[PATCH] powerpc: Merge vdso's and add vdso support to 32 bits kernel

This patch moves the vdso's to arch/powerpc, adds support for the 32
bits vdso to the 32 bits kernel, rename systemcfg (finally !), and adds
some new (still untested) routines to both vdso's: clock_gettime() with
support for CLOCK_REALTIME and CLOCK_MONOTONIC, clock_getres() (same
clocks) and get_tbfreq() for glibc to retreive the timebase frequency.

Tom,Steve: The implementation of get_tbfreq() I've done for 32 bits
returns a long long (r3, r4) not a long. This is such that if we ever
add support for >4Ghz timebases on ppc32, the userland interface won't
have to change.

I have tested gettimeofday() using some glibc patches in both ppc32 and
ppc64 kernels using 32 bits userland (I haven't had a chance to test a
64 bits userland yet, but the implementation didn't change and was
tested earlier). I haven't tested yet the new functions.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 746 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
new file mode 100644
index 000000000000..0d4d8bec0df4
--- /dev/null
+++ b/arch/powerpc/kernel/vdso.c
@@ -0,0 +1,746 @@
+/*
+ *  linux/arch/ppc64/kernel/vdso.c
+ *
+ *    Copyright (C) 2004 Benjamin Herrenschmidt, IBM Corp.
+ *			 <benh@kernel.crashing.org>
+ *
+ *  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; either version
+ *  2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/smp.h>
+#include <linux/smp_lock.h>
+#include <linux/stddef.h>
+#include <linux/unistd.h>
+#include <linux/slab.h>
+#include <linux/user.h>
+#include <linux/elf.h>
+#include <linux/security.h>
+#include <linux/bootmem.h>
+
+#include <asm/pgtable.h>
+#include <asm/system.h>
+#include <asm/processor.h>
+#include <asm/mmu.h>
+#include <asm/mmu_context.h>
+#include <asm/lmb.h>
+#include <asm/machdep.h>
+#include <asm/cputable.h>
+#include <asm/sections.h>
+#include <asm/vdso.h>
+#include <asm/vdso_datapage.h>
+
+#undef DEBUG
+
+#ifdef DEBUG
+#define DBG(fmt...) printk(fmt)
+#else
+#define DBG(fmt...)
+#endif
+
+/* Max supported size for symbol names */
+#define MAX_SYMNAME	64
+
+extern char vdso32_start, vdso32_end;
+static void *vdso32_kbase = &vdso32_start;
+unsigned int vdso32_pages;
+unsigned long vdso32_sigtramp;
+unsigned long vdso32_rt_sigtramp;
+
+#ifdef CONFIG_PPC64
+extern char vdso64_start, vdso64_end;
+static void *vdso64_kbase = &vdso64_start;
+unsigned int vdso64_pages;
+unsigned long vdso64_rt_sigtramp;
+#endif /* CONFIG_PPC64 */
+
+/*
+ * The vdso data page (aka. systemcfg for old ppc64 fans) is here.
+ * Once the early boot kernel code no longer needs to muck around
+ * with it, it will become dynamically allocated
+ */
+static union {
+	struct vdso_data	data;
+	u8			page[PAGE_SIZE];
+} vdso_data_store __attribute__((__section__(".data.page_aligned")));
+struct vdso_data *vdso_data = &vdso_data_store.data;
+
+/* Format of the patch table */
+struct vdso_patch_def
+{
+	unsigned long	ftr_mask, ftr_value;
+	const char	*gen_name;
+	const char	*fix_name;
+};
+
+/* Table of functions to patch based on the CPU type/revision
+ *
+ * Currently, we only change sync_dicache to do nothing on processors
+ * with a coherent icache
+ */
+static struct vdso_patch_def vdso_patches[] = {
+	{
+		CPU_FTR_COHERENT_ICACHE, CPU_FTR_COHERENT_ICACHE,
+		"__kernel_sync_dicache", "__kernel_sync_dicache_p5"
+	},
+	{
+		CPU_FTR_USE_TB, 0,
+		"__kernel_gettimeofday", NULL
+	},
+};
+
+/*
+ * Some infos carried around for each of them during parsing at
+ * boot time.
