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VMAllocateMemory

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This commit is contained in:
Elliot Nunn 2018-08-13 20:51:32 +08:00
parent ffe78b1a62
commit fd02e62892
2 changed files with 74 additions and 70 deletions
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2
NanoKernel/NKEquates.s
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@ -156,7 +156,7 @@ Pattr_Paged equ 0x400 ; Pageable area with RPN = (68k Page Descripto
PMDT_InvalidAddress equ 0xA00 ; Known combinations when Pattr_NotPTE=1...
PMDT_Available equ 0xA01
PMDT_Paged equ 0xC00 ; = Pattr_NotPTE + Pattr_Paged
PMDT_Paged equ 0xC00 ; = Pattr_NotPTE + Pattr_Paged (can be created by VMAllocateMemory)
; When Pattr_NotPTE=0, the PMDT describes a non-pageable area, and these apply:
Pattr_PTE_Single equ 0x400 ; Only one page

142
NanoKernel/NKLegacyVM.s
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@ -60,7 +60,7 @@ VMTab ; Placeholders indented
vmtabLine VMLRU ; 22 sweep pages for least recently used ones
vmtabLine VMMarkUndefined ; 23
vmtabLine VMMakePageWriteThrough ; 24
vmtabLine VMAllocateMemory ; 25
vmtabLine VMAllocateMemory ; 25 create logical area by stealing from "high memory"
VMTabEnd
########################################################################
@ -723,91 +723,92 @@ VMShouldClean ; page a0/r4 // bool d0/r3
########################################################################
VMAllocateMemory ; first_page a0/r4, page_count a1/r5, align d1/r6
lwz r7, KDP.VMPageArray(r1)
VMAllocateMemory ; first_page a0/r4, page_count a1/r5, align_mask d1/r6
; Allocate and wire a logical area with the specified physical alignment.
; The physical RAM is acquired by *shrinking* the VM area (hopefully in early boot).
lwz r7, KDP.VMPageArray(r1) ; Assert: r5 positive, VM off, r4 and r6 < 0x100000
lwz r8, KDP.PhysicalPageArray(r1)
cmpwi cr6, r5, 0
cmpw cr7, r7, r8
or r7, r4, r6 ; r4/r6 are page numbers?
or r7, r4, r6
rlwinm. r7, r7, 0, 0xFFF00000
; Prepare for PageInfo calls (r4 and r9!), saving the first_page arg in r7.
ble cr6, vmRetNeg1
lwz r9, KDP.VMLogicalPages(r1)
bne cr7, vmRetNeg1 ; diff page arrays: already inited?
bne cr7, vmRetNeg1
mr r7, r4
bne vmRetNeg1
mr r4, r9
slwi r6, r6, 12
subi r5, r5, 1
@for_each_logical_page
; Scan the VM area right->left until we have enough (aligned) physical RAM to steal.
slwi r6, r6, 12 ; r6 = mask of bits that must be zero in phys base
subi r5, r5, 1 ; r5 = page_count - 1
@pageloop
subi r4, r4, 1
bl PageInfo
bcl BO_IF, bM68pdInHTAB, DeletePTE ; clear from HTAB
bcl BO_IF, bM68pdInHTAB, DeletePTE ; Naturally this RAM should be expunged from the HTAB
lwz r9, KDP.VMLogicalPages(r1)
subf r8, r4, r9
cmplw cr7, r5, r8
and. r8, r16, r6
bge cr7, @for_each_logical_page
bne @for_each_logical_page
bge cr7, @pageloop ; Don't yet have enough pages: next!
bne @pageloop ; This page is not aligned: next!
cmpwi cr6, r6, 0 ; If no alignment is required then we can assume
beq cr6, @exitpageloop ; that discontiguous RAM is okay. (cr6_eq = 1)
cmpwi cr6, r6, 0
beq cr6, @donelogicalpgs
slwi r8, r5, 2
lwzx r8, r15, r8
slwi r14, r5, 12
add r14, r14, r16
xor r8, r8, r14
rlwinm. r8, r8, 0, 0, 19
bne @for_each_logical_page
@donelogicalpgs
rlwinm. r8, r8, 0, 0xFFFFF000
bne @pageloop ; Physical RAM discontiguous: next!
@exitpageloop ; cr6_eq = !(can be discontiguous)
; Fail if the requested area is in seg 0-3, or sized > 4 GB
lis r9, 4
cmplw cr7, r7, r9
rlwinm. r9, r7, 0, 0, 11
rlwinm. r9, r7, 0, 0xFFF00000
blt cr7, vmRetNeg1
bne vmRetNeg1
; Find the PMDT containing the new area.
lwz r14, KDP.CurMap.SegMapPtr(r1)
rlwinm r9, r7, 19, 25, 28
lwzx r14, r14, r9
clrlwi r9, r7, 0x10
lhz r8, 0x0000(r14)
b VMAllocateMemory_0xf4
VMAllocateMemory_0xf0
lhzu r8, 0x0008(r14)
VMAllocateMemory_0xf4
lhz r16, 0x0002(r14)
clrlwi r9, r7, 16
lhz r8, PMDT.PageIdx(r14)
b @enterpmdtloop
@pmdtloop
lhzu r8, PMDT.Size + PMDT.PageIdx(r14)
@enterpmdtloop
lhz r16, PMDT.PageCount(r14)
subf r8, r8, r9
cmplw cr7, r8, r16
bgt cr7, VMAllocateMemory_0xf0
add r8, r8, r5
bgt cr7, @pmdtloop
add r8, r8, r5 ; if PMDT does not fully enclose the area, fail!
