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-rw-r--r--arch/x86/entry/vdso/vma.c383
1 files changed, 383 insertions, 0 deletions
diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
new file mode 100644
index 000000000..a1c31bb23
--- /dev/null
+++ b/arch/x86/entry/vdso/vma.c
@@ -0,0 +1,383 @@
+/*
+ * 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/sched/task_stack.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/random.h>
+#include <linux/elf.h>
+#include <linux/cpu.h>
+#include <linux/ptrace.h>
+#include <asm/pvclock.h>
+#include <asm/vgtod.h>
+#include <asm/proto.h>
+#include <asm/vdso.h>
+#include <asm/vvar.h>
+#include <asm/page.h>
+#include <asm/desc.h>
+#include <asm/cpufeature.h>
+#include <asm/mshyperv.h>
+
+#if defined(CONFIG_X86_64)
+unsigned int __read_mostly vdso64_enabled = 1;
+#endif
+
+void __init init_vdso_image(const struct vdso_image *image)
+{
+ BUG_ON(image->size % PAGE_SIZE != 0);
+
+ apply_alternatives((struct alt_instr *)(image->data + image->alt),
+ (struct alt_instr *)(image->data + image->alt +
+ image->alt_len));
+}
+
+struct linux_binprm;
+
+static int vdso_fault(const struct vm_special_mapping *sm,
+ struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+ const struct vdso_image *image = vma->vm_mm->context.vdso_image;
+
+ if (!image || (vmf->pgoff << PAGE_SHIFT) >= image->size)
+ return VM_FAULT_SIGBUS;
+
+ vmf->page = virt_to_page(image->data + (vmf->pgoff << PAGE_SHIFT));
+ get_page(vmf->page);
+ return 0;
+}
+
+static void vdso_fix_landing(const struct vdso_image *image,
+ struct vm_area_struct *new_vma)
+{
+#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
+ if (in_ia32_syscall() && image == &vdso_image_32) {
+ struct pt_regs *regs = current_pt_regs();
+ unsigned long vdso_land = image->sym_int80_landing_pad;
+ unsigned long old_land_addr = vdso_land +
+ (unsigned long)current->mm->context.vdso;
+
+ /* Fixing userspace landing - look at do_fast_syscall_32 */
+ if (regs->ip == old_land_addr)
+ regs->ip = new_vma->vm_start + vdso_land;
+ }
+#endif
+}
+
+static int vdso_mremap(const struct vm_special_mapping *sm,
+ struct vm_area_struct *new_vma)
+{
+ unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
+ const struct vdso_image *image = current->mm->context.vdso_image;
+
+ if (image->size != new_size)
+ return -EINVAL;
+
+ vdso_fix_landing(image, new_vma);
+ current->mm->context.vdso = (void __user *)new_vma->vm_start;
+
+ return 0;
+}
+
+static int vvar_fault(const struct vm_special_mapping *sm,
+ struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+ const struct vdso_image *image = vma->vm_mm->context.vdso_image;
+ long sym_offset;
+ int ret = -EFAULT;
+
+ if (!image)
+ return VM_FAULT_SIGBUS;
+
+ sym_offset = (long)(vmf->pgoff << PAGE_SHIFT) +
+ image->sym_vvar_start;
+
+ /*
+ * Sanity check: a symbol offset of zero means that the page
+ * does not exist for this vdso image, not that the page is at
+ * offset zero relative to the text mapping. This should be
+ * impossible here, because sym_offset should only be zero for
+ * the page past the end of the vvar mapping.
+ */
+ if (sym_offset == 0)
+ return VM_FAULT_SIGBUS;
+
+ if (sym_offset == image->sym_vvar_page) {
+ ret = vm_insert_pfn(vma, vmf->address,
+ __pa_symbol(&__vvar_page) >> PAGE_SHIFT);
+ } else if (sym_offset == image->sym_pvclock_page) {
+ struct pvclock_vsyscall_time_info *pvti =
+ pvclock_get_pvti_cpu0_va();
+ if (pvti && vclock_was_used(VCLOCK_PVCLOCK)) {
+ ret = vm_insert_pfn_prot(
+ vma,
+ vmf->address,
+ __pa(pvti) >> PAGE_SHIFT,
+ pgprot_decrypted(vma->vm_page_prot));
+ }
+ } else if (sym_offset == image->sym_hvclock_page) {
+ struct ms_hyperv_tsc_page *tsc_pg = hv_get_tsc_page();
+
+ if (tsc_pg && vclock_was_used(VCLOCK_HVCLOCK))
+ ret = vm_insert_pfn(vma, vmf->address,
+ vmalloc_to_pfn(tsc_pg));
+ }
+
+ if (ret == 0 || ret == -EBUSY)
+ return VM_FAULT_NOPAGE;
+
+ return VM_FAULT_SIGBUS;
+}
+
+static const struct vm_special_mapping vdso_mapping = {
+ .name = "[vdso]",
+ .fault = vdso_fault,
+ .mremap = vdso_mremap,
+};
+static const struct vm_special_mapping vvar_mapping = {
+ .name = "[vvar]",
+ .fault = vvar_fault,
+};
+
+/*
+ * Add vdso and vvar mappings to current process.
