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 15 #if ELF_CLASS == ELFCLASS32 16 typedef Elf32_auxv_t elf_auxv_t; 17 #else 18 typedef Elf64_auxv_t elf_auxv_t; 19 #endif 20 21 char * elf_aux_platform; 22 long elf_aux_hwcap; 23 24 unsigned long vsyscall_ehdr; 25 unsigned long vsyscall_end; 26 27 unsigned long __kernel_vsyscall; 28 29 __init void scan_elf_aux( char **envp) 30 { 31 long page_size = 0; 32 elf_auxv_t * auxv; 33 34 while ( *envp++ != NULL) ; 35 36 for ( auxv = (elf_auxv_t *)envp; auxv->a_type != AT_NULL; auxv++) { 37 switch ( auxv->a_type ) { 38 case AT_SYSINFO: 39 __kernel_vsyscall = auxv->a_un.a_val; 40 break; 41 case AT_SYSINFO_EHDR: 42 vsyscall_ehdr = auxv->a_un.a_val; 43 break; 44 case AT_HWCAP: 45 elf_aux_hwcap = auxv->a_un.a_val; 46 break; 47 case AT_PLATFORM: 48 /* elf.h removed the pointer elements from 49 * a_un, so we have to use a_val, which is 50 * all that's left. 51 */ 52 elf_aux_platform = (char *) auxv->a_un.a_val; 53 break; 54 case AT_PAGESZ: 55 page_size = auxv->a_un.a_val; 56 break; 57 } 58 } 59 if ( ! __kernel_vsyscall || ! vsyscall_ehdr || 60 ! elf_aux_hwcap || ! elf_aux_platform || 61 ! page_size || (vsyscall_ehdr % page_size) ) { 62 __kernel_vsyscall = 0; 63 vsyscall_ehdr = 0; 64 elf_aux_hwcap = 0; 65 elf_aux_platform = "i586"; 66 } 67 else { 68 vsyscall_end = vsyscall_ehdr + page_size; 69 } 70 } 71