--- /dev/null
+/*
+ * Copyright 2012 Tilera Corporation. All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, version 2.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT. See the GNU General Public License for
+ * more details.
+ */
+
+#include <linux/binfmts.h>
+#include <linux/compat.h>
+#include <linux/elf.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+
+#include <asm/vdso.h>
+#include <asm/mman.h>
+#include <asm/sections.h>
+
+#include <arch/sim.h>
+
+/* The alignment of the vDSO. */
+#define VDSO_ALIGNMENT PAGE_SIZE
+
+
+static unsigned int vdso_pages;
+static struct page **vdso_pagelist;
+
+#ifdef CONFIG_COMPAT
+static unsigned int vdso32_pages;
+static struct page **vdso32_pagelist;
+#endif
+static int vdso_ready;
+
+/*
+ * The vdso data page.
+ */
+static union {
+ struct vdso_data data;
+ u8 page[PAGE_SIZE];
+} vdso_data_store __page_aligned_data;
+
+struct vdso_data *vdso_data = &vdso_data_store.data;
+
+static unsigned int __read_mostly vdso_enabled = 1;
+
+static struct page **vdso_setup(void *vdso_kbase, unsigned int pages)
+{
+ int i;
+ struct page **pagelist;
+
+ pagelist = kzalloc(sizeof(struct page *) * (pages + 1), GFP_KERNEL);
+ BUG_ON(pagelist == NULL);
+ for (i = 0; i < pages - 1; i++) {
+ struct page *pg = virt_to_page(vdso_kbase + i*PAGE_SIZE);
+ ClearPageReserved(pg);
+ pagelist[i] = pg;
+ }
+ pagelist[pages - 1] = virt_to_page(vdso_data);
+ pagelist[pages] = NULL;
+
+ return pagelist;
+}
+
+static int __init vdso_init(void)
+{
+ int data_pages = sizeof(vdso_data_store) >> PAGE_SHIFT;
+
+ /*
+ * We can disable vDSO support generally, but we need to retain
+ * one page to support the two-bundle (16-byte) rt_sigreturn path.
+ */
+ if (!vdso_enabled) {
+ size_t offset = (unsigned long)&__vdso_rt_sigreturn;
+ static struct page *sigret_page;
+ sigret_page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+ BUG_ON(sigret_page == NULL);
+ vdso_pagelist = &sigret_page;
+ vdso_pages = 1;
+ BUG_ON(offset >= PAGE_SIZE);
+ memcpy(page_address(sigret_page) + offset,
+ vdso_start + offset, 16);
+#ifdef CONFIG_COMPAT
+ vdso32_pages = vdso_pages;
+ vdso32_pagelist = vdso_pagelist;
+#endif
+ vdso_ready = 1;
+ return 0;
+ }
+
+ vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
+ vdso_pages += data_pages;
+ vdso_pagelist = vdso_setup(vdso_start, vdso_pages);
+
+#ifdef CONFIG_COMPAT
+ vdso32_pages = (vdso32_end - vdso32_start) >> PAGE_SHIFT;
+ vdso32_pages += data_pages;
+ vdso32_pagelist = vdso_setup(vdso32_start, vdso32_pages);
+#endif
+
+ smp_wmb();
+ vdso_ready = 1;
+
+ return 0;
+}
+arch_initcall(vdso_init);
+
+const char *arch_vma_name(struct vm_area_struct *vma)
+{
+ if (vma->vm_mm && vma->vm_start == VDSO_BASE)
+ return "[vdso]";
+#ifndef __tilegx__
+ if (vma->vm_start == MEM_USER_INTRPT)
+ return "[intrpt]";
+#endif
+ return NULL;
+}
+
+int setup_vdso_pages(void)
+{
+ struct page **pagelist;
+ unsigned long pages;
+ struct mm_struct *mm = current->mm;
+ unsigned long vdso_base = 0;
+ int retval = 0;
+
+ if (!vdso_ready)
+ return 0;
+
+ mm->context.vdso_base = 0;
+
+ pagelist = vdso_pagelist;
+ pages = vdso_pages;
+#ifdef CONFIG_COMPAT
+ if (is_compat_task()) {
+ pagelist = vdso32_pagelist;
+ pages = vdso32_pages;
+ }
+#endif
+
+ /*
+ * vDSO has a problem and was disabled, just don't "enable" it for the
+ * process.
+ */
+ if (pages == 0)
+ return 0;
+
+ vdso_base = get_unmapped_area(NULL, vdso_base,
+ (pages << PAGE_SHIFT) +
+ ((VDSO_ALIGNMENT - 1) & PAGE_MASK),
+ 0, 0);
+ if (IS_ERR_VALUE(vdso_base)) {
+ retval = vdso_base;
+ return retval;
+ }
+
+ /* Add required alignment. */
+ vdso_base = ALIGN(vdso_base, VDSO_ALIGNMENT);
+
+ /*
+ * Put vDSO base into mm struct. We need to do this before calling
+ * install_special_mapping or the perf counter mmap tracking code
+ * will fail to recognise it as a vDSO (since arch_vma_name fails).
+ */
+ mm->context.vdso_base = vdso_base;
+
+ /*
+ * our vma flags don't have VM_WRITE so by default, the process isn't
+ * allowed to write those pages.
+ * gdb can break that with ptrace interface, and thus trigger COW on
+ * those pages but it's then your responsibility to never do that on
+ * the "data" page of the vDSO or you'll stop getting kernel updates
+ * and your nice userland gettimeofday will be totally dead.
+ * It's fine to use that for setting breakpoints in the vDSO code
+ * pages though
+ */
+ retval = install_special_mapping(mm, vdso_base,
+ pages << PAGE_SHIFT,
+ VM_READ|VM_EXEC |
+ VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
+ pagelist);
+ if (retval)
+ mm->context.vdso_base = 0;
+
+ return retval;
+}
+
+static __init int vdso_func(char *s)
+{
+ return kstrtouint(s, 0, &vdso_enabled);
+}
+__setup("vdso=", vdso_func);
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