https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86774
Richard Henderson <rth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2018-08-01
CC| |mattst88 at gmail dot com,
| |uros at gcc dot gnu.org
Ever confirmed|0 |1
--- Comment #1 from Richard Henderson <rth at gcc dot gnu.org> ---
Browsing back through old manuals, I think the only way to ensure
a barrier against speculation is the HW_REI/STALL instruction, but
that is available only to PALcode.
In an ideal world, we'd roll out a new PALcode entry point that
did nothing but issue a memory barrier and return with a stall.
Sadly, there will never again be a firmware update for Alphas.
Probably the best we can really do is just a trap barrier plus
a memory barrier. It's not a complete fix, but it would narrow
the window.
Unless someone can find an existing non-privileged PALcode entry
point that just so happens to end in HW_REI/STALL? I'm having
trouble tracking down any sources at the moment -- many of the
old domains have lapsed.
