On Tue, May 10, 2016 at 06:53:18PM +0200, Borislav Petkov wrote:
> static __always_inline unsigned int __arch_hweight32(unsigned int w)
> {
> - unsigned int res = 0;
> + unsigned int res;
>
> - asm (ALTERNATIVE("call __sw_hweight32", POPCNT32, X86_FEATURE_POPCNT)
> - : "="REG_OUT (res)
> - : REG_IN (w));
> + if (likely(static_cpu_has(X86_FEATURE_POPCNT))) {
> + /* popcnt %eax, %eax */
> + asm volatile(POPCNT32
> + : "="REG_OUT (res)
> + : REG_IN (w));
>
> - return res;
> + return res;
> + }
> + return __sw_hweight32(w);
> }
So what was wrong with using the normal thunk_*.S wrappers for the
calls? That would allow you to use the alternative() stuff which does
generate smaller code.
