x86/paravirt: implement PVOP_CALL macros for callee-save functions

Impact: Optimization

Functions with the callee save calling convention clobber many fewer
registers than the normal C calling convention.  Implement variants of
PVOP_V?CALL* accordingly.  This only bothers with functions up to 3
args, since functions with more args may as well use the normal
calling convention.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

arch/x86/include/asm/paravirt.h

@@ -510,25 +510,45 @@ int paravirt_disable_iospace(void);
  * makes sure the incoming and outgoing types are always correct.
  */
 #ifdef CONFIG_X86_32
-#define PVOP_VCALL_ARGS			unsigned long __eax, __edx, __ecx
+#define PVOP_VCALL_ARGS				\
+	unsigned long __eax = __eax, __edx = __edx, __ecx = __ecx
 #define PVOP_CALL_ARGS			PVOP_VCALL_ARGS
+
+#define PVOP_CALL_ARG1(x)		"a" ((unsigned long)(x))
+#define PVOP_CALL_ARG2(x)		"d" ((unsigned long)(x))
+#define PVOP_CALL_ARG3(x)		"c" ((unsigned long)(x))
+
 #define PVOP_VCALL_CLOBBERS		"=a" (__eax), "=d" (__edx),	\
 					"=c" (__ecx)
 #define PVOP_CALL_CLOBBERS		PVOP_VCALL_CLOBBERS
+
+#define PVOP_VCALLEE_CLOBBERS		"=a" (__eax)
+#define PVOP_CALLEE_CLOBBERS		PVOP_VCALLEE_CLOBBERS
+
 #define EXTRA_CLOBBERS
 #define VEXTRA_CLOBBERS
-#else
-#define PVOP_VCALL_ARGS		unsigned long __edi, __esi, __edx, __ecx
+#else  /* CONFIG_X86_64 */
+#define PVOP_VCALL_ARGS					\
+	unsigned long __edi = __edi, __esi = __esi,	\
+		__edx = __edx, __ecx = __ecx
 #define PVOP_CALL_ARGS		PVOP_VCALL_ARGS, __eax
+
+#define PVOP_CALL_ARG1(x)		"D" ((unsigned long)(x))
+#define PVOP_CALL_ARG2(x)		"S" ((unsigned long)(x))
+#define PVOP_CALL_ARG3(x)		"d" ((unsigned long)(x))
+#define PVOP_CALL_ARG4(x)		"c" ((unsigned long)(x))
+
 #define PVOP_VCALL_CLOBBERS	"=D" (__edi),				\
 				"=S" (__esi), "=d" (__edx),		\
 				"=c" (__ecx)
-
 #define PVOP_CALL_CLOBBERS	PVOP_VCALL_CLOBBERS, "=a" (__eax)
 
+#define PVOP_VCALLEE_CLOBBERS	"=a" (__eax)
+#define PVOP_CALLEE_CLOBBERS	PVOP_VCALLEE_CLOBBERS
+
 #define EXTRA_CLOBBERS	 , "r8", "r9", "r10", "r11"
 #define VEXTRA_CLOBBERS	 , "rax", "r8", "r9", "r10", "r11"
-#endif
+#endif	/* CONFIG_X86_32 */
 
 #ifdef CONFIG_PARAVIRT_DEBUG
 #define PVOP_TEST_NULL(op)	BUG_ON(op == NULL)
@@ -536,10 +556,11 @@ int paravirt_disable_iospace(void);
 #define PVOP_TEST_NULL(op)	((void)op)
 #endif
 
