asm volatile()

in include/asm/futex.h [24:62]

• 36 lines of code
• 2 McCabe index (conditional complexity)

	asm volatile(					\
	"	movi	$ta, #0\n"				\
	"1:	llw	%1, [%2+$ta]\n"				\
	"	" insn "\n"					\
	"2:	scw	%0, [%2+$ta]\n"				\
	"	beqz	%0, 1b\n"				\
	"	movi	%0, #0\n"				\
	"3:\n"							\
	__futex_atomic_ex_table("%4")				\
	: "=&r" (ret), "=&r" (oldval)				\
	: "r" (uaddr), "r" (oparg), "i" (-EFAULT)		\
	: "cc", "memory")
static inline int
futex_atomic_cmpxchg_inatomic(u32 * uval, u32 __user * uaddr,
			      u32 oldval, u32 newval)
{
	int ret = 0;
	u32 val, tmp, flags;

	if (!access_ok(uaddr, sizeof(u32)))
		return -EFAULT;

	smp_mb();
	asm volatile ("       movi    $ta, #0\n"
		      "1:     llw     %1, [%6 + $ta]\n"
		      "       sub     %3, %1, %4\n"
		      "       cmovz   %2, %5, %3\n"
		      "       cmovn   %2, %1, %3\n"
		      "2:     scw     %2, [%6 + $ta]\n"
		      "       beqz    %2, 1b\n"
		      "3:\n                   " __futex_atomic_ex_table("%7")
		      :"+&r"(ret), "=&r"(val), "=&r"(tmp), "=&r"(flags)
		      :"r"(oldval), "r"(newval), "r"(uaddr), "i"(-EFAULT)
		      :"$ta", "memory");
	smp_mb();

	*uval = val;
	return ret;
}