304 lines
6.6 KiB
C
304 lines
6.6 KiB
C
/*
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* Copyright 2007 Andi Kleen, SUSE Labs.
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* Subject to the GPL, v.2
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*
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* This contains most of the x86 vDSO kernel-side code.
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*/
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#include <linux/mm.h>
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#include <linux/err.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/random.h>
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#include <linux/elf.h>
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#include <linux/cpu.h>
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#include <asm/vgtod.h>
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#include <asm/proto.h>
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#include <asm/vdso.h>
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#include <asm/vvar.h>
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#include <asm/page.h>
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#include <asm/hpet.h>
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#include <asm/desc.h>
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#if defined(CONFIG_X86_64)
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unsigned int __read_mostly vdso64_enabled = 1;
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#endif
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void __init init_vdso_image(const struct vdso_image *image)
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{
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int i;
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int npages = (image->size) / PAGE_SIZE;
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BUG_ON(image->size % PAGE_SIZE != 0);
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for (i = 0; i < npages; i++)
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image->text_mapping.pages[i] =
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virt_to_page(image->data + i*PAGE_SIZE);
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apply_alternatives((struct alt_instr *)(image->data + image->alt),
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(struct alt_instr *)(image->data + image->alt +
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image->alt_len));
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}
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struct linux_binprm;
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/*
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* Put the vdso above the (randomized) stack with another randomized
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* offset. This way there is no hole in the middle of address space.
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* To save memory make sure it is still in the same PTE as the stack
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* top. This doesn't give that many random bits.
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*
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* Note that this algorithm is imperfect: the distribution of the vdso
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* start address within a PMD is biased toward the end.
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*
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* Only used for the 64-bit and x32 vdsos.
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*/
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static unsigned long vdso_addr(unsigned long start, unsigned len)
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{
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#ifdef CONFIG_X86_32
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return 0;
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#else
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unsigned long addr, end;
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unsigned offset;
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/*
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* Round up the start address. It can start out unaligned as a result
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* of stack start randomization.
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*/
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start = PAGE_ALIGN(start);
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/* Round the lowest possible end address up to a PMD boundary. */
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end = (start + len + PMD_SIZE - 1) & PMD_MASK;
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if (end >= TASK_SIZE_MAX)
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end = TASK_SIZE_MAX;
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end -= len;
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if (end > start) {
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offset = get_random_int() % (((end - start) >> PAGE_SHIFT) + 1);
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addr = start + (offset << PAGE_SHIFT);
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} else {
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addr = start;
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}
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/*
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* Forcibly align the final address in case we have a hardware
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* issue that requires alignment for performance reasons.
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*/
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addr = align_vdso_addr(addr);
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return addr;
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#endif
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}
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static int map_vdso(const struct vdso_image *image, bool calculate_addr)
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{
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struct mm_struct *mm = current->mm;
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struct vm_area_struct *vma;
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unsigned long addr, text_start;
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int ret = 0;
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static struct page *no_pages[] = {NULL};
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static struct vm_special_mapping vvar_mapping = {
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.name = "[vvar]",
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.pages = no_pages,
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};
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if (calculate_addr) {
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addr = vdso_addr(current->mm->start_stack,
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image->size - image->sym_vvar_start);
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} else {
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addr = 0;
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}
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down_write(&mm->mmap_sem);
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addr = get_unmapped_area(NULL, addr,
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image->size - image->sym_vvar_start, 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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text_start = addr - image->sym_vvar_start;
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current->mm->context.vdso = (void __user *)text_start;
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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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vma = _install_special_mapping(mm,
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text_start,
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image->size,
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VM_READ|VM_EXEC|
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VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
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&image->text_mapping);
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if (IS_ERR(vma)) {
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ret = PTR_ERR(vma);
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goto up_fail;
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}
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vma = _install_special_mapping(mm,
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addr,
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-image->sym_vvar_start,
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VM_READ|VM_MAYREAD,
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&vvar_mapping);
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if (IS_ERR(vma)) {
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ret = PTR_ERR(vma);
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goto up_fail;
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}
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if (image->sym_vvar_page)
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ret = remap_pfn_range(vma,
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text_start + image->sym_vvar_page,
