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Diffstat (limited to 'arch/x86/entry/vdso/vma.c')
-rw-r--r--arch/x86/entry/vdso/vma.c285
1 files changed, 285 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..afe105b2f907
--- /dev/null
+++ b/arch/x86/entry/vdso/vma.c
@@ -0,0 +1,285 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2007 Andi Kleen, SUSE Labs.
+ *
+ * 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 <linux/vdso_datastore.h>
+
+#include <asm/pvclock.h>
+#include <asm/vgtod.h>
+#include <asm/proto.h>
+#include <asm/vdso.h>
+#include <asm/tlb.h>
+#include <asm/page.h>
+#include <asm/desc.h>
+#include <asm/cpufeature.h>
+#include <asm/vdso/vsyscall.h>
+#include <clocksource/hyperv_timer.h>
+
+static_assert(VDSO_NR_PAGES + VDSO_NR_VCLOCK_PAGES == __VDSO_PAGES);
+
+unsigned int vclocks_used __read_mostly;
+
+#if defined(CONFIG_X86_64)
+unsigned int __read_mostly vdso64_enabled = 1;
+#endif
+
+int __init init_vdso_image(const struct vdso_image *image)
+{
+ BUILD_BUG_ON(VDSO_CLOCKMODE_MAX >= 32);
+ 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));
+
+ return 0;
+}
+
+struct linux_binprm;
+
+static vm_fault_t 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 (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;
+ }
+}
+
+static int vdso_mremap(const struct vm_special_mapping *sm,
+ struct vm_area_struct *new_vma)
+{
+ const struct vdso_image *image = current->mm->context.vdso_image;
+
+ vdso_fix_landing(image, new_vma);
+ current->mm->context.vdso = (void __user *)new_vma->vm_start;
+
+ return 0;
+}
+
+static vm_fault_t vvar_vclock_fault(const struct vm_special_mapping *sm,
+ struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+ switch (vmf->pgoff) {
+#ifdef CONFIG_PARAVIRT_CLOCK
+ case VDSO_PAGE_PVCLOCK_OFFSET:
+ {
+ struct pvclock_vsyscall_time_info *pvti =
+ pvclock_get_pvti_cpu0_va();
+
+ if (pvti && vclock_was_used(VDSO_CLOCKMODE_PVCLOCK))
+ return vmf_insert_pfn_prot(vma, vmf->address,
+ __pa(pvti) >> PAGE_SHIFT,
+ pgprot_decrypted(vma->vm_page_prot));
+ break;
+ }
+#endif /* CONFIG_PARAVIRT_CLOCK */
+#ifdef CONFIG_HYPERV_TIMER
+ case VDSO_PAGE_HVCLOCK_OFFSET:
+ {
+ unsigned long pfn = hv_get_tsc_pfn();
+ if (pfn && vclock_was_used(VDSO_CLOCKMODE_HVCLOCK))
+ return vmf_insert_pfn(vma, vmf->address, pfn);
+ break;
+ }
+#endif /* CONFIG_HYPERV_TIMER */
+ }
+
+ 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_vclock_mapping = {
+ .name = "[vvar_vclock]",
+ .fault = vvar_vclock_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 (mmap_write_lock_killable(mm))
+ return -EINTR;
+
+ addr = get_unmapped_area(NULL, addr,
+ image->size + __VDSO_PAGES * PAGE_SIZE, 0, 0);
+ if (IS_ERR_VALUE(addr)) {
+ ret = addr;
+ goto up_fail;
+ }
+
+ text_start = addr + __VDSO_PAGES * PAGE_SIZE;
+
+ /*
+ * 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|
+ VM_SEALED_SYSMAP,
+ &vdso_mapping);
+
+ if (IS_ERR(vma)) {
+ ret = PTR_ERR(vma);
+ goto up_fail;
+ }
+
+ vma = vdso_install_vvar_mapping(mm, addr);
+ if (IS_ERR(vma)) {
+ ret = PTR_ERR(vma);
+ do_munmap(mm, text_start, image->size, NULL);
+ goto up_fail;
+ }
+
+ vma = _install_special_mapping(mm,
+ VDSO_VCLOCK_PAGES_START(addr),
+ VDSO_NR_VCLOCK_PAGES * PAGE_SIZE,
+ VM_READ|VM_MAYREAD|VM_IO|VM_DONTDUMP|
+ VM_PFNMAP|VM_SEALED_SYSMAP,
+ &vvar_vclock_mapping);
+
+ if (IS_ERR(vma)) {
+ ret = PTR_ERR(vma);
+ do_munmap(mm, text_start, image->size, NULL);
+ do_munmap(mm, addr, image->size, NULL);
+ goto up_fail;
+ }
+
+ current->mm->context.vdso = (void __user *)text_start;
+ current->mm->context.vdso_image = image;
+
+up_fail:
+ mmap_write_unlock(mm);
+ return ret;
+}
+
+int map_vdso_once(const struct vdso_image *image, unsigned long addr)
+{
+ struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma;
+ VMA_ITERATOR(vmi, mm, 0);
+
+ mmap_write_lock(mm);
+ /*
+ * Check if we have already mapped vdso blob - fail to prevent
+ * abusing from userspace install_special_mapping, which may
+ * not do accounting and rlimit right.
+ * We could search vma near context.vdso, but it's a slowpath,
+ * so let's explicitly check all VMAs to be completely sure.
+ */
+ for_each_vma(vmi, vma) {
+ if (vma_is_special_mapping(vma, &vdso_mapping) ||
+ vma_is_special_mapping(vma, &vdso_vvar_mapping) ||
+ vma_is_special_mapping(vma, &vvar_vclock_mapping)) {
+ mmap_write_unlock(mm);
+ return -EEXIST;
+ }
+ }
+ mmap_write_unlock(mm);
+
+ return map_vdso(image, addr);
+}
+
+static int load_vdso32(void)
+{
+ if (vdso32_enabled != 1) /* Other values all mean "disabled" */
+ return 0;
+
+ return map_vdso(&vdso_image_32, 0);
+}
+
+int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
+{
+ if (IS_ENABLED(CONFIG_X86_64)) {
+ if (!vdso64_enabled)
+ return 0;
+
+ return map_vdso(&vdso_image_64, 0);
+ }
+
+ return load_vdso32();
+}
+
+#ifdef CONFIG_COMPAT
+int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
+ int uses_interp, bool x32)
+{
+ if (IS_ENABLED(CONFIG_X86_X32_ABI) && x32) {
+ if (!vdso64_enabled)
+ return 0;
+ return map_vdso(&vdso_image_x32, 0);
+ }
+
+ if (IS_ENABLED(CONFIG_IA32_EMULATION))
+ return load_vdso32();
+
+ return 0;
+}
+#endif
+
+bool arch_syscall_is_vdso_sigreturn(struct pt_regs *regs)
+{
+ const struct vdso_image *image = current->mm->context.vdso_image;
+ unsigned long vdso = (unsigned long) current->mm->context.vdso;
+
+ if (in_ia32_syscall() && image == &vdso_image_32) {
+ if (regs->ip == vdso + image->sym_vdso32_sigreturn_landing_pad ||
+ regs->ip == vdso + image->sym_vdso32_rt_sigreturn_landing_pad)
+ return true;
+ }
+ return false;
+}
+
+#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 /* CONFIG_X86_64 */
generated by cgit (git 2.34.1) at 2025-12-25 08:14:19 +0000