572 lines
16 KiB
C
Executable file
572 lines
16 KiB
C
Executable file
#include "userprog/process.h"
|
||
#include <debug.h>
|
||
#include <inttypes.h>
|
||
#include <round.h>
|
||
#include <stdio.h>
|
||
#include <stdlib.h>
|
||
#include <string.h>
|
||
#include "userprog/gdt.h"
|
||
#include "userprog/pagedir.h"
|
||
#include "userprog/tss.h"
|
||
#include "filesys/directory.h"
|
||
#include "filesys/file.h"
|
||
#include "filesys/filesys.h"
|
||
#include "threads/flags.h"
|
||
#include "threads/init.h"
|
||
#include "threads/interrupt.h"
|
||
#include "threads/palloc.h"
|
||
#include "threads/thread.h"
|
||
#include "threads/vaddr.h"
|
||
#include "lib/kernel/list.h"
|
||
|
||
static struct arg {
|
||
struct list_elem elem;
|
||
char* data;
|
||
void* addr;
|
||
};
|
||
|
||
struct arguments {
|
||
int argc;
|
||
char** argv;
|
||
};
|
||
|
||
static thread_func start_process NO_RETURN;
|
||
static bool load (const char *cmdline, void (**eip) (void), void **esp);
|
||
|
||
/* Starts a new thread running a user program loaded from
|
||
FILENAME. The new thread may be scheduled (and may even exit)
|
||
before process_execute() returns. Returns the new process's
|
||
thread id, or TID_ERROR if the thread cannot be created. */
|
||
tid_t
|
||
process_execute (const char *file_name)
|
||
{
|
||
char *fn_copy;
|
||
tid_t tid;
|
||
|
||
/* Make a copy of FILE_NAME.
|
||
Otherwise there's a race between the caller and load(). */
|
||
fn_copy = palloc_get_page (0);
|
||
if (fn_copy == NULL)
|
||
return TID_ERROR;
|
||
strlcpy (fn_copy, file_name, PGSIZE);
|
||
|
||
size_t n = strlen(file_name), i;
|
||
char* program_name[n+1];
|
||
for (i = 0; i < n; i++) {
|
||
if (file_name[i] == ' ') {
|
||
break;
|
||
}
|
||
}
|
||
strlcpy(program_name, file_name, i+1);
|
||
|
||
/* Create a new thread to execute FILE_NAME. */
|
||
tid = thread_create (program_name, PRI_DEFAULT, start_process, fn_copy);
|
||
if (tid == TID_ERROR)
|
||
palloc_free_page (fn_copy);
|
||
|
||
return tid;
|
||
}
|
||
|
||
/* A thread function that loads a user process and starts it
|
||
running. */
|
||
static void
|
||
start_process (void *file_name_)
|
||
{
|
||
char *cmdline = file_name_;
|
||
|
||
struct intr_frame if_;
|
||
bool success;
|
||
|
||
// Populate the stack
|
||
struct list arg_list;
|
||
list_init(&arg_list);
|
||
|
||
char *token, *save_ptr;
|
||
|
||
// tokenize cmdline
|
||
for (token = strtok_r(cmdline, " ", &save_ptr); token != NULL;
|
||
token = strtok_r(NULL, " ", &save_ptr)) {
|
||
struct arg* it = malloc(sizeof(struct arg));
|
||
it->data = token;
|
||
list_push_back(&arg_list, it);
|
||
}
|
||
|
||
char* program_name = list_entry(list_front(&arg_list), struct arg, elem)->data;
|
||
|
||
/* Initialize interrupt frame and load executable. */
|
||
memset (&if_, 0, sizeof if_);
|
||
if_.gs = if_.fs = if_.es = if_.ds = if_.ss = SEL_UDSEG;
|
||
if_.cs = SEL_UCSEG;
|
||
if_.eflags = FLAG_IF | FLAG_MBS;
|
||
success = load (program_name, &if_.eip, &if_.esp);
|
||
|
||
list_reverse(&arg_list);
|
||
|
||
// put argv[i][...] on stack and keep track of addresses
|
||
struct list_elem* e;
|
||
for (e = list_begin(&arg_list); e != list_end(&arg_list); e = list_next(e)) {
|
||
struct arg* i = list_entry(e, struct arg, elem);
|
||
size_t bytes = strlen(i->data) + 1;
|
||
if_.esp -= bytes;
|
||
i->addr = if_.esp;
|
||
memcpy(if_.esp, i->data, bytes);
|
||
}
|
||
|
||
// put terminator of argv[] (argv[4] in example)
