On Fri, Jan 12, 2018 at 7:52 AM, Andrew Turner <and...@freebsd.org> wrote:
> > > On 12 Jan 2018, at 14:37, Warner Losh <i...@bsdimp.com> wrote: > > > > On Fri, Jan 12, 2018 at 7:15 AM, Andrew Turner <and...@freebsd.org> wrote: > >> >> >> On 12 Jan 2018, at 14:10, Marcin Wojtas <m...@semihalf.com> wrote: >> >> Hi Andrew, >> >> >> >> 2018-01-12 15:01 GMT+01:00 Andrew Turner <and...@freebsd.org>: >> >> Author: andrew >> Date: Fri Jan 12 14:01:38 2018 >> New Revision: 327876 >> URL: https://svnweb.freebsd.org/changeset/base/327876 >> >> Log: >> Workaround Spectre Variant 2 on arm64. >> >> We need to handle two cases: >> >> 1. One process attacking another process. >> 2. A process attacking the kernel. >> >> For the first case we clear the branch predictor state on context switch >> between different processes. For the second we do this when taking an >> instruction abort on a non-userspace address. >> >> To clear the branch predictor state a per-CPU function pointer has been >> added. This is set by the new cpu errata code based on if the CPU is >> known to be affected. >> >> On Cortex-A57, A72, A73, and A75 we call into the PSCI firmware as newer >> versions of this will clear the branch predictor state for us. >> >> It has been reported the ThunderX is unaffected, however the ThunderX2 is >> vulnerable. The Qualcomm Falkor core is also affected. As FreeBSD doesn't >> yet run on the ThunderX2 or Falkor no workaround is included for these >> CPUs. >> >> >> Regardless ThunderX2 / Falkor work-arounds, do I understand correctly >> that pure CA72 machines, such as Marvell Armada 7k/8k are immune to >> Variant 2 now? >> >> >> It is my understanding that the A72 will be immune with this patch and an >> updated Arm Trusted Firmware as documented in [1]. >> >> Andrew >> >> [1] https://github.com/ARM-software/arm-trusted-firmware/wik >> i/ARM-Trusted-Firmware-Security-Advisory-TFV-6 >> > > Are you also working on aarch32 mitigation? > > > No. I think a similar technique could be used, however as aarch32 has > instructions to invalidate the branch predictor these can be used directly. > That's my reading as well. It looks fairly easy to do it always, but I've not researched it sufficiently. Warner _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
