf/build_fragments/armv7-eabihf--uclibc--bleeding-edge-2018.11-1.defc
onfig > .config

This defconfig was used to only build the 2018.11-1 bleeding-edge toolchain.


Can you use the following defconfig ?
I'm able to reproduce it on my host

BR2_arm=y
BR2_cortex_m4=y
BR2_GLOBAL_PATCH_DIR="board/stmicroelectronics/stm32f469-
disco/patches"
BR2_KERNEL_HEADERS_4_19=y
BR2_TOOLCHAIN_BUILDROOT_LOCALE=y
BR2_PTHREAD_DEBUG=y
BR2_BINUTILS_VERSION_2_33_X=y
BR2_GCC_VERSION_9_X=y
BR2_TOOLCHAIN_BUILDROOT_CXX=y
BR2_LINUX_KERNEL=y
BR2_LINUX_KERNEL_CUSTOM_VERSION=y
BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="4.11"
BR2_LINUX_KERNEL_DEFCONFIG="stm32"
BR2_LINUX_KERNEL_CONFIG_FRAGMENT_FILES="$(LINUX_DIR)/arch/arm/c
onfigs/dram_0x00000000.config"
BR2_LINUX_KERNEL_IMAGE_TARGET_CUSTOM=y
BR2_LINUX_KERNEL_IMAGE_TARGET_NAME="xipImage"
BR2_LINUX_KERNEL_DTS_SUPPORT=y
BR2_LINUX_KERNEL_INTREE_DTS_NAME="stm32f469-disco"
BR2_PACKAGE_BUSYBOX_CONFIG="package/busybox/busybox-
minimal.config"
BR2_TARGET_ROOTFS_INITRAMFS=y
# BR2_TARGET_ROOTFS_TAR is not set
BR2_TARGET_AFBOOT_STM32=y
BR2_PACKAGE_HOST_OPENOCD=y

This defconfig was created by merging the two defconfig from [1].
The first one is used to build the toolchain.
The second one is used to build a kernel + the rootfs using the toolchain
previously generated.

[1] https://gitlab.com/kubu93/toolchains-builder/-/jobs/319395300

Best regards,
Romain

quoted

    make olddefconfig
    make -j

but All I keep hitting are options mismatch in gmp.

Thanks,
Tamar

quoted

-----Original Message-----
From: Nick Clifton <redacted>
Sent: Monday, October 14, 2019 6:45 AM
To: Romain Naour <redacted>; Tamar Christina
[off-list ref]
Cc: binutils at sourceware.org; buildroot <redacted>
Subject: Re: GNU Binutils 2.33.1 has been released.

Hi Romain,

quoted

I tested this new version using toolchain-builder project [1] and
discovered some regressions on arm cortex-m4 and SH4 architectures.

quoted

There is a segfault in elf2flt while building busybox:
"ld (ld-elf2flt):
/builds/kubu93/toolchains-builder/build/opt/armv7m--uclibc--bleeding
-e dge-2/arm-buildroot-uclinux-uclibcgnueabi/bin/elf2flt

Hmm, that is worrying, but I suppose that it could be a bug in
elf2flt rather than the binutils.  Maybe...

Is this problem specific to the ARM architecture ?  (Ie does elf2flt
work when compiled and run for other architecures ?)  If so, then I
would suspect a problem with the changes to the ARM specific code in
the BFD library, and I would probably ask one of the ARM regulars to
take a look.  (Hi Tamar...)

Are you able to find out where the segmentation fault is occurring ?
Is it inside the BFD library somewhere ?

quoted

- sh4 [4]: (sh4, binutils 2.33.1, kernel headers 4.19.79, Glibc |
uClibc-ng | musl, Qemu 3.1)

The system doesn't boot under Qemu.

*sigh* This one will probably be even harder to investigate.  Not
being familiar with Qemu, I do not what the best approach would be.
Can we get it to tell us why the boot fails ?  Does it think that a binary is

invalid somehow ?

quoted

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Cheers
  Nick