[PATCH v4 00/12] ARM: vfp: Switch to C API to en/disable softirqs

[Guenter Roeck]

On Mon, Mar 20, 2023 at 02:18:33PM +0100, Ard Biesheuvel wrote:
> As it turns out, enabling or disabling softirqs from asm code is more
> tricky than it looks. Simply bumping the associated bit in preempt_count
> does the trick for uninstrumented kernels, but with lockdep or preempt
> debug enabled, we really need to call the C versions, as replicating
> their behavior in asm fully is intractible.
> 
> So let's rework the existing code a little bit so we can interpose a
> little C helper 'vfp_entry()' that disables softirqs before calling the
> existing vfpstate handling code in asm. Re-enabling softirqs from asm
> code is more straight-forward, as we can simply perform a tail call via
> a C routine that is guaranteed to be callable as a function.
> 
> However, since calling these APIs from asm code is still not ideal,
> let's reimplement the whole thing in C (patch #4)
> 

FWIW, all my qemu tests passed for this series.

Guenter