+ */
+struct lib32_elfinfo
+{
+	Elf32_Ehdr	*hdr;		/* ptr to ELF */
+	Elf32_Sym	*dynsym;	/* ptr to .dynsym section */
+	unsigned long	dynsymsize;	/* size of .dynsym section */
+	char		*dynstr;	/* ptr to .dynstr section */
+	unsigned long	text;		/* offset of .text section in .so */
+};
+
+struct lib64_elfinfo
+{
+	Elf64_Ehdr	*hdr;
+	Elf64_Sym	*dynsym;
+	unsigned long	dynsymsize;
+	char		*dynstr;
+	unsigned long	text;
+};
+
+
+#ifdef __DEBUG
+static void dump_one_vdso_page(struct page *pg, struct page *upg)
+{
+	printk("kpg: %p (c:%d,f:%08lx)", __va(page_to_pfn(pg) << PAGE_SHIFT),
+	       page_count(pg),
+	       pg->flags);
+	if (upg/* && pg != upg*/) {
+		printk(" upg: %p (c:%d,f:%08lx)", __va(page_to_pfn(upg)
+						       << PAGE_SHIFT),
+		       page_count(upg),
+		       upg->flags);
+	}
+	printk("\n");
+}
+
+static void dump_vdso_pages(struct vm_area_struct * vma)
+{
+	int i;
+
+	if (!vma || test_thread_flag(TIF_32BIT)) {
+		printk("vDSO32 @ %016lx:\n", (unsigned long)vdso32_kbase);
+		for (i=0; i<vdso32_pages; i++) {
+			struct page *pg = virt_to_page(vdso32_kbase +
+						       i*PAGE_SIZE);
+			struct page *upg = (vma && vma->vm_mm) ?
+				follow_page(vma->vm_mm, vma->vm_start +
+					    i*PAGE_SIZE, 0)
+				: NULL;
+			dump_one_vdso_page(pg, upg);
+		}
+	}
+	if (!vma || !test_thread_flag(TIF_32BIT)) {
+		printk("vDSO64 @ %016lx:\n", (unsigned long)vdso64_kbase);
+		for (i=0; i<vdso64_pages; i++) {
+			struct page *pg = virt_to_page(vdso64_kbase +
+						       i*PAGE_SIZE);
+			struct page *upg = (vma && vma->vm_mm) ?
+				follow_page(vma->vm_mm, vma->vm_start +
+					    i*PAGE_SIZE, 0)
+				: NULL;
+			dump_one_vdso_page(pg, upg);
+		}
+	}
+}
+#endif /* DEBUG */
+
+/*
+ * Keep a dummy vma_close for now, it will prevent VMA merging.
+ */
+static void vdso_vma_close(struct vm_area_struct * vma)
+{
+}
+
+/*
+ * Our nopage() function, maps in the actual vDSO kernel pages, they will
+ * be mapped read-only by do_no_page(), and eventually COW'ed, either
+ * right away for an initial write access, or by do_wp_page().
+ */
+static struct page * vdso_vma_nopage(struct vm_area_struct * vma,
+				     unsigned long address, int *type)
+{
+	unsigned long offset = address - vma->vm_start;
+	struct page *pg;
+#ifdef CONFIG_PPC64
+	void *vbase = test_thread_flag(TIF_32BIT) ?
+		vdso32_kbase : vdso64_kbase;
+#else
+	void *vbase = vdso32_kbase;
+#endif
+
+	DBG("vdso_vma_nopage(current: %s, address: %016lx, off: %lx)\n",
+	    current->comm, address, offset);
+
+	if (address < vma->vm_start || address > vma->vm_end)
+		return NOPAGE_SIGBUS;
+
+	/*
+	 * Last page is systemcfg.
