1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0 2*4882a593Smuzhiyun /* 3*4882a593Smuzhiyun * arch/um/kernel/elf_aux.c 4*4882a593Smuzhiyun * 5*4882a593Smuzhiyun * Scan the Elf auxiliary vector provided by the host to extract 6*4882a593Smuzhiyun * information about vsyscall-page, etc. 7*4882a593Smuzhiyun * 8*4882a593Smuzhiyun * Copyright (C) 2004 Fujitsu Siemens Computers GmbH 9*4882a593Smuzhiyun * Author: Bodo Stroesser (bodo.stroesser@fujitsu-siemens.com) 10*4882a593Smuzhiyun */ 11*4882a593Smuzhiyun #include <elf.h> 12*4882a593Smuzhiyun #include <stddef.h> 13*4882a593Smuzhiyun #include <init.h> 14*4882a593Smuzhiyun #include <elf_user.h> 15*4882a593Smuzhiyun #include <mem_user.h> 16*4882a593Smuzhiyun 17*4882a593Smuzhiyun typedef Elf32_auxv_t elf_auxv_t; 18*4882a593Smuzhiyun 19*4882a593Smuzhiyun /* These are initialized very early in boot and never changed */ 20*4882a593Smuzhiyun char * elf_aux_platform; 21*4882a593Smuzhiyun extern long elf_aux_hwcap; 22*4882a593Smuzhiyun unsigned long vsyscall_ehdr; 23*4882a593Smuzhiyun unsigned long vsyscall_end; 24*4882a593Smuzhiyun unsigned long __kernel_vsyscall; 25*4882a593Smuzhiyun scan_elf_aux(char ** envp)26*4882a593Smuzhiyun__init void scan_elf_aux( char **envp) 27*4882a593Smuzhiyun { 28*4882a593Smuzhiyun long page_size = 0; 29*4882a593Smuzhiyun elf_auxv_t * auxv; 30*4882a593Smuzhiyun 31*4882a593Smuzhiyun while ( *envp++ != NULL) ; 32*4882a593Smuzhiyun 33*4882a593Smuzhiyun for ( auxv = (elf_auxv_t *)envp; auxv->a_type != AT_NULL; auxv++) { 34*4882a593Smuzhiyun switch ( auxv->a_type ) { 35*4882a593Smuzhiyun case AT_SYSINFO: 36*4882a593Smuzhiyun __kernel_vsyscall = auxv->a_un.a_val; 37*4882a593Smuzhiyun /* See if the page is under TASK_SIZE */ 38*4882a593Smuzhiyun if (__kernel_vsyscall < (unsigned long) envp) 39*4882a593Smuzhiyun __kernel_vsyscall = 0; 40*4882a593Smuzhiyun break; 41*4882a593Smuzhiyun case AT_SYSINFO_EHDR: 42*4882a593Smuzhiyun vsyscall_ehdr = auxv->a_un.a_val; 43*4882a593Smuzhiyun /* See if the page is under TASK_SIZE */ 44*4882a593Smuzhiyun if (vsyscall_ehdr < (unsigned long) envp) 45*4882a593Smuzhiyun vsyscall_ehdr = 0; 46*4882a593Smuzhiyun break; 47*4882a593Smuzhiyun case AT_HWCAP: 48*4882a593Smuzhiyun elf_aux_hwcap = auxv->a_un.a_val; 49*4882a593Smuzhiyun break; 50*4882a593Smuzhiyun case AT_PLATFORM: 51*4882a593Smuzhiyun /* elf.h removed the pointer elements from 52*4882a593Smuzhiyun * a_un, so we have to use a_val, which is 53*4882a593Smuzhiyun * all that's left. 54*4882a593Smuzhiyun */ 55*4882a593Smuzhiyun elf_aux_platform = 56*4882a593Smuzhiyun (char *) (long) auxv->a_un.a_val; 57*4882a593Smuzhiyun break; 58*4882a593Smuzhiyun case AT_PAGESZ: 59*4882a593Smuzhiyun page_size = auxv->a_un.a_val; 60*4882a593Smuzhiyun break; 61*4882a593Smuzhiyun } 62*4882a593Smuzhiyun } 63*4882a593Smuzhiyun if ( ! __kernel_vsyscall || ! vsyscall_ehdr || 64*4882a593Smuzhiyun ! elf_aux_hwcap || ! elf_aux_platform || 65*4882a593Smuzhiyun ! page_size || (vsyscall_ehdr % page_size) ) { 66*4882a593Smuzhiyun __kernel_vsyscall = 0; 67*4882a593Smuzhiyun vsyscall_ehdr = 0; 68*4882a593Smuzhiyun elf_aux_hwcap = 0; 69*4882a593Smuzhiyun elf_aux_platform = "i586"; 70*4882a593Smuzhiyun } 71*4882a593Smuzhiyun else { 72*4882a593Smuzhiyun vsyscall_end = vsyscall_ehdr + page_size; 73*4882a593Smuzhiyun } 74*4882a593Smuzhiyun } 75