| b.liu | e958203 | 2025-04-17 19:18:16 +0800 | [diff] [blame^] | 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 | } |