On Thu, May 01, 2014 at 10:31:06AM +0100, Peter Maydell wrote: > On 1 May 2014 10:02, Alex Bennée <alex.ben...@linaro.org> wrote: > > > > Edgar E. Iglesias <edgar.igles...@gmail.com> writes: > > > >> From: "Edgar E. Iglesias" <edgar.igles...@xilinx.com> > >> > >> For linked branches, updates to the link register happen > >> conceptually after the read of the branch target register. > >> > >> Signed-off-by: Edgar E. Iglesias <edgar.igles...@xilinx.com> > > > > I'm trying to think of a case where this could actually cause a problem > > but I can't. However from a clarity/correctness point of view it's > > better. > > Well, we actually misexecute "BLR LR" otherwise, right? > That's probably not very common but there's no reason it > might not occur (eg call to a function pointer from a > function where LR has been saved on entry and is free > for use as a generic tempreg).
Right. For example, the kernel/kvm actually does this in arch/arm64/kvm/hyp.S:773: blr lr Thanks, Edgar