|
||
size_t bytes = sizeof(void*); // size of pointers on stack
|
||
if_.esp -= bytes;
|
||
|
||
{
|
||
uint32_t write[1] = {0};
|
||
memcpy(if_.esp, write, sizeof(uint32_t));
|
||
}
|
||
|
||
// put addresses of argv[i] on stack
|
||
for (e = list_begin(&arg_list); e != list_end(&arg_list);) {
|
||
struct arg* i = list_entry(e, struct arg, elem);
|
||
if_.esp -= bytes;
|
||
{
|
||
uint32_t write[1] = {i->addr};
|
||
memcpy(if_.esp, write, sizeof(uint32_t));
|
||
}
|
||
e = list_next(e);
|
||
|
||
}
|
||
|
||
//put argv
|
||
if_.esp -= bytes;
|
||
{
|
||
uint32_t write[1] = {if_.esp + bytes};
|
||
memcpy(if_.esp, write, sizeof(uint32_t));
|
||
}
|
||
//put argc
|
||
if_.esp -= bytes;
|
||
{
|
||
uint32_t write[1] = {list_size(&arg_list)};
|
||
memcpy(if_.esp, write, sizeof(uint32_t));
|
||
}
|
||
|
||
//put return address
|
||
if_.esp -= bytes;
|
||
{
|
||
uint32_t write[1] = {0};
|
||
memcpy(if_.esp, write, sizeof(uint32_t));
|
||
}
|
||
|
||
/* If load failed, quit. */
|
||
palloc_free_page (program_name);
|
||
if (!success)
|
||
thread_exit ();
|
||
|
||
/* Start the user process by simulating a return from an
|
||
interrupt, implemented by intr_exit (in
|
||
threads/intr-stubs.S). Because intr_exit takes all of its
|
||
arguments on the stack in the form of a `struct intr_frame',
|
||
we just point the stack pointer (%esp) to our stack frame
|
||
and jump to it. */
|
||
asm volatile ("movl %0, %%esp; jmp intr_exit" : : "g" (&if_) : "memory");
|
||
NOT_REACHED ();
|
||
}
|
||
|
||
/* Waits for thread TID to die and returns its exit status. If
|
||
it was terminated by the kernel (i.e. killed due to an
|
||
exception), returns -1. If TID is invalid or if it was not a
|
||
child of the calling process, or if process_wait() has already
|
||
been successfully called for the given TID, returns -1
|
||
immediately, without waiting.
|
||
|
||
This function will be implemented in problem 2-2. For now, it
|
||
does nothing. */
|
||
int
|
||
process_wait (tid_t child_tid)
|
||
{
|
||
//printf("process wait for: %s on: %ul\n", thread_current()->name, child_tid);
|
||
|
||
struct thread* child = thread_get_by_tid(child_tid);
|
||
if (child == NULL || child->waited_on_before) {
|
||
//printf("child not found\n");
|
||
return -1;
|
||
}
|
||
|
||
//printf("child is: %s\n", child->name);
|
||
|
||
sema_down(&child->waiting_sem);
|
||
int status = child->exit_status;
|
||
//printf("Wait exit: %s %d\n",child->name, status);
|
||
child->waited_on_before = 1;
|
||
sema_up(&(thread_current()->parent_sem));
|
||
return status;
|
||
}
|
||
|
||
/* Free the current process's resources. */
|
||
void
|
||
process_exit (void)
|
||
{
|
||
struct thread *cur = thread_current ();
|
||
uint32_t *pd;
|
||
|
||
/* Destroy the current process's page directory and switch back
|
||
to the kernel-only page directory. */
|
||
pd = cur->pagedir;
|
||
if (pd != NULL)
|
||
{
|
||
/* Correct ordering here is crucial. We must set
|
||
cur->pagedir to NULL before switching page directories,
|
||
so that a timer interrupt can't switch back to the
|
||
process page directory. We must activate the base page
|
||
directory before destroying the process's page
|
||
directory, or our active page directory will be one
|
||
that's been freed (and cleared). */
|
||
cur->pagedir = NULL;
|
||
pagedir_activate (NULL);
|
||
pagedir_destroy (pd);
|
||
}
|
||
}
|
||
|
||
/* Sets up the CPU for running user code in the current
|
||
thread.
