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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: Vineet Gupta <vgupta@synopsys.com>
This commit is contained in:
Vineet Gupta 2013-06-12 13:49:02 +05:30
parent 3abc944802
commit 3e1ae44188
3 changed files with 8 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
arch/arc/kernel/entry.S
View File

@ -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

3
arch/arc/mm/fault.c
View File

@ -52,7 +52,7 @@ bad_area:
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);

14
arch/arc/mm/tlbex.S
View File

@ -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