tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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
19typedef Elf32_auxv_t elf_auxv_t;
20#else
21typedef Elf64_auxv_t elf_auxv_t;
22#endif
23
24char * elf_aux_platform;
25long elf_aux_hwcap;
26
27unsigned long vsyscall_ehdr;
28unsigned long vsyscall_end;
29
30unsigned long __kernel_vsyscall;
31
32__init void scan_elf_aux( char **envp)
33{
34 long page_size = 0;
35 elf_auxv_t * auxv;
36
37 while ( *envp++ != NULL) ;
38
39 for ( auxv = (elf_auxv_t *)envp; auxv->a_type != AT_NULL; auxv++) {
40 switch ( auxv->a_type ) {
41 case AT_SYSINFO:
42 __kernel_vsyscall = auxv->a_un.a_val;
43 break;
44 case AT_SYSINFO_EHDR:
45 vsyscall_ehdr = auxv->a_un.a_val;
46 /* See if the page is under TASK_SIZE */
47 if (vsyscall_ehdr < (unsigned long) envp)
48 vsyscall_ehdr = 0;
49 break;
50 case AT_HWCAP:
51 elf_aux_hwcap = auxv->a_un.a_val;
52 break;
53 case AT_PLATFORM:
54 /* elf.h removed the pointer elements from
55 * a_un, so we have to use a_val, which is
56 * all that's left.
57 */
58 elf_aux_platform =
59 (char *) (long) auxv->a_un.a_val;
60 break;
61 case AT_PAGESZ:
62 page_size = auxv->a_un.a_val;
63 break;
64 }
65 }
66 if ( ! __kernel_vsyscall || ! vsyscall_ehdr ||
67 ! elf_aux_hwcap || ! elf_aux_platform ||
68 ! page_size || (vsyscall_ehdr % page_size) ) {
69 __kernel_vsyscall = 0;
70 vsyscall_ehdr = 0;
71 elf_aux_hwcap = 0;
72 elf_aux_platform = "i586";
73 }
74 else {
75 vsyscall_end = vsyscall_ehdr + page_size;
76 }
77}