/home/lenb/src/to-linus-stable branch 'acpi-2.6.12'
[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 <asm/elf.h>
13 #include "init.h"
14 #include "elf_user.h"
15 #include "mem_user.h"
16
17 #if ELF_CLASS == ELFCLASS32
18 typedef Elf32_auxv_t elf_auxv_t;
19 #else
20 typedef Elf64_auxv_t elf_auxv_t;
21 #endif
22
23 char * elf_aux_platform;
24 long elf_aux_hwcap;
25
26 unsigned long vsyscall_ehdr;
27 unsigned long vsyscall_end;
28
29 unsigned long __kernel_vsyscall;
30
31 __init void scan_elf_aux( char **envp)
32 {
33         long page_size = 0;
34         elf_auxv_t * auxv;
35
36         while ( *envp++ != NULL) ;
37
38         for ( auxv = (elf_auxv_t *)envp; auxv->a_type != AT_NULL; auxv++) {
39                 switch ( auxv->a_type ) {
40                         case AT_SYSINFO:
41                                 __kernel_vsyscall = auxv->a_un.a_val;
42                                 break;
43                         case AT_SYSINFO_EHDR:
44                                 vsyscall_ehdr = auxv->a_un.a_val;
45                                 /* See if the page is under TASK_SIZE */
46                                 if (vsyscall_ehdr < (unsigned long) envp)
47                                         vsyscall_ehdr = 0;
48                                 break;
49                         case AT_HWCAP:
50                                 elf_aux_hwcap = auxv->a_un.a_val;
51                                 break;
52                         case AT_PLATFORM:
53                                 /* elf.h removed the pointer elements from
54                                  * a_un, so we have to use a_val, which is
55                                  * all that's left.
56                                  */
57                                 elf_aux_platform = (char *) auxv->a_un.a_val;
58                                 break;
59                         case AT_PAGESZ:
60                                 page_size = auxv->a_un.a_val;
61                                 break;
62                 }
63         }
64         if ( ! __kernel_vsyscall || ! vsyscall_ehdr ||
65              ! elf_aux_hwcap || ! elf_aux_platform ||
66              ! page_size || (vsyscall_ehdr % page_size) ) {
67                 __kernel_vsyscall = 0;
68                 vsyscall_ehdr = 0;
69                 elf_aux_hwcap = 0;
70                 elf_aux_platform = "i586";
71         }
72         else {
73                 vsyscall_end = vsyscall_ehdr + page_size;
74         }
75 }