Redo cpuid feature detection

We already have a proper cpuid feature API used in
userland, but Linux took it out for KERNEL use, to
plug into the Linux API. We do not have a kernel API to
use, so we might as well use the userland one.

This makes it nice and consistent, and more easy to read.

Signed-off-by: Jorgen Lundman <lundman@lundman.net>

include/os/macos/spl/sys/processor.h

@@ -31,8 +31,53 @@
 #include <sys/types.h>
 
 extern uint32_t getcpuid(void);
-extern uint64_t spl_cpuid_features(void);
+
+#if defined(__amd64__) || defined(__i386__)
+
+extern int __cpuid_count(unsigned int __level, unsigned int __sublevel,
+	unsigned int __eax, unsigned int __ebx,
+	unsigned int __ecx, unsigned int __edx);
+
+#define	__cpuid_count(level, count, a, b, c, d) \
+	__asm__("xchg{l}\t{%%}ebx, %1\n\t" \
+		"cpuid\n\t" \
+		"xchg{l}\t{%%}ebx, %1\n\t" \
+		: "=a" (a), "=r" (b), "=c" (c), "=d" (d) \
+		: "0" (level), "2" (count))
+
+#define	__cpuid(level, a, b, c, d) \
+	__asm__("xchg{l}\t{%%}ebx, %1\n\t" \
+		"cpuid\n\t" \
+		"xchg{l}\t{%%}ebx, %1\n\t" \
+		: "=a" (a), "=r" (b), "=c" (c), "=d" (d) \
+		: "0" (level))
+
+static inline unsigned int
+__get_cpuid_max(unsigned int __ext, unsigned int *__sig)
+{
+	unsigned int __eax, __ebx, __ecx, __edx;
+	__cpuid(__ext, __eax, __ebx, __ecx, __edx);
+	if (__sig)
+		*__sig = __ebx;
+	return (__eax);
+}
+
+/* macOS does have do_cpuid() macro */
+static inline int
+__get_cpuid(unsigned int __level,
+    unsigned int *__eax, unsigned int *__ebx,
+    unsigned int *__ecx, unsigned int *__edx)
+{
+	unsigned int __ext = __level & 0x80000000;
+	if (__get_cpuid_max(__ext, 0) < __level)
+		return (0);
+	__cpuid(__level, *__eax, *__ebx, *__ecx, *__edx);
+	return (1);
+}
+
+#endif // x86
 
 typedef int	processorid_t;
+extern int spl_processor_init(void);
 
 #endif /* _SPL_PROCESSOR_H */