From: acevest <zhaoyanbai@126.com>
Date: Tue, 30 Dec 2025 09:27:38 +0000 (+0800)
Subject: 内核空间所有页表都固定分配出来(不再变动)便于所有进程共享内核地址空间
X-Git-Url: http://repos.zhaoyanbai.com/Mou_128.png?a=commitdiff_plain;h=5b0e9ed1df0555445cbd0c2409d58ceb56292e59;p=kernel.git

内核空间所有页表都固定分配出来(不再变动)便于所有进程共享内核地址空间
---

diff --git a/kernel/task_init.c b/kernel/task_init.c
index 1a30bf0..6670b3d 100644
--- a/kernel/task_init.c
+++ b/kernel/task_init.c
@@ -194,7 +194,7 @@ void init_task_entry() {
 
 #if 1
     kernel_task("ide/1", disk_task_entry, (void *)1);
-    kernel_task("user", user_task_entry, NULL);
+    // kernel_task("user", user_task_entry, NULL);
     kernel_task("tskA", taskA_entry, NULL);
     kernel_task("tskB", taskB_entry, NULL);
     kernel_task("tskC", taskC_entry, NULL);
diff --git a/mm/bootmem.c b/mm/bootmem.c
index 05facda..f7f8853 100644
--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -294,11 +294,11 @@ find_next_block:
     }
 
     reserve_bootmem(bgn_pfn, end_pfn);
-    region = pfn2va(bgn_pfn);
+    region = pfn2pa(bgn_pfn);
 
     pbd->prepare_alloc_pfn = end_pfn;
 
-    printk("%s alloc bootmem size: %x pfn cnt: %d [%d, %d)\n", title, size, pfn_cnt, bgn_pfn, end_pfn);
+    printk("[bootmem][%s] alloc size: 0x%x pfn cnt: %d [%d, %d) %x\n", title, size, pfn_cnt, bgn_pfn, end_pfn, region);
 
     return region;
 }
diff --git a/mm/buddy.c b/mm/buddy.c
index c8d4f99..e2a16e2 100644
--- a/mm/buddy.c
+++ b/mm/buddy.c
@@ -207,6 +207,7 @@ void init_buddy_system() {
     unsigned long page_map_size = pfn_cnt * sizeof(page_t);
     void *alloc_from_bootmem(unsigned long size, char *title);
     buddy_system.page_map = alloc_from_bootmem(page_map_size, "buddy");
+    buddy_system.page_map = pa2va(buddy_system.page_map);
     if (0 == buddy_system.page_map) {
         printk("can not go on playing...\n");
         while (1);
diff --git a/mm/mm.c b/mm/mm.c
index c370ea7..15d5ed6 100644
--- a/mm/mm.c
+++ b/mm/mm.c
@@ -39,41 +39,72 @@ void set_page_shared(void *x) {
     pte[get_npte(addr)] |= PAGE_US;
 }
 
+char *paging_page = "paging";
+
 void init_paging() {
     unsigned int i;
     unsigned long pfn = 0;
-    pte_t *pte = 0;
-    unsigned long *pgtb_addr = 0;
+    pte_t *pg_table = 0;
     void *alloc_from_bootmem(unsigned long size, char *title);
 
     // 在multiboot.S是已经初始化了BOOT_INIT_PAGETBL_CNT个页
     // 这里接着初始化剩余的页
     // 最大限制内存1G
     for (pfn = pa2pfn(BOOT_INIT_PAGETBL_CNT << 22); pfn < bootmem_data.max_pfn; ++pfn) {
-        unsigned long ti = pfn % PAGE_PTE_CNT;
+        unsigned long npte = pfn % PAGE_PTE_CNT;
         unsigned long page_addr = (unsigned long)pfn2pa(pfn);
-        if (ti == 0) {
-            pgtb_addr = (unsigned long *)alloc_from_bootmem(PAGE_SIZE, "paging");
-            if (0 == pgtb_addr) {
+        if (npte == 0) {
+            pg_table = (pte_t *)alloc_from_bootmem(PAGE_SIZE, paging_page);
+            if (0 == pg_table) {
                 panic("no pages for paging...");
             }
 
-            memset((void *)pgtb_addr, 0, PAGE_SIZE);
+            memset((void *)pg_table, 0, PAGE_SIZE);
 
