+; WARNING : The refill handler has been modified, see below !!!
+
/*
* Copyright (C) 2003 Axis Communications AB
*
; Note that the code is optimized to minimize stalls (makes the code harder
; to read).
;
+; WARNING !!!
+; Modified by Mikael Asker 060725: added a workaround for strange TLB
+; behavior. If the same PTE is present in more than one set, the TLB
+; doesn't recognize it and we get stuck in a loop of refill exceptions.
+; The workaround detects such loops and exits them by flushing
+; the TLB contents. The problem and workaround were verified
+; in VCS by Mikael Starvik.
+;
; Each page is 8 KB. Each PMD holds 8192/4 PTEs (each PTE is 4 bytes) so each
; PMD holds 16 MB of virtual memory.
; Bits 0-12 : Offset within a page
; Bits 24-31 : PMD offset within the PGD
.macro MMU_REFILL_HANDLER handler, mmu
+ .data
+1: .dword 0 ; refill_count
+ ; == 0 <=> last_refill_cause is invalid
+2: .dword 0 ; last_refill_cause
+ .text
.globl \handler
\handler:
subq 4, $sp
subq 4, $sp
move \mmu, $srs ; Select MMU support register bank
move.d $acr, [$sp]
- subq 4, $sp
- move.d $r0, [$sp]
+ subq 12, $sp
+ move.d 1b, $acr ; Point to refill_count
+ movem $r2, [$sp]
+
+ test.d [$acr] ; refill_count == 0 ?
+ beq 5f ; yes, last_refill_cause is invalid
+ move.d $acr, $r1
+
+ ; last_refill_cause is valid, investigate cause
+ addq 4, $r1 ; Point to last_refill_cause
+ move $s3, $r0 ; Get rw_mm_cause
+ move.d [$r1], $r2 ; Get last_refill_cause
+ cmp.d $r0, $r2 ; rw_mm_cause == last_refill_cause ?
+ beq 6f ; yes, increment count
+ moveq 1, $r2
+
+ ; rw_mm_cause != last_refill_cause
+ move.d $r2, [$acr] ; refill_count = 1
+ move.d $r0, [$r1] ; last_refill_cause = rw_mm_cause
+
+3: ; Probably not in a loop, continue normal processing
#ifdef CONFIG_SMP
move $s7, $acr ; PGD
#else
move.d per_cpu__current_pgd, $acr ; PGD
#endif
; Look up PMD in PGD
- move $s3, $r0 ; rw_mm_cause
lsrq 24, $r0 ; Get PMD index into PGD (bit 24-31)
move.d [$acr], $acr ; PGD for the current process
addi $r0.d, $acr, $acr
move $s3, $r0 ; rw_mm_cause
move.d [$acr], $acr ; Get PMD
- beq 1f
+ beq 8f
; Look up PTE in PMD
lsrq PAGE_SHIFT, $r0
and.w PAGE_MASK, $acr ; Remove PMD flags
and.d 0x7ff, $r0 ; Get PTE index into PMD (bit 13-23)
addi $r0.d, $acr, $acr
move.d [$acr], $acr ; Get PTE
- beq 2f
- move.d [$sp+], $r0 ; Pop r0 in delayslot
+ beq 9f
+ movem [$sp], $r2 ; Restore r0-r2 in delay slot
+ addq 12, $sp
; Store in TLB
move $acr, $s5
- ; Return
+4: ; Return
move.d [$sp+], $acr
- move [$sp], $srs
+ move [$sp], $srs
addq 4, $sp
rete
rfe
-1: ; PMD missing, let the mm subsystem fix it up.
- move.d [$sp+], $r0 ; Pop r0
-2: ; PTE missing, let the mm subsystem fix it up.
+
+5: ; last_refill_cause is invalid
+ moveq 1, $r2
+ addq 4, $r1 ; Point to last_refill_cause
+ move.d $r2, [$acr] ; refill_count = 1
+ move $s3, $r0 ; Get rw_mm_cause
+ ba 3b ; Continue normal processing
+ move.d $r0,[$r1] ; last_refill_cause = rw_mm_cause
+
+6: ; rw_mm_cause == last_refill_cause
+ move.d [$acr], $r2 ; Get refill_count
+ cmpq 4, $r2 ; refill_count > 4 ?
+ bhi 7f ; yes
+ addq 1, $r2 ; refill_count++
+ ba 3b ; Continue normal processing
+ move.d $r2, [$acr]
+
+7: ; refill_count > 4, error
+ move.d $acr, $r0 ; Save pointer to refill_count
+ clear.d [$r0] ; refill_count = 0
+
+ ;; rewind the short stack
+ movem [$sp], $r2 ; Restore r0-r2
+ addq 12, $sp
+ move.d [$sp+], $acr
+ move [$sp], $srs
+ addq 4, $sp
+ ;; Keep it simple (slow), save all the regs.
+ SAVE_ALL
+ jsr __flush_tlb_all
+ nop
+ ba ret_from_intr ; Return
+ nop
+
+8: ; PMD missing, let the mm subsystem fix it up.
+ movem [$sp], $r2 ; Restore r0-r2
+9: ; PTE missing, let the mm subsystem fix it up.
+ addq 12, $sp
move.d [$sp+], $acr
- move [$sp], $srs
+ move [$sp], $srs
addq 4, $sp
SAVE_ALL
move \mmu, $srs
git.samba.org / sfrench / cifs-2.6.git / blobdiff