On Tue, Apr 16, 2019 at 9:03 PM Kees Cook <keesc...@chromium.org> wrote: > > On Tue, Apr 16, 2019 at 12:08 PM Mark Rutland <mark.rutl...@arm.com> wrote: > > > > On Mon, Apr 15, 2019 at 10:22:27AM -0700, Nick Desaulniers wrote: > > > On Mon, Apr 15, 2019 at 10:06 AM Mark Rutland <mark.rutl...@arm.com> > > > wrote: > > > > It would be nice if we could simply rely on a more recent binutils these > > > > days, which supports the generic S<op0>_<op1>_<cn>_<Cm>_<op2> sysreg > > > > definition. That would mean we could get rid of the whole msr_s/mrs_s > > > > hack by turning that into a CPP macro which built that name.
Mark, can you give me a test case for this? I'd like to check if clang's integrated assembler supports this or not, so we can file an issue and fix it if not. > > > > > > > > It looks like binutils has been able to do that since September 2014... > > > > > > > > Are folk using toolchains older than that to compile kernels? > > > > > > Do you have a link to a commit? If we can pinpoint the binutils > > > version, that might help. > > > > IIUC any version of binutils with commit: > > > > df7b4545b2b49572 ("[PATCH/AArch64] Generic support for all system > > registers using mrs and msr") > > > > ... should be sufficent. > > This appears to be binutils 2.25: > > $ git describe --match 'binutils-2_*' --contains df7b4545b2b49572 > binutils-2_25~418 > > Documentation/process/changes.rst lists 2.20 as current minimum for binutils. > > Ubuntu's old LTS (Trusty, Apr 2014) has 2.24, and that release is > about to exit support this month. > > Debian's old-stable (Apr 2015) has 2.25. It's about to exit support > when Debian Buster releases. > > RHEL6 (2010) has 2.20. RHEL7 (2014) has 2.25. > > It seems not unreasonable to require 2.25 at least for arm64 builds? + Arnd who has a really good feel for which distros ship what. -- Thanks, ~Nick Desaulniers