+	 */
+	if ((vma->vm_end - address) <= PAGE_SIZE)
+		pg = virt_to_page(vdso_data);
+	else
+		pg = virt_to_page(vbase + offset);
+
+	get_page(pg);
+	DBG(" ->page count: %d\n", page_count(pg));
+
+	return pg;
+}
+
+static struct vm_operations_struct vdso_vmops = {
+	.close	= vdso_vma_close,
+	.nopage	= vdso_vma_nopage,
+};
+
+/*
+ * This is called from binfmt_elf, we create the special vma for the
+ * vDSO and insert it into the mm struct tree
+ */
+int arch_setup_additional_pages(struct linux_binprm *bprm,
+				int executable_stack)
+{
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma;
+	unsigned long vdso_pages;
+	unsigned long vdso_base;
+
+#ifdef CONFIG_PPC64
+	if (test_thread_flag(TIF_32BIT)) {
+		vdso_pages = vdso32_pages;
+		vdso_base = VDSO32_MBASE;
+	} else {
+		vdso_pages = vdso64_pages;
+		vdso_base = VDSO64_MBASE;
+	}
+#else
+	vdso_pages = vdso32_pages;
+	vdso_base = VDSO32_MBASE;
+#endif
+
+	current->thread.vdso_base = 0;
+
+	/* vDSO has a problem and was disabled, just don't "enable" it for the
+	 * process
+	 */
+	if (vdso_pages == 0)
+		return 0;
+
+	vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
+	if (vma == NULL)
+		return -ENOMEM;
+
+	memset(vma, 0, sizeof(*vma));
+
+	/* Add a page to the vdso size for the data page */
+	vdso_pages ++;
+
+	/*
+	 * pick a base address for the vDSO in process space. We try to put it
+	 * at vdso_base which is the "natural" base for it, but we might fail
+	 * and end up putting it elsewhere.
+	 */
+	vdso_base = get_unmapped_area(NULL, vdso_base,
+				      vdso_pages << PAGE_SHIFT, 0, 0);
+	if (vdso_base & ~PAGE_MASK) {
+		kmem_cache_free(vm_area_cachep, vma);
+		return (int)vdso_base;
+	}
+
+	current->thread.vdso_base = vdso_base;
+
+	vma->vm_mm = mm;
+	vma->vm_start = current->thread.vdso_base;
+	vma->vm_end = vma->vm_start + (vdso_pages << PAGE_SHIFT);
+
+	/*
+	 * 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
+	 */
+	vma->vm_flags = VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE |
+		VM_MAYEXEC | VM_RESERVED;
+	vma->vm_flags |= mm->def_flags;
+	vma->vm_page_prot = protection_map[vma->vm_flags & 0x7];
+	vma->vm_ops = &vdso_vmops;
+
+	down_write(&mm->mmap_sem);
+	if (insert_vm_struct(mm, vma)) {
+		up_write(&mm->mmap_sem);
+		kmem_cache_free(vm_area_cachep, vma);
+		return -ENOMEM;
+	}
+	mm->total_vm += (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
+	up_write(&mm->mmap_sem);
+
+	return 0;
+}
+
+static void * __init find_section32(Elf32_Ehdr *ehdr, const char *secname,
+				  unsigned long *size)
+{
+	Elf32_Shdr *sechdrs;
+	unsigned int i;
+	char *secnames;
+
+	/* Grab section headers and strings so we can tell who is who */
+	sechdrs = (void *)ehdr + ehdr->e_shoff;
+	secnames = (void *)ehdr + sechdrs[ehdr->e_shstrndx].sh_offset;
