1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * (C) Copyright 2002 Linus Torvalds 4 * Portions based on the vdso-randomization code from exec-shield: 5 * Copyright(C) 2005-2006, Red Hat, Inc., Ingo Molnar 6 * 7 * This file contains the needed initializations to support sysenter. 8 */ 9 10 #include <linux/init.h> 11 #include <linux/smp.h> 12 #include <linux/kernel.h> 13 #include <linux/mm_types.h> 14 #include <linux/elf.h> 15 16 #include <asm/processor.h> 17 #include <asm/vdso.h> 18 19 #ifdef CONFIG_COMPAT_VDSO 20 #define VDSO_DEFAULT 0 21 #else 22 #define VDSO_DEFAULT 1 23 #endif 24 25 /* 26 * Should the kernel map a VDSO page into processes and pass its 27 * address down to glibc upon exec()? 28 */ 29 unsigned int __read_mostly vdso32_enabled = VDSO_DEFAULT; 30 31 static int __init vdso32_setup(char *s) 32 { 33 vdso32_enabled = simple_strtoul(s, NULL, 0); 34 35 if (vdso32_enabled > 1) { 36 pr_warn("vdso32 values other than 0 and 1 are no longer allowed; vdso disabled\n"); 37 vdso32_enabled = 0; 38 } 39 40 return 1; 41 } 42 43 /* 44 * For consistency, the argument vdso32=[012] affects the 32-bit vDSO 45 * behavior on both 64-bit and 32-bit kernels. 46 * On 32-bit kernels, vdso=[012] means the same thing. 47 */ 48 __setup("vdso32=", vdso32_setup); 49 50 #ifdef CONFIG_X86_32 51 __setup_param("vdso=", vdso_setup, vdso32_setup, 0); 52 #endif 53 54 #ifdef CONFIG_X86_64 55 56 #ifdef CONFIG_SYSCTL 57 /* Register vsyscall32 into the ABI table */ 58 #include <linux/sysctl.h> 59 60 static struct ctl_table abi_table2[] = { 61 { 62 .procname = "vsyscall32", 63 .data = &vdso32_enabled, 64 .maxlen = sizeof(int), 65 .mode = 0644, 66 .proc_handler = proc_dointvec_minmax, 67 .extra1 = SYSCTL_ZERO, 68 .extra2 = SYSCTL_ONE, 69 }, 70 {} 71 }; 72 73 static __init int ia32_binfmt_init(void) 74 { 75 register_sysctl("abi", abi_table2); 76 return 0; 77 } 78 __initcall(ia32_binfmt_init); 79 #endif /* CONFIG_SYSCTL */ 80 81 #endif /* CONFIG_X86_64 */ 82