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-rw-r--r--Documentation/kernel-parameters.txt7
-rw-r--r--arch/arc/mm/mmap.c2
-rw-r--r--arch/arm/mm/mmap.c4
-rw-r--r--arch/frv/mm/elf-fdpic.c2
-rw-r--r--arch/mips/mm/mmap.c2
-rw-r--r--arch/parisc/kernel/sys_parisc.c15
-rw-r--r--arch/powerpc/mm/slice.c2
-rw-r--r--arch/sh/mm/mmap.c4
-rw-r--r--arch/sparc/kernel/sys_sparc_64.c4
-rw-r--r--arch/sparc/mm/hugetlbpage.c2
-rw-r--r--arch/tile/mm/hugetlbpage.c2
-rw-r--r--arch/x86/kernel/sys_x86_64.c4
-rw-r--r--arch/x86/mm/hugetlbpage.c2
-rw-r--r--arch/xtensa/kernel/syscall.c2
-rw-r--r--fs/hugetlbfs/inode.c2
-rw-r--r--fs/proc/task_mmu.c4
-rw-r--r--include/linux/mm.h53
-rw-r--r--mm/gup.c5
-rw-r--r--mm/memory.c38
-rw-r--r--mm/mmap.c149
20 files changed, 147 insertions, 158 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index cb76a3cf0763..86c91be8647c 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -3154,6 +3154,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
spia_pedr=
spia_peddr=
+ stack_guard_gap= [MM]
+ override the default stack gap protection. The value
+ is in page units and it defines how many pages prior
+ to (for stacks growing down) resp. after (for stacks
+ growing up) the main stack are reserved for no other
+ mapping. Default value is 256 pages.
+
stacktrace [FTRACE]
Enabled the stack tracer on boot up.
diff --git a/arch/arc/mm/mmap.c b/arch/arc/mm/mmap.c
index 2e06d56e987b..cf4ae6958240 100644
--- a/arch/arc/mm/mmap.c
+++ b/arch/arc/mm/mmap.c
@@ -64,7 +64,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
vma = find_vma(mm, addr);
if (TASK_SIZE - len >= addr &&
- (!vma || addr + len <= vma->vm_start))
+ (!vma || addr + len <= vm_start_gap(vma)))
return addr;
}
diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
index 5e85ed371364..8f9d1cf505dd 100644
--- a/arch/arm/mm/mmap.c
+++ b/arch/arm/mm/mmap.c
@@ -89,7 +89,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
vma = find_vma(mm, addr);
if (TASK_SIZE - len >= addr &&
- (!vma || addr + len <= vma->vm_start))
+ (!vma || addr + len <= vm_start_gap(vma)))
return addr;
}
@@ -140,7 +140,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
addr = PAGE_ALIGN(addr);
vma = find_vma(mm, addr);
if (TASK_SIZE - len >= addr &&
- (!vma || addr + len <= vma->vm_start))
+ (!vma || addr + len <= vm_start_gap(vma)))
return addr;
}
diff --git a/arch/frv/mm/elf-fdpic.c b/arch/frv/mm/elf-fdpic.c
index 836f14707a62..efa59f1f8022 100644
--- a/arch/frv/mm/elf-fdpic.c
+++ b/arch/frv/mm/elf-fdpic.c
@@ -74,7 +74,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi
addr = PAGE_ALIGN(addr);
vma = find_vma(current->mm, addr);
if (TASK_SIZE - len >= addr &&
- (!vma || addr + len <= vma->vm_start))
+ (!vma || addr + len <= vm_start_gap(vma)))
goto success;
}
diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c
index f1baadd56e82..9be924f08f34 100644
--- a/arch/mips/mm/mmap.c
+++ b/arch/mips/mm/mmap.c
@@ -92,7 +92,7 @@ static unsigned long arch_get_unmapped_area_common(struct file *filp,
vma = find_vma(mm, addr);
if (TASK_SIZE - len >= addr &&
- (!vma || addr + len <= vma->vm_start))
+ (!vma || addr + len <= vm_start_gap(vma)))
return addr;
}
diff --git a/arch/parisc/kernel/sys_parisc.c b/arch/parisc/kernel/sys_parisc.c