+
+	/* Find the section they want */
+	for (i = 1; i < ehdr->e_shnum; i++) {
+		if (strcmp(secnames+sechdrs[i].sh_name, secname) == 0) {
+			if (size)
+				*size = sechdrs[i].sh_size;
+			return (void *)ehdr + sechdrs[i].sh_offset;
+		}
+	}
+	*size = 0;
+	return NULL;
+}
+
+static Elf32_Sym * __init find_symbol32(struct lib32_elfinfo *lib,
+					const char *symname)
+{
+	unsigned int i;
+	char name[MAX_SYMNAME], *c;
+
+	for (i = 0; i < (lib->dynsymsize / sizeof(Elf32_Sym)); i++) {
+		if (lib->dynsym[i].st_name == 0)
+			continue;
+		strlcpy(name, lib->dynstr + lib->dynsym[i].st_name,
+			MAX_SYMNAME);
+		c = strchr(name, '@');
+		if (c)
+			*c = 0;
+		if (strcmp(symname, name) == 0)
+			return &lib->dynsym[i];
+	}
+	return NULL;
+}
+
+/* Note that we assume the section is .text and the symbol is relative to
+ * the library base
+ */
+static unsigned long __init find_function32(struct lib32_elfinfo *lib,
+					    const char *symname)
+{
+	Elf32_Sym *sym = find_symbol32(lib, symname);
+
+	if (sym == NULL) {
+		printk(KERN_WARNING "vDSO32: function %s not found !\n",
+		       symname);
+		return 0;
+	}
+	return sym->st_value - VDSO32_LBASE;
+}
+
+static int vdso_do_func_patch32(struct lib32_elfinfo *v32,
+				struct lib64_elfinfo *v64,
+				const char *orig, const char *fix)
+{
+	Elf32_Sym *sym32_gen, *sym32_fix;
+
+	sym32_gen = find_symbol32(v32, orig);
+	if (sym32_gen == NULL) {
+		printk(KERN_ERR "vDSO32: Can't find symbol %s !\n", orig);
+		return -1;
+	}
+	if (fix == NULL) {
+		sym32_gen->st_name = 0;
+		return 0;
+	}
+	sym32_fix = find_symbol32(v32, fix);
+	if (sym32_fix == NULL) {
+		printk(KERN_ERR "vDSO32: Can't find symbol %s !\n", fix);
+		return -1;
+	}
+	sym32_gen->st_value = sym32_fix->st_value;
+	sym32_gen->st_size = sym32_fix->st_size;
+	sym32_gen->st_info = sym32_fix->st_info;
+	sym32_gen->st_other = sym32_fix->st_other;
+	sym32_gen->st_shndx = sym32_fix->st_shndx;
+
+	return 0;
+}
+
+
+#ifdef CONFIG_PPC64
+
+static void * __init find_section64(Elf64_Ehdr *ehdr, const char *secname,
+				  unsigned long *size)
+{
+	Elf64_Shdr *sechdrs;
+	unsigned int i;
+	char *secnames;
+
+	/* Grab section headers and strings so we can tell who is who */
+	sechdrs = (void *)ehdr + ehdr->e_shoff;
+	secnames = (void *)ehdr + sechdrs[ehdr->e_shstrndx].sh_offset;
+
+	/* Find the section they want */
+	for (i = 1; i < ehdr->e_shnum; i++) {
+		if (strcmp(secnames+sechdrs[i].sh_name, secname) == 0) {
+			if (size)
+				*size = sechdrs[i].sh_size;
+			return (void *)ehdr + sechdrs[i].sh_offset;
+		}
+	}
+	if (size)
+		*size = 0;
+	return NULL;
+}
+
+static Elf64_Sym * __init find_symbol64(struct lib64_elfinfo *lib,
+					const char *symname)
+{
+	unsigned int i;
+	char name[MAX_SYMNAME], *c;
