On Fri, 20 Dec 2019 at 20:27, Beata Michalska <beata.michal...@linaro.org> wrote: > > On ARMv7 & ARMv8 some load/store instructions might trigger a data abort > exception with no valid ISS info to be decoded. The lack of decode info > makes it at least tricky to emulate those instruction which is one of the > (many) reasons why KVM will not even try to do so. > > Add suport for handling those by requesting KVM to inject external > dabt into the quest. > > Signed-off-by: Beata Michalska <beata.michal...@linaro.org> > --- > + /* > + * Get current PC before it will get updated to except vector entry > + */ > + target_ulong ins_addr = is_a64(env) ? env->pc > + /* AArch32 mode vs T32 aka Thumb mode */ > + : env->regs[15] - (env->thumb ? 4 : 8);
Another thing that occurred to me last night -- why do we need to do this adjustment of the PC/r15 ? If this is the kernel handing control to userspace to say "this is not an instruction I can handle, maybe you'd like to try" then surely it should do so with the PC pointing at the offending instruction? Similarly, if we ask the kernel to inject a data abort I would expect that the kernel would do the work of adjusting the PC forwards as the architecture requires when taking the exception. thanks -- PMM
