ARC: entry: Add more common chores to EXCEPTION_PROLOGUE

THe high level structure of most ARC exception handlers is
 1. save regfile with EXCEPTION_PROLOGUE
 2. setup r0: EFA (not part of pt_regs)
 3. setup r1: pointer to pt_regs (SP)
 4. drop down to pure kernel mode (from exception)
 5. call the Linux "C" handler

Remove the boiler plate code by moving #2, #3, #4 into #1.

The exceptions to most exceptions are syscall Trap and Machine check
which don't do some of above for various reasons, so call a newly
introduced variant EXCEPTION_PROLOGUE_KEEP_AE (same as original
EXCEPTION_PROLOGUE)
Tested-by: Pavel Kozlov <Pavel.Kozlov@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@kernel.org>

arch/arc/include/asm/entry-arcv2.h

@@ -75,7 +75,7 @@
 .endm
 
 /*------------------------------------------------------------------------*/
-.macro EXCEPTION_PROLOGUE
+.macro EXCEPTION_PROLOGUE_KEEP_AE
 
 	; Before jumping to Exception Vector, hardware micro-ops did following:
 	;   1. SP auto-switched to kernel mode stack
@@ -104,6 +104,16 @@
 	; OUTPUT: r10 has ECR expected by EV_Trap
 .endm
 
+.macro EXCEPTION_PROLOGUE
+
+	EXCEPTION_PROLOGUE_KEEP_AE	; return ECR in r10
+
+	lr  r0, [efa]
+	mov r1, sp
+
+	FAKE_RET_FROM_EXCPN		; clobbers r9
+.endm
+
 /*------------------------------------------------------------------------
  * This macro saves the registers manually which would normally be autosaved
  * by hardware on taken interrupts. It is used by

arch/arc/include/asm/entry-compact.h

@@ -140,7 +140,7 @@
  *
  * After this it is safe to call the "C" handlers
  *-------------------------------------------------------------*/
-.macro EXCEPTION_PROLOGUE
+.macro EXCEPTION_PROLOGUE_KEEP_AE
 
 	/* Need at least 1 reg to code the early exception prologue */
 	PROLOG_FREEUP_REG r9, @ex_saved_reg1
@@ -179,6 +179,16 @@
 	; OUTPUT: r10 has ECR expected by EV_Trap
 .endm
 
+.macro EXCEPTION_PROLOGUE
+
+	EXCEPTION_PROLOGUE_KEEP_AE	; return ECR in r10
+
+	lr  r0, [efa]
+	mov r1, sp
+
+	FAKE_RET_FROM_EXCPN		; clobbers r9
+.endm
+
 /*--------------------------------------------------------------
  * Restore all registers used by system call or Exceptions
  * SP should always be pointing to the next free stack element

arch/arc/kernel/entry-arcv2.S

@@ -125,11 +125,6 @@ ENTRY(mem_service)
 
 	EXCEPTION_PROLOGUE
 
-	lr  r0, [efa]
-	mov r1, sp
-
-	FAKE_RET_FROM_EXCPN
-
 	bl  do_memory_error
 	b   ret_from_exception
 END(mem_service)
@@ -138,11 +133,6 @@ ENTRY(EV_Misaligned)
 
 	EXCEPTION_PROLOGUE
 
-	lr  r0, [efa]	; Faulting Data address
-	mov r1, sp
-
-	FAKE_RET_FROM_EXCPN
-
 	SAVE_CALLEE_SAVED_USER
 	mov r2, sp              ; callee_regs
 
@@ -163,11 +153,6 @@ ENTRY(EV_TLBProtV)
 
 	EXCEPTION_PROLOGUE
 
-	lr  r0, [efa]	; Faulting Data address
-	mov r1, sp	; pt_regs
-
-	FAKE_RET_FROM_EXCPN
-
 	mov blink, ret_from_exception
 	b   do_page_fault
 

arch/arc/kernel/entry-compact.S

@@ -256,16 +256,6 @@ ENTRY(EV_TLBProtV)
 
 	EXCEPTION_PROLOGUE	; ECR returned in r10
 
-	lr  r0, [efa]	; Faulting Data address (not part of pt_regs saved above)
-
-	; Exception auto-disables further Intr/exceptions.
-	; Re-enable them by pretending to return from exception
-	; (so rest of handler executes in pure K mode)
-
-	FAKE_RET_FROM_EXCPN
-
-	mov   r1, sp	; Handle to pt_regs
-
 	;------ (5) Type of Protection Violation? ----------
 	;
 	; ProtV Hardware Exception is triggered for Access Faults of 2 types
@@ -301,9 +291,6 @@ END(EV_TLBProtV)
 ENTRY(call_do_page_fault)
 
 	EXCEPTION_PROLOGUE
-	lr  r0, [efa]	; Faulting Data address
-	mov   r1, sp
-	FAKE_RET_FROM_EXCPN
 
 	mov blink, ret_from_exception
 	b  do_page_fault

arch/arc/kernel/entry.S

@@ -80,11 +80,6 @@ ENTRY(instr_service)
 
 	EXCEPTION_PROLOGUE
 
-	lr  r0, [efa]
-	mov r1, sp
-
-	FAKE_RET_FROM_EXCPN
-
 	bl  do_insterror_or_kprobe
 	b   ret_from_exception
 END(instr_service)
@@ -95,7 +90,7 @@ END(instr_service)
 
 ENTRY(EV_MachineCheck)
 
-	EXCEPTION_PROLOGUE	; ECR returned in r10
+	EXCEPTION_PROLOGUE_KEEP_AE	; ECR returned in r10
 
 	lr  r0, [efa]
 	mov r1, sp
@@ -128,11 +123,6 @@ ENTRY(EV_PrivilegeV)
 
 	EXCEPTION_PROLOGUE
 
-	lr  r0, [efa]
-	mov r1, sp
-
-	FAKE_RET_FROM_EXCPN
-
 	bl  do_privilege_fault
 	b   ret_from_exception
 END(EV_PrivilegeV)
@@ -144,11 +134,6 @@ ENTRY(EV_Extension)
 
 	EXCEPTION_PROLOGUE
 
-	lr  r0, [efa]
-	mov r1, sp
-
-	FAKE_RET_FROM_EXCPN
-
 	bl  do_extension_fault
 	b   ret_from_exception
 END(EV_Extension)
@@ -229,7 +214,7 @@ trap_with_param:
 
 ENTRY(EV_Trap)
 
-	EXCEPTION_PROLOGUE
+	EXCEPTION_PROLOGUE_KEEP_AE
 
 	lr  r12, [efa]