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 16 #if ELF_CLASS == ELFCLASS32 17 typedef Elf32_auxv_t elf_auxv_t; 18 #else 19 typedef Elf64_auxv_t elf_auxv_t; 20 #endif 21 22 char * elf_aux_platform; 23 long elf_aux_hwcap; 24 25 unsigned long vsyscall_ehdr; 26 unsigned long vsyscall_end; 27 28 unsigned long __kernel_vsyscall; 29 30 __init void scan_elf_aux( char **envp) 31 { 32 long page_size = 0; 33 elf_auxv_t * auxv; 34 35 while ( *envp++ != NULL) ; 36 37 for ( auxv = (elf_auxv_t *)envp; auxv->a_type != AT_NULL; auxv++) { 38 switch ( auxv->a_type ) { 39 case AT_SYSINFO: 40 __kernel_vsyscall = auxv->a_un.a_val; 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 = (char *) 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