cmplw cr7, r8, r16
bgt cr7, vmRetNeg1
lwz r16, 0x0004(r14)
; That PMDT had better be Available, because we're replacing it with one for our area.
lwz r16, PMDT.Word2(r14)
slwi r8, r7, 16
andi. r16, r16, EveryPattr
cmpwi r16, 0xa01
cmpwi r16, PMDT_Available
or r8, r8, r5
addi r5, r5, PMDT_Available
addi r5, r5, 1
bne vmRetNeg1
stw r8, 0x0000(r14)
bnel cr6, VMAllocateMemory_0x2e8
stw r8, 0(r14) ; PMDT.PageIdx/PageCount
bnel cr6, ReclaimLeftoverFromVMAlloc ; Move our area to the very end of VMPageArray
rotlwi r15, r15, 10
ori r15, r15, PMDT_Paged
stw r15, PMDT.Word2(r14)
lwz r7, KDP.VMPhysicalPages(r1) ; proof positive that this precedes VMInit!
; Disappear the RAM we stole. We've always been at war with Eastasia.
lwz r7, KDP.VMPhysicalPages(r1)
subf r7, r5, r7
stw r7, KDP.VMPhysicalPages(r1)
stw r7, KDP.VMLogicalPages(r1)
@ -815,53 +816,56 @@ VMAllocateMemory_0xf4
stw r8, KDP.SysInfo.UsableMemorySize(r1)
stw r8, KDP.SysInfo.LogicalMemorySize(r1)
addi r14, r1, KDP.SegMaps-8 ; Update every PMDT in the VM area
; Because we rearranged the VMPageArray, rewrite the VM area PMDTs
addi r14, r1, KDP.SegMaps-8
lwz r15, KDP.VMPageArray(r1)
li r8, 0 ; r8 = upper PMDT denoting whole-segment
li r8, 0 ; r8 = upper PMDT denoting whole-segment
subi r7, r7, 1
ori r8, r8, 0xffff
@nextseg
cmplwi r7, 0xffff
cmplwi r7, 0xffff
lwzu r16, 8(r14)
rotlwi r9, r15, 10
ori r9, r9, PMDT_Paged
stw r8, 0(r16) ; PMDT.PageIdx/PageCount = whole segment
stw r8, 0(r16) ; PMDT.PageIdx/PageCount = whole segment
stw r9, PMDT.Word2(r16)
addis r15, r15, 4
subis r7, r7, 1
bgt @nextseg
sth r7, PMDT.PageCount(r16) ; (last segment is partial)
sth r7, PMDT.PageCount(r16) ; (last segment is partial)
b vmRet1
ReclaimLeftoverFromVMAlloc ; 68kpds_to_steal r15 // 68kpds_to_steal r15
; We had to steal extra pages to ensure physically aligned backing. Return
; the "tail" pages that we won't use to the "body" of the VM area. Do this
; by exchanging the stolen 68k-PDs for the tail ones, then changing r15.
lwz r16, 0(r15) ; r16 = first stolen 68k-PD
VMAllocateMemory_0x2e8
lwz r16, 0x0000(r15)
lwz r7, KDP.VMPhysicalPages(r1)
lwz r8, KDP.VMPageArray(r1)
slwi r7, r7, 2
lwz r7, KDP.VMPhysicalPages(r1) ; r7 = where to move stolen 68k-PDs
lwz r8, KDP.VMPageArray(r1) ; r8 = last 68k-PD to overwrite
slwi r7, r7, 2
add r7, r7, r8
slwi r8, r5, 2
slwi r8, r5, 2
subf r7, r8, r7
cmplw r15, r7
beqlr
subi r7, r7, 4
VMAllocateMemory_0x310
cmplw r15, r7 ; Return early if there is no tail.
beqlr
subi r7, r7, 4 ; Carefully move "tail" 68k-PDs down
@tailmoveloop ; to the end of the VM area "body"
lwzx r9, r15, r8
cmplw r15, r7
stw r9, 0x0000(r15)
addi r15, r15, 0x04
blt VMAllocateMemory_0x310
stw r9, 0(r15)
addi r15, r15, 4
blt @tailmoveloop
VMAllocateMemory_0x324
cmpwi r8, 0x04
subi r8, r8, 4
stwu r16, 0x0004(r7)
addi r16, r16, 0x1000
bgt VMAllocateMemory_0x324
@stolenfillloop ; Then carelessly reconstitute the
cmpwi r8, 4 ; stolen 68k-PDs that we just over-
subi r8, r8, 4 ; wrote. We can be careless because
stwu r16, 4(r7) ; we know that the physical pages
addi r16, r16, 0x1000 ; are contiguous.
bgt @stolenfillloop
blr
########################################################################