X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Fuserprog%2Faddrspace.c;h=10d561658146c5f0f329b4ba74ae56ef85586ff3;hb=e49318880e6420e9b5a4ae9ffb986b49f89798e0;hp=ea8767c84e2f4f33e5bd4e5a1f28f20c59960c62;hpb=5aa19f8c89021f712c6aa4ea275b2be8c980503c;p=pintos-anon diff --git a/src/userprog/addrspace.c b/src/userprog/addrspace.c index ea8767c..10d5616 100644 --- a/src/userprog/addrspace.c +++ b/src/userprog/addrspace.c @@ -4,15 +4,84 @@ #include #include #include +#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/mmu.h" -#include "threads/paging.h" #include "threads/palloc.h" #include "threads/thread.h" +static thread_func execute_thread 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 before + addrspace_execute() returns.*/ +tid_t +addrspace_execute (const char *filename) +{ + char *fn_copy; + tid_t tid; + + /* Make a copy of FILENAME. + Otherwise there's a race between the caller and load(). */ + fn_copy = palloc_get (0); + if (fn_copy == NULL) + return TID_ERROR; + strlcpy (fn_copy, filename, PGSIZE); + + /* Create a new thread to execute FILENAME. */ + tid = thread_create (filename, PRI_DEFAULT, execute_thread, fn_copy); + if (tid == TID_ERROR) + palloc_free (fn_copy); + return tid; +} + +/* A thread function that loads a user process and starts it + running. */ +static void +execute_thread (void *filename_) +{ + char *filename = filename_; + struct intr_frame if_; + bool success; + + /* Initialize interrupt frame and load executable. */ + memset (&if_, 0, sizeof if_); + if_.es = SEL_UDSEG; + if_.ds = SEL_UDSEG; + if_.cs = SEL_UCSEG; + if_.eflags = FLAG_IF | FLAG_MBS; + if_.ss = SEL_UDSEG; + success = load (filename, &if_.eip, &if_.esp); + + /* If load failed, quit. */ + palloc_free (filename); + if (!success) + thread_exit (); + + /* Switch page tables. */ + addrspace_activate (); + + /* Start the user process by simulating a return from an + interrupt, implemented by intr_exit (in + threads/intr-stubs.pl). 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 ("mov %0, %%esp\n" + "jmp intr_exit\n" + : /* no outputs */ + : "g" (&if_)); + NOT_REACHED (); +} + /* We load ELF binaries. The following definitions are taken from the ELF specification, [ELF1], more-or-less verbatim. */ @@ -76,28 +145,28 @@ struct Elf32_Phdr #define PF_W 2 /* Writable. */ #define PF_R 4 /* Readable. */ -static bool load_segment (struct thread *, struct file *, - const struct Elf32_Phdr *); -static bool setup_stack (struct thread *); +static bool load_segment (struct file *, const struct Elf32_Phdr *); +static bool setup_stack (void **esp); /* Aborts loading an executable, with an error message. */ #define LOAD_ERROR(MSG) \ do { \ - printf ("addrspace_load: %s: ", filename); \ + printf ("load: %s: ", filename); \ printf MSG; \ printf ("\n"); \ goto done; \ } while (0) -/* Loads an ELF executable from FILENAME into T, - and stores the executable's entry point into *START. +/* Loads an ELF executable from FILENAME 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 -addrspace_load (struct thread *t, const char *filename, void (**start) (void)) +load (const char *filename, void (**eip) (void), void **esp) { + struct thread *t = thread_current (); struct Elf32_Ehdr ehdr; - struct file file; - bool file_open = false; + struct file *file = NULL; off_t file_ofs; bool success = false; int i; @@ -108,12 +177,12 @@ addrspace_load (struct thread *t, const char *filename, void (**start) (void)) LOAD_ERROR (("page directory allocation failed")); /* Open executable file. */ - file_open = filesys_open (filename, &file); - if (!file_open) + file = filesys_open (filename); + if (file == NULL) LOAD_ERROR (("open failed")); /* Read and verify executable header. */ - if (file_read (&file, &ehdr, sizeof ehdr) != sizeof ehdr) + if (file_read (file, &ehdr, sizeof ehdr) != sizeof ehdr) LOAD_ERROR (("error reading executable header")); if (memcmp (ehdr.e_ident, "\177ELF\1\1\1", 7) != 0) LOAD_ERROR (("file is not ELF")); @@ -135,8 +204,8 @@ addrspace_load (struct thread *t, const char *filename, void (**start) (void)) { struct Elf32_Phdr phdr; - file_seek (&file, file_ofs); - if (file_read (&file, &phdr, sizeof phdr) != sizeof phdr) + file_seek (file, file_ofs); + if (file_read (file, &phdr, sizeof