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 | } |
75 | |