+++ /dev/null
-/*
- * Copyright 2007 Andi Kleen, SUSE Labs.
- * Subject to the GPL, v.2
- *
- * This contains most of the x86 vDSO kernel-side code.
- */
-#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/vgtod.h>
-#include <asm/proto.h>
-#include <asm/vdso.h>
-#include <asm/vvar.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;
-#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));
-}
-
-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.
- *
- * Note that this algorithm is imperfect: the distribution of the vdso
- * start address within a PMD is biased toward the end.
- *
- * 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;
-
- /*
- * Round up the start address. It can start out unaligned as a result
- * of stack start randomization.
- */
- start = PAGE_ALIGN(start);
-
- /* Round the lowest possible end address up to a PMD boundary. */
- end = (start + len + PMD_SIZE - 1) & PMD_MASK;
- if (end >= TASK_SIZE_MAX)
- end = TASK_SIZE_MAX;
- end -= len;
-
- if (end > start) {
- offset = get_random_int() % (((end - start) >> PAGE_SHIFT) + 1);
- addr = start + (offset << PAGE_SHIFT);
- } else {
- addr = start;
- }
-
- /*
- * Forcibly align the final address in case we have a hardware
- * issue that requires alignment for performance reasons.
- */
- 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
-static void vgetcpu_cpu_init(void *arg)
-{
- int cpu = smp_processor_id();
- 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.limit0 = cpu | ((node & 0xf) << 12);
- d.limit = node >> 4;
- d.type = 5; /* RO data, expand down, accessed */
- d.dpl = 3; /* Visible to user code */
- d.s = 1; /* Not a system segment */
- d.p = 1; /* Present */
- d.d = 1; /* 32-bit */
-
- write_gdt_entry(get_cpu_gdt_table(cpu), GDT_ENTRY_PER_CPU, &d, DESCTYPE_S);
-}
-
-static int
-vgetcpu_cpu_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, vgetcpu_cpu_init, NULL, 1);
-
- return NOTIFY_DONE;
-}
-
-static int __init init_vdso(void)
-{
- init_vdso_image(&vdso_image_64);
-
-#ifdef CONFIG_X86_X32_ABI
- init_vdso_image(&vdso_image_x32);
-#endif
-
- cpu_notifier_register_begin();
-
- on_each_cpu(vgetcpu_cpu_init, NULL, 1);
- /* notifier priority > KVM */
- __hotcpu_notifier(vgetcpu_cpu_notifier, 30);
-
- cpu_notifier_register_done();
-
- return 0;
-}
-subsys_initcall(init_vdso);
-#endif /* CONFIG_X86_64 */
git.samba.org / sfrench / cifs-2.6.git / blobdiff