1 files changed, 193 insertions, 0 deletions
diff --git a/arch/mips/kernel/vdso.c b/arch/mips/kernel/vdso.c
new file mode 100644
index 0000000000..f6d40e43f1
--- /dev/null
+++ b/arch/mips/kernel/vdso.c
@@ -0,0 +1,193 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2015 Imagination Technologies
+ * Author: Alex Smith <alex.smith@imgtec.com>
+ */
+
+#include <linux/binfmts.h>
+#include <linux/elf.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/ioport.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/random.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/timekeeper_internal.h>
+
+#include <asm/abi.h>
+#include <asm/mips-cps.h>
+#include <asm/page.h>
+#include <asm/vdso.h>
+#include <vdso/helpers.h>
+#include <vdso/vsyscall.h>
+
+/* Kernel-provided data used by the VDSO. */
+static union mips_vdso_data mips_vdso_data __page_aligned_data;
+struct vdso_data *vdso_data = mips_vdso_data.data;
+
+/*
+ * Mapping for the VDSO data/GIC pages. The real pages are mapped manually, as
+ * what we map and where within the area they are mapped is determined at
+ * runtime.
+ */
+static struct page *no_pages[] = { NULL };
+static struct vm_special_mapping vdso_vvar_mapping = {
+	.name = "[vvar]",
+	.pages = no_pages,
+};
+
+static void __init init_vdso_image(struct mips_vdso_image *image)
+{
+	unsigned long num_pages, i;
+	unsigned long data_pfn;
+
+	BUG_ON(!PAGE_ALIGNED(image->data));
+	BUG_ON(!PAGE_ALIGNED(image->size));
+
+	num_pages = image->size / PAGE_SIZE;
+
+	data_pfn = __phys_to_pfn(__pa_symbol(image->data));
+	for (i = 0; i < num_pages; i++)
+		image->mapping.pages[i] = pfn_to_page(data_pfn + i);
+}
+
+static int __init init_vdso(void)
+{
+	init_vdso_image(&vdso_image);
+
+#ifdef CONFIG_MIPS32_O32
+	init_vdso_image(&vdso_image_o32);
+#endif
+
+#ifdef CONFIG_MIPS32_N32
+	init_vdso_image(&vdso_image_n32);
+#endif
+
+	return 0;
+}
+subsys_initcall(init_vdso);
+
+static unsigned long vdso_base(void)
+{
+	unsigned long base = STACK_TOP;
+
+	if (IS_ENABLED(CONFIG_MIPS_FP_SUPPORT)) {
+		/* Skip the delay slot emulation page */
+		base += PAGE_SIZE;
+	}
+
+	if (current->flags & PF_RANDOMIZE) {
+		base += get_random_u32_below(VDSO_RANDOMIZE_SIZE);
+		base = PAGE_ALIGN(base);
+	}
+
+	return base;
+}
+
+int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
+{
+	struct mips_vdso_image *image = current->thread.abi->vdso;
+	struct mm_struct *mm = current->mm;
+	unsigned long gic_size, vvar_size, size, base, data_addr, vdso_addr, gic_pfn, gic_base;
+	struct vm_area_struct *vma;
+	int ret;
+
+	if (mmap_write_lock_killable(mm))
+		return -EINTR;
+
+	if (IS_ENABLED(CONFIG_MIPS_FP_SUPPORT)) {
+		/* Map delay slot emulation page */
+		base = mmap_region(NULL, STACK_TOP, PAGE_SIZE,
+				VM_READ | VM_EXEC |
+				VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
+				0, NULL);
+		if (IS_ERR_VALUE(base)) {
+			ret = base;
+			goto out;
+		}
+	}
+
+	/*
+	 * Determine total area size. This includes the VDSO data itself, the
+	 * data page, and the GIC user page if present. Always create a mapping
+	 * for the GIC user area if the GIC is present regardless of whether it
+	 * is the current clocksource, in case it comes into use later on. We
+	 * only map a page even though the total area is 64K, as we only need
+	 * the counter registers at the start.
+	 */
+	gic_size = mips_gic_present() ? PAGE_SIZE : 0;
+	vvar_size = gic_size + PAGE_SIZE;
+	size = vvar_size + image->size;
+
+	/*
+	 * Find a region that's large enough for us to perform the
+	 * colour-matching alignment below.
+	 */
+	if (cpu_has_dc_aliases)
+		size += shm_align_mask + 1;
+
+	base = get_unmapped_area(NULL, vdso_base(), size, 0, 0);
+	if (IS_ERR_VALUE(base)) {
+		ret = base;
+		goto out;
+	}
+
+	/*
+	 * If we suffer from dcache aliasing, ensure that the VDSO data page
+	 * mapping is coloured the same as the kernel's mapping of that memory.
+	 * This ensures that when the kernel updates the VDSO data userland
+	 * will observe it without requiring cache invalidations.
+	 */
+	if (cpu_has_dc_aliases) {
+		base = __ALIGN_MASK(base, shm_align_mask);
+		base += ((unsigned long)vdso_data - gic_size) & shm_align_mask;
+	}
+
+	data_addr = base + gic_size;
+	vdso_addr = data_addr + PAGE_SIZE;
+
+	vma = _install_special_mapping(mm, base, vvar_size,
+				       VM_READ | VM_MAYREAD,
+				       &vdso_vvar_mapping);
+	if (IS_ERR(vma)) {
+		ret = PTR_ERR(vma);
+		goto out;
+	}
+
+	/* Map GIC user page. */
+	if (gic_size) {
+		gic_base = (unsigned long)mips_gic_base + MIPS_GIC_USER_OFS;
+		gic_pfn = PFN_DOWN(__pa(gic_base));
+
+		ret = io_remap_pfn_range(vma, base, gic_pfn, gic_size,
+					 pgprot_noncached(vma->vm_page_prot));
+		if (ret)
+			goto out;
+	}
+
+	/* Map data page. */
+	ret = remap_pfn_range(vma, data_addr,
+			      virt_to_phys(vdso_data) >> PAGE_SHIFT,
+			      PAGE_SIZE, vma->vm_page_prot);
+	if (ret)
+		goto out;
+
+	/* Map VDSO image. */
+	vma = _install_special_mapping(mm, vdso_addr, image->size,
+				       VM_READ | VM_EXEC |
+				       VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
+				       &image->mapping);
+	if (IS_ERR(vma)) {
+		ret = PTR_ERR(vma);
+		goto out;
+	}
+
+	mm->context.vdso = (void *)vdso_addr;
+	ret = 0;
+
+out:
+	mmap_write_unlock(mm);
+	return ret;
+}