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 19typedef Elf32_auxv_t elf_auxv_t; 20#else 21typedef Elf64_auxv_t elf_auxv_t; 22#endif 23 24/* These are initialized very early in boot and never changed */ 25char * elf_aux_platform; 26long elf_aux_hwcap; 27unsigned long vsyscall_ehdr; 28unsigned long vsyscall_end; 29unsigned 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 /* See if the page is under TASK_SIZE */ 43 if (__kernel_vsyscall < (unsigned long) envp) 44 __kernel_vsyscall = 0; 45 break; 46 case AT_SYSINFO_EHDR: 47 vsyscall_ehdr = auxv->a_un.a_val; 48 /* See if the page is under TASK_SIZE */ 49 if (vsyscall_ehdr < (unsigned long) envp) 50 vsyscall_ehdr = 0; 51 break; 52 case AT_HWCAP: 53 elf_aux_hwcap = auxv->a_un.a_val; 54 break; 55 case AT_PLATFORM: 56 /* elf.h removed the pointer elements from 57 * a_un, so we have to use a_val, which is 58 * all that's left. 59 */ 60 elf_aux_platform = 61 (char *) (long) auxv->a_un.a_val; 62 break; 63 case AT_PAGESZ: 64 page_size = auxv->a_un.a_val; 65 break; 66 } 67 } 68 if ( ! __kernel_vsyscall || ! vsyscall_ehdr || 69 ! elf_aux_hwcap || ! elf_aux_platform || 70 ! page_size || (vsyscall_ehdr % page_size) ) { 71 __kernel_vsyscall = 0; 72 vsyscall_ehdr = 0; 73 elf_aux_hwcap = 0; 74 elf_aux_platform = "i586"; 75 } 76 else { 77 vsyscall_end = vsyscall_ehdr + page_size; 78 } 79} 80