arch/s390/kernel/vdso.c - arm/linux - Git at Google

 /*
  * vdso setup for s390
  *
  *  Copyright IBM Corp. 2008
  *  Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License (version 2 only)
  * as published by the Free Software Foundation.
  */

 #include <linux/init.h>
 #include <linux/errno.h>
 #include <linux/sched.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/smp.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 <linux/compat.h>
 #include <asm/asm-offsets.h>
 #include <asm/pgtable.h>
 #include <asm/processor.h>
 #include <asm/mmu.h>
 #include <asm/mmu_context.h>
 #include <asm/sections.h>
 #include <asm/vdso.h>
 #include <asm/facility.h>

 #ifdef CONFIG_COMPAT
 extern char vdso32_start, vdso32_end;
 static void *vdso32_kbase = &vdso32_start;
 static unsigned int vdso32_pages;
 static struct page **vdso32_pagelist;
 #endif

 extern char vdso64_start, vdso64_end;
 static void *vdso64_kbase = &vdso64_start;
 static unsigned int vdso64_pages;
 static struct page **vdso64_pagelist;

 /*
  * Should the kernel map a VDSO page into processes and pass its
  * address down to glibc upon exec()?
  */
 unsigned int __read_mostly vdso_enabled = 1;

 static int vdso_fault(const struct vm_special_mapping *sm,
 		      struct vm_area_struct *vma, struct vm_fault *vmf)
 {
 	struct page **vdso_pagelist;
 	unsigned long vdso_pages;

 	vdso_pagelist = vdso64_pagelist;
 	vdso_pages = vdso64_pages;
 #ifdef CONFIG_COMPAT
 	if (is_compat_task()) {
 		vdso_pagelist = vdso32_pagelist;
 		vdso_pages = vdso32_pages;
 	}
 #endif

 	if (vmf->pgoff >= vdso_pages)
 		return VM_FAULT_SIGBUS;

 	vmf->page = vdso_pagelist[vmf->pgoff];
 	get_page(vmf->page);
 	return 0;
 }

 static int vdso_mremap(const struct vm_special_mapping *sm,
 		       struct vm_area_struct *vma)
 {
 	unsigned long vdso_pages;

 	vdso_pages = vdso64_pages;
 #ifdef CONFIG_COMPAT
 	if (is_compat_task())
 		vdso_pages = vdso32_pages;
 #endif

 	if ((vdso_pages << PAGE_SHIFT) != vma->vm_end - vma->vm_start)
 		return -EINVAL;

 	if (WARN_ON_ONCE(current->mm != vma->vm_mm))
 		return -EFAULT;

 	current->mm->context.vdso_base = vma->vm_start;
 	return 0;
 }

 static const struct vm_special_mapping vdso_mapping = {
 	.name = "[vdso]",
 	.fault = vdso_fault,
 	.mremap = vdso_mremap,
 };

 static int __init vdso_setup(char *s)
 {
 	unsigned long val;
 	int rc;

 	rc = 0;
 	if (strncmp(s, "on", 3) == 0)
 		vdso_enabled = 1;
 	else if (strncmp(s, "off", 4) == 0)
 		vdso_enabled = 0;
 	else {
 		rc = kstrtoul(s, 0, &val);
 		vdso_enabled = rc ? 0 : !!val;
 	}
 	return !rc;
 }
 __setup("vdso=", vdso_setup);

 /*
  * 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;

 /*
  * Setup vdso data page.
  */
 static void __init vdso_init_data(struct vdso_data *vd)
 {
 	vd->ectg_available = test_facility(31);
 }

 /*
  * Allocate/free per cpu vdso data.
  */
 #define SEGMENT_ORDER	2

 int vdso_alloc_per_cpu(struct lowcore *lowcore)
 {
 	unsigned long segment_table, page_table, page_frame;
 	struct vdso_per_cpu_data *vd;
 	u32 *psal, *aste;
 	int i;

 	lowcore->vdso_per_cpu_data = __LC_PASTE;

 	if (!vdso_enabled)
 		return 0;

 	segment_table = __get_free_pages(GFP_KERNEL, SEGMENT_ORDER);
 	page_table = get_zeroed_page(GFP_KERNEL | GFP_DMA);
 	page_frame = get_zeroed_page(GFP_KERNEL);
 	if (!segment_table || !page_table || !page_frame)
 		goto out;
 	arch_set_page_dat(virt_to_page(segment_table), SEGMENT_ORDER);
 	arch_set_page_dat(virt_to_page(page_table), 0);

