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Commit 3e1ae441 authored by Vineet Gupta's avatar Vineet Gupta
Browse files

ARC: [mm] Remove @write argument to do_page_fault() 



This can be ascertained within do_page_fault() since it gets the full
ECR (Exception Cause Register).

Further, for both the callers of do_page_fault(): Prot-V / D-TLB-Miss,
the cause sub-fields in ECR are same for same type of access, making the
code much more simpler.

D-TLB-Miss [LD] 0x00_21_01_00
Prot-V     [LD] 0x00_23_01_00
                        ^^
D-TLB-Miss [ST] 0x00_21_02_00
Prot-V     [ST] 0x00_23_02_00
                        ^^
D-TLB-Miss [EX] 0x00_21_03_00
Prot-V     [EX] 0x00_23_03_00
                        ^^

This helps code consolidation, which is even better when moving code from
assembler to "C".

Signed-off-by: default avatarVineet Gupta <vgupta@synopsys.com>
parent 3abc9448

arch/arc/kernel/entry.S

+4 −10
Original line number Diff line number Diff line
@@ -355,8 +355,8 @@ ARC_ENTRY EV_TLBProtV 
	;  ecr and efa were not saved in case an Intr sneaks in

	;  after fake rtie

	;

	lr  r3, [ecr]

	lr  r4, [efa]

	lr  r2, [ecr]

	lr  r1, [efa]	; Faulting Data address



	; --------(4) Return from CPU Exception Mode ---------

	;  Fake a rtie, but rtie to next label
@@ -371,23 +371,17 @@ ARC_ENTRY EV_TLBProtV 
	;   -Access Violaton (WRITE to READ ONLY Page) - for linux COW

	;   -Unaligned Access (READ/WRITE on odd boundary)

	;

	cmp r3, 0x230400    ; Misaligned data access ?

	cmp r2, 0x230400    ; Misaligned data access ?

	beq 4f



	;========= (6a) Access Violation Processing ========

	cmp r3, 0x230100

	mov r1, 0x0              ; if LD exception ? write = 0

	mov.ne r1, 0x1           ; else write = 1



	mov r2, r4              ; faulting address

	mov r0, sp              ; pt_regs

	bl  do_page_fault

	b   ret_from_exception



	;========== (6b) Non aligned access ============

4:

	mov r0, r3              ; cause code

	mov r1, r4              ; faulting address

	mov r0, r2              ; cause code

	mov r2, sp              ; pt_regs



#ifdef  CONFIG_ARC_MISALIGN_ACCESS

arch/arc/mm/fault.c

+2 −1
Original line number Diff line number Diff line
@@ -52,7 +52,7 @@ static int handle_vmalloc_fault(struct mm_struct *mm, unsigned long address) 
	return 1;

}



void do_page_fault(struct pt_regs *regs, int write, unsigned long address,

void do_page_fault(struct pt_regs *regs, unsigned long address,

		   unsigned long cause_code)

{

	struct vm_area_struct *vma = NULL;
@@ -60,6 +60,7 @@ void do_page_fault(struct pt_regs *regs, int write, unsigned long address, 
	struct mm_struct *mm = tsk->mm;

	siginfo_t info;

	int fault, ret;

	int write = cause_code & (1 << ECR_C_BIT_DTLB_ST_MISS);  /* ST/EX */

	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |

				(write ? FAULT_FLAG_WRITE : 0);

arch/arc/mm/tlbex.S

+2 −12
Original line number Diff line number Diff line
@@ -381,18 +381,8 @@ do_slow_path_pf: 


	; ------- setup args for Linux Page fault Hanlder ---------

	mov_s r0, sp

	lr  r2, [efa]

	lr  r3, [ecr]



	; Both st and ex imply WRITE access of some sort, hence do_page_fault( )

	; invoked with write=1 for DTLB-st/ex Miss and write=0 for ITLB miss or

	; DTLB-ld Miss

	; DTLB Miss Cause code is ld = 0x01 , st = 0x02, ex = 0x03

	; Following code uses that fact that st/ex have one bit in common



	btst_s r3,  ECR_C_BIT_DTLB_ST_MISS

	mov.z  r1, 0

	mov.nz r1, 1

	lr  r1, [efa]

	lr  r2, [ecr]



	; We don't want exceptions to be disabled while the fault is handled.

	; Now that we have saved the context we return from exception hence