|
||
This function is called on every context switch. */
|
||
void
|
||
process_activate (void)
|
||
{
|
||
struct thread *t = thread_current ();
|
||
|
||
/* Activate thread's page tables. */
|
||
pagedir_activate (t->pagedir);
|
||
|
||
/* Set thread's kernel stack for use in processing
|
||
interrupts. */
|
||
tss_update ();
|
||
}
|
||
|
||
/* We load ELF binaries. The following definitions are taken
|
||
from the ELF specification, [ELF1], more-or-less verbatim. */
|
||
|
||
/* ELF types. See [ELF1] 1-2. */
|
||
typedef uint32_t Elf32_Word, Elf32_Addr, Elf32_Off;
|
||
typedef uint16_t Elf32_Half;
|
||
|
||
/* For use with ELF types in printf(). */
|
||
#define PE32Wx PRIx32 /* Print Elf32_Word in hexadecimal. */
|
||
#define PE32Ax PRIx32 /* Print Elf32_Addr in hexadecimal. */
|
||
#define PE32Ox PRIx32 /* Print Elf32_Off in hexadecimal. */
|
||
#define PE32Hx PRIx16 /* Print Elf32_Half in hexadecimal. */
|
||
|
||
/* Executable header. See [ELF1] 1-4 to 1-8.
|
||
This appears at the very beginning of an ELF binary. */
|
||
struct Elf32_Ehdr
|
||
{
|
||
unsigned char e_ident[16];
|
||
Elf32_Half e_type;
|
||
Elf32_Half e_machine;
|
||
Elf32_Word e_version;
|
||
Elf32_Addr e_entry;
|
||
Elf32_Off e_phoff;
|
||
Elf32_Off e_shoff;
|
||
Elf32_Word e_flags;
|
||
Elf32_Half e_ehsize;
|
||
Elf32_Half e_phentsize;
|
||
Elf32_Half e_phnum;
|
||
Elf32_Half e_shentsize;
|
||
Elf32_Half e_shnum;
|
||
Elf32_Half e_shstrndx;
|
||
};
|
||
|
||
/* Program header. See [ELF1] 2-2 to 2-4.
|
||
There are e_phnum of these, starting at file offset e_phoff
|
||
(see [ELF1] 1-6). */
|
||
struct Elf32_Phdr
|
||
{
|
||
Elf32_Word p_type;
|
||
Elf32_Off p_offset;
|
||
Elf32_Addr p_vaddr;
|
||
Elf32_Addr p_paddr;
|
||
Elf32_Word p_filesz;
|
||
Elf32_Word p_memsz;
|
||
Elf32_Word p_flags;
|
||
Elf32_Word p_align;
|
||
};
|
||
|
||
/* Values for p_type. See [ELF1] 2-3. */
|
||
#define PT_NULL 0 /* Ignore. */
|
||
#define PT_LOAD 1 /* Loadable segment. */
|
||
#define PT_DYNAMIC 2 /* Dynamic linking info. */
|
||
#define PT_INTERP 3 /* Name of dynamic loader. */
|
||
#define PT_NOTE 4 /* Auxiliary info. */
|
||
#define PT_SHLIB 5 /* Reserved. */
|
||
#define PT_PHDR 6 /* Program header table. */
|
||
#define PT_STACK 0x6474e551 /* Stack segment. */
|
||
|
||
/* Flags for p_flags. See [ELF3] 2-3 and 2-4. */
|
||
#define PF_X 1 /* Executable. */
|
||
#define PF_W 2 /* Writable. */
|
||
#define PF_R 4 /* Readable. */
|
||
|
||
static bool setup_stack (void **esp);
|
||
static bool validate_segment (const struct Elf32_Phdr *, struct file *);
|
||
static bool load_segment (struct file *file, off_t ofs, uint8_t *upage,
|
||
uint32_t read_bytes, uint32_t zero_bytes,
|
||
bool writable);
|
||
|
||
/* Loads an ELF executable from FILE_NAME into the current thread.
|
||
Stores the executable's entry point into *EIP
|
||
and its initial stack pointer into *ESP.
