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 typedef Elf32_auxv_t elf_auxv_t; 17 18 /* These are initialized very early in boot and never changed */ 19 char * elf_aux_platform; 20 extern long elf_aux_hwcap; 21 unsigned long vsyscall_ehdr; 22 unsigned long vsyscall_end; 23 unsigned long __kernel_vsyscall; 24 25 __init void scan_elf_aux( char **envp) 26 { 27 long page_size = 0; 28 elf_auxv_t * auxv; 29 30 while ( *envp++ != NULL) ; 31 32 for ( auxv = (elf_auxv_t *)envp; auxv->a_type != AT_NULL; auxv++) { 33 switch ( auxv->a_type ) { 34 case AT_SYSINFO: 35 __kernel_vsyscall = auxv->a_un.a_val; 36 /* See if the page is under TASK_SIZE */ 37 if (__kernel_vsyscall < (unsigned long) envp) 38 __kernel_vsyscall = 0; 39 break; 40 case AT_SYSINFO_EHDR: 41 vsyscall_ehdr = auxv->a_un.a_val; 42 /* See if the page is under TASK_SIZE */ 43 if (vsyscall_ehdr < (unsigned long) envp) 44 vsyscall_ehdr = 0; 45 break; 46 case AT_HWCAP: 47 elf_aux_hwcap = auxv->a_un.a_val; 48 break; 49 case AT_PLATFORM: 50 /* elf.h removed the pointer elements from 51 * a_un, so we have to use a_val, which is 52 * all that's left. 53 */ 54 elf_aux_platform = 55 (char *) (long) auxv->a_un.a_val; 56 break; 57 case AT_PAGESZ: 58 page_size = auxv->a_un.a_val; 59 break; 60 } 61 } 62 if ( ! __kernel_vsyscall || ! vsyscall_ehdr || 63 ! elf_aux_hwcap || ! elf_aux_platform || 64 ! page_size || (vsyscall_ehdr % page_size) ) { 65 __kernel_vsyscall = 0; 66 vsyscall_ehdr = 0; 67 elf_aux_hwcap = 0; 68 elf_aux_platform = "i586"; 69 } 70 else { 71 vsyscall_end = vsyscall_ehdr + page_size; 72 } 73 } 74