On 28/09/2020 13:05, Jan Beulich wrote:
> --- a/xen/include/asm-x86/regs.h
> +++ b/xen/include/asm-x86/regs.h
> @@ -15,4 +15,18 @@
> (diff == 0);
> \
> })
>
> +#define read_sreg(name) ({ \
> + unsigned int __sel; \
> + asm volatile ( "mov %%" STR(name) ",%0" : "=r" (__sel) ); \
> + __sel; \
> +})
> +
> +static inline void read_sregs(struct cpu_user_regs *regs)
> +{
> + asm volatile ( "mov %%ds, %0" : "=m" (regs->ds) );
> + asm volatile ( "mov %%es, %0" : "=m" (regs->es) );
> + asm volatile ( "mov %%fs, %0" : "=m" (regs->fs) );
> + asm volatile ( "mov %%gs, %0" : "=m" (regs->gs) );
It occurs to me that reads don't need to be volatile. There are no side
effects.
With that fixed, Reviewed-by: Andrew Cooper <andrew.coop...@citrix.com>