index 5aba01ac457f..4dda73c44fee 100644
--- a/arch/parisc/kernel/sys_parisc.c
+++ b/arch/parisc/kernel/sys_parisc.c
@@ -88,7 +88,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
unsigned long len, unsigned long pgoff, unsigned long flags)
{
struct mm_struct *mm = current->mm;
- struct vm_area_struct *vma;
+ struct vm_area_struct *vma, *prev;
unsigned long task_size = TASK_SIZE;
int do_color_align, last_mmap;
struct vm_unmapped_area_info info;
@@ -115,9 +115,10 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
else
addr = PAGE_ALIGN(addr);
- vma = find_vma(mm, addr);
+ vma = find_vma_prev(mm, addr, &prev);
if (task_size - len >= addr &&
- (!vma || addr + len <= vma->vm_start))
+ (!vma || addr + len <= vm_start_gap(vma)) &&
+ (!prev || addr >= vm_end_gap(prev)))
goto found_addr;
}
@@ -141,7 +142,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
const unsigned long len, const unsigned long pgoff,
const unsigned long flags)
{
- struct vm_area_struct *vma;
+ struct vm_area_struct *vma, *prev;
struct mm_struct *mm = current->mm;
unsigned long addr = addr0;
int do_color_align, last_mmap;
@@ -175,9 +176,11 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
addr = COLOR_ALIGN(addr, last_mmap, pgoff);
else
addr = PAGE_ALIGN(addr);
- vma = find_vma(mm, addr);
+
+ vma = find_vma_prev(mm, addr, &prev);
if (TASK_SIZE - len >= addr &&
- (!vma || addr + len <= vma->vm_start))
+ (!vma || addr + len <= vm_start_gap(vma)) &&
+ (!prev || addr >= vm_end_gap(prev)))
goto found_addr;
}
diff --git a/arch/powerpc/mm/slice.c b/arch/powerpc/mm/slice.c
index b0c75cc15efc..7477de0e6e3c 100644
--- a/arch/powerpc/mm/slice.c
+++ b/arch/powerpc/mm/slice.c
@@ -103,7 +103,7 @@ static int slice_area_is_free(struct mm_struct *mm, unsigned long addr,
if ((mm->task_size - len) < addr)
return 0;
vma = find_vma(mm, addr);
- return (!vma || (addr + len) <= vma->vm_start);
+ return (!vma || (addr + len) <= vm_start_gap(vma));
}
static int slice_low_has_vma(struct mm_struct *mm, unsigned long slice)
diff --git a/arch/sh/mm/mmap.c b/arch/sh/mm/mmap.c
index 6777177807c2..7df7d5944188 100644
--- a/arch/sh/mm/mmap.c
+++ b/arch/sh/mm/mmap.c
@@ -63,7 +63,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
vma = find_vma(mm, addr);
if (TASK_SIZE - len >= addr &&
- (!vma || addr + len <= vma->vm_start))
+ (!vma || addr + len <= vm_start_gap(vma)))
return addr;
}
@@ -113,7 +113,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
vma = find_vma(mm, addr);
if (TASK_SIZE - len >= addr &&
- (!vma || addr + len <= vma->vm_start))
+ (!vma || addr + len <= vm_start_gap(vma)))
return addr;
}
diff --git a/arch/sparc/kernel/sys_sparc_64.c b/arch/sparc/kernel/sys_sparc_64.c
index c690c8e16a96..7f0f7c01b297 100644
--- a/arch/sparc/kernel/sys_sparc_64.c
+++ b/arch/sparc/kernel/sys_sparc_64.c
@@ -118,7 +118,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi
vma = find_vma(mm, addr);
if (task_size - len >= addr &&
- (!vma || addr + len <= vma->vm_start))
+ (!vma || addr + len <= vm_start_gap(vma)))
return addr;
}
@@ -181,7 +181,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
vma = find_vma(mm, addr);
if (task_size - len >= addr &&
- (!vma || addr + len <= vma->vm_start))
