openkylin
/
linux
mirror of https://gitee.com/openkylin/linux.git
9
0
Fork 0
Code Issues Projects Releases Wiki Activity

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: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Ingo Molnar 2016-09-15 08:56:21 +02:00
parent 91b7bd39e6
commit 3947f49302
1 changed files with 48 additions and 50 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

98
arch/x86/entry/vdso/vma.c
View File

@ -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)
{