Merge master.kernel.org:/pub/scm/linux/kernel/git/jejb/scsi-misc-2.6
[linux-2.6] / arch / um / os-Linux / elf_aux.c
1 /*
2  *  arch/um/kernel/elf_aux.c
3  *
4  *  Scan the Elf auxiliary vector provided by the host to extract
5  *  information about vsyscall-page, etc.
6  *
7  *  Copyright (C) 2004 Fujitsu Siemens Computers GmbH
8  *  Author: Bodo Stroesser (bodo.stroesser@fujitsu-siemens.com)
9  */
10 #include <elf.h>
11 #include <stddef.h>
12 #include "init.h"
13 #include "elf_user.h"
14 #include "mem_user.h"
15 #include <kern_constants.h>
16
17 /* Use the one from the kernel - the host may miss it, if having old headers. */
18 #if UM_ELF_CLASS == UM_ELFCLASS32
19 typedef Elf32_auxv_t elf_auxv_t;
20 #else
21 typedef Elf64_auxv_t elf_auxv_t;
22 #endif
23
24 char * elf_aux_platform;
25 long elf_aux_hwcap;
26
27 unsigned long vsyscall_ehdr;
28 unsigned long vsyscall_end;
29
30 unsigned long __kernel_vsyscall;
31
32 __init void scan_elf_aux( char **envp)
33 {
34         long page_size = 0;
35         elf_auxv_t * auxv;
36
37         while ( *envp++ != NULL) ;
38
39         for ( auxv = (elf_auxv_t *)envp; auxv->a_type != AT_NULL; auxv++) {
40                 switch ( auxv->a_type ) {
41                         case AT_SYSINFO:
42                                 __kernel_vsyscall = auxv->a_un.a_val;
43                                 break;
44                         case AT_SYSINFO_EHDR:
45                                 vsyscall_ehdr = auxv->a_un.a_val;
46                                 /* See if the page is under TASK_SIZE */
47                                 if (vsyscall_ehdr < (unsigned long) envp)
48                                         vsyscall_ehdr = 0;
49                                 break;
50                         case AT_HWCAP:
51                                 elf_aux_hwcap = auxv->a_un.a_val;
52                                 break;
53                         case AT_PLATFORM:
54                                 /* elf.h removed the pointer elements from
55                                  * a_un, so we have to use a_val, which is
56                                  * all that's left.
57                                  */
58                                 elf_aux_platform =
59                                         (char *) (long) auxv->a_un.a_val;
60                                 break;
61                         case AT_PAGESZ:
62                                 page_size = auxv->a_un.a_val;
63                                 break;
64                 }
65         }
66         if ( ! __kernel_vsyscall || ! vsyscall_ehdr ||
67              ! elf_aux_hwcap || ! elf_aux_platform ||
68              ! page_size || (vsyscall_ehdr % page_size) ) {
69                 __kernel_vsyscall = 0;
70                 vsyscall_ehdr = 0;
71                 elf_aux_hwcap = 0;
72                 elf_aux_platform = "i586";
73         }
74         else {
75                 vsyscall_end = vsyscall_ehdr + page_size;
76         }
77 }