Merge HEAD from master.kernel.org:/home/rmk/linux-2.6-arm.git
[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
16 #if ELF_CLASS == ELFCLASS32
17 typedef Elf32_auxv_t elf_auxv_t;
18 #else
19 typedef Elf64_auxv_t elf_auxv_t;
20 #endif
21
22 char * elf_aux_platform;
23 long elf_aux_hwcap;
24
25 unsigned long vsyscall_ehdr;
26 unsigned long vsyscall_end;
27
28 unsigned long __kernel_vsyscall;
29
30 __init void scan_elf_aux( char **envp)
31 {
32         long page_size = 0;
33         elf_auxv_t * auxv;
34
35         while ( *envp++ != NULL) ;
36
37         for ( auxv = (elf_auxv_t *)envp; auxv->a_type != AT_NULL; auxv++) {
38                 switch ( auxv->a_type ) {
39                         case AT_SYSINFO:
40                                 __kernel_vsyscall = auxv->a_un.a_val;
41                                 break;
42                         case AT_SYSINFO_EHDR:
43                                 vsyscall_ehdr = auxv->a_un.a_val;
44                                 /* See if the page is under TASK_SIZE */
45                                 if (vsyscall_ehdr < (unsigned long) envp)
46                                         vsyscall_ehdr = 0;
47                                 break;
48                         case AT_HWCAP:
49                                 elf_aux_hwcap = auxv->a_un.a_val;
50                                 break;
51                         case AT_PLATFORM:
52                                 /* elf.h removed the pointer elements from
53                                  * a_un, so we have to use a_val, which is
54                                  * all that's left.
55                                  */
56                                 elf_aux_platform = (char *) auxv->a_un.a_val;
57                                 break;
58                         case AT_PAGESZ:
59                                 page_size = auxv->a_un.a_val;
60                                 break;
61                 }
62         }
63         if ( ! __kernel_vsyscall || ! vsyscall_ehdr ||
64              ! elf_aux_hwcap || ! elf_aux_platform ||
65              ! page_size || (vsyscall_ehdr % page_size) ) {
66                 __kernel_vsyscall = 0;
67                 vsyscall_ehdr = 0;
68                 elf_aux_hwcap = 0;
69                 elf_aux_platform = "i586";
70         }
71         else {
72                 vsyscall_end = vsyscall_ehdr + page_size;
73         }
74 }