#include "addrspace.h"
+#include <inttypes.h>
+#include "debug.h"
+#include "file.h"
+#include "filesys.h"
+#include "init.h"
+#include "lib.h"
+#include "mmu.h"
+#include "malloc.h"
+#include "paging.h"
+#include "palloc.h"
/* We load ELF binaries. The following definitions are taken
- from the ELF specification more-or-less literally. */
+ from the ELF specification more-or-less verbatim. */
/* ELF types. */
typedef uint32_t Elf32_Word, Elf32_Addr, Elf32_Off;
typedef uint16_t Elf32_Half;
+#define PE32Wx PRIx32
+#define PE32Ax PRIx32
+#define PE32Ox PRIx32
+#define PE32Hx PRIx16
+
/* Executable header.
This appears at the very beginning of an ELF binary. */
struct Elf32_Ehdr
Elf32_Word p_align;
};
-/* Values for p_type in struct Elf32_Phdr. */
-#define PT_NULL 0 /* Ignore this program header. */
-#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. */
+/* Values for p_type. */
+#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. */
+#define PF_X 1 /* Executable. */
+#define PF_W 2 /* Writable. */
+#define PF_R 4 /* Readable. */
#define LOAD_ERROR(MSG) \
do { \
goto error; \
} while (0)
+static bool
+install_page (struct addrspace *as, void *upage, void *kpage)
+{
+ /* Verify that there's not already a page at that virtual
+ address, then map our page there. */
+ if (pagedir_get_page (as->pagedir, upage) == NULL
+ && pagedir_set_page (as->pagedir, upage, kpage, true))
+ return true;
+ else
+ {
+ palloc_free (kpage);
+ return false;
+ }
+}
+
+static bool
+load_segment (struct addrspace *as, struct file *file,
+ const struct Elf32_Phdr *phdr)
+{
+ void *start, *end;
+ uint8_t *upage;
+ off_t filesz_left;
+
+ ASSERT (as != NULL);
+ ASSERT (file != NULL);
+ ASSERT (phdr != NULL);
+ ASSERT (phdr->p_type == PT_LOAD);
+
+ /* p_offset and p_vaddr must be congruent modulo PGSIZE. */
+ if (phdr->p_offset % PGSIZE != phdr->p_vaddr % PGSIZE)
+ {
+ printk ("%#08"PE32Ox" and %#08"PE32Ax" not congruent modulo %#x\n",
+ phdr->p_offset, phdr->p_vaddr, (unsigned) PGSIZE);
+ return false;
+ }
+
+ /* p_memsz must be at least as big as p_filesz. */
+ if (phdr->p_memsz < phdr->p_filesz)
+ {
+ printk ("p_memsz (%08"PE32Wx") < p_filesz (%08"PE32Wx")\n",
+ phdr->p_memsz, phdr->p_filesz);
+ return false;
+ }
+
+ /* Validate virtual memory region to be mapped. */
+ start = pg_round_down ((void *) phdr->p_vaddr);
+ end = pg_round_up ((void *) (phdr->p_vaddr + phdr->p_memsz));
+ if (start >= PHYS_BASE || end >= PHYS_BASE || end < start)
+ {
+ printk ("bad virtual region %08lx...%08lx\n",
+ (unsigned long) start, (unsigned long) end);
+ return false;
+ }
+
+ filesz_left = phdr->p_filesz + (phdr->p_vaddr & PGMASK);
+ file_seek (file, ROUND_DOWN (phdr->p_offset, PGSIZE));
+ for (upage = start; upage < (uint8_t *) end; upage += PGSIZE)
+ {
+ size_t read_bytes = filesz_left >= PGSIZE ? PGSIZE : filesz_left;
+ size_t zero_bytes = PGSIZE - read_bytes;
+ uint8_t *kpage = palloc_get (0);
+ if (kpage == NULL)
+ return false;
+
+ if (file_read (file, kpage, read_bytes) != (int) read_bytes)
+ return false;
+ memset (kpage + read_bytes, 0, zero_bytes);