+ * @image - blob to map
+ * @addr - request a specific address (zero to map at free addr)
+ */
+static int map_vdso(const struct vdso_image *image, unsigned long addr)
+{
+ struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma;
+ unsigned long text_start;
+ int ret = 0;
+
+ if (down_write_killable(&mm->mmap_sem))
+ return -EINTR;
+
+ 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;
+
+ /*
+ * 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,
+ &vdso_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|VM_IO|VM_DONTDUMP|
+ VM_PFNMAP,
+ &vvar_mapping);
+
+ if (IS_ERR(vma)) {
+ ret = PTR_ERR(vma);
+ do_munmap(mm, text_start, image->size, NULL);
+ } else {
+ current->mm->context.vdso = (void __user *)text_start;
+ current->mm->context.vdso_image = image;
+ }
+
+up_fail:
+ up_write(&mm->mmap_sem);
+ return ret;
+}
+
+#ifdef CONFIG_X86_64
+/*
+ * 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)
+{
+ 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;
+}
+
+static int map_vdso_randomized(const struct vdso_image *image)
+{
+ unsigned long addr = vdso_addr(current->mm->start_stack, image->size-image->sym_vvar_start);
+
+ return map_vdso(image, addr);
+}
+#endif
+
+int map_vdso_once(const struct vdso_image *image, unsigned long addr)
+{
+ struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma;
+
+ down_write(&mm->mmap_sem);
+ /*
+ * Check if we have already mapped vdso blob - fail to prevent
+ * abusing from userspace install_speciall_mapping, which may
+ * not do accounting and rlimit right.
+ * We could search vma near context.vdso, but it's a slowpath,
+ * so let's explicitely check all VMAs to be completely sure.
+ */
+ for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ if (vma_is_special_mapping(vma, &vdso_mapping) ||
+ vma_is_special_mapping(vma, &vvar_mapping)) {
+ up_write(&mm->mmap_sem);
+ return -EEXIST;
+ }
+ }
+ up_write(&mm->mmap_sem);
+
+ return map_vdso(image, addr);
+}
+
+#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
+static int load_vdso32(void)
+{
+ if (vdso32_enabled != 1) /* Other values all mean "disabled" */
+ return 0;
+
+ return map_vdso(&vdso_image_32, 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_randomized(&vdso_image_64);
+}
+
+#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_randomized(&vdso_image_x32);
+ }
+#endif
+#ifdef CONFIG_IA32_EMULATION
+ return load_vdso32();
+#else
+ return 0;
+#endif
+}
+#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 1;
+}
+__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 (boot_cpu_has(X86_FEATURE_RDTSCP) || boot_cpu_has(X86_FEATURE_RDPID))
+ 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.limit1 = 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_rw(cpu), GDT_ENTRY_PER_CPU, &d, DESCTYPE_S);
+}
+
+static int vgetcpu_online(unsigned int cpu)
+{
+ return smp_call_function_single(cpu, vgetcpu_cpu_init, NULL, 1);
+}
+
+static int __init init_vdso(void)
+{
+ init_vdso_image(&vdso_image_64);
+
+#ifdef CONFIG_X86_X32_ABI
+ init_vdso_image(&vdso_image_x32);
+#endif
+
+ /* notifier priority > KVM */
+ return cpuhp_setup_state(CPUHP_AP_X86_VDSO_VMA_ONLINE,
+ "x86/vdso/vma:online", vgetcpu_online, NULL);
+}
+subsys_initcall(init_vdso);
+#endif /* CONFIG_X86_64 */
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-25 22:37:26 +0000