[PATCH] i386: PARAVIRT: Fix patch site clobbers to include return reg…

…ister

Fix a few clobbers to include the return register.  The clobbers set
is the set of all registers modified (or may be modified) by the code
snippet, regardless of whether it was deliberate or accidental.

Also, make sure that callsites which are used in contexts which don't
allow clobbers actually save and restore all clobberable registers.

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>

arch/i386/kernel/entry.S

@@ -338,7 +338,7 @@ sysenter_past_esp:
 	jae syscall_badsys
 	call *sys_call_table(,%eax,4)
 	movl %eax,PT_EAX(%esp)
-	DISABLE_INTERRUPTS(CLBR_ECX|CLBR_EDX)
+	DISABLE_INTERRUPTS(CLBR_ANY)
 	TRACE_IRQS_OFF
 	movl TI_flags(%ebp), %ecx
 	testw $_TIF_ALLWORK_MASK, %cx

include/asm-i386/paravirt.h

@@ -535,7 +535,7 @@ static inline unsigned long __raw_local_save_flags(void)
 				  "popl %%edx; popl %%ecx")
 		     : "=a"(f)
 		     : paravirt_type(save_fl),
-		       paravirt_clobber(CLBR_NONE)
+		       paravirt_clobber(CLBR_EAX)
 		     : "memory", "cc");
 	return f;
 }
@@ -620,27 +620,29 @@ static inline unsigned long __raw_local_irq_save(void)
 	.popsection
 
 #define INTERRUPT_RETURN					\
-	PARA_SITE(PARA_PATCH(PARAVIRT_iret), CLBR_ANY,		\
+	PARA_SITE(PARA_PATCH(PARAVIRT_iret), CLBR_NONE,		\
 		  jmp *%cs:paravirt_ops+PARAVIRT_iret)
 
 #define DISABLE_INTERRUPTS(clobbers)					\
 	PARA_SITE(PARA_PATCH(PARAVIRT_irq_disable), clobbers,		\
-		  pushl %ecx; pushl %edx;				\
+		  pushl %eax; pushl %ecx; pushl %edx;			\
 		  call *%cs:paravirt_ops+PARAVIRT_irq_disable;		\
-		  popl %edx; popl %ecx)					\
+		  popl %edx; popl %ecx; popl %eax)			\
 
 #define ENABLE_INTERRUPTS(clobbers)					\
 	PARA_SITE(PARA_PATCH(PARAVIRT_irq_enable), clobbers,		\
-		  pushl %ecx; pushl %edx;				\
+		  pushl %eax; pushl %ecx; pushl %edx;			\
 		  call *%cs:paravirt_ops+PARAVIRT_irq_enable;		\
-		  popl %edx; popl %ecx)
+		  popl %edx; popl %ecx; popl %eax)
 
 #define ENABLE_INTERRUPTS_SYSEXIT					\
-	PARA_SITE(PARA_PATCH(PARAVIRT_irq_enable_sysexit), CLBR_ANY,	\
+	PARA_SITE(PARA_PATCH(PARAVIRT_irq_enable_sysexit), CLBR_NONE,	\
 		  jmp *%cs:paravirt_ops+PARAVIRT_irq_enable_sysexit)
 
 #define GET_CR0_INTO_EAX			\
-	call *paravirt_ops+PARAVIRT_read_cr0
+	push %ecx; push %edx;			\
+	call *paravirt_ops+PARAVIRT_read_cr0;	\
+	pop %edx; pop %ecx
 
 #endif /* __ASSEMBLY__ */
 #endif /* CONFIG_PARAVIRT */