/* * linux/arch/i386/kernel/sysenter.c * * (C) Copyright 2002 Linus Torvalds * Portions based on the vdso-randomization code from exec-shield: * Copyright(C) 2005-2006, Red Hat, Inc., Ingo Molnar * * This file contains the needed initializations to support sysenter. */ #include <linux/init.h> #include <linux/smp.h> #include <linux/thread_info.h> #include <linux/sched.h> #include <linux/gfp.h> #include <linux/string.h> #include <linux/elf.h> #include <linux/mm.h> #include <linux/module.h> #include <asm/cpufeature.h> #include <asm/msr.h> #include <asm/pgtable.h> #include <asm/unistd.h> /* * Should the kernel map a VDSO page into processes and pass its * address down to glibc upon exec()? */ unsigned int __read_mostly vdso_enabled = 1; EXPORT_SYMBOL_GPL(vdso_enabled); static int __init vdso_setup(char *s) { vdso_enabled = simple_strtoul(s, NULL, 0); return 1; } __setup("vdso=", vdso_setup); extern asmlinkage void sysenter_entry(void); void enable_sep_cpu(void) { int cpu = get_cpu(); struct tss_struct *tss = &per_cpu(init_tss, cpu); if (!boot_cpu_has(X86_FEATURE_SEP)) { put_cpu(); return; } tss->ss1 = __KERNEL_CS; tss->esp1 = sizeof(struct tss_struct) + (unsigned long) tss; wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0); wrmsr(MSR_IA32_SYSENTER_ESP, tss->esp1, 0); wrmsr(MSR_IA32_SYSENTER_EIP, (unsigned long) sysenter_entry, 0); put_cpu(); } /* * These symbols are defined by vsyscall.o to mark the bounds * of the ELF DSO images included therein. */ extern const char vsyscall_int80_start, vsyscall_int80_end; extern const char vsyscall_sysenter_start, vsyscall_sysenter_end; static void *syscall_page; int __init sysenter_setup(void) { syscall_page = (void *)get_zeroed_page(GFP_ATOMIC); #ifdef CONFIG_COMPAT_VDSO __set_fixmap(FIX_VDSO, __pa(syscall_page), PAGE_READONLY); printk("Compat vDSO mapped to %08lx.\n", __fix_to_virt(FIX_VDSO)); #else /* * In the non-compat case the ELF coredumping code needs the fixmap: */ __set_fixmap(FIX_VDSO, __pa(syscall_page), PAGE_KERNEL_RO); #endif if (!boot_cpu_has(X86_FEATURE_SEP)) { memcpy(syscall_page, &vsyscall_int80_start, &vsyscall_int80_end - &vsyscall_int80_start); return 0; } memcpy(syscall_page, &vsyscall_sysenter_start, &vsyscall_sysenter_end - &vsyscall_sysenter_start); return 0; } static struct page *syscall_nopage(struct vm_area_struct *vma, unsigned long adr, int *type) { struct page *p = virt_to_page(adr - vma->vm_start + syscall_page); get_page(p); return p; } /* Prevent VMA merging */ static void syscall_vma_close(struct vm_area_struct *vma) { } static struct vm_operations_struct syscall_vm_ops = { .close = syscall_vma_close, .nopage = syscall_nopage, }; /* Defined in vsyscall-sysenter.S */ extern void SYSENTER_RETURN; /* Setup a VMA at program startup for the vsyscall page */ int arch_setup_additional_pages(struct linux_binprm *bprm, int exstack) { struct vm_area_struct *vma; struct mm_struct *mm = current->mm; unsigned long addr; int ret; down_write(&mm->mmap_sem); addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0); if (IS_ERR_VALUE(addr)) { ret = addr; goto up_fail; } vma = kmem_cache_zalloc(vm_area_cachep, SLAB_KERNEL); if (!vma) { ret = -ENOMEM; goto up_fail; } vma->vm_start = addr; vma->vm_end = addr + PAGE_SIZE; /* MAYWRITE to allow gdb to COW and set breakpoints */ vma->vm_flags = VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC|VM_MAYWRITE; vma->vm_flags |= mm->def_flags; vma->vm_page_prot = protection_map[vma->vm_flags & 7]; vma->vm_ops = &syscall_vm_ops; vma->vm_mm = mm; ret = insert_vm_struct(mm, vma); if (unlikely(ret)) { kmem_cache_free(vm_area_cachep, vma); goto up_fail; } current->mm->context.vdso = (void *)addr; current_thread_info()->sysenter_return = (void *)VDSO_SYM(&SYSENTER_RETURN); mm->total_vm++; up_fail: up_write(&mm->mmap_sem); return ret; } const char *arch_vma_name(struct vm_area_struct *vma) { if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso) return "[vdso]"; return NULL; } struct vm_area_struct *get_gate_vma(struct task_struct *tsk) { return NULL; } int in_gate_area(struct task_struct *task, unsigned long addr) { return 0; } int in_gate_area_no_task(unsigned long addr) { return 0; }