|
||
Returns true if successful, false otherwise. */
|
||
bool
|
||
load (const char *file_name, void (**eip) (void), void **esp)
|
||
{
|
||
struct thread *t = thread_current ();
|
||
struct Elf32_Ehdr ehdr;
|
||
struct file *file = NULL;
|
||
off_t file_ofs;
|
||
bool success = false;
|
||
int i;
|
||
|
||
/* Allocate and activate page directory. */
|
||
t->pagedir = pagedir_create ();
|
||
if (t->pagedir == NULL)
|
||
goto done;
|
||
process_activate ();
|
||
|
||
/* Open executable file. */
|
||
file = filesys_open (file_name);
|
||
if (file == NULL)
|
||
{
|
||
printf ("load: %s: open failed\n", file_name);
|
||
goto done;
|
||
}
|
||
|
||
/* Read and verify executable header. */
|
||
if (file_read (file, &ehdr, sizeof ehdr) != sizeof ehdr
|
||
|| memcmp (ehdr.e_ident, "\177ELF\1\1\1", 7)
|
||
|| ehdr.e_type != 2
|
||
|| ehdr.e_machine != 3
|
||
|| ehdr.e_version != 1
|
||
|| ehdr.e_phentsize != sizeof (struct Elf32_Phdr)
|
||
|| ehdr.e_phnum > 1024)
|
||
{
|
||
printf ("load: %s: error loading executable\n", file_name);
|
||
goto done;
|
||
}
|
||
|
||
/* Read program headers. */
|
||
file_ofs = ehdr.e_phoff;
|
||
for (i = 0; i < ehdr.e_phnum; i++)
|
||
{
|
||
struct Elf32_Phdr phdr;
|
||
|
||
if (file_ofs < 0 || file_ofs > file_length (file))
|
||
goto done;
|
||
file_seek (file, file_ofs);
|
||
|
||
if (file_read (file, &phdr, sizeof phdr) != sizeof phdr)
|
||
goto done;
|
||
file_ofs += sizeof phdr;
|
||
switch (phdr.p_type)
|
||
{
|
||
case PT_NULL:
|
||
case PT_NOTE:
|
||
case PT_PHDR:
|
||
case PT_STACK:
|
||
default:
|
||
/* Ignore this segment. */
|
||
break;
|
||
case PT_DYNAMIC:
|
||
case PT_INTERP:
|
||
case PT_SHLIB:
|
||
goto done;
|
||
case PT_LOAD:
|
||
if (validate_segment (&phdr, file))
|
||
{
|
||
bool writable = (phdr.p_flags & PF_W) != 0;
|
||
uint32_t file_page = phdr.p_offset & ~PGMASK;
|
||
uint32_t mem_page = phdr.p_vaddr & ~PGMASK;
|
||
uint32_t page_offset = phdr.p_vaddr & PGMASK;
|
||
uint32_t read_bytes, zero_bytes;
|
||
if (phdr.p_filesz > 0)
|
||
{
|
||
/* Normal segment.
|
||
Read initial part from disk and zero the rest. */
|
||
read_bytes = page_offset + phdr.p_filesz;
|
||
zero_bytes = (ROUND_UP (page_offset + phdr.p_memsz, PGSIZE)
|
||
- read_bytes);
|
||
}
|
||
else
|
||
{
|
||
/* Entirely zero.
|
||
Don't read anything from disk. */
|
||
read_bytes = 0;
|
||
zero_bytes = ROUND_UP (page_offset + phdr.p_memsz, PGSIZE);
|
||
}
|
||
if (!load_segment (file, file_page, (void *) mem_page,
|
||
read_bytes, zero_bytes, writable))
|
||
goto done;
|
||
}
|
||
else
|
||
goto done;
|
||
break;
|
||
}
|
||
}
|
||
|
||
/* Set up stack. */
|
||
if (!setup_stack (esp))
|
||
goto done;
|
||
|
||
/* Start address. */
|
||
*eip = (void (*) (void)) ehdr.e_entry;
|
||
|
||
success = true;
|
||
|
||
done:
|
||
/* We arrive here whether the load is successful or not. */
|
||
file_close (file);
|
||
return success;
|
||
}
|
||
|
||
/* load() helpers. */
|
||
|
||
static bool install_page (void *upage, void *kpage, bool writable);
|
||
|
||
/* Checks whether PHDR describes a valid, loadable segment in
|
||
FILE and returns true if so, false otherwise. */
|
||
static bool
|
||
validate_segment (const struct Elf32_Phdr *phdr, struct file *file)
|
||
{
|
||
/* p_offset and p_vaddr must have the same page offset. */
|
||
if ((phdr->p_offset & PGMASK) != (phdr->p_vaddr & PGMASK))
|
||
return false;
|
||
|
||
/* p_offset must point within FILE. */
|
||
if (phdr->p_offset > (Elf32_Off) file_length (file))
|
||
return false;
|
||
|
||
/* p_memsz must be at least as big as p_filesz. */
|
||
if (phdr->p_memsz < phdr->p_filesz)
|
||
return false;
|
||
|
||
/* The segment must not be empty. */
|
||
if (phdr->p_memsz == 0)
|
||
return false;
|
||
|
||
/* The virtual memory region must both start and end within the
|
||
user address space range. */
|
||
if (!is_user_vaddr ((void *) phdr->p_vaddr))
|
||
return false;
|
||
if (!is_user_vaddr ((void *) (phdr->p_vaddr + phdr->p_memsz)))
|
||
return false;
|
||
|
||
/* The region cannot "wrap around" across the kernel virtual
|
||
address space. */
|
||
if (phdr->p_vaddr + phdr->p_memsz < phdr->p_vaddr)
|
||
return false;
|
||
|
||
/* Disallow mapping page 0.