+ filesz_left -= read_bytes;
+
+ if (!install_page (as, upage, kpage))
+ return false;
+ }
+
+ return true;
+}
+
+static bool
+setup_stack (struct addrspace *as)
+{
+ uint8_t *kpage = palloc_get (PAL_ZERO);
+ if (kpage == NULL)
+ {
+ printk ("failed to allocate process stack\n");
+ return false;
+ }
+
+ return install_page (as, ((uint8_t *) PHYS_BASE) - PGSIZE, kpage);
+}
+
bool
-addrspace_load (struct addrspace *as, const char *filename)
+addrspace_load (struct addrspace *as, const char *filename,
+ void (**start) (void))
{
- Elf32_Ehdr ehdr;
- struct file *file;
+ struct Elf32_Ehdr ehdr;
+ struct file *file = NULL;
+ off_t file_ofs;
+ bool success = false;
+ int i;
+
+ as->pagedir = pagedir_create ();
file = filesys_open (filename);
if (file == NULL)
/* Read and verify executable header. */
if (file_read (file, &ehdr, sizeof ehdr) != sizeof ehdr)
LOAD_ERROR (("error reading executable header"));
- if (memcmp (ehdr.e_ident, "\x7fELF\1\1\1", 7) != 0)
- LOAD_ERROR (("not an ELF file"));
+ if (memcmp (ehdr.e_ident, "\177ELF\1\1\1", 7) != 0)
+ LOAD_ERROR (("file is not ELF"));
if (ehdr.e_type != 2)
- LOAD_ERROR (("not an executable"));
+ LOAD_ERROR (("ELF file is not an executable"));
if (ehdr.e_machine != 3)
- LOAD_ERROR (("not an x86 binary"));
+ LOAD_ERROR (("ELF executable is not x86"));
if (ehdr.e_version != 1)
- LOAD_ERROR (("unknown ELF version %d", (int) ehdr.e_version));
+ LOAD_ERROR (("ELF executable hasunknown version %d",
+ (int) ehdr.e_version));
if (ehdr.e_phentsize != sizeof (struct Elf32_Phdr))
- LOAD_ERROR (("bad program header size", (int) ehdr.e_phentsize));
+ LOAD_ERROR (("bad ELF program header size"));
if (ehdr.e_phnum > 1024)
- LOAD_ERROR (("too many program headers"));
+ LOAD_ERROR (("too many ELF program headers"));
/* Read program headers. */
+ file_ofs = ehdr.e_phoff;
+ for (i = 0; i < ehdr.e_phnum; i++)
+ {
+ struct Elf32_Phdr phdr;
- as->page_dir = create_page_dir ();
- list_init (&as->vmas);
+ 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)
+ {
+ case PT_NULL:
+ case PT_NOTE:
+ case PT_PHDR:
+ case PT_STACK:
+ /* Ignore this segment. */
+ break;
+ case PT_DYNAMIC:
+ case PT_INTERP:
+ case PT_SHLIB:
+ /* Reject the executable. */
+ LOAD_ERROR (("unsupported ELF segment type %d\n", phdr.p_type));
+ break;
+ default:
+ printk ("unknown ELF segment type %08x\n", phdr.p_type);
+ break;
+ case PT_LOAD:
+ if (!load_segment (as, file, &phdr))
+ goto error;
+ break;
+ }
+ }
-
-
+ /* Set up stack. */
+ if (!setup_stack (as))
+ goto error;
+
+ /* Start address. */
+ *start = (void (*) (void)) ehdr.e_entry;
+ success = true;
+
+ error:
+ if (file != NULL)
+ file_close (file);
+ if (!success)
+ addrspace_destroy (as);
+ return success;
+}
+
+void
+addrspace_destroy (struct addrspace *as)
+{
+ if (as != NULL && as->pagedir != NULL)
+ pagedir_destroy (as->pagedir);
+}
+
+void
+addrspace_activate (struct addrspace *as)
+{
+ ASSERT (as != NULL);
+
+ if (as->pagedir != NULL)
+ pagedir_activate (as->pagedir);
+ tss->esp0 = (uint32_t) pg_round_down (as) + PGSIZE;
}
projects / pintos-anon / blobdiff