Chloe M.
140 lines
2.9 KiB
C
140 lines
2.9 KiB
C
/*
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* Copyright (c) 2026, Chloe M.
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* Provided under the BSD-3 clause.
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*
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* Description: Virtual memory manager
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* Author: Chloe M.
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*/
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#include <mm/vmm.h>
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#include <mm/vad.h>
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#include <mm/pmm.h>
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#include <hal/mmu.h>
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#include <hal/page.h>
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#include <ex/trace.h>
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#include <ke/knot.h>
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#include <stapi/status.h>
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#include <string.h>
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#define VALLOC_MAX_PAGES 8192
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#define VALLOC_MAX (VALLOC_BASE + (VALLOC_MAX_PAGES * PAGESIZE))
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#define PAGES_PER_GRAB 16
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#define DTRACE(Fmt, ...) \
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TRACE("[ VMM ]: " Fmt, ##__VA_ARGS__)
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static MMU_VAS KernelVas;
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static MM_VAD_LIST VadList;
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static UPTR BumpPtr;
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/*
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* TODO: Add some locking around this
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*/
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static ST_STATUS
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MmGrabPages(VOID)
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{
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USIZE MaxOff;
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UPTR AllocBase;
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MMU_VAS Vas;
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MM_PFN AllocPfn;
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ST_STATUS Status;
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MaxOff = PAGES_PER_GRAB * PAGESIZE;
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HalMmuReadVas(&Vas);
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for (USIZE Off = 0; Off < MaxOff; Off += PAGESIZE) {
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/* Don't blast past the limit */
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if ((BumpPtr + Off) >= VALLOC_MAX) {
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return STATUS_NO_MEMORY;
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}
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AllocBase = BumpPtr + Off;
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AllocPfn = MmRequestFrame();
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if (AllocPfn == 0) {
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return STATUS_NO_MEMORY;
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}
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Status = HalMmuMapSingle(
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&Vas,
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AllocBase,
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AllocPfn << LOG2_PAGESIZE,
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PAGE_READWRITE,
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PAGESIZE_4K
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);
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if (Status != STATUS_SUCCESS) {
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return Status;
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}
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MmVadListAppend(&VadList, VAD_FROM_VMA(AllocBase));
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}
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BumpPtr = AllocBase;
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return STATUS_SUCCESS;
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}
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/*
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* TODO: Consider locking
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*/
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VOID *
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MmAllocPages(USIZE Count)
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{
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MM_VAD *First, *Vad;
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ST_STATUS Status;
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if (Count == 0) {
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return NULL;
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}
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First = NULL;
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/*
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* Request a VAD from the allocation VAD list and pull in
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* more pages if we need to.
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*
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* XXX: We need to consider how we'll deal with fragmentation
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* here, once it fills up it may become fragmented.
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*/
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for (USIZE Iter = 0; Iter < Count; ++Iter) {
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Vad = MmVadListPop(&VadList);
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if (Vad == NULL) {
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Status = MmGrabPages();
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if (Status != STATUS_SUCCESS)
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return NULL;
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Vad = MmVadListPop(&VadList);
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}
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/* Still no pages? */
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if (Vad == NULL) {
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return NULL;
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}
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if (First == NULL) {
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First = Vad;
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}
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}
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RtlMemSet(First, 0, sizeof(*First));
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return (VOID *)First;
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}
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VOID
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MmInitVmm(VOID)
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{
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MMU_VAS OldVas;
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ST_STATUS Status;
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DTRACE("breeding kvas from bootstrap instance...\n");
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HalMmuReadVas(&OldVas);
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Status = HalMmuForkVas(&OldVas, &KernelVas);
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if (Status != STATUS_SUCCESS) {
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KeKnot(KNOT_OOM, "could not fork bootstrap vas\n");
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}
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HalMmuWriteVas(&KernelVas);
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DTRACE("ah!~... [ok @ %p]\n", VAS_BASE(&KernelVas));
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BumpPtr = VALLOC_BASE;
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}
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