[lld] r293519 - ELF: Align RELRO to the target page size rather than the max page size.

[Rui Ueyama via llvm-commits]

Yes please.

On Jan 30, 2017 10:32 AM, "Peter Collingbourne" <peter at pcc.me.uk> wrote:

> ruiu: OK to backport this to the 4.0 branch?
>
> Peter
>
> On Mon, Jan 30, 2017 at 10:20 AM, Peter Collingbourne via llvm-commits <
> llvm-commits at lists.llvm.org> wrote:
>
>> Author: pcc
>> Date: Mon Jan 30 12:20:07 2017
>> New Revision: 293519
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=293519&view=rev
>> Log:
>> ELF: Align RELRO to the target page size rather than the max page size.
>>
>> If no bss sections appear after the relro segment, the loader will round
>> the r/w segment size to the target's page size. Align the relro size in
>> the
>> same way to ensure that it does not extend past the end of the program's
>> own memory region.
>>
>> Differential Revision: https://reviews.llvm.org/D29242
>>
>> Added:
>>     lld/trunk/test/ELF/aarch64-relro.s
>> Modified:
>>     lld/trunk/ELF/Writer.cpp
>>
>> Modified: lld/trunk/ELF/Writer.cpp
>> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Writer.cpp
>> ?rev=293519&r1=293518&r2=293519&view=diff
>> ============================================================
>> ==================
>> --- lld/trunk/ELF/Writer.cpp (original)
>> +++ lld/trunk/ELF/Writer.cpp Mon Jan 30 12:20:07 2017
>> @@ -1498,7 +1498,7 @@ template <class ELFT> void Writer<ELFT>:
>>        // The glibc dynamic loader rounds the size down, so we need to
>> round up
>>        // to protect the last page. This is a no-op on FreeBSD which
>> always
>>        // rounds up.
>> -      P.p_memsz = alignTo(P.p_memsz, Config->MaxPageSize);
>> +      P.p_memsz = alignTo(P.p_memsz, Target->PageSize);
>>      }
>>
>>      // The TLS pointer goes after PT_TLS. At least glibc will align it,
>>
>> Added: lld/trunk/test/ELF/aarch64-relro.s
>> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/aarch
>> 64-relro.s?rev=293519&view=auto
>> ============================================================
>> ==================
>> --- lld/trunk/test/ELF/aarch64-relro.s (added)
>> +++ lld/trunk/test/ELF/aarch64-relro.s Mon Jan 30 12:20:07 2017
>> @@ -0,0 +1,13 @@
>> +# RUN: llvm-mc -filetype=obj -triple=aarch64-unknown-freebsd %s -o %t
>> +# RUN: ld.lld %t -o %t2
>> +# RUN: llvm-readobj -program-headers %t2 | FileCheck %s
>> +
>> +# CHECK:      Type: PT_GNU_RELRO
>> +# CHECK-NEXT: Offset:
>> +# CHECK-NEXT: VirtualAddress:
>> +# CHECK-NEXT: PhysicalAddress:
>> +# CHECK-NEXT: FileSize:
>> +# CHECK-NEXT: MemSize: 4096
>> +
>> +.section .data.rel.ro,"aw",%progbits
>> +.byte 1
>>
>>
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>>
>
>
>
> --
> --
> Peter
>
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