load program ok

.vscode/settings.json

@@ -1,6 +1,6 @@
 {
 	"editor.detectIndentation": false,
-	"editor.tabSize": 8,
+	"editor.tabSize": 4,
 	"editor.insertSpaces": false,
 	"files.associations": {
 		"*.h": "c",

inc/elf.h

@@ -46,7 +46,9 @@ struct Secthdr {
 	u32 sh_addralign;
 	u32 sh_entsize;
 };
-
+typedef struct Elf Elf32_Ehdr;
+typedef struct Proghdr Elf32_Phdr;
+typedef struct Secthdr Elf32_Shdr;
 // Values for Proghdr::p_type
 #define PT_LOAD			1
 

kern/main.c

@@ -3,6 +3,7 @@
 #include <string.h>
 #include <type.h>
 #include <x86.h>
+#include <elf.h>
 
 #include <kern/fs.h>
 #include <kern/kmalloc.h>
@@ -37,6 +38,23 @@ init_segment_regs(PROCESS *p_proc)
 		| RPL_USER;
 }
 
+static inline void
+lml_map(phyaddr_t cr3, uintptr_t vaddr, phyaddr_t paddr, u32 flags) {
+	uintptr_t *pde_ptr = (uintptr_t *)K_PHY2LIN(cr3);
+	// pde_ptr += PDX(3 * GB); // get page table base addr
+	// get pdx item, pde_ptr + PDX(vaddr)
+	pde_ptr += PDX(vaddr);
+	if (!(*pde_ptr & PTE_P)) {
+		// pdx ot exists, allocate a page and assign to pde
+		*pde_ptr = phy_malloc_4k() | PTE_P | flags;
+	}
+	uintptr_t *ptx_ptr = (uintptr_t *)K_PHY2LIN(*pde_ptr & (~0xfff));
+	// get ptx item
+	ptx_ptr += PTX(vaddr);
+	// assume paddr is allocated, just set it to paddr[31:12] | FLAGS
+	*ptx_ptr = (paddr & (~0xfff)) | PTE_P | flags;
+}
+
 /*
  * 内核的main函数
  * 用于初始化用户进程，然后将执行流交给用户进程
@@ -69,15 +87,49 @@ void kernel_main(void)
 		// 推荐将文件加载到3GB + 48MB处，应用程序保证不会有16MB那么大
 		read_file(filename[i], (void *)K_PHY2LIN(48 * MB));
 		// 现在你就需要将从磁盘中读出的ELF文件解析到用户进程的地址空间中
-		panic("unimplement! load elf file");
+		// panic("unimplement! load elf file");
-		
+// ---------------------------- load elf --------------------------------------
+		void * elf_start = (void *)K_PHY2LIN(48 * MB);
+		assert(*(u32*)elf_start == ELF_MAGIC);
+		Elf32_Ehdr* ehdr = (Elf32_Ehdr*) elf_start;
+		for (int i = 0; i < ehdr->e_phnum; ++ i) {
+			Elf32_Phdr* phdr = elf_start + i * ehdr->e_phentsize + ehdr->e_phoff;
+			if (phdr->p_type == PT_LOAD) {
+				u32 vpage_fst = phdr->p_va & (~0xfff); // clear low 12 bit, start of the first pg
+				u32 vpage_lst = (phdr->p_va + phdr->p_memsz - 1) & (~0xfff); //  start of the last pg
+// in fact, we allocate 4k aligned vpage to every segment; its ok because elf32 segment align is 0x1000
+				u32 page_num = ((vpage_lst - vpage_fst) >> 12) + 1;
+				phyaddr_t newpage = 0; // useless initialization
+				for (int j = 0; j < page_num; ++ j) {
+					newpage = phy_malloc_4k();
+					lml_map(p_proc->pcb.cr3, vpage_fst + (j << 12), newpage, PTE_P | PTE_W | PTE_U);
+				}
+				phyaddr_t page_start = newpage - (page_num - 1) * 4 * KB;
+				memcpy((void*)K_PHY2LIN(page_start), (void*)(elf_start + phdr->p_offset), phdr->p_filesz);
+				memset((void*)K_PHY2LIN(page_start) + phdr->p_filesz, 0, phdr->p_memsz - phdr->p_filesz);
+			}
+		}
+
 		// 上一个实验中，我们开栈是用内核中的一个数组临时充当栈
 		// 但是现在就不行了，用户是无法访问内核的地址空间（3GB ~ 3GB + 128MB）
 		// 需要你自行处理给用户分配用户栈。
-		panic("unimplement! init user stack and esp");
+// ---------------------------- alloc user stack ------------------------------
+		phyaddr_t ustack_low = phy_malloc_4k();
+		for (int i = 0; i < 6; ++ i) phy_malloc_4k();
+		phyaddr_t ustack_high = phy_malloc_4k(); // alloc 8 pages, 32KB stack for each program
+		for (int i = 0; i < 8; ++ i) {
+			lml_map(p_proc->pcb.cr3, (3*GB - (8-i)*PGSIZE), ustack_low + i*PGSIZE, PTE_P | PTE_W | PTE_U);
+		}
+		p_proc->pcb.user_regs.esp = 3*GB;
+		// p_proc->pcb.user_regs.esp -= 4;
+		// uintptr_t* ustack_top = (uintptr_t*)K_PHY2LIN(ustack_high + PGSIZE);
+		// ustack_top --;
+		// *ustack_top = ehdr->e_entry;
+		p_proc->pcb.user_regs.eip = ehdr->e_entry;
 		// 初始化用户寄存器
 		p_proc->pcb.user_regs.eflags = 0x1202; /* IF=1, IOPL=1 */
 		
+		// panic("unimplement! init user stack and esp");
 		// 接下来初始化内核寄存器，
 		// 为什么需要初始化内核寄存器原因是加入了系统调用后
 		// 非常有可能出现系统调用执行过程中插入其余中断的情况，