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Commit 3947f493 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

x86/vdso: Only define map_vdso_randomized() if CONFIG_X86_64 



... otherwise the compiler complains:

   arch/x86/entry/vdso/vma.c:252:12: warning: ‘map_vdso_randomized’ defined but not used [-Wunused-function]

But the #ifdeffery here is getting pretty ugly, so move around
vdso_addr() as well to cluster the dependencies a bit more.

It's still not particulary pretty though ...

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Dmitry Safonov <dsafonov@virtuozzo.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: gorcunov@openvz.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: oleg@redhat.com
Cc: xemul@virtuozzo.com
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 91b7bd39

arch/x86/entry/vdso/vma.c

+48 −50
Original line number Diff line number Diff line
@@ -37,54 +37,6 @@ void __init init_vdso_image(const struct vdso_image *image) 


struct linux_binprm;



/*

 * Put the vdso above the (randomized) stack with another randomized

 * offset.  This way there is no hole in the middle of address space.

 * To save memory make sure it is still in the same PTE as the stack

 * top.  This doesn't give that many random bits.

 *

 * Note that this algorithm is imperfect: the distribution of the vdso

 * start address within a PMD is biased toward the end.

 *

 * Only used for the 64-bit and x32 vdsos.

 */

static unsigned long vdso_addr(unsigned long start, unsigned len)

{

#ifdef CONFIG_X86_32

	return 0;

#else

	unsigned long addr, end;

	unsigned offset;



	/*

	 * Round up the start address.  It can start out unaligned as a result

	 * of stack start randomization.

	 */

	start = PAGE_ALIGN(start);



	/* Round the lowest possible end address up to a PMD boundary. */

	end = (start + len + PMD_SIZE - 1) & PMD_MASK;

	if (end >= TASK_SIZE_MAX)

		end = TASK_SIZE_MAX;

	end -= len;



	if (end > start) {

		offset = get_random_int() % (((end - start) >> PAGE_SHIFT) + 1);

		addr = start + (offset << PAGE_SHIFT);

	} else {

		addr = start;

	}



	/*

	 * Forcibly align the final address in case we have a hardware

	 * issue that requires alignment for performance reasons.

	 */

	addr = align_vdso_addr(addr);



	return addr;

#endif

}



static int vdso_fault(const struct vm_special_mapping *sm,

		      struct vm_area_struct *vma, struct vm_fault *vmf)

{
@@ -249,12 +201,58 @@ static int map_vdso(const struct vdso_image *image, unsigned long addr) 
	return ret;

}



#ifdef CONFIG_X86_64

/*

 * Put the vdso above the (randomized) stack with another randomized

 * offset.  This way there is no hole in the middle of address space.

 * To save memory make sure it is still in the same PTE as the stack

 * top.  This doesn't give that many random bits.

 *

 * Note that this algorithm is imperfect: the distribution of the vdso

 * start address within a PMD is biased toward the end.

 *

 * Only used for the 64-bit and x32 vdsos.

 */

static unsigned long vdso_addr(unsigned long start, unsigned len)

{

	unsigned long addr, end;

	unsigned offset;



	/*

	 * Round up the start address.  It can start out unaligned as a result

	 * of stack start randomization.

	 */

	start = PAGE_ALIGN(start);



	/* Round the lowest possible end address up to a PMD boundary. */

	end = (start + len + PMD_SIZE - 1) & PMD_MASK;

	if (end >= TASK_SIZE_MAX)

		end = TASK_SIZE_MAX;

	end -= len;



	if (end > start) {

		offset = get_random_int() % (((end - start) >> PAGE_SHIFT) + 1);

		addr = start + (offset << PAGE_SHIFT);

	} else {

		addr = start;

	}



	/*

	 * Forcibly align the final address in case we have a hardware

	 * issue that requires alignment for performance reasons.

	 */

	addr = align_vdso_addr(addr);



	return addr;

}



static int map_vdso_randomized(const struct vdso_image *image)

{

	unsigned long addr = vdso_addr(current->mm->start_stack,

				 image->size - image->sym_vvar_start);

	unsigned long addr = vdso_addr(current->mm->start_stack, image->size-image->sym_vvar_start);



	return map_vdso(image, addr);

}

#endif



int map_vdso_once(const struct vdso_image *image, unsigned long addr)

{