 	/* Initialize per-cpu vdso data page */
 	vd = (struct vdso_per_cpu_data *) page_frame;
 	vd->cpu_nr = lowcore->cpu_nr;
 	vd->node_id = cpu_to_node(vd->cpu_nr);

 	/* Set up access register mode page table */
 	clear_table((unsigned long *) segment_table, _SEGMENT_ENTRY_EMPTY,
 		    PAGE_SIZE << SEGMENT_ORDER);
 	clear_table((unsigned long *) page_table, _PAGE_INVALID,
 		    256*sizeof(unsigned long));

 	*(unsigned long *) segment_table = _SEGMENT_ENTRY + page_table;
 	*(unsigned long *) page_table = _PAGE_PROTECT + page_frame;

 	psal = (u32 *) (page_table + 256*sizeof(unsigned long));
 	aste = psal + 32;

 	for (i = 4; i < 32; i += 4)
 		psal[i] = 0x80000000;

 	lowcore->paste[4] = (u32)(addr_t) psal;
 	psal[0] = 0x02000000;
 	psal[2] = (u32)(addr_t) aste;
 	*(unsigned long *) (aste + 2) = segment_table +
 		_ASCE_TABLE_LENGTH + _ASCE_USER_BITS + _ASCE_TYPE_SEGMENT;
 	aste[4] = (u32)(addr_t) psal;
 	lowcore->vdso_per_cpu_data = page_frame;

 	return 0;

 out:
 	free_page(page_frame);
 	free_page(page_table);
 	free_pages(segment_table, SEGMENT_ORDER);
 	return -ENOMEM;
 }

 void vdso_free_per_cpu(struct lowcore *lowcore)
 {
 	unsigned long segment_table, page_table, page_frame;
 	u32 *psal, *aste;

 	if (!vdso_enabled)
 		return;

 	psal = (u32 *)(addr_t) lowcore->paste[4];
 	aste = (u32 *)(addr_t) psal[2];
 	segment_table = *(unsigned long *)(aste + 2) & PAGE_MASK;
 	page_table = *(unsigned long *) segment_table;
 	page_frame = *(unsigned long *) page_table;

 	free_page(page_frame);
 	free_page(page_table);
 	free_pages(segment_table, SEGMENT_ORDER);
 }

 static void vdso_init_cr5(void)
 {
 	unsigned long cr5;

 	if (!vdso_enabled)
 		return;
 	cr5 = offsetof(struct lowcore, paste);
 	__ctl_load(cr5, 5, 5);
 }

 /*
  * 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 uses_interp)
 {
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma;
 	unsigned long vdso_pages;
 	unsigned long vdso_base;
 	int rc;

 	if (!vdso_enabled)
 		return 0;
 	/*
 	 * Only map the vdso for dynamically linked elf binaries.
 	 */
 	if (!uses_interp)
 		return 0;

 	vdso_pages = vdso64_pages;
 #ifdef CONFIG_COMPAT
 	if (is_compat_task())
 		vdso_pages = vdso32_pages;
 #endif
 	/*
 	 * vDSO has a problem and was disabled, just don't "enable" it for
 	 * the process
 	 */
 	if (vdso_pages == 0)
 		return 0;

 	/*
 	 * 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.
 	 */
 	if (down_write_killable(&mm->mmap_sem))
 		return -EINTR;
 	vdso_base = get_unmapped_area(NULL, 0, vdso_pages << PAGE_SHIFT, 0, 0);
 	if (IS_ERR_VALUE(vdso_base)) {
 		rc = vdso_base;
 		goto out_up;
 	}