+
+	for (i = 0; i < (lib->dynsymsize / sizeof(Elf64_Sym)); i++) {
+		if (lib->dynsym[i].st_name == 0)
+			continue;
+		strlcpy(name, lib->dynstr + lib->dynsym[i].st_name,
+			MAX_SYMNAME);
+		c = strchr(name, '@');
+		if (c)
+			*c = 0;
+		if (strcmp(symname, name) == 0)
+			return &lib->dynsym[i];
+	}
+	return NULL;
+}
+
+/* Note that we assume the section is .text and the symbol is relative to
+ * the library base
+ */
+static unsigned long __init find_function64(struct lib64_elfinfo *lib,
+					    const char *symname)
+{
+	Elf64_Sym *sym = find_symbol64(lib, symname);
+
+	if (sym == NULL) {
+		printk(KERN_WARNING "vDSO64: function %s not found !\n",
+		       symname);
+		return 0;
+	}
+#ifdef VDS64_HAS_DESCRIPTORS
+	return *((u64 *)(vdso64_kbase + sym->st_value - VDSO64_LBASE)) -
+		VDSO64_LBASE;
+#else
+	return sym->st_value - VDSO64_LBASE;
+#endif
+}
+
+static int vdso_do_func_patch64(struct lib32_elfinfo *v32,
+				struct lib64_elfinfo *v64,
+				const char *orig, const char *fix)
+{
+	Elf64_Sym *sym64_gen, *sym64_fix;
+
+	sym64_gen = find_symbol64(v64, orig);
+	if (sym64_gen == NULL) {
+		printk(KERN_ERR "vDSO64: Can't find symbol %s !\n", orig);
+		return -1;
+	}
+	if (fix == NULL) {
+		sym64_gen->st_name = 0;
+		return 0;
+	}
+	sym64_fix = find_symbol64(v64, fix);
+	if (sym64_fix == NULL) {
+		printk(KERN_ERR "vDSO64: Can't find symbol %s !\n", fix);
+		return -1;
+	}
+	sym64_gen->st_value = sym64_fix->st_value;
+	sym64_gen->st_size = sym64_fix->st_size;
+	sym64_gen->st_info = sym64_fix->st_info;
+	sym64_gen->st_other = sym64_fix->st_other;
+	sym64_gen->st_shndx = sym64_fix->st_shndx;
+
+	return 0;
+}
+
+#endif /* CONFIG_PPC64 */
+
+
+static __init int vdso_do_find_sections(struct lib32_elfinfo *v32,
+					struct lib64_elfinfo *v64)
+{
+	void *sect;
+
+	/*
+	 * Locate symbol tables & text section
+	 */
+
+	v32->dynsym = find_section32(v32->hdr, ".dynsym", &v32->dynsymsize);
+	v32->dynstr = find_section32(v32->hdr, ".dynstr", NULL);
+	if (v32->dynsym == NULL || v32->dynstr == NULL) {
+		printk(KERN_ERR "vDSO32: required symbol section not found\n");
+		return -1;
+	}
+	sect = find_section32(v32->hdr, ".text", NULL);
+	if (sect == NULL) {
+		printk(KERN_ERR "vDSO32: the .text section was not found\n");
+		return -1;
+	}
+	v32->text = sect - vdso32_kbase;
+
+#ifdef CONFIG_PPC64
+	v64->dynsym = find_section64(v64->hdr, ".dynsym", &v64->dynsymsize);
+	v64->dynstr = find_section64(v64->hdr, ".dynstr", NULL);
+	if (v64->dynsym == NULL || v64->dynstr == NULL) {
+		printk(KERN_ERR "vDSO64: required symbol section not found\n");
+		return -1;
+	}
+	sect = find_section64(v64->hdr, ".text", NULL);
+	if (sect == NULL) {
+		printk(KERN_ERR "vDSO64: the .text section was not found\n");
+		return -1;
