On 24/08/2015 02:23, Emilio G. Cota wrote:
> +void HELPER(aie_st_pre)(CPUArchState *env, target_ulong vaddr)
> +{
> + if (unlikely(env->aie_lock_enabled)) {
> + if (env->aie_locked) {
> + return;
> + }
Now that I've reviewed your code more carefully, the approach you're
using looks more promising than I thought. There are advantages over
Alvise's code, namely:
- cache-line vs. page granularity
- avoiding the global TLB flush (due to the virtually indexed TLBs)
- easy support for user-mode emulation
and some of the disadvantages look more easily fixable than I thought,
too (e.g. TLB entry bloat).
The main advantage of Alvise's code, on the other hand, is the minimal
overhead when there are no active LL/SC combinations and the better
integration with TCG.
A random idea: would it be possible to move some of the helper code to
generated TCG code? For example, maintaining a count of outstanding
load-locked operations and forcing the slow path for stores if it is
non-zero?
Paolo
> + aie_st_lock_ret(env, vaddr, GETRA());
> + } else {
> + hwaddr paddr = h_get_st_phys(env, vaddr, GETRA());
> +
> + if (unlikely(aie_entry_exists(paddr))) {
> + h_aie_lock(env, paddr);
> + }
> + }
> +}