phdr) != sizeof phdr) LOAD_ERROR (("error reading program header")); file_ofs += sizeof phdr; switch (phdr.p_type) @@ -157,28 +226,24 @@ addrspace_load (struct thread *t, const char *filename, void (**start) (void)) printf ("unknown ELF segment type %08x\n", phdr.p_type); break; case PT_LOAD: - if (!load_segment (t, &file, &phdr)) + if (!load_segment (file, &phdr)) goto done; break; } } /* Set up stack. */ - if (!setup_stack (t)) + if (!setup_stack (esp)) goto done; /* Start address. */ - *start = (void (*) (void)) ehdr.e_entry; + *eip = (void (*) (void)) ehdr.e_entry; success = true; done: - /* We arrive here whether the load is successful or not. - We can distinguish based on `success'. */ - if (file_open) - file_close (&file); - if (!success) - addrspace_destroy (t); + /* We arrive here whether the load is successful or not. */ + file_close (file); return success; } @@ -187,6 +252,8 @@ addrspace_load (struct thread *t, const char *filename, void (**start) (void)) void addrspace_destroy (struct thread *t) { + ASSERT (t != thread_current ()); + if (t->pagedir != NULL) { pagedir_destroy (t->pagedir); @@ -194,11 +261,12 @@ addrspace_destroy (struct thread *t) } } -/* Sets up the CPU for running user code in thread T, if any. */ +/* Sets up the CPU for running user code in the current + thread. */ void -addrspace_activate (struct thread *t) +addrspace_activate (void) { - ASSERT (t != NULL); + struct thread *t = thread_current (); /* Activate T's page tables. */ pagedir_activate (t->pagedir); @@ -209,14 +277,12 @@ addrspace_activate (struct thread *t) /* addrspace_load() helpers. */ -static bool install_page (struct thread *, void *upage, void *kpage); +static bool install_page (void *upage, void *kpage); -/* Loads the segment described by PHDR from FILE into thread T's - user address space. Return true if successful, false - otherwise. */ +/* Loads the segment described by PHDR from FILE into user + address space. Return true if successful, false otherwise. */ static bool -load_segment (struct thread *t, struct file *file, - const struct Elf32_Phdr *phdr) +load_segment (struct file *file, const struct Elf32_Phdr *phdr) { void *start, *end; /* Page-rounded segment start and end. */ uint8_t *upage; /* Iterator from start to end. */ @@ -229,7 +295,6 @@ load_segment (struct thread *t, struct file *file, from swap. */ //bool read_only = (phdr->p_flags & PF_W) == 0; - ASSERT (t != NULL); ASSERT (file != NULL); ASSERT (phdr != NULL); ASSERT (phdr->p_type == PT_LOAD); @@ -274,7 +339,7 @@ load_segment (struct thread *t, struct file *file, file into the page and zero the rest. */ size_t read_bytes = filesz_left >= PGSIZE ? PGSIZE : filesz_left; size_t zero_bytes = PGSIZE - read_bytes; - uint8_t *kpage = palloc_get (0); + uint8_t *kpage = palloc_get (PAL_USER); if (kpage == NULL) return false; @@ -288,7 +353,7 @@ load_segment (struct thread *t, struct file *file, filesz_left -= read_bytes; /* Add the page to the process's address space. */ - if (!install_page (t, upage, kpage)) + if (!install_page (upage, kpage)) { palloc_free (kpage); return false; @@ -298,19 +363,21 @@ load_segment (struct thread *t, struct file *file, return true; } -/* Create a minimal stack for T by mapping a zeroed page at the - top of user virtual memory. */ +/* Create a minimal stack by mapping a zeroed page at the top of + user virtual memory. */ static bool -setup_stack (struct thread *t) +setup_stack (void **esp) { uint8_t *kpage; bool success = false; - kpage = palloc_get (PAL_ZERO); + kpage = palloc_get (PAL_USER | PAL_ZERO); if (kpage != NULL) { - success = install_page (t, ((uint8_t *) PHYS_BASE) - PGSIZE, kpage); - if (!success) + success = install_page (((uint8_t *) PHYS_BASE) - PGSIZE, kpage); + if (success) + *esp = PHYS_BASE; + else palloc_free (kpage); } else @@ -320,11 +387,13 @@ setup_stack (struct thread *t) } /* Adds a mapping from user virtual address UPAGE to kernel - virtual address KPAGE to T's page tables. Fails if UPAGE is + virtual address KPAGE to the page table. Fails if UPAGE is already mapped or if memory allocation fails. */ static bool -install_page (struct thread *t, void *upage, void *kpage) +install_page (void *upage, void *kpage) { + 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