| /* |
| * Set up the VMAs to tell the VM about the vDSO. |
| * Copyright 2007 Andi Kleen, SUSE Labs. |
| * Subject to the GPL, v.2 |
| */ |
| #include <linux/mm.h> |
| #include <linux/err.h> |
| #include <linux/sched.h> |
| #include <linux/slab.h> |
| #include <linux/init.h> |
| #include <linux/random.h> |
| #include <linux/elf.h> |
| #include <linux/cpu.h> |
| #include <asm/vsyscall.h> |
| #include <asm/vgtod.h> |
| #include <asm/proto.h> |
| #include <asm/vdso.h> |
| #include <asm/page.h> |
| #include <asm/hpet.h> |
| #include <asm/desc.h> |
| |
| #if defined(CONFIG_X86_64) |
| unsigned int __read_mostly vdso64_enabled = 1; |
| |
| extern unsigned short vdso_sync_cpuid; |
| #endif |
| |
| void __init init_vdso_image(const struct vdso_image *image) |
| { |
| int i; |
| int npages = (image->size) / PAGE_SIZE; |
| |
| BUG_ON(image->size % PAGE_SIZE != 0); |
| for (i = 0; i < npages; i++) |
| image->text_mapping.pages[i] = |
| virt_to_page(image->data + i*PAGE_SIZE); |
| |
| apply_alternatives((struct alt_instr *)(image->data + image->alt), |
| (struct alt_instr *)(image->data + image->alt + |
| image->alt_len)); |
| } |
| |
| #if defined(CONFIG_X86_64) |
| static int __init init_vdso(void) |
| { |
| init_vdso_image(&vdso_image_64); |
| |
| #ifdef CONFIG_X86_X32_ABI |
| init_vdso_image(&vdso_image_x32); |
| #endif |
| |
| return 0; |
| } |
| subsys_initcall(init_vdso); |
| #endif |
| |
| struct linux_binprm; |
| |
| /* Put the vdso above the (randomized) stack with another randomized offset. |
| This way there is no hole in the middle of address space. |
| To save memory make sure it is still in the same PTE as the stack top. |
| This doesn't give that many random bits. |
| |
| Only used for the 64-bit and x32 vdsos. */ |
| static unsigned long vdso_addr(unsigned long start, unsigned len) |
| { |
| #ifdef CONFIG_X86_32 |
| return 0; |
| #else |
| unsigned long addr, end; |
| unsigned offset; |
| end = (start + PMD_SIZE - 1) & PMD_MASK; |
| if (end >= TASK_SIZE_MAX) |
| end = TASK_SIZE_MAX; |
| end -= len; |
| /* This loses some more bits than a modulo, but is cheaper */ |
| offset = get_random_int() & (PTRS_PER_PTE - 1); |
| addr = start + (offset << PAGE_SHIFT); |
| if (addr >= end) |
| addr = end; |
| |
| /* |
| * page-align it here so that get_unmapped_area doesn't |
| * align it wrongfully again to the next page. addr can come in 4K |
| * unaligned here as a result of stack start randomization. |
| */ |
| addr = PAGE_ALIGN(addr); |
| addr = align_vdso_addr(addr); |
| |
| return addr; |
| #endif |
| } |
| |
| static int map_vdso(const struct vdso_image *image, bool calculate_addr) |
| { |
| struct mm_struct *mm = current->mm; |
| struct vm_area_struct *vma; |
| unsigned long addr, text_start; |
| int ret = 0; |
| static struct page *no_pages[] = {NULL}; |
| static struct vm_special_mapping vvar_mapping = { |
| .name = "[vvar]", |
| .pages = no_pages, |
| }; |
| |
| if (calculate_addr) { |
| addr = vdso_addr(current->mm->start_stack, |
| image->size - image->sym_vvar_start); |
| } else { |
| addr = 0; |
| } |
| |
| down_write(&mm->mmap_sem); |
| |
| addr = get_unmapped_area(NULL, addr, |
| image->size - image->sym_vvar_start, 0, 0); |
| if (IS_ERR_VALUE(addr)) { |
| ret = addr; |
| goto up_fail; |
| } |
| |
| text_start = addr - image->sym_vvar_start; |
| current->mm->context.vdso = (void __user *)text_start; |
| |
| /* |
| * MAYWRITE to allow gdb to COW and set breakpoints |
| */ |
| vma = _install_special_mapping(mm, |
| text_start, |
| image->size, |
| VM_READ|VM_EXEC| |
| VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, |
| &image->text_mapping); |
| |
| if (IS_ERR(vma)) { |
| ret = PTR_ERR(vma); |
| goto up_fail; |
| } |
| |
| vma = _install_special_mapping(mm, |
| addr, |
| -image->sym_vvar_start, |
