1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * arch/um/kernel/elf_aux.c
4 *
5 * Scan the ELF auxiliary vector provided by the host to extract
6 * 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>
13 #include <init.h>
14 #include <elf_user.h>
15 #include <mem_user.h>
16 #include "internal.h"
17
18 typedef Elf32_auxv_t elf_auxv_t;
19
20 /* These are initialized very early in boot and never changed */
21 char * elf_aux_platform;
22 extern long elf_aux_hwcap;
23 unsigned long vsyscall_ehdr;
24 unsigned long vsyscall_end;
25 unsigned long __kernel_vsyscall;
26
27 __init void scan_elf_aux( char **envp)
28 {
29 long page_size = 0;
30 elf_auxv_t * auxv;
31
32 while ( *envp++ != NULL) ;
33
34 for ( auxv = (elf_auxv_t *)envp; auxv->a_type != AT_NULL; auxv++) {
35 switch ( auxv->a_type ) {
36 case AT_SYSINFO:
37 __kernel_vsyscall = auxv->a_un.a_val;
38 /* See if the page is under TASK_SIZE */
39 if (__kernel_vsyscall < (unsigned long) envp)
40 __kernel_vsyscall = 0;
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 =
57 (char *) (long) 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 }
76
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