+ (!vma || addr + len <= vm_start_gap(vma)))
return addr;
}
diff --git a/arch/sparc/mm/hugetlbpage.c b/arch/sparc/mm/hugetlbpage.c
index d329537739c6..15034695b839 100644
--- a/arch/sparc/mm/hugetlbpage.c
+++ b/arch/sparc/mm/hugetlbpage.c
@@ -115,7 +115,7 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
addr = ALIGN(addr, HPAGE_SIZE);
vma = find_vma(mm, addr);
if (task_size - len >= addr &&
- (!vma || addr + len <= vma->vm_start))
+ (!vma || addr + len <= vm_start_gap(vma)))
return addr;
}
if (mm->get_unmapped_area == arch_get_unmapped_area)
diff --git a/arch/tile/mm/hugetlbpage.c b/arch/tile/mm/hugetlbpage.c
index e514899e1100..94c240634fc6 100644
--- a/arch/tile/mm/hugetlbpage.c
+++ b/arch/tile/mm/hugetlbpage.c
@@ -265,7 +265,7 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
addr = ALIGN(addr, huge_page_size(h));
vma = find_vma(mm, addr);
if (TASK_SIZE - len >= addr &&
- (!vma || addr + len <= vma->vm_start))
+ (!vma || addr + len <= vm_start_gap(vma)))
return addr;
}
if (current->mm->get_unmapped_area == arch_get_unmapped_area)
diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c
index 30277e27431a..d050393d3be2 100644
--- a/arch/x86/kernel/sys_x86_64.c
+++ b/arch/x86/kernel/sys_x86_64.c
@@ -127,7 +127,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
addr = PAGE_ALIGN(addr);
vma = find_vma(mm, addr);
if (end - len >= addr &&
- (!vma || addr + len <= vma->vm_start))
+ (!vma || addr + len <= vm_start_gap(vma)))
return addr;
}
@@ -166,7 +166,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
addr = PAGE_ALIGN(addr);
vma = find_vma(mm, addr);
if (TASK_SIZE - len >= addr &&
- (!vma || addr + len <= vma->vm_start))
+ (!vma || addr + len <= vm_start_gap(vma)))
return addr;
}
diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c
index 006cc914994b..fd277c4dd2e0 100644
--- a/arch/x86/mm/hugetlbpage.c
+++ b/arch/x86/mm/hugetlbpage.c
@@ -156,7 +156,7 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
addr = ALIGN(addr, huge_page_size(h));
vma = find_vma(mm, addr);
if (TASK_SIZE - len >= addr &&
- (!vma || addr + len <= vma->vm_start))
+ (!vma || addr + len <= vm_start_gap(vma)))
return addr;
}
if (mm->get_unmapped_area == arch_get_unmapped_area)
diff --git a/arch/xtensa/kernel/syscall.c b/arch/xtensa/kernel/syscall.c
index 5d3f7a119ed1..1ff0b92eeae7 100644
--- a/arch/xtensa/kernel/syscall.c
+++ b/arch/xtensa/kernel/syscall.c
@@ -86,7 +86,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
/* At this point: (!vmm || addr < vmm->vm_end). */
if (TASK_SIZE - len < addr)
return -ENOMEM;
- if (!vmm || addr + len <= vmm->vm_start)
+ if (!vmm || addr + len <= vm_start_gap(vmm))
return addr;
addr = vmm->vm_end;
if (flags & MAP_SHARED)
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index e3ac491424fc..3a4af9d401c3 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -171,7 +171,7 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
addr = ALIGN(addr, huge_page_size(h));
vma = find_vma(mm, addr);
if (TASK_SIZE - len >= addr &&
- (!vma || addr + len <= vma->vm_start))
+ (!vma || addr + len <= vm_start_gap(vma)))
return addr;
}
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 5825f6d944ce..fb073b9fe25e 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -273,11 +273,7 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