-#define __PVOP_CALL(rettype, op, pre, post, ...)			\
+#define ____PVOP_CALL(rettype, op, clbr, call_clbr, extra_clbr,		\
+		      pre, post, ...)					\
 	({								\
 		rettype __ret;						\
-		PVOP_CALL_ARGS;					\
+		PVOP_CALL_ARGS;						\
 		PVOP_TEST_NULL(op);					\
 		/* This is 32-bit specific, but is okay in 64-bit */	\
 		/* since this condition will never hold */		\
@@ -547,70 +568,113 @@ int paravirt_disable_iospace(void);
 			asm volatile(pre				\
 				     paravirt_alt(PARAVIRT_CALL)	\
 				     post				\
-				     : PVOP_CALL_CLOBBERS		\
+				     : call_clbr			\
 				     : paravirt_type(op),		\
-				       paravirt_clobber(CLBR_ANY),	\
+				       paravirt_clobber(clbr),		\
 				       ##__VA_ARGS__			\
-				     : "memory", "cc" EXTRA_CLOBBERS);	\
+				     : "memory", "cc" extra_clbr);	\
 			__ret = (rettype)((((u64)__edx) << 32) | __eax); \
 		} else {						\
 			asm volatile(pre				\
 				     paravirt_alt(PARAVIRT_CALL)	\
 				     post				\
-				     : PVOP_CALL_CLOBBERS		\
+				     : call_clbr			\
 				     : paravirt_type(op),		\
-				       paravirt_clobber(CLBR_ANY),	\
+				       paravirt_clobber(clbr),		\
 				       ##__VA_ARGS__			\
-				     : "memory", "cc" EXTRA_CLOBBERS);	\
+				     : "memory", "cc" extra_clbr);	\
 			__ret = (rettype)__eax;				\
 		}							\
 		__ret;							\
 	})
-#define __PVOP_VCALL(op, pre, post, ...)				\
+
+#define __PVOP_CALL(rettype, op, pre, post, ...)			\
+	____PVOP_CALL(rettype, op, CLBR_ANY, PVOP_CALL_CLOBBERS,	\
+		      EXTRA_CLOBBERS, pre, post, ##__VA_ARGS__)
+
+#define __PVOP_CALLEESAVE(rettype, op, pre, post, ...)			\
+	____PVOP_CALL(rettype, op.func, CLBR_RET_REG,			\
+		      PVOP_CALLEE_CLOBBERS, ,				\
+		      pre, post, ##__VA_ARGS__)
+
+
+#define ____PVOP_VCALL(op, clbr, call_clbr, extra_clbr, pre, post, ...)	\
 	({								\
 		PVOP_VCALL_ARGS;					\
 		PVOP_TEST_NULL(op);					\
 		asm volatile(pre					\
 			     paravirt_alt(PARAVIRT_CALL)		\
 			     post					\
-			     : PVOP_VCALL_CLOBBERS			\
+			     : call_clbr				\
 			     : paravirt_type(op),			\
-			       paravirt_clobber(CLBR_ANY),		\
+			       paravirt_clobber(clbr),			\
 			       ##__VA_ARGS__				\
-			     : "memory", "cc" VEXTRA_CLOBBERS);		\
+			     : "memory", "cc" extra_clbr);		\
 	})
 
+#define __PVOP_VCALL(op, pre, post, ...)				\
+	____PVOP_VCALL(op, CLBR_ANY, PVOP_VCALL_CLOBBERS,		\
+		       VEXTRA_CLOBBERS,					\
+		       pre, post, ##__VA_ARGS__)
+
+#define __PVOP_VCALLEESAVE(rettype, op, pre, post, ...)			\
+	____PVOP_CALL(rettype, op.func, CLBR_RET_REG,			\
+		      PVOP_VCALLEE_CLOBBERS, ,				\
+		      pre, post, ##__VA_ARGS__)
+
+
+
 #define PVOP_CALL0(rettype, op)						\
 	__PVOP_CALL(rettype, op, "", "")
 #define PVOP_VCALL0(op)							\
 	__PVOP_VCALL(op, "", "")
 
+#define PVOP_CALLEE0(rettype, op)					\
+	__PVOP_CALLEESAVE(rettype, op, "", "")
+#define PVOP_VCALLEE0(op)						\
+	__PVOP_VCALLEESAVE(op, "", "")
+
+
 #define PVOP_CALL1(rettype, op, arg1)					\
-	__PVOP_CALL(rettype, op, "", "", "0" ((unsigned long)(arg1)))
+	__PVOP_CALL(rettype, op, "", "", PVOP_CALL_ARG1(arg1))
 #define PVOP_VCALL1(op, arg1)						\
-	__PVOP_VCALL(op, "", "", "0" ((unsigned long)(arg1)))
+	__PVOP_VCALL(op, "", "", PVOP_CALL_ARG1(arg1))
+
+#define PVOP_CALLEE1(rettype, op, arg1)					\
+	__PVOP_CALLEESAVE(rettype, op, "", "", PVOP_CALL_ARG1(arg1))
+#define PVOP_VCALLEE1(op, arg1)						\
+	__PVOP_VCALLEESAVE(op, "", "", PVOP_CALL_ARG1(arg1))
+
 
