[U-Boot] [PATCH] efi_loader: Rename sections to allow for implicit data

[Simon Glass]

Hi,

On 9 August 2018 at 23:45, Bin Meng <bmeng.cn at gmail.com> wrote:
>
> Hi Alex,
>
> On Wed, Aug 8, 2018 at 1:16 AM, Alexander Graf <agraf at suse.de> wrote:
> >
> >
> >> Am 07.08.2018 um 18:12 schrieb Simon Glass <sjg at chromium.org>:
> >>
> >> Hi Alex,
> >>
> >>> On 11 June 2018 at 23:48, Alexander Graf <agraf at suse.de> wrote:
> >>> Some times gcc may generate data that is then used within code that may
> >>> be part of an efi runtime section. That data could be jump tables,
> >>> constants or strings.
> >>>
> >>> In order to make sure we catch these, we need to ensure that gcc emits
> >>> them into a section that we can relocate together with all the other
> >>> efi runtime bits. This only works if the -ffunction-sections and
> >>> -fdata-sections flags are passed and the efi runtime functions are
> >>> in a section that starts with ".text".
> >>>
> >>> Up to now we had all efi runtime bits in sections that did not
> >>> interfere with the normal section naming scheme, but this forces
> >>> us to do so. Hence we need to move the efi_loader text/data/rodata
> >>> sections before the global *(.text*) catch-all section.
> >>>
> >>> With this patch in place, we should hopefully have an easier time
> >>> to extend the efi runtime functionality in the future.
> >>>
> >>> Signed-off-by: Alexander Graf <agraf at suse.de>
> >>> ---
> >>> arch/arm/config.mk                        |  4 ++--
> >>> arch/arm/cpu/armv8/u-boot.lds             | 24 +++++++++++++--------
> >>> arch/arm/cpu/u-boot.lds                   | 36 ++++++++++++++++++-------------
> >>> arch/arm/mach-zynq/u-boot.lds             | 36 ++++++++++++++++++-------------
> >>> arch/riscv/cpu/ax25/u-boot.lds            | 26 +++++++++++++---------
> >>> arch/sandbox/config.mk                    |  3 +++
> >>> arch/sandbox/cpu/u-boot.lds               |  9 ++++----
> >>> arch/x86/config.mk                        |  2 +-
> >>> arch/x86/cpu/u-boot.lds                   | 32 ++++++++++++++-------------
> >>> board/qualcomm/dragonboard410c/u-boot.lds | 17 +++++++++++++--
> >>> board/qualcomm/dragonboard820c/u-boot.lds | 24 +++++++++++++--------
> >>> board/ti/am335x/u-boot.lds                | 36 ++++++++++++++++++-------------
> >>> include/efi_loader.h                      |  4 ++--
> >>> 13 files changed, 154 insertions(+), 99 deletions(-)
> >>>
> >>
> >> I missed this at the time, probably thinking the subject made it sound
> >> innocuous. There is no 'sandbox:' tag.
> >>
> >> This seems to break sandbox in a pretty strange way:
> >>
> >> gdb --args /tmp/crosfw/sandbox/u-boot -D
> >> GNU gdb (Debian 7.12-6) 7.12.0.20161007-git
> >> Copyright (C) 2016 Free Software Foundation, Inc.
> >> License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
> >> This is free software: you are free to change and redistribute it.
> >> There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
> >> and "show warranty" for details.
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> >> Reading symbols from /tmp/crosfw/sandbox/u-boot...done.
> >> (gdb) r
> >> Starting program: /tmp/crosfw/sandbox/u-boot -D
> >> [Thread debugging using libthread_db enabled]
> >> Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
> >>
> >> Program received signal SIGSEGV, Segmentation fault.
> >> 0x0000555555571520 in open at plt ()
> >> (gdb) up
> >> #1  0x0000555555571e9a in sandbox_read_fdt_from_file ()
> >>    at /home/sjg/c/src/third_party/u-boot/files/arch/sandbox/cpu/cpu.c:264
> >> 264 fd = os_open(fname, OS_O_RDONLY);
> >> (gdb) print fname
> >> $1 = 0x7ffff7ff0000 "/tmp/crosfw/sandbox/u-boot.dtb"
> >> (gdb) q
> >>
> >>
> >> Also the commit message suggests that this patch changes sandbox to
> >> use --gc-sections, which is not obvious from the subject. I think that
> >> should be a separate commit and in fact it should really be separate
> >> commits for each arch, I think. That might help people notice it...
> >>
> >> I only noticed now since the EFI pull request has landed.
> >
> > Can you try my bss patch really quick? Maybe we're just overwriting gd.
> >
> > Alex
> >
>
> This patch breaks efi-x86_app_defconfig. The EFI application no longer
> boots. I was testing on top of u-boot/master.
>
> If I do:
>
> diff --git a/arch/x86/config.mk b/arch/x86/config.mk
> index 586e11a..fc119ec 100644
> --- a/arch/x86/config.mk
> +++ b/arch/x86/config.mk
> @@ -24,7 +24,6 @@ endif
>  ifeq ($(IS_32BIT),y)
>  PLATFORM_CPPFLAGS += -march=i386 -m32
>  # TODO: These break on x86_64; need to debug further
> -PLATFORM_RELFLAGS += -fdata-sections
>  else
>  PLATFORM_CPPFLAGS += $(if $(CONFIG_SPL_BUILD),,-fpic) -fno-common -m64
>  endif
>
> Then it boots again. Can you please take a look?
>
> Regards,
> Bin

Please can we revert the offending patch quickly for the release? I am
not comfortable with the sandbox changes either (data-sections, etc.).

Regards,
Simon