From: Avi Kivity <[email protected]>
Signed-off-by: Avi Kivity <[email protected]>
diff --git a/x86/external-module-compat.h b/x86/external-module-compat.h
index 193ce91..13a218b 100644
--- a/x86/external-module-compat.h
+++ b/x86/external-module-compat.h
@@ -9,6 +9,79 @@
#include "../external-module-compat-comm.h"
#include <asm/msr.h>
+#include <asm/asm.h>
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,26)
+
+#ifdef CONFIG_X86_64
+#define DECLARE_ARGS(val, low, high) unsigned low, high
+#define EAX_EDX_VAL(val, low, high) ((low) | ((u64)(high) << 32))
+#define EAX_EDX_ARGS(val, low, high) "a" (low), "d" (high)
+#define EAX_EDX_RET(val, low, high) "=a" (low), "=d" (high)
+#else
+#define DECLARE_ARGS(val, low, high) unsigned long long val
+#define EAX_EDX_VAL(val, low, high) (val)
+#define EAX_EDX_ARGS(val, low, high) "A" (val)
+#define EAX_EDX_RET(val, low, high) "=A" (val)
+#endif
+
+#ifndef __ASM_EX_SEC
+# define __ASM_EX_SEC " .section __ex_table,\"a\"\n"
+#endif
+
+#ifndef _ASM_EXTABLE
+# define _ASM_EXTABLE(from,to) \
+ __ASM_EX_SEC \
+ _ASM_ALIGN "\n" \
+ _ASM_PTR #from "," #to "\n" \
+ " .previous\n"
+#endif
+
+#ifndef __ASM_SEL
+#ifdef CONFIG_X86_32
+# define __ASM_SEL(a,b) __ASM_FORM(a)
+#else
+# define __ASM_SEL(a,b) __ASM_FORM(b)
+#endif
+#endif
+
+#ifndef __ASM_FORM
+# define __ASM_FORM(x) " " #x " "
+#endif
+
+#ifndef _ASM_PTR
+#define _ASM_PTR __ASM_SEL(.long, .quad)
+#endif
+
+#ifndef _ASM_ALIGN
+#define _ASM_ALIGN __ASM_SEL(.balign 4, .balign 8)
+#endif
+
+static inline unsigned long long native_read_msr_safe(unsigned int msr,
+ int *err)
+{
+ DECLARE_ARGS(val, low, high);
+
+ asm volatile("2: rdmsr ; xor %[err],%[err]\n"
+ "1:\n\t"
+ ".section .fixup,\"ax\"\n\t"
+ "3: mov %[fault],%[err] ; jmp 1b\n\t"
+ ".previous\n\t"
+ _ASM_EXTABLE(2b, 3b)
+ : [err] "=r" (*err), EAX_EDX_RET(val, low, high)
+ : "c" (msr), [fault] "i" (-EFAULT));
+ return EAX_EDX_VAL(val, low, high);
+}
+
+static inline int rdmsrl_safe(unsigned msr, unsigned long long *p)
+{
+ int err;
+
+ *p = native_read_msr_safe(msr, &err);
+ return err;
+}
+
+#endif
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,22)
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