[cmdline] Add "cpuid" command

Allow x86 CPU feature flags (such as support for 64-bit mode) to be
checked using the "cpuid" command.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

1 files changed, 154 insertions, 0 deletions

diff --git a/src/arch/x86/core/cpuid.c b/src/arch/x86/core/cpuid.c
new file mode 100644
index 000000000..cf9dd6dde
--- /dev/null
+++ b/src/arch/x86/core/cpuid.c
@@ -0,0 +1,154 @@
+/*
+ * Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <string.h>
+#include <ipxe/cpuid.h>
+
+/** @file
+ *
+ * x86 CPU feature detection
+ *
+ */
+
+/**
+ * Check whether or not CPUID instruction is supported
+ *
+ * @ret is_supported	CPUID instruction is supported
+ */
+static int cpuid_is_supported ( void ) {
+	unsigned long original;
+	unsigned long inverted;
+
+	__asm__ ( "pushf\n\t"
+		  "pushf\n\t"
+		  "pop %0\n\t"
+		  "mov %0,%1\n\t"
+		  "xor %2,%1\n\t"
+		  "push %1\n\t"
+		  "popf\n\t"
+		  "pushf\n\t"
+		  "pop %1\n\t"
+		  "popf\n\t"
+		  : "=&r" ( original ), "=&r" ( inverted )
+		  : "ir" ( CPUID_FLAG ) );
+	return ( ( original ^ inverted ) & CPUID_FLAG );
+}
+
+/**
+ * Issue CPUID instruction
+ *
+ * @v operation		CPUID operation
+ * @v eax		Output via %eax
+ * @v ebx		Output via %ebx
+ * @v ecx		Output via %ecx
+ * @v edx		Output via %edx
+ */
+static inline __attribute__ (( always_inline )) void
+cpuid ( uint32_t operation, uint32_t *eax, uint32_t *ebx, uint32_t *ecx,
+	uint32_t *edx ) {
+
+	__asm__ ( "cpuid"
+		  : "=a" ( *eax ), "=b" ( *ebx ), "=c" ( *ecx ), "=d" ( *edx )
+		  : "0" ( operation ) );
+}
+
+/**
+ * Get Intel-defined x86 CPU features
+ *
+ * @v features		x86 CPU features to fill in
+ */
+static void x86_intel_features ( struct x86_features *features ) {
+	uint32_t max_level;
+	uint32_t discard_a;
+	uint32_t discard_b;
+	uint32_t discard_c;
+	uint32_t discard_d;
+
+	/* Check that features are available via CPUID */
+	cpuid ( CPUID_VENDOR_ID, &max_level, &discard_b, &discard_c,
+		&discard_d );
+	if ( max_level < CPUID_FEATURES ) {
+		DBGC ( features, "CPUID has no Intel-defined features (max "
+		       "level %08x)\n", max_level );
+		return;
+	}
+
+	/* Get features */
+	cpuid ( CPUID_FEATURES, &discard_a, &discard_b,
+		&features->intel.ecx, &features->intel.edx );
+	DBGC ( features, "CPUID Intel features: %%ecx=%08x, %%edx=%08x\n",
+	       features->intel.ecx, features->intel.edx );
+
+}
+
+/**
+ * Get AMD-defined x86 CPU features
+ *
+ * @v features		x86 CPU features to fill in
+ */
+static void x86_amd_features ( struct x86_features *features ) {
+	uint32_t max_level;
+	uint32_t discard_a;
+	uint32_t discard_b;
+	uint32_t discard_c;
+	uint32_t discard_d;
+
+	/* Check that features are available via CPUID */
+	cpuid ( CPUID_AMD_MAX_FN, &max_level, &discard_b, &discard_c,
+		&discard_d );
+	if ( ( max_level & CPUID_AMD_CHECK_MASK ) != CPUID_AMD_CHECK ) {
+		DBGC ( features, "CPUID has no extended functions\n" );
+		return;
+	}
+	if ( max_level < CPUID_AMD_FEATURES ) {
+		DBGC ( features, "CPUID has no AMD-defined features (max "
+		       "level %08x)\n", max_level );
+		return;
+	}
+
+	/* Get features */
+	cpuid ( CPUID_AMD_FEATURES, &discard_a, &discard_b,
+		&features->amd.ecx, &features->amd.edx );
+	DBGC ( features, "CPUID AMD features: %%ecx=%08x, %%edx=%08x\n",
+	       features->amd.ecx, features->amd.edx );
+}
+
+/**
+ * Get x86 CPU features
+ *
+ * @v features		x86 CPU features to fill in
+ */
+void x86_features ( struct x86_features *features ) {
+
+	/* Clear all features */
+	memset ( features, 0, sizeof ( *features ) );
+
+	/* Check that CPUID instruction is available */
+	if ( ! cpuid_is_supported() ) {
+		DBGC ( features, "CPUID instruction is not supported\n" );
+		return;
+	}
+
+	/* Get Intel-defined features */
+	x86_intel_features ( features );
+
+	/* Get AMD-defined features */
+	x86_amd_features ( features );
+}