On Tue, Oct 28, 2014 at 01:34:42AM +0000, Wang, Yalin wrote: > > From: Will Deacon [mailto:will.deacon@xxxxxxx] > > > +++ b/arch/arm/include/asm/bitrev.h > > > @@ -0,0 +1,28 @@ > > > +#ifndef __ASM_ARM_BITREV_H > > > +#define __ASM_ARM_BITREV_H > > > + > > > +static __always_inline __attribute_const__ u32 __arch_bitrev32(u32 x) > > > +{ > > > + if (__builtin_constant_p(x)) { > > > + x = (x >> 16) | (x << 16); > > > + x = ((x & 0xFF00FF00) >> 8) | ((x & 0x00FF00FF) << 8); > > > + x = ((x & 0xF0F0F0F0) >> 4) | ((x & 0x0F0F0F0F) << 4); > > > + x = ((x & 0xCCCCCCCC) >> 2) | ((x & 0x33333333) << 2); > > > + return ((x & 0xAAAAAAAA) >> 1) | ((x & 0x55555555) << 1); > > > + } > > > + __asm__ ("rbit %0, %1" : "=r" (x) : "r" (x)); > > > > I think you need to use %w0 and %w1 here, otherwise you bit-reverse the 64- > > bit register. > For arm64 in arch/arm64/include/asm/bitrev.h. > I have use __asm__ ("rbit %w0, %w1" : "=r" (x) : "r" (x)); > For arm , I use __asm__ ("rbit %0, %1" : "=r" (x) : "r" (x)); > Am I right ? Yup, sorry, I didn't realise this patch covered both architectures. It would probably be a good idea to split it into 3 parts: a core part, then the two architectural bits. Will -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>