[cfe-commits] [llvm-commits] [PATCH] [asan] Use zero-based shadow by default on Android

[Chandler Carruth]

On Fri, May 25, 2012 at 3:16 AM, Evgeniy Stepanov <eugeni.stepanov at gmail.com
> wrote:

> On Wed, May 23, 2012 at 4:07 PM, Evgeniy Stepanov
> <eugeni.stepanov at gmail.com> wrote:
> > Good point. Both patches landed, here is another one that adds a
> > driver check for -pie.
>
> ping w/ a patch
>

LGTM

The diagnostic says that '-pie' is required with ASan on Android, but
nothing about during compiling vs. during linking? Do we blanket require
this flag, or does it only apply to some steps? Might be nice to make the
diagnostic explicit here.


>
>
> > On Wed, May 23, 2012 at 3:04 PM, Chandler Carruth <chandlerc at google.com>
> wrote:
> >> On Wed, May 23, 2012 at 3:58 AM, Evgeniy Stepanov
> >> <eugeni.stepanov at gmail.com> wrote:
> >>>
> >>> Note that this change will require building binaries with -fPIE -pie.
> >>> I believe there is really no way around this. We can not change shadow
> >>> location on a per-binary basic because of the shared runtime, and
> >>> there is no universal location that fit both PIE and non-PIE.
> >>>
> >>> I'm going to land this soon, then add some runtime checks to ensure
> >>> that the shadow does not silently override any preexisting mappings.
> >>
> >>
> >> I haven't looked at the patches, but it would be good to also teach the
> >> Clang driver to produce an error if the appropriate options are not
> attached
> >> to the compile and link commands but '-faddress-sanitizer' is.
> >>
> >>>
> >>>
> >>> On Tue, May 22, 2012 at 6:43 PM, Kostya Serebryany <kcc at google.com>
> wrote:
> >>> > Both look good, thanks!
> >>> > --kcc
> >>> >
> >>> > On Tue, May 22, 2012 at 6:38 PM, Evgeniy Stepanov
> >>> > <eugeni.stepanov at gmail.com> wrote:
> >>> >>
> >>> >> Hi,
> >>> >>
> >>> >> these patches (one to llvm, another to compiler-rt) change ASan
> >>> >> default shadow offset on Android to zero. This seems to marginally
> >>> >> improve performance of Thumb code, significantly (~5%) saves code
> >>> >> size, and avoids address space collisions with the main executable
> in
> >>> >> a non-ASLR case.
> >>> >>
> >>> >> Please review.
> >>> >>
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