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

[Hans Wennborg via llvm-commits]

Sgtm.

Peter, go ahead and commit it to the branch (or let me know, and I'll do it).

On Mon, Jan 30, 2017 at 4:38 PM, Rui Ueyama via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
> 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/aarch64-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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>>> llvm-commits at lists.llvm.org
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>>
>>
>>
>>
>> --
>> --
>> Peter
>
>
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