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
16typedef Elf32_auxv_t elf_auxv_t;
17
18/* These are initialized very early in boot and never changed */
19char * elf_aux_platform;
20extern long elf_aux_hwcap;
21unsigned long vsyscall_ehdr;
22unsigned long vsyscall_end;
23unsigned long __kernel_vsyscall;
24
25__init void scan_elf_aux( char **envp)
26{
27	long page_size = 0;
28	elf_auxv_t * auxv;
29
30	while ( *envp++ != NULL) ;
31
32	for ( auxv = (elf_auxv_t *)envp; auxv->a_type != AT_NULL; auxv++) {
33		switch ( auxv->a_type ) {
34			case AT_SYSINFO:
35				__kernel_vsyscall = auxv->a_un.a_val;
36				/* See if the page is under TASK_SIZE */
37				if (__kernel_vsyscall < (unsigned long) envp)
38					__kernel_vsyscall = 0;
39				break;
40			case AT_SYSINFO_EHDR:
41				vsyscall_ehdr = auxv->a_un.a_val;
42				/* See if the page is under TASK_SIZE */
43				if (vsyscall_ehdr < (unsigned long) envp)
44					vsyscall_ehdr = 0;
45				break;
46			case AT_HWCAP:
47				elf_aux_hwcap = auxv->a_un.a_val;
48				break;
49			case AT_PLATFORM:
50                                /* elf.h removed the pointer elements from
51                                 * a_un, so we have to use a_val, which is
52                                 * all that's left.
53                                 */
54				elf_aux_platform =
55					(char *) (long) auxv->a_un.a_val;
56				break;
57			case AT_PAGESZ:
58				page_size = auxv->a_un.a_val;
59				break;
60		}
61	}
62	if ( ! __kernel_vsyscall || ! vsyscall_ehdr ||
63	     ! elf_aux_hwcap || ! elf_aux_platform ||
64	     ! page_size || (vsyscall_ehdr % page_size) ) {
65		__kernel_vsyscall = 0;
66		vsyscall_ehdr = 0;
67		elf_aux_hwcap = 0;
68		elf_aux_platform = "i586";
69	}
70	else {
71		vsyscall_end = vsyscall_ehdr + page_size;
72	}
73}
74