141 lines
4.7 KiB
C
141 lines
4.7 KiB
C
/*
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* UTSM 页表/MMIO 映射服务实现
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*
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* 算法说明：
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* - is_mapped: 标准 x86_64 四级页表 walk，O(1)（固定 4 级），
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* 页表页均为 RAM，经 HHDM 直映射访问，全程不触发 #PF。
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* - map_mmio: 对 [phys, phys+size) 逐 4K 页在 HHDM 空间 (hhdm+phys)
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* 补建 P|RW|PCD|PWT 映射。若中间级已存在则复用；若整页已被
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* Limine 大页覆盖则跳过（is_mapped 先行判定）。页表页由
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* dma_alloc_pages 提供（低 4G、4K 对齐、返回即清零）。
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* - not-present 项不会被 TLB 缓存，新映射无需 invlpg；
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* 仍对每页执行 invlpg 作为防御性措施（成本可忽略）。
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*/
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#include <utsm/paging.h>
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#include <utsm/dma.h>
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#include <utsm/log.h>
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#include "../arch/x86_64/limine.h"
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extern volatile struct limine_hhdm_request g_hhdm_request;
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#define PTE_PRESENT (1ULL << 0)
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#define PTE_RW (1ULL << 1)
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#define PTE_PWT (1ULL << 3) /* MMIO: write-through */
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#define PTE_PCD (1ULL << 4) /* MMIO: cache disable */
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#define PTE_PS (1ULL << 7) /* 1G/2M 大页标志 */
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#define PTE_ADDR_MASK 0x000FFFFFFFFFF000ULL
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#define PAGE_4K 4096ULL
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static u64 paging_hhdm(void) {
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return g_hhdm_request.response ? g_hhdm_request.response->offset : 0;
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}
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static u64 paging_read_cr3(void) {
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u64 v;
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__asm__ volatile("mov %%cr3, %0" : "=r"(v));
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return v & PTE_ADDR_MASK;
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}
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/* 返回 0=未映射；1=4K PTE；2=2M PDE；3=1G PDPTE */
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static int paging_is_mapped_impl(u64 vaddr) {
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u64 hhdm = paging_hhdm();
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if (!hhdm) return 0;
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u64 *pml4 = (u64 *)(paging_read_cr3() + hhdm);
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u64 pml4e = pml4[(vaddr >> 39) & 0x1FF];
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if (!(pml4e & PTE_PRESENT)) return 0;
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u64 *pdpt = (u64 *)((pml4e & PTE_ADDR_MASK) + hhdm);
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u64 pdpte = pdpt[(vaddr >> 30) & 0x1FF];
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if (!(pdpte & PTE_PRESENT)) return 0;
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if (pdpte & PTE_PS) return 3;
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u64 *pd = (u64 *)((pdpte & PTE_ADDR_MASK) + hhdm);
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u64 pde = pd[(vaddr >> 21) & 0x1FF];
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if (!(pde & PTE_PRESENT)) return 0;
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if (pde & PTE_PS) return 2;
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u64 *pt = (u64 *)((pde & PTE_ADDR_MASK) + hhdm);
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u64 pte = pt[(vaddr >> 12) & 0x1FF];
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if (!(pte & PTE_PRESENT)) return 0;
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return 1;
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}
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/* 分配一个清零的 4K 页作为页表页，返回物理地址；失败返回 0 */
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static u64 paging_alloc_table(void) {
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dkm_dma_buffer buf;
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if (dma_alloc_pages(1, PAGE_4K, 0, &buf) != 0) return 0;
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return buf.phys;
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}
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static int paging_map_mmio_impl(u64 phys, u64 size) {
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u64 hhdm = paging_hhdm();
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if (!hhdm || !size) return -1;
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u64 begin = phys & ~(PAGE_4K - 1ULL);
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u64 end = (phys + size + PAGE_4K - 1ULL) & ~(PAGE_4K - 1ULL);
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u64 mapped = 0;
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u64 skipped = 0;
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for (u64 p = begin; p < end; p += PAGE_4K) {
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u64 v = hhdm + p;
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if (paging_is_mapped_impl(v)) {
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skipped++; /* Limine 已覆盖（含 1G/2M 大页） */
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continue;
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}
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u64 *pml4 = (u64 *)(paging_read_cr3() + hhdm);
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u64 idx4 = (v >> 39) & 0x1FF;
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if (!(pml4[idx4] & PTE_PRESENT)) {
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u64 t = paging_alloc_table();
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if (!t) { log_error("[PAGING] alloc PDPT failed"); return -2; }
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pml4[idx4] = t | PTE_PRESENT | PTE_RW;
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}
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u64 *pdpt = (u64 *)((pml4[idx4] & PTE_ADDR_MASK) + hhdm);
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u64 idx3 = (v >> 30) & 0x1FF;
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if (pdpt[idx3] & PTE_PRESENT) {
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if (pdpt[idx3] & PTE_PS) { skipped++; continue; } /* 1G 大页已覆盖 */
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} else {
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u64 t = paging_alloc_table();
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if (!t) { log_error("[PAGING] alloc PD failed"); return -3; }
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pdpt[idx3] = t | PTE_PRESENT | PTE_RW;
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}
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u64 *pd = (u64 *)((pdpt[idx3] & PTE_ADDR_MASK) + hhdm);
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u64 idx2 = (v >> 21) & 0x1FF;
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if (pd[idx2] & PTE_PRESENT) {
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if (pd[idx2] & PTE_PS) { skipped++; continue; } /* 2M 大页已覆盖 */
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} else {
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u64 t = paging_alloc_table();
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if (!t) { log_error("[PAGING] alloc PT failed"); return -4; }
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pd[idx2] = t | PTE_PRESENT | PTE_RW;
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}
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u64 *pt = (u64 *)((pd[idx2] & PTE_ADDR_MASK) + hhdm);
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u64 idx1 = (v >> 12) & 0x1FF;
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pt[idx1] = p | PTE_PRESENT | PTE_RW | PTE_PCD | PTE_PWT;
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__asm__ volatile("invlpg (%0)" :: "r"(v) : "memory");
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mapped++;
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}
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log_info("[PAGING] map_mmio done");
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log_hex64("[PAGING] phys=", phys);
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log_hex64("[PAGING] size=", size);
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log_hex64("[PAGING] 4K pages mapped=", mapped);
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log_hex64("[PAGING] pages already covered=", skipped);
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return 0;
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}
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static const dkm_mmio_api g_mmio_api = {
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.is_mapped = paging_is_mapped_impl,
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.map_mmio = paging_map_mmio_impl,
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.cr3 = paging_read_cr3
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};
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const dkm_mmio_api *paging_get_api(void) {
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return &g_mmio_api;
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}
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