 	/*
 	 * 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 = _install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
 				       VM_READ|VM_EXEC|
 				       VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
 				       &vdso_mapping);
 	if (IS_ERR(vma)) {
 		rc = PTR_ERR(vma);
 		goto out_up;
 	}

 	current->mm->context.vdso_base = vdso_base;
 	rc = 0;

 out_up:
 	up_write(&mm->mmap_sem);
 	return rc;
 }

 static int __init vdso_init(void)
 {
 	int i;

 	if (!vdso_enabled)
 		return 0;
 	vdso_init_data(vdso_data);
 #ifdef CONFIG_COMPAT
 	/* Calculate the size of the 32 bit vDSO */
 	vdso32_pages = ((&vdso32_end - &vdso32_start
 			 + PAGE_SIZE - 1) >> PAGE_SHIFT) + 1;

 	/* Make sure pages are in the correct state */
 	vdso32_pagelist = kzalloc(sizeof(struct page *) * (vdso32_pages + 1),
 				  GFP_KERNEL);
 	BUG_ON(vdso32_pagelist == NULL);
 	for (i = 0; i < vdso32_pages - 1; i++) {
 		struct page *pg = virt_to_page(vdso32_kbase + i*PAGE_SIZE);
 		ClearPageReserved(pg);
 		get_page(pg);
 		vdso32_pagelist[i] = pg;
 	}
 	vdso32_pagelist[vdso32_pages - 1] = virt_to_page(vdso_data);
 	vdso32_pagelist[vdso32_pages] = NULL;
 #endif

 	/* Calculate the size of the 64 bit vDSO */
 	vdso64_pages = ((&vdso64_end - &vdso64_start
 			 + PAGE_SIZE - 1) >> PAGE_SHIFT) + 1;

 	/* Make sure pages are in the correct state */
 	vdso64_pagelist = kzalloc(sizeof(struct page *) * (vdso64_pages + 1),
 				  GFP_KERNEL);
 	BUG_ON(vdso64_pagelist == NULL);
 	for (i = 0; i < vdso64_pages - 1; i++) {
 		struct page *pg = virt_to_page(vdso64_kbase + i*PAGE_SIZE);
 		ClearPageReserved(pg);
 		get_page(pg);
 		vdso64_pagelist[i] = pg;
 	}
 	vdso64_pagelist[vdso64_pages - 1] = virt_to_page(vdso_data);
 	vdso64_pagelist[vdso64_pages] = NULL;
 	if (vdso_alloc_per_cpu(&S390_lowcore))
 		BUG();
 	vdso_init_cr5();

 	get_page(virt_to_page(vdso_data));

 	return 0;
 }
 early_initcall(vdso_init);
	/*
	* vdso setup for s390
	*
	* Copyright IBM Corp. 2008
	* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License (version 2 only)
	* as published by the Free Software Foundation.
	*/

	#include <linux/init.h>
	#include <linux/errno.h>
	#include <linux/sched.h>
	#include <linux/kernel.h>
	#include <linux/mm.h>
	#include <linux/smp.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 <linux/compat.h>
	#include <asm/asm-offsets.h>
	#include <asm/pgtable.h>
	#include <asm/processor.h>
	#include <asm/mmu.h>
	#include <asm/mmu_context.h>
	#include <asm/sections.h>
	#include <asm/vdso.h>
	#include <asm/facility.h>

	#ifdef CONFIG_COMPAT
	extern char vdso32_start, vdso32_end;
	static void *vdso32_kbase = &vdso32_start;
	static unsigned int vdso32_pages;
	static struct page **vdso32_pagelist;
	#endif

	extern char vdso64_start, vdso64_end;
	static void *vdso64_kbase = &vdso64_start;
	static unsigned int vdso64_pages;
	static struct page **vdso64_pagelist;

	/*
	* Should the kernel map a VDSO page into processes and pass its
	* address down to glibc upon exec()?
	*/
	unsigned int __read_mostly vdso_enabled = 1;

	static int vdso_fault(const struct vm_special_mapping *sm,
	struct vm_area_struct vma, struct vm_fault vmf)
	{
	struct page **vdso_pagelist;
	unsigned long vdso_pages;

	vdso_pagelist = vdso64_pagelist;
	vdso_pages = vdso64_pages;
	#ifdef CONFIG_COMPAT
	if (is_compat_task()) {
	vdso_pagelist = vdso32_pagelist;
	vdso_pages = vdso32_pages;
	}
	#endif

	if (vmf->pgoff >= vdso_pages)
	return VM_FAULT_SIGBUS;

