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Merge branch 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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Pull x86 vdso updates from Ingo Molnar:
 "The main changes in this cycle centered around adding support for
  32-bit compatible C/R of the vDSO on 64-bit kernels, by Dmitry
  Safonov"

* 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/vdso: Use CONFIG_X86_X32_ABI to enable vdso prctl
  x86/vdso: Only define map_vdso_randomized() if CONFIG_X86_64
  x86/vdso: Only define prctl_map_vdso() if CONFIG_CHECKPOINT_RESTORE
  x86/signal: Add SA_{X32,IA32}_ABI sa_flags
  x86/ptrace: Down with test_thread_flag(TIF_IA32)
  x86/coredump: Use pr_reg size, rather that TIF_IA32 flag
  x86/arch_prctl/vdso: Add ARCH_MAP_VDSO_*
  x86/vdso: Replace calculate_addr in map_vdso() with addr
  x86/vdso: Unmap vdso blob on vvar mapping failure
This commit is contained in:
Linus Torvalds
2016-10-03 17:29:01 -07:00
parent 6aebe7f9e8 6e68b08728
commit 8e4ef63867
15 changed files with 220 additions and 106 deletions
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175
arch/x86/entry/vdso/vma.c
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@@ -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)
{
@@ -176,30 +128,28 @@ static int vvar_fault(const struct vm_special_mapping *sm,
return VM_FAULT_SIGBUS;
}
static int map_vdso(const struct vdso_image *image, bool calculate_addr)
static const struct vm_special_mapping vdso_mapping = {
.name = "[vdso]",
.fault = vdso_fault,
.mremap = vdso_mremap,
};
static const struct vm_special_mapping vvar_mapping = {
.name = "[vvar]",
.fault = vvar_fault,
};
/*
* Add vdso and vvar mappings to current process.
* @image - blob to map
* @addr - request a specific address (zero to map at free addr)
*/
static int map_vdso(const struct vdso_image *image, unsigned long addr)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
unsigned long addr, text_start;
unsigned long text_start;
int ret = 0;
static const struct vm_special_mapping vdso_mapping = {
.name = "[vdso]",
.fault = vdso_fault,
.mremap = vdso_mremap,
};
static const struct vm_special_mapping vvar_mapping = {
.name = "[vvar]",
.fault = vvar_fault,
};
if (calculate_addr) {
addr = vdso_addr(current->mm->start_stack,
image->size - image->sym_vvar_start);
} else {
addr = 0;
}
if (down_write_killable(&mm->mmap_sem))
return -EINTR;
@@ -238,24 +188,104 @@ static int map_vdso(const struct vdso_image *image, bool calculate_addr)
if (IS_ERR(vma)) {
ret = PTR_ERR(vma);
goto up_fail;
do_munmap(mm, text_start, image->size);
}
up_fail:
if (ret)
if (ret) {
current->mm->context.vdso = NULL;
current->mm->context.vdso_image = NULL;
}
up_write(&mm->mmap_sem);
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);
return map_vdso(image, addr);
}
#endif
int map_vdso_once(const struct vdso_image *image, unsigned long addr)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
down_write(&mm->mmap_sem);
/*
* Check if we have already mapped vdso blob - fail to prevent
* abusing from userspace install_speciall_mapping, which may
* not do accounting and rlimit right.
* We could search vma near context.vdso, but it's a slowpath,
* so let's explicitely check all VMAs to be completely sure.
*/
for (vma = mm->mmap; vma; vma = vma->vm_next) {
if (vma_is_special_mapping(vma, &vdso_mapping) ||
vma_is_special_mapping(vma, &vvar_mapping)) {
up_write(&mm->mmap_sem);
return -EEXIST;
}
}
up_write(&mm->mmap_sem);
return map_vdso(image, addr);
}
#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
static int load_vdso32(void)
{
if (vdso32_enabled != 1) /* Other values all mean "disabled" */
return 0;
return map_vdso(&vdso_image_32, false);
return map_vdso(&vdso_image_32, 0);
}
#endif
@@ -265,7 +295,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
if (!vdso64_enabled)
return 0;
return map_vdso(&vdso_image_64, true);
return map_vdso_randomized(&vdso_image_64);
}
#ifdef CONFIG_COMPAT
@@ -276,8 +306,7 @@ int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
if (test_thread_flag(TIF_X32)) {
if (!vdso64_enabled)
return 0;
return map_vdso(&vdso_image_x32, true);
return map_vdso_randomized(&vdso_image_x32);
}
#endif
#ifdef CONFIG_IA32_EMULATION