x86: Discard .note.gnu.property sections

When switching to kernel.org x86_64 gcc 11.1.0 toolchain, u-boot.rom
built from qemu-x86_defconfig no longer boots anymore. Investigation
shows that U-Boot fails at a very early stage during the boot process,
in fdtdec_prepare_fdt() where fdt_check_header() complains that there
is not a valid device tree found at gd->fdt_blob which points to _end.
Now _end points to an allocated section .note.gnu.property which of
course is wrong.

This issue is however not seen when using the default Ubuntu 20.04 gnu
toolchain (gcc 9.3.0 with binutils 2.34). Further investigation shows
that it is caused by a behavior change of binutils v2.36 which is part
of the kernel.org gcc 11.1.0 toolchain, via the following commit:

  939b95c77bf2 ("Linux/x86: Configure gas with --enable-x86-used-note by default")

In fact, there was already a regression bug report [1] for binutils two
months ago, but the binutils folks did not think it is a bug :(

To resolve this, there are several options:

* pass -Wa,-mx86-used-note=no to gas
* pass -R .note.gnu.property to objcopy
* discard the section in the linker script

Linux kernel uses the discard way [2], so let's do the same for U-Boot.

[1] https://sourceware.org/bugzilla/show_bug.cgi?id=27753
[2] commit 4caffe6a28d3 ("x86/vdso: Discard .note.gnu.property sections in vDSO")

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
This commit is contained in:
Bin Meng 2021-06-18 15:09:30 +08:00
parent 1ce892cb1c
commit 6fbe06a6ce
3 changed files with 3 additions and 0 deletions

View file

@ -107,4 +107,5 @@ SECTIONS
/DISCARD/ : { *(.plt*) }
/DISCARD/ : { *(.interp*) }
/DISCARD/ : { *(.gnu*) }
/DISCARD/ : { *(.note.gnu.property) }
}

View file

@ -82,6 +82,7 @@ SECTIONS
/DISCARD/ : { *(.plt*) }
/DISCARD/ : { *(.interp*) }
/DISCARD/ : { *(.gnu*) }
/DISCARD/ : { *(.note.gnu.property) }
#if defined(CONFIG_SPL_X86_16BIT_INIT) || defined(CONFIG_TPL_X86_16BIT_INIT)
/*

View file

@ -105,6 +105,7 @@ SECTIONS
/DISCARD/ : { *(.plt*) }
/DISCARD/ : { *(.interp*) }
/DISCARD/ : { *(.gnu*) }
/DISCARD/ : { *(.note.gnu.property) }
#ifdef CONFIG_X86_16BIT_INIT
/*