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 <kernel-offsets.h> 16 17 #if HOST_ELF_CLASS == ELFCLASS32 18 typedef Elf32_auxv_t elf_auxv_t; 19 #else 20 typedef Elf64_auxv_t elf_auxv_t; 21 #endif 22 23 char * elf_aux_platform; 24 long elf_aux_hwcap; 25 26 unsigned long vsyscall_ehdr; 27 unsigned long vsyscall_end; 28 29 unsigned long __kernel_vsyscall; 30 31 __init void scan_elf_aux( char **envp) 32 { 33 long page_size = 0; 34 elf_auxv_t * auxv; 35 36 while ( *envp++ != NULL) ; 37 38 for ( auxv = (elf_auxv_t *)envp; auxv->a_type != AT_NULL; auxv++) { 39 switch ( auxv->a_type ) { 40 case AT_SYSINFO: 41 __kernel_vsyscall = auxv->a_un.a_val; 42 break; 43 case AT_SYSINFO_EHDR: 44 vsyscall_ehdr = auxv->a_un.a_val; 45 /* See if the page is under TASK_SIZE */ 46 if (vsyscall_ehdr < (unsigned long) envp) 47 vsyscall_ehdr = 0; 48 break; 49 case AT_HWCAP: 50 elf_aux_hwcap = auxv->a_un.a_val; 51 break; 52 case AT_PLATFORM: 53 /* elf.h removed the pointer elements from 54 * a_un, so we have to use a_val, which is 55 * all that's left. 56 */ 57 elf_aux_platform = (char *) auxv->a_un.a_val; 58 break; 59 case AT_PAGESZ: 60 page_size = auxv->a_un.a_val; 61 break; 62 } 63 } 64 if ( ! __kernel_vsyscall || ! vsyscall_ehdr || 65 ! elf_aux_hwcap || ! elf_aux_platform || 66 ! page_size || (vsyscall_ehdr % page_size) ) { 67 __kernel_vsyscall = 0; 68 vsyscall_ehdr = 0; 69 elf_aux_hwcap = 0; 70 elf_aux_platform = "i586"; 71 } 72 else { 73 vsyscall_end = vsyscall_ehdr + page_size; 74 } 75 } 76