	vmf->page = vdso_pagelist[vmf->pgoff];
	get_page(vmf->page);
	return 0;
	}

	static int vdso_mremap(const struct vm_special_mapping *sm,
	struct vm_area_struct *vma)
	{
	unsigned long vdso_pages;

	vdso_pages = vdso64_pages;
	#ifdef CONFIG_COMPAT
	if (is_compat_task())
	vdso_pages = vdso32_pages;
	#endif

	if ((vdso_pages << PAGE_SHIFT) != vma->vm_end - vma->vm_start)
	return -EINVAL;

	if (WARN_ON_ONCE(current->mm != vma->vm_mm))
	return -EFAULT;

	current->mm->context.vdso_base = vma->vm_start;
	return 0;
	}

	static const struct vm_special_mapping vdso_mapping = {
	.name = "[vdso]",
	.fault = vdso_fault,
	.mremap = vdso_mremap,
	};

	static int __init vdso_setup(char *s)
	{
	unsigned long val;
	int rc;

	rc = 0;
	if (strncmp(s, "on", 3) == 0)
	vdso_enabled = 1;
	else if (strncmp(s, "off", 4) == 0)
	vdso_enabled = 0;
	else {
	rc = kstrtoul(s, 0, &val);
	vdso_enabled = rc ? 0 : !!val;
	}
	return !rc;
	}
	__setup("vdso=", vdso_setup);

	/*
	* 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;

	/*
	* Setup vdso data page.
	*/
	static void __init vdso_init_data(struct vdso_data *vd)
	{
	vd->ectg_available = test_facility(31);
	}

	/*
	* Allocate/free per cpu vdso data.
	*/
	#define SEGMENT_ORDER 2

	int vdso_alloc_per_cpu(struct lowcore *lowcore)
	{
	unsigned long segment_table, page_table, page_frame;
	struct vdso_per_cpu_data *vd;
	u32 psal, aste;
	int i;

	lowcore->vdso_per_cpu_data = __LC_PASTE;

	if (!vdso_enabled)
	return 0;

	segment_table = __get_free_pages(GFP_KERNEL, SEGMENT_ORDER);
	page_table = get_zeroed_page(GFP_KERNEL \| GFP_DMA);
	page_frame = get_zeroed_page(GFP_KERNEL);
	if (!segment_table \|\| !page_table \|\| !page_frame)
	goto out;
	arch_set_page_dat(virt_to_page(segment_table), SEGMENT_ORDER);
	arch_set_page_dat(virt_to_page(page_table), 0);

	/* Initialize per-cpu vdso data page */
	vd = (struct vdso_per_cpu_data *) page_frame;
	vd->cpu_nr = lowcore->cpu_nr;
	vd->node_id = cpu_to_node(vd->cpu_nr);

	/* Set up access register mode page table */
	clear_table((unsigned long *) segment_table, _SEGMENT_ENTRY_EMPTY,
	PAGE_SIZE << SEGMENT_ORDER);
	clear_table((unsigned long *) page_table, _PAGE_INVALID,
	256*sizeof(unsigned long));

	(unsigned long ) segment_table = _SEGMENT_ENTRY + page_table;
	(unsigned long ) page_table = _PAGE_PROTECT + page_frame;

	psal = (u32 ) (page_table + 256sizeof(unsigned long));
	aste = psal + 32;

	for (i = 4; i < 32; i += 4)
	psal[i] = 0x80000000;

	lowcore->paste[4] = (u32)(addr_t) psal;
	psal[0] = 0x02000000;
	psal[2] = (u32)(addr_t) aste;
	(unsigned long ) (aste + 2) = segment_table +
	_ASCE_TABLE_LENGTH + _ASCE_USER_BITS + _ASCE_TYPE_SEGMENT;
	aste[4] = (u32)(addr_t) psal;
	lowcore->vdso_per_cpu_data = page_frame;

	return 0;

	out:
	free_page(page_frame);
	free_page(page_table);
	free_pages(segment_table, SEGMENT_ORDER);
	return -ENOMEM;
	}

	void vdso_free_per_cpu(struct lowcore *lowcore)
	{
	unsigned long segment_table, page_table, page_frame;
	u32 psal, aste;

	if (!vdso_enabled)
	return;

