608784d4ec57e73f0d74a1e0ea3223c89db58cea
[pandora-kernel.git] / 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 /* These are initialized very early in boot and never changed */
25 char * elf_aux_platform;
26 long elf_aux_hwcap;
27 unsigned long vsyscall_ehdr;
28 unsigned long vsyscall_end;
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                                 /* See if the page is under TASK_SIZE */
43                                 if (__kernel_vsyscall < (unsigned long) envp)
44                                         __kernel_vsyscall = 0;
45                                 break;
46                         case AT_SYSINFO_EHDR:
47                                 vsyscall_ehdr = auxv->a_un.a_val;
48                                 /* See if the page is under TASK_SIZE */
49                                 if (vsyscall_ehdr < (unsigned long) envp)
50                                         vsyscall_ehdr = 0;
51                                 break;
52                         case AT_HWCAP:
53                                 elf_aux_hwcap = auxv->a_un.a_val;
54                                 break;
55                         case AT_PLATFORM:
56                                 /* elf.h removed the pointer elements from
57                                  * a_un, so we have to use a_val, which is
58                                  * all that's left.
59                                  */
60                                 elf_aux_platform =
61                                         (char *) (long) auxv->a_un.a_val;
62                                 break;
63                         case AT_PAGESZ:
64                                 page_size = auxv->a_un.a_val;
65                                 break;
66                 }
67         }
68         if ( ! __kernel_vsyscall || ! vsyscall_ehdr ||
69              ! elf_aux_hwcap || ! elf_aux_platform ||
70              ! page_size || (vsyscall_ehdr % page_size) ) {
71                 __kernel_vsyscall = 0;
72                 vsyscall_ehdr = 0;
73                 elf_aux_hwcap = 0;
74                 elf_aux_platform = "i586";
75         }
76         else {
77                 vsyscall_end = vsyscall_ehdr + page_size;
78         }
79 }