[PATCH] i386: PARAVIRT: Use patch site IDs computed from offset in paravirt_ops structure

Use patch type identifiers derived from the offset of the operation in
the paravirt_ops structure.  This avoids having to maintain a separate
enum for patch site types.

Also, since the identifier is derived from the offset into
paravirt_ops, the offset can be derived from the identifier.  This is
used to remove replicated information in the various callsite macros,
which has been a source of bugs in the past.

This patch also drops the fused save_fl+cli operation, which doesn't
really add much and makes things more complex - specifically because
it breaks the 1:1 relationship between identifiers and offsets.  If
this operation turns out to be particularly beneficial, then the right
answer is to define a new entrypoint for it.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Zachary Amsden <zach@vmware.com>

1 files changed, 92 insertions, 85 deletions

diff --git a/include/asm-i386/paravirt.h b/include/asm-i386/paravirt.h
index b4cc2fc4031..1dbc01f4ed4 100644
--- a/include/asm-i386/paravirt.h
+++ b/include/asm-i386/paravirt.h
@@ -4,19 +4,8 @@
  * para-virtualization: those hooks are defined here. */
 
 #ifdef CONFIG_PARAVIRT
-#include <linux/stringify.h>
 #include <asm/page.h>
 
-/* These are the most performance critical ops, so we want to be able to patch
- * callers */
-#define PARAVIRT_IRQ_DISABLE 0
-#define PARAVIRT_IRQ_ENABLE 1
-#define PARAVIRT_RESTORE_FLAGS 2
-#define PARAVIRT_SAVE_FLAGS 3
-#define PARAVIRT_SAVE_FLAGS_IRQ_DISABLE 4
-#define PARAVIRT_INTERRUPT_RETURN 5
-#define PARAVIRT_STI_SYSEXIT 6
-
 /* Bitmask of what can be clobbered: usually at least eax. */
 #define CLBR_NONE 0x0
 #define CLBR_EAX 0x1
@@ -191,6 +180,28 @@ struct paravirt_ops
 
 extern struct paravirt_ops paravirt_ops;
 
+#define PARAVIRT_PATCH(x)					\
+	(offsetof(struct paravirt_ops, x) / sizeof(void *))
+
+#define paravirt_type(type)					\
+	[paravirt_typenum] "i" (PARAVIRT_PATCH(type))
+#define paravirt_clobber(clobber)		\
+	[paravirt_clobber] "i" (clobber)
+
+#define PARAVIRT_CALL	"call *paravirt_ops+%c[paravirt_typenum]*4;"
+
+#define _paravirt_alt(insn_string, type, clobber)	\
+	"771:\n\t" insn_string "\n" "772:\n"		\
+	".pushsection .parainstructions,\"a\"\n"	\
+	"  .long 771b\n"				\
+	"  .byte " type "\n"				\
+	"  .byte 772b-771b\n"				\
+	"  .short " clobber "\n"			\
+	".popsection\n"
+
+#define paravirt_alt(insn_string)				\
+	_paravirt_alt(insn_string, "%c[paravirt_typenum]", "%c[paravirt_clobber]")
+
 #define paravirt_enabled() (paravirt_ops.paravirt_enabled)
 
 static inline void load_esp0(struct tss_struct *tss,
@@ -515,93 +526,89 @@ struct paravirt_patch_site {
 extern struct paravirt_patch_site __parainstructions[],
 	__parainstructions_end[];
 
-#define paravirt_alt(insn_string, typenum, clobber)	\
-	"771:\n\t" insn_string "\n" "772:\n"		\
-	".pushsection .parainstructions,\"a\"\n"	\
-	"  .long 771b\n"				\
-	"  .byte " __stringify(typenum) "\n"		\
-	"  .byte 772b-771b\n"				\
-	"  .short " __stringify(clobber) "\n"		\
-	".popsection"
-
 static inline unsigned long __raw_local_save_flags(void)
 {
 	unsigned long f;
 
