On 16.04.21 00:21, Sean Christopherson wrote:
Drop the instrumentation_{begin,end}() annonations from the common KVM
guest enter/exit helpers, and massage the x86 code as needed to preserve
the necessary annotations. x86 is the only architecture whose transition
flow is tagged as noinstr, and more specifically, it is the only
architecture for which instrumentation_{begin,end}() can be non-empty.
No other architecture supports CONFIG_STACK_VALIDATION=y, and s390 is the
only other architecture that support CONFIG_DEBUG_ENTRY=y. For
instrumentation annontations to be meaningful, both aformentioned configs
must be enabled.
Letting x86 deal with the annotations avoids unnecessary nops by
squashing back-to-back instrumention-safe sequences.
We have considered implementing objtool for s390. Not sure where we
stand and if we will do this or not. Sven/Heiko?
So maybe drop this patch until every other arch agrees that there are
no plans to implement this.
