[PATCH] fix CPUID handling

[Alexander Graf <alex@csgraf.de>]

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So this is a new version of the same patch. It should be rather safe
now, as most cases are handled by gcc.

Signed-off-by: Alexander Graf <alex@csgraf.de>

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diff --git a/qemu/qemu-kvm-x86.c b/qemu/qemu-kvm-x86.c
index 37354fb..3062d1b 100644
--- a/qemu/qemu-kvm-x86.c
+++ b/qemu/qemu-kvm-x86.c
@@ -427,36 +427,22 @@ static void host_cpuid(uint32_t function, uint32_t *eax, uint32_t *ebx,
 {
     uint32_t vec[4];
 
-    vec[0] = function;
-    asm volatile (
-#ifdef __x86_64__
-	 "sub $128, %%rsp \n\t"  /* skip red zone */
-         "push %0;  push %%rsi \n\t"
-	 "push %%rax; push %%rbx; push %%rcx; push %%rdx \n\t"
-	 "mov 8*5(%%rsp), %%rsi \n\t"
-	 "mov (%%rsi), %%eax \n\t"
-	 "cpuid \n\t"
-	 "mov %%eax, (%%rsi) \n\t"
-	 "mov %%ebx, 4(%%rsi) \n\t"
-	 "mov %%ecx, 8(%%rsi) \n\t"
-	 "mov %%edx, 12(%%rsi) \n\t"
-	 "pop %%rdx; pop %%rcx; pop %%rbx; pop %%rax \n\t"
-	 "pop %%rsi; pop %0 \n\t"
-	 "add $128, %%rsp"
+#if defined(__i386__) && defined(__PIC__)
+    /* We need to handle ebx manually, as PIC code requires it */
+    asm volatile("movl %%ebx, %%esi \n\t"
+                "cpuid \n\t"
+                "movl %%ebx, %1 \n\t"
+                "movl %%esi, %%ebx"
+                : "=a" (vec[0]), "=r" (vec[1]), "=c" (vec[2]), "=d" (vec[3])
+                : "0"(function)
+                : "esi", "cc");
 #else
-         "push %0;  push %%esi \n\t"
-	 "push %%eax; push %%ebx; push %%ecx; push %%edx \n\t"
-	 "mov 4*5(%%esp), %%esi \n\t"
-	 "mov (%%esi), %%eax \n\t"
-	 "cpuid \n\t"
-	 "mov %%eax, (%%esi) \n\t"
-	 "mov %%ebx, 4(%%esi) \n\t"
-	 "mov %%ecx, 8(%%esi) \n\t"
-	 "mov %%edx, 12(%%esi) \n\t"
-	 "pop %%edx; pop %%ecx; pop %%ebx; pop %%eax \n\t"
-	 "pop %%esi; pop %0 \n\t"
+    asm volatile("cpuid"
+                : "=a" (vec[0]), "=b" (vec[1]),"=c" (vec[2]), "=d" (vec[3]) 
+                : "0"(function)
+                : "cc");
 #endif
-	 : : "rm"(vec) : "memory");
+
     if (eax)
 	*eax = vec[0];
     if (ebx)

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