| VM_READ|VM_MAYREAD, |
| &vvar_mapping); |
| |
| if (IS_ERR(vma)) { |
| ret = PTR_ERR(vma); |
| goto up_fail; |
| } |
| |
| if (image->sym_vvar_page) |
| ret = remap_pfn_range(vma, |
| text_start + image->sym_vvar_page, |
| __pa_symbol(&__vvar_page) >> PAGE_SHIFT, |
| PAGE_SIZE, |
| PAGE_READONLY); |
| |
| if (ret) |
| goto up_fail; |
| |
| #ifdef CONFIG_HPET_TIMER |
| if (hpet_address && image->sym_hpet_page) { |
| ret = io_remap_pfn_range(vma, |
| text_start + image->sym_hpet_page, |
| hpet_address >> PAGE_SHIFT, |
| PAGE_SIZE, |
| pgprot_noncached(PAGE_READONLY)); |
| |
| if (ret) |
| goto up_fail; |
| } |
| #endif |
| |
| up_fail: |
| if (ret) |
| current->mm->context.vdso = NULL; |
| |
| up_write(&mm->mmap_sem); |
| return ret; |
| } |
| |
| #if defined(CONFIG_X86_32) || defined(CONFIG_COMPAT) |
| static int load_vdso32(void) |
| { |
| int ret; |
| |
| if (vdso32_enabled != 1) /* Other values all mean "disabled" */ |
| return 0; |
| |
| ret = map_vdso(selected_vdso32, false); |
| if (ret) |
| return ret; |
| |
| if (selected_vdso32->sym_VDSO32_SYSENTER_RETURN) |
| current_thread_info()->sysenter_return = |
| current->mm->context.vdso + |
| selected_vdso32->sym_VDSO32_SYSENTER_RETURN; |
| |
| return 0; |
| } |
| #endif |
| |
| #ifdef CONFIG_X86_64 |
| int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) |
| { |
| if (!vdso64_enabled) |
| return 0; |
| |
| return map_vdso(&vdso_image_64, true); |
| } |
| |
| #ifdef CONFIG_COMPAT |
| int compat_arch_setup_additional_pages(struct linux_binprm *bprm, |
| int uses_interp) |
| { |
| #ifdef CONFIG_X86_X32_ABI |
| if (test_thread_flag(TIF_X32)) { |
| if (!vdso64_enabled) |
| return 0; |
| |
| return map_vdso(&vdso_image_x32, true); |
| } |
| #endif |
| |
| return load_vdso32(); |
| } |
| #endif |
| #else |
| int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) |
| { |
| return load_vdso32(); |
| } |
| #endif |
| |
| #ifdef CONFIG_X86_64 |
| static __init int vdso_setup(char *s) |
| { |
| vdso64_enabled = simple_strtoul(s, NULL, 0); |
| return 0; |
| } |
| __setup("vdso=", vdso_setup); |
| #endif |
| |
| #ifdef CONFIG_X86_64 |
| /* |
| * Assume __initcall executes before all user space. Hopefully kmod |
| * doesn't violate that. We'll find out if it does. |
| */ |
| static void vsyscall_set_cpu(int cpu) |
| { |
| struct desc_struct d; |
| unsigned long node = 0; |
| #ifdef CONFIG_NUMA |
| node = cpu_to_node(cpu); |
| #endif |
| if (cpu_has(&cpu_data(cpu), X86_FEATURE_RDTSCP)) |
| write_rdtscp_aux((node << 12) | cpu); |
| |
| /* |
| * Store cpu number in limit so that it can be loaded |
| * quickly in user space in vgetcpu. (12 bits for the CPU |
| * and 8 bits for the node) |
| */ |
| d = (struct desc_struct) { |
| .limit0 = cpu | ((node & 0xf) << 12), |
| .limit = node >> 4, |
| .type = 4, /* RO data, expand down */ |
| .dpl = 3, /* Visible to user code */ |
| .s = 1, /* Not a system segment */ |
| .p = 1, /* Present */ |
| }; |
| |
| write_gdt_entry(get_cpu_gdt_table(cpu), GDT_ENTRY_PER_CPU, &d, DESCTYPE_S); |
| } |
| |
| static void cpu_vsyscall_init(void *arg) |
| { |
| /* preemption should be already off */ |
| vsyscall_set_cpu(raw_smp_processor_id()); |
| } |
| |
| static int |
| cpu_vsyscall_notifier(struct notifier_block *n, unsigned long action, void *arg) |
| { |
| long cpu = (long)arg; |
| |
| if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) |
| smp_call_function_single(cpu, cpu_vsyscall_init, NULL, 1); |
| |
| return NOTIFY_DONE; |
| } |
| |
| static int __init vsyscall_init(void) |
| { |
| cpu_notifier_register_begin(); |
| |
| on_each_cpu(cpu_vsyscall_init, NULL, 1); |
| /* notifier priority > KVM */ |
| __hotcpu_notifier(cpu_vsyscall_notifier, 30); |
| |
| cpu_notifier_register_done(); |
| |
| return 0; |
| } |
| __initcall(vsyscall_init); |
| #endif |