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__pa_symbol(&__vvar_page) >> PAGE_SHIFT,
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PAGE_SIZE,
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PAGE_READONLY);
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if (ret)
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goto up_fail;
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#ifdef CONFIG_HPET_TIMER
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if (hpet_address && image->sym_hpet_page) {
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ret = io_remap_pfn_range(vma,
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text_start + image->sym_hpet_page,
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hpet_address >> PAGE_SHIFT,
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PAGE_SIZE,
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pgprot_noncached(PAGE_READONLY));
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if (ret)
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goto up_fail;
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}
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#endif
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up_fail:
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if (ret)
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current->mm->context.vdso = NULL;
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up_write(&mm->mmap_sem);
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return ret;
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}
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#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
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static int load_vdso32(void)
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{
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int ret;
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if (vdso32_enabled != 1) /* Other values all mean "disabled" */
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return 0;
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ret = map_vdso(selected_vdso32, false);
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if (ret)
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return ret;
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if (selected_vdso32->sym_VDSO32_SYSENTER_RETURN)
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current_thread_info()->sysenter_return =
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current->mm->context.vdso +
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selected_vdso32->sym_VDSO32_SYSENTER_RETURN;
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return 0;
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}
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#endif
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#ifdef CONFIG_X86_64
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int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
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{
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if (!vdso64_enabled)
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return 0;
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return map_vdso(&vdso_image_64, true);
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}
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#ifdef CONFIG_COMPAT
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int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
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int uses_interp)
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{
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#ifdef CONFIG_X86_X32_ABI
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if (test_thread_flag(TIF_X32)) {
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if (!vdso64_enabled)
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return 0;
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return map_vdso(&vdso_image_x32, true);
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}
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#endif
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#ifdef CONFIG_IA32_EMULATION
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return load_vdso32();
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#else
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return 0;
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#endif
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}
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#endif
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#else
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int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
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{
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return load_vdso32();
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}
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#endif
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#ifdef CONFIG_X86_64
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static __init int vdso_setup(char *s)
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{
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vdso64_enabled = simple_strtoul(s, NULL, 0);
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return 0;
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}
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__setup("vdso=", vdso_setup);
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#endif
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#ifdef CONFIG_X86_64
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static void vgetcpu_cpu_init(void *arg)
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{
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int cpu = smp_processor_id();
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struct desc_struct d = { };
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unsigned long node = 0;
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#ifdef CONFIG_NUMA
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node = cpu_to_node(cpu);
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#endif
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if (cpu_has(&cpu_data(cpu), X86_FEATURE_RDTSCP))
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write_rdtscp_aux((node << 12) | cpu);
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/*
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* Store cpu number in limit so that it can be loaded
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* quickly in user space in vgetcpu. (12 bits for the CPU
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* and 8 bits for the node)
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*/
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d.limit0 = cpu | ((node & 0xf) << 12);
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d.limit = node >> 4;
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d.type = 5; /* RO data, expand down, accessed */
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d.dpl = 3; /* Visible to user code */
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d.s = 1; /* Not a system segment */
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d.p = 1; /* Present */
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d.d = 1; /* 32-bit */
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write_gdt_entry(get_cpu_gdt_table(cpu), GDT_ENTRY_PER_CPU, &d, DESCTYPE_S);
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}
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static int
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vgetcpu_cpu_notifier(struct notifier_block *n, unsigned long action, void *arg)
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{
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long cpu = (long)arg;
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if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN)
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smp_call_function_single(cpu, vgetcpu_cpu_init, NULL, 1);
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return NOTIFY_DONE;
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}
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static int __init init_vdso(void)
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{
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init_vdso_image(&vdso_image_64);
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#ifdef CONFIG_X86_X32_ABI
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init_vdso_image(&vdso_image_x32);
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#endif
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cpu_notifier_register_begin();
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on_each_cpu(vgetcpu_cpu_init, NULL, 1);
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/* notifier priority > KVM */
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__hotcpu_notifier(vgetcpu_cpu_notifier, 30);
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cpu_notifier_register_done();
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return 0;
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}
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subsys_initcall(init_vdso);
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#endif /* CONFIG_X86_64 */
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