x86/asm/entry, x86/vdso: Move the vDSO code to arch/x86/entry/vdso/

Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

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 */