2 * (C) Copyright 2002 Linus Torvalds
3 * Portions based on the vdso-randomization code from exec-shield:
4 * Copyright(C) 2005-2006, Red Hat, Inc., Ingo Molnar
6 * This file contains the needed initializations to support sysenter.
9 #include <linux/init.h>
10 #include <linux/smp.h>
11 #include <linux/thread_info.h>
12 #include <linux/sched.h>
13 #include <linux/gfp.h>
14 #include <linux/string.h>
15 #include <linux/elf.h>
17 #include <linux/err.h>
18 #include <linux/module.h>
19 #include <linux/slab.h>
21 #include <asm/cpufeature.h>
23 #include <asm/pgtable.h>
24 #include <asm/unistd.h>
26 #include <asm/tlbflush.h>
28 #include <asm/proto.h>
29 #include <asm/fixmap.h>
33 #ifdef CONFIG_COMPAT_VDSO
34 #define VDSO_DEFAULT 0
36 #define VDSO_DEFAULT 1
40 #define vdso_enabled sysctl_vsyscall32
41 #define arch_setup_additional_pages syscall32_setup_pages
45 * Should the kernel map a VDSO page into processes and pass its
46 * address down to glibc upon exec()?
48 unsigned int __read_mostly vdso_enabled = VDSO_DEFAULT;
50 static int __init vdso_setup(char *s)
52 vdso_enabled = simple_strtoul(s, NULL, 0);
55 pr_warn("vdso32 values other than 0 and 1 are no longer allowed; vdso disabled\n");
61 * For consistency, the argument vdso32=[012] affects the 32-bit vDSO
62 * behavior on both 64-bit and 32-bit kernels.
63 * On 32-bit kernels, vdso=[012] means the same thing.
65 __setup("vdso32=", vdso_setup);
68 __setup_param("vdso=", vdso32_setup, vdso_setup, 0);
70 EXPORT_SYMBOL_GPL(vdso_enabled);
73 static struct page **vdso32_pages;
74 static unsigned vdso32_size;
78 #define vdso32_sysenter() (boot_cpu_has(X86_FEATURE_SYSENTER32))
79 #define vdso32_syscall() (boot_cpu_has(X86_FEATURE_SYSCALL32))
81 /* May not be __init: called during resume */
82 void syscall32_cpu_init(void)
84 /* Load these always in case some future AMD CPU supports
85 SYSENTER from compat mode too. */
86 wrmsrl_safe(MSR_IA32_SYSENTER_CS, (u64)__KERNEL_CS);
87 wrmsrl_safe(MSR_IA32_SYSENTER_ESP, 0ULL);
88 wrmsrl_safe(MSR_IA32_SYSENTER_EIP, (u64)ia32_sysenter_target);
90 wrmsrl(MSR_CSTAR, ia32_cstar_target);
93 #else /* CONFIG_X86_32 */
95 #define vdso32_sysenter() (boot_cpu_has(X86_FEATURE_SEP))
96 #define vdso32_syscall() (0)
98 void enable_sep_cpu(void)
101 struct tss_struct *tss = &per_cpu(init_tss, cpu);
103 if (!boot_cpu_has(X86_FEATURE_SEP)) {
108 tss->x86_tss.ss1 = __KERNEL_CS;
109 tss->x86_tss.sp1 = sizeof(struct tss_struct) + (unsigned long) tss;
110 wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
111 wrmsr(MSR_IA32_SYSENTER_ESP, tss->x86_tss.sp1, 0);
112 wrmsr(MSR_IA32_SYSENTER_EIP, (unsigned long) ia32_sysenter_target, 0);
116 #endif /* CONFIG_X86_64 */
118 int __init sysenter_setup(void)
120 char *vdso32_start, *vdso32_end;
124 if (vdso32_syscall()) {
125 vdso32_start = vdso32_syscall_start;
126 vdso32_end = vdso32_syscall_end;
127 vdso32_pages = vdso32_syscall_pages;
130 if (vdso32_sysenter()) {
131 vdso32_start = vdso32_sysenter_start;
132 vdso32_end = vdso32_sysenter_end;
133 vdso32_pages = vdso32_sysenter_pages;
135 vdso32_start = vdso32_int80_start;
136 vdso32_end = vdso32_int80_end;
137 vdso32_pages = vdso32_int80_pages;
140 npages = ((vdso32_end - vdso32_start) + PAGE_SIZE - 1) / PAGE_SIZE;
141 vdso32_size = npages << PAGE_SHIFT;
142 for (i = 0; i < npages; i++)
143 vdso32_pages[i] = virt_to_page(vdso32_start + i*PAGE_SIZE);
145 patch_vdso32(vdso32_start, vdso32_size);
150 /* Setup a VMA at program startup for the vsyscall page */
151 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
153 struct mm_struct *mm = current->mm;
156 struct vm_area_struct *vma;
158 #ifdef CONFIG_X86_X32_ABI
159 if (test_thread_flag(TIF_X32))
160 return x32_setup_additional_pages(bprm, uses_interp);
163 if (vdso_enabled != 1) /* Other values all mean "disabled" */
166 down_write(&mm->mmap_sem);
168 addr = get_unmapped_area(NULL, 0, vdso32_size + VDSO_OFFSET(VDSO_PREV_PAGES), 0, 0);
169 if (IS_ERR_VALUE(addr)) {
174 addr += VDSO_OFFSET(VDSO_PREV_PAGES);
176 current->mm->context.vdso = (void *)addr;
179 * MAYWRITE to allow gdb to COW and set breakpoints
181 ret = install_special_mapping(mm,
185 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
191 vma = _install_special_mapping(mm,
192 addr - VDSO_OFFSET(VDSO_PREV_PAGES),
193 VDSO_OFFSET(VDSO_PREV_PAGES),
202 ret = remap_pfn_range(vma,
203 addr - VDSO_OFFSET(VDSO_VVAR_PAGE),
204 __pa_symbol(&__vvar_page) >> PAGE_SHIFT,
211 #ifdef CONFIG_HPET_TIMER
213 ret = io_remap_pfn_range(vma,
214 addr - VDSO_OFFSET(VDSO_HPET_PAGE),
215 hpet_address >> PAGE_SHIFT,
217 pgprot_noncached(PAGE_READONLY));
224 current_thread_info()->sysenter_return =
225 VDSO32_SYMBOL(addr, SYSENTER_RETURN);
229 current->mm->context.vdso = NULL;
231 up_write(&mm->mmap_sem);
238 subsys_initcall(sysenter_setup);
241 /* Register vsyscall32 into the ABI table */
242 #include <linux/sysctl.h>
244 static struct ctl_table abi_table2[] = {
246 .procname = "vsyscall32",
247 .data = &sysctl_vsyscall32,
248 .maxlen = sizeof(int),
250 .proc_handler = proc_dointvec
255 static struct ctl_table abi_root_table2[] = {
264 static __init int ia32_binfmt_init(void)
266 register_sysctl_table(abi_root_table2);
269 __initcall(ia32_binfmt_init);
272 #else /* CONFIG_X86_32 */
274 const char *arch_vma_name(struct vm_area_struct *vma)
276 if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso)
281 struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
286 int in_gate_area(struct mm_struct *mm, unsigned long addr)
291 int in_gate_area_no_mm(unsigned long addr)
296 #endif /* CONFIG_X86_64 */