libroot/x86_64: implement get_cpuid() in user mode

cpuid is available in user mode as well and it doesn't look like there
are going to be any x86 platforms with significantly different CPUs anytime
soon.

Signed-off-by: Paweł Dziepak <[email protected]>

src/system/libroot/os/arch/x86_64/system_info.cpp

@@ -1,4 +1,5 @@
 /* 
+ * Cp[yright 2014, Paweł Dziepak, [email protected].
  * Copyright 2003-2004, Axel Dörfler, [email protected].
  * Distributed under the terms of the MIT License.
  */
@@ -11,6 +12,10 @@
 status_t
 get_cpuid(cpuid_info* info, uint32 eaxRegister, uint32 cpuNum)
 {
-	return _kern_get_cpuid(info, eaxRegister, cpuNum);
+	__asm__("cpuid"
+		: "=a" (info->regs.eax), "=b" (info->regs.ebx), "=c" (info->regs.ecx),
+			"=d" (info->regs.edx)
+		: "a" (eaxRegister), "c" (0));
+	return B_OK;
 }