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 19 typedef Elf32_auxv_t elf_auxv_t; 20 #else 21 typedef Elf64_auxv_t elf_auxv_t; 22 #endif 23 24 char * elf_aux_platform; 25 long elf_aux_hwcap; 26 27 unsigned long vsyscall_ehdr; 28 unsigned long vsyscall_end; 29 30 unsigned 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 } 78