[Patch, AArch64, LD/BFD] Cortex-A53 Erratum 835769 -- LD segfaults with unordered maps.

[Tejas Belagod <tejas dot belagod at arm dot com>]

Hi,

The BFD/LD patch for Cortex-A53 erratum 
835769(https://sourceware.org/ml/binutils/2014-10/msg00199.html) does 
not handle a particular case of the AArch64 ELF ABI where mapping 
symbols are allowed to be unordered in the symbol table(not in address 
order). The unordering causes section maps to be traversed with 
incorrect span boundaries(in the erratum scanning function) which causes 
memory faults. The attached patch fixes this issue by ordering the 
section maps by their 'vma' before starting to traverse them.

While this is not an issue with a the GNU toolchain, it is a potential 
issue with Clang/LLVM. We have observed atleast one case where LLVM 
generates an ELF object with mapping symbols unordered in the symbol 
table and causes a fault. We have been unable to construct a test case 
with the GNU toolchain. We have verified by manual inspection the 
correctness of the traversal with this patch for an LLVM-generated ELF 
object which triggered this issue. This patch has been bootstrapped on 
aarch64-linux and regressed.

OK for trunk, 2.24 and 2.25?

Thanks,
Tejas.

Changelog:

2014-11-21  Tejas Belagod  <tejas.belagod@arm.com>

	* elfnn-aarch64.c (erratum_835769_scan): Sort map list.
	(elf_aarch64_compare_mapping): New.

Attachment: a_53-erratum-224-8-1.txt
Description: Text document