Re: [PATCH] efi: let the generic relocate code handle all relocations

[Sascha Hauer <s.hauer@pengutronix.de>]

On Tue, Apr 05, 2016 at 09:33:25AM +0200, Michael Olbrich wrote:
> Part of the barebox code and variables are put in separate sections
> (.barebox* and .initcall*). When this code is compiled as position
> independent code then the compiler creates corresponding .rela.barebox* and
> .rela.initcall* sections with the relocation table entries.
> These sections don't match the .rela.data* wildcard in the linker script.
> As a result, they are not added to the .rela section during linking but are
> added individually after it instead. And when the EFI binary is created
> from the ELF binary, these sections are not copied.
> This has two side effects:
> 
> 1. The corresponding relocations are not handled by the generic relocation
> code. 'fixup_tables()' was added to do these relocations manually.
> 
> 2. In the DYNAMIC section, the RELASZ entry contains the total size of
> relocations in bytes. This includes the .rela.barebox* and .rela.initcall*
> sections. This value is not modified when the EFI binary is created. So the
> value is too large.
> The generic relocation code in _relocate() used this value when iterating
> over all relocation entries. With the wrong RELASZ value it iterates beyond
> the end of the .rela section into uninitialized memory. After power-on this
> memory is zero and the relocation code interprets this as 'nothing to do',
> so there is no visible effect. After a soft reset, random data in that area
> may produce a seemingly valid relocation entry, a random address is
> modified and barebox crashes.
> 
> This patch adds the .rela.barebox* and .rela.initcall* sections to the
> normal .rela section. The RELASZ now contains the correct size and the
> generic relocation code works correctly. 'fixup_tables()' must be removed
> at the same time to avoid relocating these entries twice.
> 
> Signed-off-by: Michael Olbrich <m.olbrich@pengutronix.de>
> ---
>  arch/efi/efi/efi.c                | 42 ---------------------------------------
>  arch/efi/lib/elf_x86_64_efi.lds.S |  2 ++
>  2 files changed, 2 insertions(+), 42 deletions(-)

Applied, thanks. And thanks for finally fixing this issue :)

Sascha


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