microblaze: Optimize SAVE_STATE macro

It is necessary to setup BIP and EE and clear EIP
only for unaligned exception handler. The rest of
hw exception handlers don't require it.
HW exception occured and we are not in virtual mode.
That's why we can do operations protected by EIP.
Interrupt, next hw exception or syscall can't occur.

EIP is cleared by rted.

This change speedup page_fault hw exception handler
which is critical path.

There is also necessary to save R11 content before
flag setup for unaligned exception.

Signed-off-by: Michal Simek <monstr@monstr.eu>

arch/microblaze/kernel/entry.S

@@ -507,9 +507,6 @@ C_ENTRY(sys_rt_sigreturn_wrapper):
 #define SAVE_STATE	\
 	swi	r1, r0, TOPHYS(PER_CPU(ENTRY_SP)); /* save stack */	\
 	swi	r11, r0, TOPHYS(r0_ram + PTO + PT_R11); /* Save r11 */	\
-	set_bip;	/*equalize initial state for all possible entries*/\
-	clear_eip;							\
-	set_ee;								\
 	/* See if already in kernel mode.*/				\
 	mfs	r11, rmsr;						\
 	nop;								\
@@ -569,7 +566,7 @@ C_ENTRY(full_exception_trap):
 	nop
 	addik	r12, r0, full_exception
 	set_vms;
-	rtbd	r12, 0;
+	rted	r12, 0;
 	nop;
 
 /*
@@ -583,6 +580,17 @@ C_ENTRY(full_exception_trap):
  * The assembler routine is in "arch/microblaze/kernel/hw_exception_handler.S"
  */
 C_ENTRY(unaligned_data_trap):
+	/* MS: I have to save r11 value and then restore it because
+	 * set_bit, clear_eip, set_ee use r11 as temp register if MSR
+	 * instructions are not used. We don't need to do if MSR instructions
+	 * are used and they use r0 instead of r11.
+	 * I am using ENTRY_SP which should be primary used only for stack
+	 * pointer saving. */
+	swi	r11, r0, TOPHYS(PER_CPU(ENTRY_SP));
+	set_bip;        /* equalize initial state for all possible entries */
+	clear_eip;
+	set_ee;
+	lwi	r11, r0, TOPHYS(PER_CPU(ENTRY_SP));
 	SAVE_STATE		/* Save registers.*/
 	/* where the trap should return need -8 to adjust for rtsd r15, 8 */
 	addik	r15, r0, ret_from_exc-8
@@ -625,7 +633,7 @@ C_ENTRY(page_fault_data_trap):
 	nop
 	addik	r12, r0, do_page_fault
 	set_vms;
-	rtbd	r12, 0;	/* interrupts enabled */
+	rted	r12, 0;	/* interrupts enabled */
 	nop;
 
 C_ENTRY(page_fault_instr_trap):
@@ -638,7 +646,7 @@ C_ENTRY(page_fault_instr_trap):
 	ori	r7, r0, 0		/* parameter unsigned long error_code */
 	addik	r12, r0, do_page_fault
 	set_vms;
-	rtbd	r12, 0;	/* interrupts enabled */
+	rted	r12, 0;	/* interrupts enabled */
 	nop;
 
 /* Entry point used to return from an exception.  */