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-rw-r--r--src/cpu.cpp16
1 files changed, 14 insertions, 2 deletions
diff --git a/src/cpu.cpp b/src/cpu.cpp
index 45b7faab4..b1d1c328f 100644
--- a/src/cpu.cpp
+++ b/src/cpu.cpp
@@ -96,9 +96,21 @@ void ottd_cpuid(int info[4], int type)
#elif defined(__x86_64__) || defined(__i386)
void ottd_cpuid(int info[4], int type)
{
+ /* The easy variant would be just cpuid, however... ebx gets clobbered by PIC. */
__asm__ __volatile__ (
- "cpuid"
- : "=a" (info[0]), "=b" (info[1]), "=c" (info[2]), "=d" (info[3])
+#if defined(__x86_64__)
+ "pushq %%rbx \n\t" // save %rbx
+#else
+ "pushl %%ebx \n\t" // save %ebx
+#endif
+ "cpuid \n\t"
+ "movl %%ebx, %1 \n\t" // write the result into output var
+#if defined(__x86_64__)
+ "popq %%rbx \n\t" // restore %rbx
+#else
+ "popl %%ebx \n\t" // restore %ebc
+#endif
+ : "=a" (info[0]), "=r" (info[1]), "=c" (info[2]), "=d" (info[3])
: "a" (type)
);
}