pd = cur->pagedir;
if (pd != NULL)
{
- /* 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
+ /* 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;
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 ("load: %s: ", filename); \
- printf MSG; \
- printf ("\n"); \
- goto done; \
- } while (0)
-
/* 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.
/* Allocate and activate page directory. */
t->pagedir = pagedir_create ();
- if (t->pagedir == NULL)
- LOAD_ERROR (("page directory allocation failed"));
+ if (t->pagedir == NULL)
+ goto done;
process_activate ();
/* Open executable file. */
file = filesys_open (filename);
- if (file == NULL)
- LOAD_ERROR (("open failed"));
+ if (file == NULL)
+ {
+ printf ("load: %s: open failed\n", filename);
+ goto done;
+ }
/* 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, "\177ELF\1\1\1", 7) != 0)
- LOAD_ERROR (("file is not ELF"));
- if (ehdr.e_type != 2)
- LOAD_ERROR (("ELF file is not an executable"));
- if (ehdr.e_machine != 3)
- LOAD_ERROR (("ELF executable is not x86"));
- if (ehdr.e_version != 1)
- LOAD_ERROR (("ELF executable has unknown version %d",
- (int) ehdr.e_version));
- if (ehdr.e_phentsize != sizeof (struct Elf32_Phdr))
- LOAD_ERROR (("bad ELF program header size"));
- if (ehdr.e_phnum > 1024)
- LOAD_ERROR (("too many ELF program headers"));
+ 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", filename);
+ goto done;
+ }
/* Read program headers. */
file_ofs = ehdr.e_phoff;
struct Elf32_Phdr phdr;
if (file_ofs < 0 || file_ofs > file_length (file))
- LOAD_ERROR (("bad file offset %ld", (long) file_ofs));
+ goto done;
file_seek (file, file_ofs);
if (file_read (file, &phdr, sizeof phdr) != sizeof phdr)
- LOAD_ERROR (("error reading program header"));
+ goto done;
file_ofs += sizeof phdr;
switch (phdr.p_type)
{
case PT_NOTE:
case PT_PHDR:
case PT_STACK:
+ default:
/* 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:
- printf ("unknown ELF segment type %08x\n", phdr.p_type);
- break;
+ goto done;
case PT_LOAD:
if (!load_segment (file, &phdr))
goto done;
/* [ELF1] 2-2 says that p_offset and p_vaddr must be congruent
modulo PGSIZE. */
if (phdr->p_offset % PGSIZE != phdr->p_vaddr % PGSIZE)
- {
- printf ("%#08"PE32Ox" and %#08"PE32Ax" not congruent modulo %#x\n",
- phdr->p_offset, phdr->p_vaddr, (unsigned) PGSIZE);
- return false;
- }
+ return false;
/* p_offset must point within file. */
if (phdr->p_offset > (Elf32_Off) file_length (file))
- {
- printf ("bad p_offset %"PE32Ox, phdr->p_offset);
- return false;
- }
+ return false;
/* [ELF1] 2-3 says that p_memsz must be at least as big as
p_filesz. */
if (phdr->p_memsz < phdr->p_filesz)
- {
- printf ("p_memsz (%08"PE32Wx") < p_filesz (%08"PE32Wx")\n",
- phdr->p_memsz, phdr->p_filesz);
- return false;
- }
+ return false;
/* Validate virtual memory region to be mapped.
The region must both start and end within the user address
- space range starting at 0 and ending at PHYS_BASE (typically
- 3 GB == 0xc0000000). We don't allow mapping page 0 .*/
+ space range. We don't allow mapping page 0.*/
start = pg_round_down ((void *) phdr->p_vaddr);
end = pg_round_up ((void *) (phdr->p_vaddr + phdr->p_memsz));
- if (start == 0 || start >= PHYS_BASE || end >= PHYS_BASE || end < start)
- {
- printf ("bad virtual region %08lx...%08lx\n",
- (unsigned long) start, (unsigned long) end);
- return false;
- }
+ if (!is_user_vaddr (start) || !is_user_vaddr (end) || end < start
+ || start == 0)
+ return false;
/* Load the segment page-by-page into memory. */
filesz_left = phdr->p_filesz + (phdr->p_vaddr & PGMASK);
else
palloc_free_page (kpage);
}
- else
- printf ("failed to allocate process stack\n");
-
return success;
}
projects / pintos-anon / blobdiff