 #define PVOP_CALL2(rettype, op, arg1, arg2)				\
-	__PVOP_CALL(rettype, op, "", "", "0" ((unsigned long)(arg1)), 	\
-	"1" ((unsigned long)(arg2)))
+	__PVOP_CALL(rettype, op, "", "", PVOP_CALL_ARG1(arg1),		\
+		    PVOP_CALL_ARG2(arg2))
 #define PVOP_VCALL2(op, arg1, arg2)					\
-	__PVOP_VCALL(op, "", "", "0" ((unsigned long)(arg1)), 		\
-	"1" ((unsigned long)(arg2)))
+	__PVOP_VCALL(op, "", "", PVOP_CALL_ARG1(arg1),			\
+		     PVOP_CALL_ARG2(arg2))
+
+#define PVOP_CALLEE2(rettype, op, arg1, arg2)				\
+	__PVOP_CALLEESAVE(rettype, op, "", "", PVOP_CALL_ARG1(arg1),	\
+			  PVOP_CALL_ARG2(arg2))
+#define PVOP_VCALLEE2(op, arg1, arg2)					\
+	__PVOP_VCALLEESAVE(op, "", "", PVOP_CALL_ARG1(arg1),		\
+			   PVOP_CALL_ARG2(arg2))
+
 
 #define PVOP_CALL3(rettype, op, arg1, arg2, arg3)			\
-	__PVOP_CALL(rettype, op, "", "", "0" ((unsigned long)(arg1)),	\
-	"1"((unsigned long)(arg2)), "2"((unsigned long)(arg3)))
+	__PVOP_CALL(rettype, op, "", "", PVOP_CALL_ARG1(arg1),		\
+		    PVOP_CALL_ARG2(arg2), PVOP_CALL_ARG3(arg3))
 #define PVOP_VCALL3(op, arg1, arg2, arg3)				\
-	__PVOP_VCALL(op, "", "", "0" ((unsigned long)(arg1)),		\
-	"1"((unsigned long)(arg2)), "2"((unsigned long)(arg3)))
+	__PVOP_VCALL(op, "", "", PVOP_CALL_ARG1(arg1),			\
+		     PVOP_CALL_ARG2(arg2), PVOP_CALL_ARG3(arg3))
 
 /* This is the only difference in x86_64. We can make it much simpler */
 #ifdef CONFIG_X86_32
 #define PVOP_CALL4(rettype, op, arg1, arg2, arg3, arg4)			\
 	__PVOP_CALL(rettype, op,					\
 		    "push %[_arg4];", "lea 4(%%esp),%%esp;",		\
-		    "0" ((u32)(arg1)), "1" ((u32)(arg2)),		\
-		    "2" ((u32)(arg3)), [_arg4] "mr" ((u32)(arg4)))
+		    PVOP_CALL_ARG1(arg1), PVOP_CALL_ARG2(arg2),		\
+		    PVOP_CALL_ARG3(arg3), [_arg4] "mr" ((u32)(arg4)))
 #define PVOP_VCALL4(op, arg1, arg2, arg3, arg4)				\
 	__PVOP_VCALL(op,						\
 		    "push %[_arg4];", "lea 4(%%esp),%%esp;",		\
@@ -618,13 +682,13 @@ int paravirt_disable_iospace(void);
 		    "2" ((u32)(arg3)), [_arg4] "mr" ((u32)(arg4)))
 #else
 #define PVOP_CALL4(rettype, op, arg1, arg2, arg3, arg4)			\
-	__PVOP_CALL(rettype, op, "", "", "0" ((unsigned long)(arg1)),	\
-	"1"((unsigned long)(arg2)), "2"((unsigned long)(arg3)),		\
-	"3"((unsigned long)(arg4)))
+	__PVOP_CALL(rettype, op, "", "",				\
+		    PVOP_CALL_ARG1(arg1), PVOP_CALL_ARG2(arg2),		\
+		    PVOP_CALL_ARG3(arg3), PVOP_CALL_ARG4(arg4))
 #define PVOP_VCALL4(op, arg1, arg2, arg3, arg4)				\
-	__PVOP_VCALL(op, "", "", "0" ((unsigned long)(arg1)),		\
-	"1"((unsigned long)(arg2)), "2"((unsigned long)(arg3)),		\
-	"3"((unsigned long)(arg4)))
+	__PVOP_VCALL(op, "", "",					\
+		     PVOP_CALL_ARG1(arg1), PVOP_CALL_ARG2(arg2),	\
+		     PVOP_CALL_ARG3(arg3), PVOP_CALL_ARG4(arg4))
 #endif
 
 static inline int paravirt_enabled(void)