-            init_pgd[get_npde(page_addr)] = (pde_t)((unsigned long)va2pa(pgtb_addr) | PAGE_P | PAGE_WR);
+            init_pgd[get_npde(page_addr)] = (pde_t)((unsigned long)(pg_table) | PAGE_P | PAGE_WR);
         }
 
-        pte = ((pte_t *)pgtb_addr) + ti;
-        *pte = (pte_t)(page_addr | PAGE_P | PAGE_WR);
+        pg_table[npte] = (pte_t)(page_addr | PAGE_P | PAGE_WR);
     }
 
     // paging for kernel space
-    unsigned long delta = get_npde(PAGE_OFFSET);
-    for (i = delta; i < PDECNT_PER_PAGE; ++i) {
-        init_pgd[i] = init_pgd[i - delta];
-        init_pgd[i - delta] = 0;
+    // 在此处让内核空间对[0, MAX_SUPT_PHYMM_SIZE]物理内存也作直接映射
+    int kernel_npde_base = get_npde(PAGE_OFFSET);
+    for (i = kernel_npde_base; i < PDECNT_PER_PAGE; ++i) {
+        init_pgd[i] = init_pgd[i - kernel_npde_base];
+    }
+
+    // 接下来还有部分内核空间需要处理，例如 VRAM_VADDR FIXED_MAP_VADDR 等
+    // 这部分空间也需要给他们分配固定的页表
+    // 这部分页表在pgd里的pde就不再允许修改了
+    // 这样，无论内核空间映射如何变化，这部分空间所有进程都能共享到变化
+    for (i = kernel_npde_base; i < PDECNT_PER_PAGE; ++i) {
+        if(0 != init_pgd[i]) {
+            continue;
+        }
+
+        // 分配一个页表
+        pte_t *pg_table = (pte_t *)alloc_from_bootmem(PAGE_SIZE, paging_page);
+        if(0 == pg_table) {
+            panic("no pages for paging...");
+        }
+
+        // 清空页表
+        memset((void *)pg_table, 0xAC, PAGE_SIZE);
+
+        // 把页表地址填入pgd
+        init_pgd[i] = (pde_t)((unsigned long)(pg_table) | PAGE_P | PAGE_WR);
+    }
+
+
+    // 建立完内核空间的页映射，需要清空用户空间的映射
+    for (i = 0; i < kernel_npde_base; ++i) {
+        init_pgd[i] = 0;
     }
 
+
+
+#if 0
     // 接下来为显存建立页映射
     unsigned long vram_phys_addr = system.vbe_phys_addr;
     printk("vram_phys_addr: 0x%x\n", vram_phys_addr);
@@ -84,7 +115,7 @@ void init_paging() {
         }
         // 后续要初始化，所以此处不用memset
         // memset((void *)pgtb_addr, 0, PAGE_SIZE);
-        init_pgd[get_npde(VRAM_VADDR_BASE) + pde_inx] = (pde_t)((unsigned long)va2pa(pgtb_addr) | PAGE_P | PAGE_WR);
+        init_pgd[get_npde(VRAM_VADDR_BASE) + pde_inx] = (pde_t)((unsigned long)(pgtb_addr) | PAGE_P | PAGE_WR);
 
         for (int pte_inx = 0; pte_inx < PTECNT_PER_PAGE; pte_inx++) {
             pgtb_addr[pte_inx] = vram_phys_addr | PAGE_P | PAGE_WR;
@@ -105,6 +136,7 @@ void init_paging() {
         // 在内存中 [B, G, R, A] 因为x86是小端序 所以实际是 ARGB 顺序
         vram[i] = 0x000000FF;
     }
+#endif
 
 #if 0
     bool flag = false;
diff --git a/scripts/link.ld b/scripts/link.ld
index e7049e0..5c62472 100644
--- a/scripts/link.ld
+++ b/scripts/link.ld
@@ -57,7 +57,6 @@ SECTIONS
     .text : AT(ADDR(.text)-kernel_virtual_addr_start) ALIGN(0x1000)
     {
         code = .;
-        /* 单独把 multiboot.S 的 .text 放在这个位置是为了便于调试，实际是可以不写这一句的 */
         *(.text)
         *(.ring3.text);
         *(.sysexit) /* last */