	psal = (u32 *)(addr_t) lowcore->paste[4];
	aste = (u32 *)(addr_t) psal[2];
	segment_table = (unsigned long )(aste + 2) & PAGE_MASK;
	page_table = (unsigned long ) segment_table;
	page_frame = (unsigned long ) page_table;

	free_page(page_frame);
	free_page(page_table);
	free_pages(segment_table, SEGMENT_ORDER);
	}

	static void vdso_init_cr5(void)
	{
	unsigned long cr5;

	if (!vdso_enabled)
	return;
	cr5 = offsetof(struct lowcore, paste);
	__ctl_load(cr5, 5, 5);
	}

	/*
	* 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 uses_interp)
	{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma;
	unsigned long vdso_pages;
	unsigned long vdso_base;
	int rc;

	if (!vdso_enabled)
	return 0;
	/*
	* Only map the vdso for dynamically linked elf binaries.
	*/
	if (!uses_interp)
	return 0;

	vdso_pages = vdso64_pages;
	#ifdef CONFIG_COMPAT
	if (is_compat_task())
	vdso_pages = vdso32_pages;
	#endif
	/*
	* vDSO has a problem and was disabled, just don't "enable" it for
	* the process
	*/
	if (vdso_pages == 0)
	return 0;

	/*
	* 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.
	*/
	if (down_write_killable(&mm->mmap_sem))
	return -EINTR;
	vdso_base = get_unmapped_area(NULL, 0, vdso_pages << PAGE_SHIFT, 0, 0);
	if (IS_ERR_VALUE(vdso_base)) {
	rc = vdso_base;
	goto out_up;
	}

	/*
	* 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 = _install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
	VM_READ\|VM_EXEC\|
	VM_MAYREAD\|VM_MAYWRITE\|VM_MAYEXEC,
	&vdso_mapping);
	if (IS_ERR(vma)) {
	rc = PTR_ERR(vma);
	goto out_up;
	}

	current->mm->context.vdso_base = vdso_base;
	rc = 0;

	out_up:
	up_write(&mm->mmap_sem);
	return rc;
	}

	static int __init vdso_init(void)
	{
	int i;

	if (!vdso_enabled)
	return 0;
	vdso_init_data(vdso_data);
	#ifdef CONFIG_COMPAT
	/* Calculate the size of the 32 bit vDSO */
	vdso32_pages = ((&vdso32_end - &vdso32_start
	+ PAGE_SIZE - 1) >> PAGE_SHIFT) + 1;

	/* Make sure pages are in the correct state */
	vdso32_pagelist = kzalloc(sizeof(struct page ) (vdso32_pages + 1),
	GFP_KERNEL);
	BUG_ON(vdso32_pagelist == NULL);
	for (i = 0; i < vdso32_pages - 1; i++) {
	struct page pg = virt_to_page(vdso32_kbase + iPAGE_SIZE);
	ClearPageReserved(pg);
	get_page(pg);
	vdso32_pagelist[i] = pg;
	}
	vdso32_pagelist[vdso32_pages - 1] = virt_to_page(vdso_data);
	vdso32_pagelist[vdso32_pages] = NULL;
	#endif

	/* Calculate the size of the 64 bit vDSO */
	vdso64_pages = ((&vdso64_end - &vdso64_start
	+ PAGE_SIZE - 1) >> PAGE_SHIFT) + 1;

	/* Make sure pages are in the correct state */
	vdso64_pagelist = kzalloc(sizeof(struct page ) (vdso64_pages + 1),
	GFP_KERNEL);
	BUG_ON(vdso64_pagelist == NULL);
	for (i = 0; i < vdso64_pages - 1; i++) {
	struct page pg = virt_to_page(vdso64_kbase + iPAGE_SIZE);
	ClearPageReserved(pg);
	get_page(pg);
	vdso64_pagelist[i] = pg;
	}
	vdso64_pagelist[vdso64_pages - 1] = virt_to_page(vdso_data);
	vdso64_pagelist[vdso64_pages] = NULL;
	if (vdso_alloc_per_cpu(&S390_lowcore))
	BUG();
	vdso_init_cr5();

	get_page(virt_to_page(vdso_data));

	return 0;
	}
	early_initcall(vdso_init);