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Greg Kroah-Hartmanb2441312017-11-01 15:07:57 +01001// SPDX-License-Identifier: GPL-2.0
Linus Torvalds1da177e2005-04-16 15:20:36 -07002/*
3 * arch/um/kernel/elf_aux.c
4 *
Alexey Dobriyan70e79862023-02-28 15:14:17 +03005 * Scan the ELF auxiliary vector provided by the host to extract
Linus Torvalds1da177e2005-04-16 15:20:36 -07006 * information about vsyscall-page, etc.
7 *
8 * Copyright (C) 2004 Fujitsu Siemens Computers GmbH
9 * Author: Bodo Stroesser (bodo.stroesser@fujitsu-siemens.com)
10 */
11#include <elf.h>
12#include <stddef.h>
Al Viro37185b32012-10-08 03:27:32 +010013#include <init.h>
14#include <elf_user.h>
15#include <mem_user.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070016
Linus Torvalds1da177e2005-04-16 15:20:36 -070017typedef Elf32_auxv_t elf_auxv_t;
Linus Torvalds1da177e2005-04-16 15:20:36 -070018
Jeff Dikec538b392007-02-10 01:44:26 -080019/* These are initialized very early in boot and never changed */
Linus Torvalds1da177e2005-04-16 15:20:36 -070020char * elf_aux_platform;
Richard Weinbergerb743ac52011-07-25 17:12:52 -070021extern long elf_aux_hwcap;
Linus Torvalds1da177e2005-04-16 15:20:36 -070022unsigned long vsyscall_ehdr;
23unsigned long vsyscall_end;
Linus Torvalds1da177e2005-04-16 15:20:36 -070024unsigned long __kernel_vsyscall;
25
26__init void scan_elf_aux( char **envp)
27{
28 long page_size = 0;
29 elf_auxv_t * auxv;
30
31 while ( *envp++ != NULL) ;
32
33 for ( auxv = (elf_auxv_t *)envp; auxv->a_type != AT_NULL; auxv++) {
34 switch ( auxv->a_type ) {
35 case AT_SYSINFO:
36 __kernel_vsyscall = auxv->a_un.a_val;
Jeff Dike14251802007-02-28 20:13:31 -080037 /* See if the page is under TASK_SIZE */
38 if (__kernel_vsyscall < (unsigned long) envp)
39 __kernel_vsyscall = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -070040 break;
41 case AT_SYSINFO_EHDR:
42 vsyscall_ehdr = auxv->a_un.a_val;
Jeff Dikea502a352005-07-29 14:03:33 -070043 /* See if the page is under TASK_SIZE */
44 if (vsyscall_ehdr < (unsigned long) envp)
45 vsyscall_ehdr = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -070046 break;
47 case AT_HWCAP:
48 elf_aux_hwcap = auxv->a_un.a_val;
49 break;
50 case AT_PLATFORM:
Jeff Dikeda00d9a2005-06-08 15:48:01 -070051 /* elf.h removed the pointer elements from
52 * a_un, so we have to use a_val, which is
53 * all that's left.
54 */
Jeff Dike64b76732005-09-16 19:27:48 -070055 elf_aux_platform =
56 (char *) (long) auxv->a_un.a_val;
Linus Torvalds1da177e2005-04-16 15:20:36 -070057 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}