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 17 typedef Elf32_auxv_t elf_auxv_t; 18 19 /* These are initialized very early in boot and never changed */ 20 char * elf_aux_platform; 21 extern long elf_aux_hwcap; 22 unsigned long vsyscall_ehdr; 23 unsigned long vsyscall_end; 24 unsigned long __kernel_vsyscall; 25 26 __init void scan_elf_aux( char **envp) 27 { 28 long page_size = 0; 29 elf_auxv_t * auxv; 30 31 while ( *envp++ != NULL) ; 32 33 for ( auxv = (elf_auxv_t *)envp; auxv->a_type != AT_NULL; auxv++) { 34 switch ( auxv->a_type ) { 35 case AT_SYSINFO: 36 __kernel_vsyscall = auxv->a_un.a_val; 37 /* See if the page is under TASK_SIZE */ 38 if (__kernel_vsyscall < (unsigned long) envp) 39 __kernel_vsyscall = 0; 40 break; 41 case AT_SYSINFO_EHDR: 42 vsyscall_ehdr = auxv->a_un.a_val; 43 /* See if the page is under TASK_SIZE */ 44 if (vsyscall_ehdr < (unsigned long) envp) 45 vsyscall_ehdr = 0; 46 break; 47 case AT_HWCAP: 48 elf_aux_hwcap = auxv->a_un.a_val; 49 break; 50 case AT_PLATFORM: 51 /* elf.h removed the pointer elements from 52 * a_un, so we have to use a_val, which is 53 * all that's left. 54 */ 55 elf_aux_platform = 56 (char *) (long) auxv->a_un.a_val; 57 break; 58 case AT_PAGESZ: 59 page_size = auxv->a_un.a_val; 60 break; 61 } 62 } 63 if ( ! __kernel_vsyscall || ! vsyscall_ehdr || 64 ! elf_aux_hwcap || ! elf_aux_platform || 65 ! page_size || (vsyscall_ehdr % page_size) ) { 66 __kernel_vsyscall = 0; 67 vsyscall_ehdr = 0; 68 elf_aux_hwcap = 0; 69 elf_aux_platform = "i586"; 70 } 71 else { 72 vsyscall_end = vsyscall_ehdr + page_size; 73 } 74 } 75