Commit 13f62e84 authored by Heiko Carstens's avatar Heiko Carstens
Browse files

s390/cmpxchg: use symbolic names for inline assembly operands 

Make cmpxchg() inline assemblies more readable by using symbolic names
for operands.

Link: https://lore.kernel.org/r/Y2J7yzQYt/bjLQXY@osiris


Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
parent 247f34f7

arch/s390/include/asm/cmpxchg.h

+42 −34
Original line number Diff line number Diff line
@@ -96,56 +96,64 @@ static __always_inline unsigned long __cmpxchg(unsigned long address, 
		shift = (3 ^ (address & 3)) << 3;

		address ^= address & 3;

		asm volatile(

			"       l       %0,%2\n"

			"0:     nr      %0,%5\n"

			"       lr      %1,%0\n"

			"       or      %0,%3\n"

			"       or      %1,%4\n"

			"       cs      %0,%1,%2\n"

			"	l	%[prev],%[address]\n"

			"0:	nr	%[prev],%[mask]\n"

			"	lr	%[tmp],%[prev]\n"

			"	or	%[prev],%[old]\n"

			"	or	%[tmp],%[new]\n"

			"	cs	%[prev],%[tmp],%[address]\n"

			"	jnl	1f\n"

			"       xr      %1,%0\n"

			"       nr      %1,%5\n"

			"	xr	%[tmp],%[prev]\n"

			"	nr	%[tmp],%[mask]\n"

			"	jnz	0b\n"

			"1:"

			: "=&d" (prev), "=&d" (tmp), "+Q" (*(int *) address)

			: "d" ((old & 0xff) << shift),

			  "d" ((new & 0xff) << shift),

			  "d" (~(0xff << shift))

			: [prev] "=&d" (prev),

			  [tmp] "=&d" (tmp),

			  [address] "+Q" (*(int *)address)

			: [old] "d" ((old & 0xff) << shift),

			  [new] "d" ((new & 0xff) << shift),

			  [mask] "d" (~(0xff << shift))

			: "memory", "cc");

		return prev >> shift;

	case 2:

		shift = (2 ^ (address & 2)) << 3;

		address ^= address & 2;

		asm volatile(

			"       l       %0,%2\n"

			"0:     nr      %0,%5\n"

			"       lr      %1,%0\n"

			"       or      %0,%3\n"

			"       or      %1,%4\n"

			"       cs      %0,%1,%2\n"

			"	l	%[prev],%[address]\n"

			"0:	nr	%[prev],%[mask]\n"

			"	lr	%[tmp],%[prev]\n"

			"	or	%[prev],%[old]\n"

			"	or	%[tmp],%[new]\n"

			"	cs	%[prev],%[tmp],%[address]\n"

			"	jnl	1f\n"

			"       xr      %1,%0\n"

			"       nr      %1,%5\n"

			"	xr	%[tmp],%[prev]\n"

			"	nr	%[tmp],%[mask]\n"

			"	jnz	0b\n"

			"1:"

			: "=&d" (prev), "=&d" (tmp), "+Q" (*(int *) address)

			: "d" ((old & 0xffff) << shift),

			  "d" ((new & 0xffff) << shift),

			  "d" (~(0xffff << shift))

			: [prev] "=&d" (prev),

			  [tmp] "=&d" (tmp),

			  [address] "+Q" (*(int *)address)

			: [old] "d" ((old & 0xffff) << shift),

			  [new] "d" ((new & 0xffff) << shift),

			  [mask] "d" (~(0xffff << shift))

			: "memory", "cc");

		return prev >> shift;

	case 4:

		asm volatile(

			"       cs      %0,%3,%1\n"

			: "=&d" (prev), "+Q" (*(int *) address)

			: "0" (old), "d" (new)

			"	cs	%[prev],%[new],%[address]\n"

			: [prev] "=&d" (prev),

			  [address] "+Q" (*(int *)address)

			: "0" (old),

			  [new] "d" (new)

			: "memory", "cc");

		return prev;

	case 8:

		asm volatile(

			"       csg     %0,%3,%1\n"

			: "=&d" (prev), "+QS" (*(long *) address)

			: "0" (old), "d" (new)

			"	csg	%[prev],%[new],%[address]\n"

			: [prev] "=&d" (prev),

			  [address] "+QS" (*(long *)address)

			: "0" (old),

			  [new] "d" (new)

			: "memory", "cc");

		return prev;

	}