Re: [Xen-devel] [PATCH v1 6/9] livepatch: Initial ARM64 support.

[Konrad Rzeszutek Wilk <konrad@xxxxxxxxxx>]

>> +    flush_xen_text_tlb_local();
>
>
> I am a bit confused. In your comment you mention the branch but flush the
> TLBs. The two are not related.

That code also flushes the I-cache (which sounds redundant with
invalidate_icache).
And it also does 'isb' ("Ensure synchronization with previous changes
to text ") which
invalidate_icache() does not.

I am wondering if should just move 'isb' in invalidate_icache() and
drop altogether the call to flush_xen_text_tlb_local()?

It works fine in simulator

>
> However, I would prefer the branch predictor to be flushed directly in
> invalidate_icache by calling BPIALLIS. This is because flushing the cache
> means that you likely want to flush the branch predictor too.

I had no trouble adding invalidate_icache to asm-arm/arm32/page.h and
having it do :

    asm volatile (
        CMD_CP32(ICIALLUIS)     /* Flush I-cache. */
        CMD_CP32(BPIALLIS)      /* Flush branch predictor. */
        : : : "memory");

But obviously that does not help ARM64.

And that is is where I hit an snag. "bp iallis" instruction does not
compile? (I also tried "bp iall", "bpiallis"). The error is:

{standard input}: Assembler messages:
{standard input}:454: Error: unknown mnemonic `bpiallis' -- `bpiallis'

Ideas?

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