summaryrefslogtreecommitdiff
path: root/arch/x86/entry/vdso/vma.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/x86/entry/vdso/vma.c')
-rw-r--r--arch/x86/entry/vdso/vma.c300
1 files changed, 300 insertions, 0 deletions
diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
new file mode 100644
index 000000000000..1c9f750c3859
--- /dev/null
+++ b/arch/x86/entry/vdso/vma.c
@@ -0,0 +1,300 @@
+/*
+ * 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 */