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almost got the term emu working and shell

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slinky55
2026-07-08 21:15:30 -05:00
parent ec3cbb4794
commit 4d98d73f5e
20 changed files with 214 additions and 228 deletions
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65
kernel/elf.c Normal file
View File

@@ -0,0 +1,65 @@
#include "elf.h"
#include "vfs.h"
#include "memory/mm.h"
#include <lib/memory.h>
uint32_t load_elf_program(const char* prgm) {
int fd = open(prgm, 0);
if (fd == -1) {
return -1;
}
elf_header_t* e_hdr = kalloc(sizeof(elf_header_t));
memset((void*)e_hdr, 0, sizeof(elf_header_t));
uint32_t bytes_rd = read(fd, e_hdr, sizeof(elf_header_t));
if (bytes_rd <= 0) {
return -1;
}
uint32_t ph_table_ptr = e_hdr->e_phoff;
elf_program_header_t* ph = kalloc(sizeof(elf_program_header_t));
uint32_t heap_start = 0;
for (uint32_t i = 0; i < e_hdr->e_phnum; i++) {
fseek(fd, ph_table_ptr);
memset((void*)ph, 0, sizeof(elf_program_header_t));
read(fd, ph, sizeof(elf_program_header_t));
if (ph->p_type == PT_LOAD) {
uint32_t vstart = ph->p_vaddr;
uint32_t vend = vstart + ph->p_memsz;
if (vend > heap_start) {
heap_start = vend;
}
uint32_t page_start = vstart & ~(PAGE_SIZE - 1);
uint32_t page_end = (vend + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1);
for (uint32_t v = page_start; v < page_end; v += PAGE_SIZE) {
void* phys_frame = p_alloc_frame();
map_page(v, (uint32_t)phys_frame, PAGE_PRESENT | PAGE_WRITABLE | PAGE_USER);
}
uint32_t data_ptr = ph->p_offset;
fseek(fd, data_ptr);
read(fd, (void*)vstart, ph->p_filesz);
// 0 out bss
if (ph->p_memsz > ph->p_filesz) {
size_t bss_size = ph->p_memsz - ph->p_filesz;
memset((void*)(vstart + ph->p_filesz), 0, bss_size);
}
}
ph_table_ptr += sizeof(elf_program_header_t);
}
uint32_t eip = e_hdr->e_entry;
kfree(ph);
kfree(e_hdr);
return eip;
}

2
kernel/elf.h
View File

@@ -34,4 +34,6 @@ typedef struct {
uint32_t p_align;
} __attribute__((packed)) elf_program_header_t;
uint32_t load_elf_program(const char* prgm);
#endif

65
kernel/kmain.c
View File

@@ -64,65 +64,14 @@ void load_root_program(const char* path) {
load_pd(cr3);
flush_tlb();
int fd = open(path, 0);
if (fd == -1) {
kprintf("failed to open program: %s\n", path);
return;;
}
elf_header_t* e_hdr = kalloc(sizeof(elf_header_t));
memset((void*)e_hdr, 0, sizeof(elf_header_t));
uint32_t bytes_rd = read(fd, e_hdr, sizeof(elf_header_t));
if (bytes_rd <= 0) {
kprintf("failed to read program data for %s\n", path);
return;
}
uint32_t ph_table_ptr = e_hdr->e_phoff;
elf_program_header_t* ph = kalloc(sizeof(elf_program_header_t));
uint32_t heap_start = 0;
for (uint32_t i = 0; i < e_hdr->e_phnum; i++) {
fseek(fd, ph_table_ptr);
memset((void*)ph, 0, sizeof(elf_program_header_t));
read(fd, ph, sizeof(elf_program_header_t));
if (ph->p_type == PT_LOAD) {
uint32_t vstart = ph->p_vaddr;
uint32_t vend = vstart + ph->p_memsz;
if (vend > heap_start) {
heap_start = vend;
}
uint32_t page_start = vstart & ~(PAGE_SIZE - 1);
uint32_t page_end = (vend + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1);
for (uint32_t v = page_start; v < page_end; v += PAGE_SIZE) {
void* phys_frame = p_alloc_frame();
map_page(v, (uint32_t)phys_frame, PAGE_PRESENT | PAGE_WRITABLE | PAGE_USER);
}
uint32_t data_ptr = ph->p_offset;
fseek(fd, data_ptr);
read(fd, (void*)vstart, ph->p_filesz);
// 0 out bss
if (ph->p_memsz > ph->p_filesz) {
size_t bss_size = ph->p_memsz - ph->p_filesz;
memset((void*)(vstart + ph->p_filesz), 0, bss_size);
}
}
ph_table_ptr += sizeof(elf_program_header_t);
}
uint32_t eip = load_elf_program(path);
uint32_t stack_sz = PAGE_SIZE * 16;
uint32_t stack_top = 0xBFFF0000;
uint32_t stack_bottom = stack_top - stack_sz;
for (uint32_t vaddr = stack_bottom; vaddr < stack_top; vaddr += PAGE_SIZE) {
void* phys_frame = p_alloc_frame();
map_page(vaddr, (uint32_t)phys_frame, PAGE_PRESENT | PAGE_WRITABLE | PAGE_USER);
void* phys_frame = p_alloc_frame();
map_page(vaddr, (uint32_t)phys_frame, PAGE_PRESENT | PAGE_WRITABLE | PAGE_USER);
}
uint32_t* u_esp = (uint32_t*)stack_top;
@@ -131,7 +80,7 @@ void load_root_program(const char* path) {
*(--u_esp) = 0; // argc = 0
process_t* process = kalloc(sizeof(process_t));
init_task(process, e_hdr->e_entry, (uint32_t)cr3, 1, (uint32_t)u_esp);
init_task(process, eip, (uint32_t)cr3, 1, (uint32_t)u_esp);
add_task(process);
unlock_scheduler();
@@ -164,8 +113,8 @@ void kmain(uint32_t magic, multiboot_info* mbi) {
kprintf("basic initializations complete\n");
vfs_node_t* vfs_root = vfs_create_root();
vfs_node_t* initrd_root = load_initrd();
if (!initrd_root) {
kprintf("failed to load initrd\n");
}
@@ -177,8 +126,8 @@ void kmain(uint32_t magic, multiboot_info* mbi) {
init_scheduler();
enable_interrupts();
kprintf("loading test program\n");
load_root_program("/test.elf");
kprintf("loading terminal program\n");
load_root_program("/vga_text_term.elf");
kprintf("kernel going to sleep...\n");
}

