1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * arch/um/kernel/elf_aux.c 4 * 5 * Scan the ELF auxiliary vector provided by the host to extract 6 * information about vsyscall-page, etc. 7 * 8 * Copyright (C) 2004 Fujitsu Siemens Computers GmbH 9 * Author: Bodo Stroesser (bodo.stroesser@fujitsu-siemens.com) 10 */ 11 #include <elf.h> 12 #include <stddef.h> 13 #include <init.h> 14 #include <elf_user.h> 15 #include <mem_user.h> 16 #include "internal.h" 17 18 typedef Elf32_auxv_t elf_auxv_t; 19 20 /* These are initialized very early in boot and never changed */ 21 char * elf_aux_platform; 22 extern long elf_aux_hwcap; 23 unsigned long vsyscall_ehdr; 24 unsigned long vsyscall_end; 25 unsigned long __kernel_vsyscall; 26 27 __init void scan_elf_aux( char **envp) 28 { 29 long page_size = 0; 30 elf_auxv_t * auxv; 31 32 while ( *envp++ != NULL) ; 33 34 for ( auxv = (elf_auxv_t *)envp; auxv->a_type != AT_NULL; auxv++) { 35 switch ( auxv->a_type ) { 36 case AT_SYSINFO: 37 __kernel_vsyscall = auxv->a_un.a_val; 38 /* See if the page is under TASK_SIZE */ 39 if (__kernel_vsyscall < (unsigned long) envp) 40 __kernel_vsyscall = 0; 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 = 57 (char *) (long) 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