163 lines
3.8 KiB
C
163 lines
3.8 KiB
C
/*
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* linux/arch/i386/kernel/sysenter.c
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*
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* (C) Copyright 2002 Linus Torvalds
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* Portions based on the vdso-randomization code from exec-shield:
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* Copyright(C) 2005-2006, Red Hat, Inc., Ingo Molnar
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*
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* This file contains the needed initializations to support sysenter.
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*/
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#include <linux/init.h>
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#include <linux/smp.h>
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#include <linux/thread_info.h>
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#include <linux/sched.h>
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#include <linux/gfp.h>
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#include <linux/string.h>
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#include <linux/elf.h>
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#include <linux/mm.h>
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#include <linux/module.h>
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#include <asm/cpufeature.h>
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#include <asm/msr.h>
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#include <asm/pgtable.h>
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#include <asm/unistd.h>
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/*
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* Should the kernel map a VDSO page into processes and pass its
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* address down to glibc upon exec()?
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*/
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#ifdef CONFIG_PARAVIRT
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unsigned int __read_mostly vdso_enabled = 0;
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#else
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unsigned int __read_mostly vdso_enabled = 1;
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#endif
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EXPORT_SYMBOL_GPL(vdso_enabled);
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static int __init vdso_setup(char *s)
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{
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vdso_enabled = simple_strtoul(s, NULL, 0);
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return 1;
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}
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__setup("vdso=", vdso_setup);
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extern asmlinkage void sysenter_entry(void);
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void enable_sep_cpu(void)
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{
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int cpu = get_cpu();
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struct tss_struct *tss = &per_cpu(init_tss, cpu);
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if (!boot_cpu_has(X86_FEATURE_SEP)) {
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put_cpu();
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return;
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}
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tss->ss1 = __KERNEL_CS;
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tss->esp1 = sizeof(struct tss_struct) + (unsigned long) tss;
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wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
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wrmsr(MSR_IA32_SYSENTER_ESP, tss->esp1, 0);
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wrmsr(MSR_IA32_SYSENTER_EIP, (unsigned long) sysenter_entry, 0);
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put_cpu();
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}
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/*
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* These symbols are defined by vsyscall.o to mark the bounds
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* of the ELF DSO images included therein.
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*/
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extern const char vsyscall_int80_start, vsyscall_int80_end;
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extern const char vsyscall_sysenter_start, vsyscall_sysenter_end;
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static struct page *syscall_pages[1];
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int __init sysenter_setup(void)
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{
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void *syscall_page = (void *)get_zeroed_page(GFP_ATOMIC);
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syscall_pages[0] = virt_to_page(syscall_page);
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#ifdef CONFIG_COMPAT_VDSO
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__set_fixmap(FIX_VDSO, __pa(syscall_page), PAGE_READONLY_EXEC);
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printk("Compat vDSO mapped to %08lx.\n", __fix_to_virt(FIX_VDSO));
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#endif
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if (!boot_cpu_has(X86_FEATURE_SEP)) {
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memcpy(syscall_page,
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&vsyscall_int80_start,
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&vsyscall_int80_end - &vsyscall_int80_start);
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return 0;
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}
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memcpy(syscall_page,
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&vsyscall_sysenter_start,
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&vsyscall_sysenter_end - &vsyscall_sysenter_start);
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return 0;
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}
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#ifndef CONFIG_COMPAT_VDSO
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/* Defined in vsyscall-sysenter.S */
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extern void SYSENTER_RETURN;
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/* Setup a VMA at program startup for the vsyscall page */
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int arch_setup_additional_pages(struct linux_binprm *bprm, int exstack)
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{
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struct mm_struct *mm = current->mm;
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unsigned long addr;
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int ret;
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down_write(&mm->mmap_sem);
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addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
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if (IS_ERR_VALUE(addr)) {
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ret = addr;
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goto up_fail;
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}
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/*
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* MAYWRITE to allow gdb to COW and set breakpoints
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*
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* Make sure the vDSO gets into every core dump.
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* Dumping its contents makes post-mortem fully interpretable later
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* without matching up the same kernel and hardware config to see
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* what PC values meant.
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*/
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ret = install_special_mapping(mm, addr, PAGE_SIZE,
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VM_READ|VM_EXEC|
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VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
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VM_ALWAYSDUMP,
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syscall_pages);
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if (ret)
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goto up_fail;
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current->mm->context.vdso = (void *)addr;
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current_thread_info()->sysenter_return =
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(void *)VDSO_SYM(&SYSENTER_RETURN);
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up_fail:
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up_write(&mm->mmap_sem);
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return ret;
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}
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const char *arch_vma_name(struct vm_area_struct *vma)
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{
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if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso)
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return "[vdso]";
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return NULL;
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}
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struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
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{
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return NULL;
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}
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int in_gate_area(struct task_struct *task, unsigned long addr)
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{
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return 0;
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}
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int in_gate_area_no_task(unsigned long addr)
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{
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return 0;
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}
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#endif
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