cpu: add function to retrieve CPU vendor information

Adding a function which can retrieve the extended CPU vendor string, if
supported.

Signed-off-by: Martin Mazein <[email protected]>

include/cpuid.h

@@ -0,0 +1,57 @@
+/*
+ * Copyright © 2020 Amazon.com, Inc. or its affiliates.
+ * All Rights Reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#ifndef KTF_CPUID_H
+#define KTF_CPUID_H
+
+#include <string.h>
+
+/* CPU vendor detection */
+#define CPUID_EXT_INFO_LEAF  0x80000000U
+#define CPUID_BRAND_INFO_MIN 0x80000002U
+#define CPUID_BRAND_INFO_MAX 0x80000004U
+
+static inline bool cpu_vendor_string(char *cpu_str) {
+    uint32_t leaf = CPUID_EXT_INFO_LEAF;
+    uint32_t ebx = 0, ecx = 0, edx = 0;
+    uint32_t eax = cpuid_eax(leaf);
+
+    if (!(eax & leaf) || (eax < CPUID_BRAND_INFO_MAX)) {
+        dprintk("Extended Function CPUID Information not supported\n");
+        return false;
+    }
+
+    for (leaf = CPUID_BRAND_INFO_MIN; leaf <= CPUID_BRAND_INFO_MAX;
+         leaf++, cpu_str += 16) {
+        cpuid(leaf, &eax, &ebx, &ecx, &edx);
+        memcpy(cpu_str, &eax, sizeof(eax));
+        memcpy(cpu_str + 4, &ebx, sizeof(ebx));
+        memcpy(cpu_str + 8, &ecx, sizeof(ecx));
+        memcpy(cpu_str + 12, &edx, sizeof(edx));
+    }
+
+    return true;
+}
+
+#endif /* KTF_CPUID_H */