Re: [PATCH] x86/boot: Fix early exception handling with CONFIG_PERF_COUNTERS

[Jan Beulich <jbeulich@xxxxxxxx>]

On 16.04.2020 10:19, Andrew Cooper wrote:
> --- a/xen/arch/x86/x86_64/entry.S
> +++ b/xen/arch/x86/x86_64/entry.S
> @@ -679,7 +679,11 @@ handle_exception_saved:
>  1:      movq  %rsp,%rdi
>          movzbl UREGS_entry_vector(%rsp),%eax
>          leaq  exception_table(%rip),%rdx
> -        PERFC_INCR(exceptions, %rax, %rbx)
> +#ifdef CONFIG_PERF_COUNTERS
> +        lea   per_cpu__perfcounters(%rip), %rdi
> +        add   STACK_CPUINFO_FIELD(per_cpu_offset)(%r14), %rdi
> +        incl  ASM_PERFC_exceptions * 4(%rdi, %rax, 4)
> +#endif
>          mov   (%rdx, %rax, 8), %rdx
>          INDIRECT_CALL %rdx
>          mov   %r15, STACK_CPUINFO_FIELD(xen_cr3)(%r14)
> 
> 
> If you're happy with that?

I'm afraid I'm not - you can't use %rdi here, it already holds the
called function's argument. I'd be fine with %rcx used instead.

Jan