-	__asm__ __volatile__(paravirt_alt( "pushl %%ecx; pushl %%edx;"
-					   "call *%1;"
-					   "popl %%edx; popl %%ecx",
-					  PARAVIRT_SAVE_FLAGS, CLBR_NONE)
-			     : "=a"(f): "m"(paravirt_ops.save_fl)
-			     : "memory", "cc");
+	asm volatile(paravirt_alt("pushl %%ecx; pushl %%edx;"
+				  PARAVIRT_CALL
+				  "popl %%edx; popl %%ecx")
+		     : "=a"(f)
+		     : paravirt_type(save_fl),
+		       paravirt_clobber(CLBR_NONE)
+		     : "memory", "cc");
 	return f;
 }
 
 static inline void raw_local_irq_restore(unsigned long f)
 {
-	__asm__ __volatile__(paravirt_alt( "pushl %%ecx; pushl %%edx;"
-					   "call *%1;"
-					   "popl %%edx; popl %%ecx",
-					  PARAVIRT_RESTORE_FLAGS, CLBR_EAX)
-			     : "=a"(f) : "m" (paravirt_ops.restore_fl), "0"(f)
-			     : "memory", "cc");
+	asm volatile(paravirt_alt("pushl %%ecx; pushl %%edx;"
+				  PARAVIRT_CALL
+				  "popl %%edx; popl %%ecx")
+		     : "=a"(f)
+		     : "0"(f),
+		       paravirt_type(restore_fl),
+		       paravirt_clobber(CLBR_EAX)
+		     : "memory", "cc");
 }
 
 static inline void raw_local_irq_disable(void)
 {
-	__asm__ __volatile__(paravirt_alt( "pushl %%ecx; pushl %%edx;"
-					   "call *%0;"
-					   "popl %%edx; popl %%ecx",
-					  PARAVIRT_IRQ_DISABLE, CLBR_EAX)
-			     : : "m" (paravirt_ops.irq_disable)
-			     : "memory", "eax", "cc");
+	asm volatile(paravirt_alt("pushl %%ecx; pushl %%edx;"
+				  PARAVIRT_CALL
+				  "popl %%edx; popl %%ecx")
+		     :
+		     : paravirt_type(irq_disable),
+		       paravirt_clobber(CLBR_EAX)
+		     : "memory", "eax", "cc");
 }
 
 static inline void raw_local_irq_enable(void)
 {
-	__asm__ __volatile__(paravirt_alt( "pushl %%ecx; pushl %%edx;"
-					   "call *%0;"
-					   "popl %%edx; popl %%ecx",
-					  PARAVIRT_IRQ_ENABLE, CLBR_EAX)
-			     : : "m" (paravirt_ops.irq_enable)
-			     : "memory", "eax", "cc");
+	asm volatile(paravirt_alt("pushl %%ecx; pushl %%edx;"
+				  PARAVIRT_CALL
+				  "popl %%edx; popl %%ecx")
+		     :
+		     : paravirt_type(irq_enable),
+		       paravirt_clobber(CLBR_EAX)
+		     : "memory", "eax", "cc");
 }
 
 static inline unsigned long __raw_local_irq_save(void)
 {
 	unsigned long f;
 
-	__asm__ __volatile__(paravirt_alt( "pushl %%ecx; pushl %%edx;"
-					   "call *%1; pushl %%eax;"
-					   "call *%2; popl %%eax;"
-					   "popl %%edx; popl %%ecx",
-					  PARAVIRT_SAVE_FLAGS_IRQ_DISABLE,
-					  CLBR_NONE)
-			     : "=a"(f)
-			     : "m" (paravirt_ops.save_fl),
-			       "m" (paravirt_ops.irq_disable)
-			     : "memory", "cc");
+	f = __raw_local_save_flags();
+	raw_local_irq_disable();
 	return f;
 }
 
-#define CLI_STRING paravirt_alt("pushl %%ecx; pushl %%edx;"		\
-		     "call *paravirt_ops+%c[irq_disable];"		\
-		     "popl %%edx; popl %%ecx",				\
-		     PARAVIRT_IRQ_DISABLE, CLBR_EAX)
+#define CLI_STRING							\
+	_paravirt_alt("pushl %%ecx; pushl %%edx;"			\
+		      "call *paravirt_ops+%c[paravirt_cli_type]*4;"	\
+		      "popl %%edx; popl %%ecx",				\
+		      "%c[paravirt_cli_type]", "%c[paravirt_clobber]")
+
+#define STI_STRING							\
+	_paravirt_alt("pushl %%ecx; pushl %%edx;"			\
+		      "call *paravirt_ops+%c[paravirt_sti_type]*4;"	\
+		      "popl %%edx; popl %%ecx",				\
+		      "%c[paravirt_sti_type]", "%c[paravirt_clobber]")
 
