On Wed, Nov 14, 2012 at 07:56:18PM +0400, Alexander Potapenko wrote: > Hi Rainer, > > The quick answer is no, although the expansion into GCC world may > require such a guideline. > We've initially implemented ASan on Linux and then ported it to > Android (which is very similar to Linux) and Mac (which is very > different), so we have little experience with porting yet. > I've summarized the differences between Linux and Mac here: > https://code.google.com/p/address-sanitizer/wiki/AddressSanitizerForMacImplementationDetails > > The core things to pay attention at are function wrapping (e.g. dlsym > on Linux, mach_override on Mac), hooking the allocations/deallocations > in the program, stack unwinding (already done for x86 and ARM), thread > creation, early initialization, debug info and symbolization. Maybe > something else. In fact if any of these points work on your platform > differently than they do on Linux/Mac, you'll have to re-implement > those. > > Regarding mach_override, it's a Mac OS-specific thing that we use > because dlsym doesn't reliably override functions (keywords: two-level > namespace) > This only works on x86/x86_64 and is just a bunch of ad-hoc hacks to > hot-patch the library code. > Extending the instruction table in mach_override.c is irrelevant to > porting, it's just a mean of making it work with some newer libraries > provided by Apple. > It won't work on any other OS (well, without some refactoring; in fact > it's possible to use it on Linux) or any other arch (one could rewrite > mach_override.c for ARM, but iOS doesn't allow code patching). > > I'm working on a replacement for mach_override, which will compile > libasan as a dynamic library on Mac OS and preload it before running > the program. > It's not ready yet, so the easiest thing for GCC will be to add some > more instructions to mach_override and stick to it for now.
Alex, Please see... http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55289#c27 So far for all the test cases that I have looked at, the problem seems to be when mach_overrride.c hits the opcodes... 48 8d 5 Can you suggest a patch for that one? It may be the only blocker to asan support on darwin (for x86_64 anyway). Jack > > Alex > > On Wed, Nov 14, 2012 at 7:08 PM, Rainer Orth > <r...@cebitec.uni-bielefeld.de> wrote: > > Hi Alex, > > > >> most certainly the functionality of asan is not intact. > >> The error messages denote that mach_override couldn't parse some of > >> the function prologues, which means some of ASan interceptors just > >> won't work. > >> In order to fix this you need to change the DEBUG definition in > >> mach_override.c, look at the bytes being parsed and fix the > >> instruction table in mach_override.c > > > > is there some guideline how to port asan to a new OS or CPU? That would > > certainly be easier than figuring things out on your own one by one. I > > guess several target and os port maintainers would want to do so in GCC. > > > > Thanks. > > Rainer > > > > -- > > ----------------------------------------------------------------------------- > > Rainer Orth, Center for Biotechnology, Bielefeld University > > > > -- > Alexander Potapenko > Software Engineer > Google Moscow
