Make cpuid functions usable when compiled with PIC

This avoids using EBX and instead uses EDI where possible,
and ESI when necessary to get the EBX value out.

This allows me to enable -fpic for SMM TSEG code.

Also add a new CPUID extended function to query with ECX set.

Change-Id: I10dbded3f3ad98a39ba7b53da59af6ca3145e2e5
Signed-off-by: Duncan Laurie <dlaurie@google.com>
Reviewed-on: http://review.coreboot.org/764
Tested-by: build bot (Jenkins)
Reviewed-by: Mathias Krause <minipli@googlemail.com>

1 files changed, 45 insertions, 12 deletions

diff --git a/src/arch/x86/include/arch/cpu.h b/src/arch/x86/include/arch/cpu.h
index 2dfcd72e95f0..891e62bbcb98 100644
--- a/src/arch/x86/include/arch/cpu.h
+++ b/src/arch/x86/include/arch/cpu.h
@@ -36,12 +36,36 @@ static inline struct cpuid_result cpuid(int op)
 {
 	struct cpuid_result result;
 	asm volatile(
-		"cpuid"
+		"mov %%ebx, %%edi;"
+		"cpuid;"
+		"mov %%ebx, %%esi;"
+		"mov %%edi, %%ebx;"
 		: "=a" (result.eax),
-		  "=b" (result.ebx),
+		  "=S" (result.ebx),
 		  "=c" (result.ecx),
 		  "=d" (result.edx)
-		: "0" (op));
+		: "0" (op)
+		: "edi");
+	return result;
+}
+
+/*
+ * Generic Extended CPUID function
+ */
+static inline struct cpuid_result cpuid_ext(int op, unsigned ecx)
+{
+	struct cpuid_result result;
+	asm volatile(
+		"mov %%ebx, %%edi;"
+		"cpuid;"
+		"mov %%ebx, %%esi;"
+		"mov %%edi, %%ebx;"
+		: "=a" (result.eax),
+		  "=S" (result.ebx),
+		  "=c" (result.ecx),
+		  "=d" (result.edx)
+		: "0" (op), "2" (ecx)
+		: "edi");
 	return result;
 }
 
@@ -52,10 +76,12 @@ static inline unsigned int cpuid_eax(unsigned int op)
 {
 	unsigned int eax;
 
-	__asm__("cpuid"
+	__asm__("mov %%ebx, %%edi;"
+		"cpuid;"
+		"mov %%edi, %%ebx;"
 		: "=a" (eax)
 		: "0" (op)
-		: "ebx", "ecx", "edx");
+		: "ecx", "edx", "edi");
 	return eax;
 }
 
@@ -63,10 +89,13 @@ static inline unsigned int cpuid_ebx(unsigned int op)
 {
 	unsigned int eax, ebx;
 
-	__asm__("cpuid"
-		: "=a" (eax), "=b" (ebx)
+	__asm__("mov %%ebx, %%edi;"
+		"cpuid;"
+		"mov %%edi, %%ebx;"
+		"mov %%edi, %%esi;"
+		: "=a" (eax), "=S" (ebx)
 		: "0" (op)
-		: "ecx", "edx" );
+		: "ecx", "edx", "edi");
 	return ebx;
 }
 
@@ -74,10 +103,12 @@ static inline unsigned int cpuid_ecx(unsigned int op)
 {
 	unsigned int eax, ecx;
 
-	__asm__("cpuid"
+	__asm__("mov %%ebx, %%edi;"
+		"cpuid;"
+		"mov %%edi, %%ebx;"
 		: "=a" (eax), "=c" (ecx)
 		: "0" (op)
-		: "ebx", "edx" );
+		: "edx", "edi");
 	return ecx;
 }
 
@@ -85,10 +116,12 @@ static inline unsigned int cpuid_edx(unsigned int op)
 {
 	unsigned int eax, edx;
 
-	__asm__("cpuid"
+	__asm__("mov %%ebx, %%edi;"
+		"cpuid;"
+		"mov %%edi, %%ebx;"
 		: "=a" (eax), "=d" (edx)
 		: "0" (op)
-		: "ebx", "ecx");
+		: "ecx", "edi");
 	return edx;
 }