+	}
+	v64->text = sect - vdso64_kbase;
+#endif /* CONFIG_PPC64 */
+
+	return 0;
+}
+
+static __init void vdso_setup_trampolines(struct lib32_elfinfo *v32,
+					  struct lib64_elfinfo *v64)
+{
+	/*
+	 * Find signal trampolines
+	 */
+
+#ifdef CONFIG_PPC64
+	vdso64_rt_sigtramp = find_function64(v64, "__kernel_sigtramp_rt64");
+#endif
+	vdso32_sigtramp	   = find_function32(v32, "__kernel_sigtramp32");
+	vdso32_rt_sigtramp = find_function32(v32, "__kernel_sigtramp_rt32");
+}
+
+static __init int vdso_fixup_datapage(struct lib32_elfinfo *v32,
+				       struct lib64_elfinfo *v64)
+{
+	Elf32_Sym *sym32;
+#ifdef CONFIG_PPC64
+	Elf64_Sym *sym64;
+
+       	sym64 = find_symbol64(v64, "__kernel_datapage_offset");
+	if (sym64 == NULL) {
+		printk(KERN_ERR "vDSO64: Can't find symbol "
+		       "__kernel_datapage_offset !\n");
+		return -1;
+	}
+	*((int *)(vdso64_kbase + sym64->st_value - VDSO64_LBASE)) =
+		(vdso64_pages << PAGE_SHIFT) -
+		(sym64->st_value - VDSO64_LBASE);
+#endif /* CONFIG_PPC64 */
+
+	sym32 = find_symbol32(v32, "__kernel_datapage_offset");
+	if (sym32 == NULL) {
+		printk(KERN_ERR "vDSO32: Can't find symbol "
+		       "__kernel_datapage_offset !\n");
+		return -1;
+	}
+	*((int *)(vdso32_kbase + (sym32->st_value - VDSO32_LBASE))) =
+		(vdso32_pages << PAGE_SHIFT) -
+		(sym32->st_value - VDSO32_LBASE);
+
+	return 0;
+}
+
+static __init int vdso_fixup_alt_funcs(struct lib32_elfinfo *v32,
+				       struct lib64_elfinfo *v64)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(vdso_patches); i++) {
+		struct vdso_patch_def *patch = &vdso_patches[i];
+		int match = (cur_cpu_spec->cpu_features & patch->ftr_mask)
+			== patch->ftr_value;
+		if (!match)
+			continue;
+
+		DBG("replacing %s with %s...\n", patch->gen_name,
+		    patch->fix_name ? "NONE" : patch->fix_name);
+
+		/*
+		 * Patch the 32 bits and 64 bits symbols. Note that we do not
+		 * patch the "." symbol on 64 bits.
+		 * It would be easy to do, but doesn't seem to be necessary,
+		 * patching the OPD symbol is enough.
+		 */
+		vdso_do_func_patch32(v32, v64, patch->gen_name,
+				     patch->fix_name);
+#ifdef CONFIG_PPC64
+		vdso_do_func_patch64(v32, v64, patch->gen_name,
+				     patch->fix_name);
+#endif /* CONFIG_PPC64 */
+	}
+
+	return 0;
+}
+
+
+static __init int vdso_setup(void)
+{
+	struct lib32_elfinfo	v32;
+	struct lib64_elfinfo	v64;
+
+	v32.hdr = vdso32_kbase;
+#ifdef CONFIG_PPC64
+	v64.hdr = vdso64_kbase;
+#endif
+	if (vdso_do_find_sections(&v32, &v64))
+		return -1;
+
+	if (vdso_fixup_datapage(&v32, &v64))
+		return -1;
+
+	if (vdso_fixup_alt_funcs(&v32, &v64))
+		return -1;
+
+	vdso_setup_trampolines(&v32, &v64);
+
+	return 0;
+}
+
+/*
+ * Called from setup_arch to initialize the bitmap of available
