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Commit 35bb092a authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

s390/vdso: use _install_special_mapping to establish vdso 



Switch to the improved _install_special_mapping function to install
the vdso mapping. This has two advantages, the arch_vma_name function
is not needed anymore and the vdso vma still has its name after its
memory location has been changed with mremap.

Tested-by: default avatarMichael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent b29e061b

arch/s390/kernel/vdso.c

+64 −27
Original line number Diff line number Diff line
@@ -50,6 +50,56 @@ static struct page **vdso64_pagelist; 
 */

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;
@@ -181,7 +231,7 @@ static void vdso_init_cr5(void) 
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)

{

	struct mm_struct *mm = current->mm;

	struct page **vdso_pagelist;

	struct vm_area_struct *vma;

	unsigned long vdso_pages;

	unsigned long vdso_base;

	int rc;
@@ -194,13 +244,10 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 
	if (!uses_interp)

		return 0;



	vdso_pagelist = vdso64_pagelist;

	vdso_pages = vdso64_pages;

#ifdef CONFIG_COMPAT

	if (is_compat_task()) {

		vdso_pagelist = vdso32_pagelist;

	if (is_compat_task())

		vdso_pages = vdso32_pages;

	}

#endif

	/*

	 * vDSO has a problem and was disabled, just don't "enable" it for
@@ -209,8 +256,6 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 
	if (vdso_pages == 0)

		return 0;



	current->mm->context.vdso_base = 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
@@ -224,13 +269,6 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 
		goto out_up;

	}



	/*

	 * 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).

	 */

	current->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.
@@ -241,24 +279,23 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 
	 * It's fine to use that for setting breakpoints in the vDSO code

	 * pages though.

	 */

	rc = install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,

	vma = _install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,

				       VM_READ|VM_EXEC|

				       VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,

				     vdso_pagelist);

	if (rc)

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

				       &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;

}



const char *arch_vma_name(struct vm_area_struct *vma)

{

	if (vma->vm_mm && vma->vm_start == vma->vm_mm->context.vdso_base)

		return "[vdso]";

	return NULL;

}



static int __init vdso_init(void)

{

	int i;