LXR linux/arch/um/os-Linux/elf

   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
  17typedef Elf32_auxv_t elf_auxv_t;
  18
  19/* These are initialized very early in boot and never changed */
  20char * elf_aux_platform;
  21extern long elf_aux_hwcap;
  22unsigned long vsyscall_ehdr;
  23unsigned long vsyscall_end;
  24unsigned 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