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
17 typedef Elf32_auxv_t elf_auxv_t;
18
19 /* These are initialized very early in boot and never changed */
20 char * elf_aux_platform;
21 extern long elf_aux_hwcap;
22 unsigned long vsyscall_ehdr;
23 unsigned long vsyscall_end;
24 unsigned 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;
37 /* See if the page is under TASK_SIZE */
38 if (__kernel_vsyscall < (unsigned long) envp)
39 __kernel_vsyscall = 0;
40 break;
41 case AT_SYSINFO_EHDR:
42 vsyscall_ehdr = auxv->a_un.a_val;
43 /* See if the page is under TASK_SIZE */
44 if (vsyscall_ehdr < (unsigned long) envp)
45 vsyscall_ehdr = 0;
46 break;
47 case AT_HWCAP:
48 elf_aux_hwcap = auxv->a_un.a_val;
49 break;
50 case AT_PLATFORM:
51 /* 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 */
55 elf_aux_platform =
56 (char *) (long) 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 }