On Fri, Jan 05, 2018 at 01:10:21PM +0100, Florian Weimer wrote: > On 01/05/2018 12:41 PM, Mark Wielaard wrote: > >On Thu, Jan 04, 2018 at 09:36:27PM -0800, John Reiser wrote: > >>2) The explicit write by the stack probe can mask a memcheck(valgrind) > >> violation, at least until memcheck groks the probe. > > > >That should not be true. The probe is done after the stack pointer is > >lowered, so memcheck/valgrind knows that memory is used. If the probe > >is done below the actual stack pointer that would be a bug in the gcc > >-fstack-protector implementation. Please do report such issues when you > >encounter them. There were indeed such bugs in the past on some > >architectures (especially in combination with no-return functions), > >but I believe they have all been fixed now. > > The generic -fstack-clash-protection in GCC has this problem, which > is why we can't use it and have to disable it on architectures where > there is no support, which currently includes armhfp. (For aarch64, > we still carry our own patch, and may have to continue doing that > even after switching to GCC 8.) I noticed as a side effect of compiling GCC for riscv64 that RISC-V's GCC doesn't support -fstack-clash-protection. Do you know what is involved to add it? From a naive point of view I don't understand why this feature depends on architecture at all. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com Fedora Windows cross-compiler. Compile Windows programs, test, and build Windows installers. Over 100 libraries supported. http://fedoraproject.org/wiki/MinGW _______________________________________________ devel mailing list -- devel@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxxxxxxxx
