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CRIS v32: Add workaround for MMU hardware bug for ETRAX FS in mm/mmu.S

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This commit is contained in:
Jesper Nilsson 2008-01-25 18:05:12 +01:00
parent 108ecfbc31
commit 3d44305abe
1 changed files with 81 additions and 12 deletions
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93
arch/cris/arch-v32/mm/mmu.S
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@ -1,3 +1,5 @@
; WARNING : The refill handler has been modified, see below !!!
/*
* Copyright (C) 2003 Axis Communications AB
*
@ -61,6 +63,14 @@
; 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
@ -68,6 +78,11 @@
; 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
@ -76,42 +91,96 @@
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], $srs
move [$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
addq 4, $sp
SAVE_ALL
move \mmu, $srs