-#define STI_STRING paravirt_alt("pushl %%ecx; pushl %%edx;"		\
-		     "call *paravirt_ops+%c[irq_enable];"		\
-		     "popl %%edx; popl %%ecx",				\
-		     PARAVIRT_IRQ_ENABLE, CLBR_EAX)
 #define CLI_STI_CLOBBERS , "%eax"
-#define CLI_STI_INPUT_ARGS \
+#define CLI_STI_INPUT_ARGS						\
 	,								\
-	[irq_disable] "i" (offsetof(struct paravirt_ops, irq_disable)),	\
-	[irq_enable] "i" (offsetof(struct paravirt_ops, irq_enable))
+	[paravirt_cli_type] "i" (PARAVIRT_PATCH(irq_disable)),		\
+	[paravirt_sti_type] "i" (PARAVIRT_PATCH(irq_enable)),		\
+	paravirt_clobber(CLBR_EAX)
+
+#undef PARAVIRT_CALL
 
 #else  /* __ASSEMBLY__ */
 
-#define PARA_PATCH(ptype, clobbers, ops)	\
+#define PARA_PATCH(off)	((off) / 4)
+
+#define PARA_SITE(ptype, clobbers, ops)		\
 771:;						\
 	ops;					\
 772:;						\
@@ -612,25 +619,25 @@ static inline unsigned long __raw_local_irq_save(void)
 	 .short clobbers;			\
 	.popsection
 
-#define INTERRUPT_RETURN				\
-	PARA_PATCH(PARAVIRT_INTERRUPT_RETURN, CLBR_ANY,	\
-	jmp *%cs:paravirt_ops+PARAVIRT_iret)
-
-#define DISABLE_INTERRUPTS(clobbers)			\
-	PARA_PATCH(PARAVIRT_IRQ_DISABLE, clobbers,	\
-	pushl %ecx; pushl %edx;				\
-	call *paravirt_ops+PARAVIRT_irq_disable;	\
-	popl %edx; popl %ecx)				\
-
-#define ENABLE_INTERRUPTS(clobbers)			\
-	PARA_PATCH(PARAVIRT_IRQ_ENABLE, clobbers,	\
-	pushl %ecx; pushl %edx;				\
-	call *%cs:paravirt_ops+PARAVIRT_irq_enable;	\
-	popl %edx; popl %ecx)
-
-#define ENABLE_INTERRUPTS_SYSEXIT			\
-	PARA_PATCH(PARAVIRT_STI_SYSEXIT, CLBR_ANY,	\
-	jmp *%cs:paravirt_ops+PARAVIRT_irq_enable_sysexit)
+#define INTERRUPT_RETURN					\
+	PARA_SITE(PARA_PATCH(PARAVIRT_iret), CLBR_ANY,		\
+		  jmp *%cs:paravirt_ops+PARAVIRT_iret)
+
+#define DISABLE_INTERRUPTS(clobbers)					\
+	PARA_SITE(PARA_PATCH(PARAVIRT_irq_disable), clobbers,		\
+		  pushl %ecx; pushl %edx;				\
+		  call *%cs:paravirt_ops+PARAVIRT_irq_disable;		\
+		  popl %edx; popl %ecx)					\
+
+#define ENABLE_INTERRUPTS(clobbers)					\
+	PARA_SITE(PARA_PATCH(PARAVIRT_irq_enable), clobbers,		\
+		  pushl %ecx; pushl %edx;				\
+		  call *%cs:paravirt_ops+PARAVIRT_irq_enable;		\
+		  popl %edx; popl %ecx)
+
+#define ENABLE_INTERRUPTS_SYSEXIT					\
+	PARA_SITE(PARA_PATCH(PARAVIRT_irq_enable_sysexit), CLBR_ANY,	\
+		  jmp *%cs:paravirt_ops+PARAVIRT_irq_enable_sysexit)
 
 #define GET_CR0_INTO_EAX			\
 	call *paravirt_ops+PARAVIRT_read_cr0