+ * syscalls in the systemcfg page
+ */
+static void __init vdso_setup_syscall_map(void)
+{
+	unsigned int i;
+	extern unsigned long *sys_call_table;
+	extern unsigned long sys_ni_syscall;
+
+
+	for (i = 0; i < __NR_syscalls; i++) {
+#ifdef CONFIG_PPC64
+		if (sys_call_table[i*2] != sys_ni_syscall)
+			vdso_data->syscall_map_64[i >> 5] |=
+				0x80000000UL >> (i & 0x1f);
+		if (sys_call_table[i*2+1] != sys_ni_syscall)
+			vdso_data->syscall_map_32[i >> 5] |=
+				0x80000000UL >> (i & 0x1f);
+#else /* CONFIG_PPC64 */
+		if (sys_call_table[i] != sys_ni_syscall)
+			vdso_data->syscall_map_32[i >> 5] |=
+				0x80000000UL >> (i & 0x1f);
+#endif /* CONFIG_PPC64 */
+	}
+}
+
+
+void __init vdso_init(void)
+{
+	int i;
+
+#ifdef CONFIG_PPC64
+	/*
+	 * Fill up the "systemcfg" stuff for backward compatiblity
+	 */
+	strcpy(vdso_data->eye_catcher, "SYSTEMCFG:PPC64");
+	vdso_data->version.major = SYSTEMCFG_MAJOR;
+	vdso_data->version.minor = SYSTEMCFG_MINOR;
+	vdso_data->processor = mfspr(SPRN_PVR);
+	vdso_data->platform = _machine;
+	vdso_data->physicalMemorySize = lmb_phys_mem_size();
+	vdso_data->dcache_size = ppc64_caches.dsize;
+	vdso_data->dcache_line_size = ppc64_caches.dline_size;
+	vdso_data->icache_size = ppc64_caches.isize;
+	vdso_data->icache_line_size = ppc64_caches.iline_size;
+
+	/*
+	 * Calculate the size of the 64 bits vDSO
+	 */
+	vdso64_pages = (&vdso64_end - &vdso64_start) >> PAGE_SHIFT;
+	DBG("vdso64_kbase: %p, 0x%x pages\n", vdso64_kbase, vdso64_pages);
+#endif /* CONFIG_PPC64 */
+
+
+	/*
+	 * Calculate the size of the 32 bits vDSO
+	 */
+	vdso32_pages = (&vdso32_end - &vdso32_start) >> PAGE_SHIFT;
+	DBG("vdso32_kbase: %p, 0x%x pages\n", vdso32_kbase, vdso32_pages);
+
+
+	/*
+	 * Setup the syscall map in the vDOS
+	 */
+	vdso_setup_syscall_map();
+	/*
+	 * Initialize the vDSO images in memory, that is do necessary
+	 * fixups of vDSO symbols, locate trampolines, etc...
+	 */
+	if (vdso_setup()) {
+		printk(KERN_ERR "vDSO setup failure, not enabled !\n");
+		vdso32_pages = 0;
+#ifdef CONFIG_PPC64
+		vdso64_pages = 0;
+#endif
+		return;
+	}
+
+	/* Make sure pages are in the correct state */
+	for (i = 0; i < vdso32_pages; i++) {
+		struct page *pg = virt_to_page(vdso32_kbase + i*PAGE_SIZE);
+		ClearPageReserved(pg);
+		get_page(pg);
+
+	}
+#ifdef CONFIG_PPC64
+	for (i = 0; i < vdso64_pages; i++) {
+		struct page *pg = virt_to_page(vdso64_kbase + i*PAGE_SIZE);
+		ClearPageReserved(pg);
+		get_page(pg);
+	}
+#endif /* CONFIG_PPC64 */
+
+	get_page(virt_to_page(vdso_data));
+}
+
+int in_gate_area_no_task(unsigned long addr)
+{
+	return 0;
+}
+
+int in_gate_area(struct task_struct *task, unsigned long addr)
+{
+	return 0;
+}
+
+struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
+{
+	return NULL;
+}
+