|
||
Not only is it a bad idea to map page 0, but if we allowed
|
||
it then user code that passed a null pointer to system calls
|
||
could quite likely panic the kernel by way of null pointer
|
||
assertions in memcpy(), etc. */
|
||
if (phdr->p_vaddr < PGSIZE)
|
||
return false;
|
||
|
||
/* It's okay. */
|
||
return true;
|
||
}
|
||
|
||
/* Loads a segment starting at offset OFS in FILE at address
|
||
UPAGE. In total, READ_BYTES + ZERO_BYTES bytes of virtual
|
||
memory are initialized, as follows:
|
||
|
||
- READ_BYTES bytes at UPAGE must be read from FILE
|
||
starting at offset OFS.
|
||
|
||
- ZERO_BYTES bytes at UPAGE + READ_BYTES must be zeroed.
|
||
|
||
The pages initialized by this function must be writable by the
|
||
user process if WRITABLE is true, read-only otherwise.
|
||
|
||
Return true if successful, false if a memory allocation error
|
||
or disk read error occurs. */
|
||
static bool
|
||
load_segment (struct file *file, off_t ofs, uint8_t *upage,
|
||
uint32_t read_bytes, uint32_t zero_bytes, bool writable)
|
||
{
|
||
ASSERT ((read_bytes + zero_bytes) % PGSIZE == 0);
|
||
ASSERT (pg_ofs (upage) == 0);
|
||
ASSERT (ofs % PGSIZE == 0);
|
||
|
||
file_seek (file, ofs);
|
||
while (read_bytes > 0 || zero_bytes > 0)
|
||
{
|
||
/* Calculate how to fill this page.
|
||
We will read PAGE_READ_BYTES bytes from FILE
|
||
and zero the final PAGE_ZERO_BYTES bytes. */
|
||
size_t page_read_bytes = read_bytes < PGSIZE ? read_bytes : PGSIZE;
|
||
size_t page_zero_bytes = PGSIZE - page_read_bytes;
|
||
|
||
/* Get a page of memory. */
|
||
uint8_t *kpage = palloc_get_page (PAL_USER);
|
||
if (kpage == NULL)
|
||
return false;
|
||
|
||
/* Load this page. */
|
||
if (file_read (file, kpage, page_read_bytes) != (int) page_read_bytes)
|
||
{
|
||
palloc_free_page (kpage);
|
||
return false;
|
||
}
|
||
memset (kpage + page_read_bytes, 0, page_zero_bytes);
|
||
|
||
/* Add the page to the process's address space. */
|
||
if (!install_page (upage, kpage, writable))
|
||
{
|
||
palloc_free_page (kpage);
|
||
return false;
|
||
}
|
||
|
||
/* Advance. */
|
||
read_bytes -= page_read_bytes;
|
||
zero_bytes -= page_zero_bytes;
|
||
upage += PGSIZE;
|
||
}
|
||
return true;
|
||
}
|
||
|
||
/* Create a minimal stack by mapping a zeroed page at the top of
|
||
user virtual memory. */
|
||
static bool
|
||
setup_stack (void **esp)
|
||
{
|
||
uint8_t *kpage;
|
||
bool success = false;
|
||
|
||
kpage = palloc_get_page (PAL_USER | PAL_ZERO);
|
||
if (kpage != NULL)
|
||
{
|
||
success = install_page (((uint8_t *) PHYS_BASE) - PGSIZE, kpage, true);
|
||
if (success)
|
||
*esp = PHYS_BASE;
|
||
else
|
||
palloc_free_page (kpage);
|
||
}
|
||
return success;
|
||
}
|
||
|
||
/* Adds a mapping from user virtual address UPAGE to kernel
|
||
virtual address KPAGE to the page table.
|
||
If WRITABLE is true, the user process may modify the page;
|
||
otherwise, it is read-only.
|
||
UPAGE must not already be mapped.
|
||
KPAGE should probably be a page obtained from the user pool
|
||
with palloc_get_page().
|
||
Returns true on success, false if UPAGE is already mapped or
|
||
if memory allocation fails. */
|
||
static bool
|
||
install_page (void *upage, void *kpage, bool writable)
|
||
{
|
||
struct thread *t = thread_current ();
|
||
|
||
/* Verify that there's not already a page at that virtual
|
||
address, then map our page there. */
|
||
return (pagedir_get_page (t->pagedir, upage) == NULL
|
||
&& pagedir_set_page (t->pagedir, upage, kpage, writable));
|
||
}
|