Peter Collingbourne <pcc@xxxxxxxxxx> writes: > The kernel currently clears the tag bits (i.e. bits 56-63) in the fault > address exposed via siginfo.si_addr and sigcontext.fault_address. However, > the tag bits may be needed by tools in order to accurately diagnose > memory errors, such as HWASan [1] or future tools based on the Memory > Tagging Extension (MTE). > > We should not stop clearing these bits in the existing fault address > fields, because there may be existing userspace applications that are > expecting the tag bits to be cleared. Instead, introduce a flag in > sigaction.sa_flags, SA_EXPOSE_TAGBITS, and only expose the tag bits > there if the signal handler has this flag set. > > In order to allow userspace to determine whether SA_EXPOSE_TAGBITS > is supported, we first introduce a mechanism for userspace to detect > kernel support for SA_* flags. > > These patches need to be applied on top of: > https://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git signal-for-v5.11 The first two patches look good and I have applied them. While I was at it I added Link tags to the LKML postings to the entire series. I don't think anyone has merged my branch into another so it should still be safe. Eric
