On Fri, 27 Sep 2019, Volodymyr Babchuk wrote: > Julien Grall writes: > > > From: Mark Rutland <mark.rutl...@arm.com> > > > > In some cases, one side of an alternative sequence is simply a number of > > NOPs used to balance the other side. Keeping track of this manually is > > tedious, and the presence of large chains of NOPs makes the code more > > painful to read than necessary. > > > > To ameliorate matters, this patch adds a new alternative_else_nop_endif, > > which automatically balances an alternative sequence with a trivial NOP > > sled. > > > > In many cases, we would like a NOP-sled in the default case, and > > instructions patched in in the presence of a feature. To enable the NOPs > > to be generated automatically for this case, this patch also adds a new > > alternative_if, and updates alternative_else and alternative_endif to > > work with either alternative_if or alternative_endif. > > > > The alternative infrastructure was originally ported from Linux. So this > > is pretty much a straight backport from commit 792d47379f4d "arm64: > > alternative: add auto-nop infrastructure". The only difference is the > > nops macro added as not yet existing in Xen. > > > > Signed-off-by: Mark Rutland <mark.rutl...@arm.com> > > [will: use new nops macro to generate nop sequences] > > Signed-off-by: Will Deacon <will.dea...@arm.com> > > [julien: Add nops and port to Xen] > > Signed-off-by: Julien Grall <julien.gr...@arm.com> > Reviewed-by: Volodymyr Babchuk <volodymyr_babc...@epam.com>
Acked-by: Stefano Stabellini <sstabell...@kernel.org> _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