4
kernel/memory/mm.c
View File

@@ -267,4 +267,8 @@ void* clone_current_pd() {
unmap_page(TEMP_TASKPD_VADDR);
return (void*)task_pd_addr;
}
void clear_current_pd() {
}

1
kernel/memory/mm.h
View File

@@ -34,6 +34,7 @@ uint32_t total_free_memory();
void* create_new_pd();
void* clone_current_pd();
void clear_current_pd();
int is_cow(uint32_t vaddr);

4
kernel/scheduler.c
View File

@@ -99,6 +99,10 @@ void init_task (
process->flags = user ? PROCESS_FLAG_USER : PROCESS_FLAG_KERNEL;
total_processes++;
if (process->kstack_top != 0) {
kfree((void*)process->kstack_top);
}
void* kstack_bottom = kalloc(PAGE_SIZE);
uint32_t kstack_top = (uint32_t)kstack_bottom + PAGE_SIZE;
process->kstack_top = kstack_top;

49
kernel/syscall.c
View File

@@ -1,15 +1,18 @@
#include <stdint.h>
#include <stddef.h>
#include <drivers/pty/pty.h>
#include "lib/memory.h"
#include "lib/ringbuf.h"
#include "memory/mm.h"
#include "process.h"
#include "scheduler.h"
#include "vfs.h"
#include "elf.h"
#include <drivers/vga/vga.h>
#include <drivers/pty/pty.h>
#include <lib/print.h>
#include <lib/string.h>
@@ -53,11 +56,13 @@ static int32_t sys_read(int fd, void* buf, size_t count) {
}
static int32_t sys_open(const char* filename, int flags) {
return -1;
return open(filename, flags);
}
static int32_t sys_close(int fd) {
return -1;
process_t* task = current_task();
task->fd_table[fd] = NULL;
return 1;
}
static int32_t sys_brk(uint32_t new_break) {
@@ -155,6 +160,42 @@ static int32_t sys_fork(registers_t* parent_regs) {
return child->pid;
}
static int32_t sys_exec(registers_t* regs, const char* prgm) {
clear_current_pd();
uint32_t eip = load_elf_program(prgm);
uint32_t stack_sz = PAGE_SIZE * 16;
uint32_t stack_top = 0xBFFF0000;
uint32_t stack_bottom = stack_top - stack_sz;
for (uint32_t vaddr = stack_bottom; vaddr < stack_top; vaddr += PAGE_SIZE) {
void* phys_frame = p_alloc_frame();
map_page(vaddr, (uint32_t)phys_frame, PAGE_PRESENT | PAGE_WRITABLE | PAGE_USER);
}
uint32_t* u_esp = (uint32_t*)stack_top;
*(--u_esp) = 0; // envp = NULL
*(--u_esp) = 0; // argv = NULL
*(--u_esp) = 0; // argc = 0
regs->eax = 0;
regs->ecx = 0;
regs->edx = 0;
regs->ebp = 0;
regs->esi = 0;
regs->edi = 0;
regs->eip = eip;
regs->useresp = (uint32_t)u_esp;
return 0;
}
static int32_t sys_dup2(int src, int dst) {
process_t* task = current_task();
task->fd_table[dst] = task->fd_table[src];
return dst;
}
void syscall(registers_t* regs) {
int32_t ret;
switch(regs->eax) {
@@ -166,6 +207,8 @@ void syscall(registers_t* regs) {
case 12: ret = sys_brk(regs->ebx); break;
case 20: ret = sys_pty((int*)regs->ebx); break;
case 21: ret = sys_fork(regs); break;
case 22: ret = sys_exec(regs, (const char*)regs->ebx); break;
case 23: ret = sys_dup2(regs->ebx, regs->ecx); break;
default: ret = -1;
}
regs->eax = ret;