/* We don't show the stack guard page in /proc/maps */
start = vma->vm_start;
- if (stack_guard_page_start(vma, start))
- start += PAGE_SIZE;
end = vma->vm_end;
- if (stack_guard_page_end(vma, end))
- end -= PAGE_SIZE;
seq_setwidth(m, 25 + sizeof(void *) * 6 - 1);
seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
diff --git a/include/linux/mm.h b/include/linux/mm.h
index e648c24e8410..35f8b59b37a7 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1241,34 +1241,6 @@ int set_page_dirty_lock(struct page *page);
int clear_page_dirty_for_io(struct page *page);
int get_cmdline(struct task_struct *task, char *buffer, int buflen);
-/* Is the vma a continuation of the stack vma above it? */
-static inline int vma_growsdown(struct vm_area_struct *vma, unsigned long addr)
-{
- return vma && (vma->vm_end == addr) && (vma->vm_flags & VM_GROWSDOWN);
-}
-
-static inline int stack_guard_page_start(struct vm_area_struct *vma,
- unsigned long addr)
-{
- return (vma->vm_flags & VM_GROWSDOWN) &&
- (vma->vm_start == addr) &&
- !vma_growsdown(vma->vm_prev, addr);
-}
-
-/* Is the vma a continuation of the stack vma below it? */
-static inline int vma_growsup(struct vm_area_struct *vma, unsigned long addr)
-{
- return vma && (vma->vm_start == addr) && (vma->vm_flags & VM_GROWSUP);
-}
-
-static inline int stack_guard_page_end(struct vm_area_struct *vma,
- unsigned long addr)
-{
- return (vma->vm_flags & VM_GROWSUP) &&
- (vma->vm_end == addr) &&
- !vma_growsup(vma->vm_next, addr);
-}
-
extern pid_t
vm_is_stack(struct task_struct *task, struct vm_area_struct *vma, int in_group);
@@ -1914,6 +1886,7 @@ void page_cache_async_readahead(struct address_space *mapping,
unsigned long max_sane_readahead(unsigned long nr);
+extern unsigned long stack_guard_gap;
/* Generic expand stack which grows the stack according to GROWS{UP,DOWN} */
extern int expand_stack(struct vm_area_struct *vma, unsigned long address);
@@ -1942,6 +1915,30 @@ static inline struct vm_area_struct * find_vma_intersection(struct mm_struct * m
return vma;
}
+static inline unsigned long vm_start_gap(struct vm_area_struct *vma)
+{
+ unsigned long vm_start = vma->vm_start;
+
+ if (vma->vm_flags & VM_GROWSDOWN) {
+ vm_start -= stack_guard_gap;
+ if (vm_start > vma->vm_start)
+ vm_start = 0;
+ }
+ return vm_start;
+}
+
+static inline unsigned long vm_end_gap(struct vm_area_struct *vma)
+{
+ unsigned long vm_end = vma->vm_end;
+
+ if (vma->vm_flags & VM_GROWSUP) {
+ vm_end += stack_guard_gap;
+ if (vm_end < vma->vm_end)
+ vm_end = -PAGE_SIZE;
+ }
+ return vm_end;
+}
+
static inline unsigned long vma_pages(struct vm_area_struct *vma)
{
return (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
diff --git a/mm/gup.c b/mm/gup.c
index 2e4b9873b5aa..4d2fd27b33ab 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -266,11 +266,6 @@ static int faultin_page(struct task_struct *tsk, struct vm_area_struct *vma,
unsigned int fault_flags = 0;
int ret;
- /* For mlock, just skip the stack guard page. */
- if ((*flags & FOLL_MLOCK) &&
- (stack_guard_page_start(vma, address) ||
- stack_guard_page_end(vma, address + PAGE_SIZE)))
- return -ENOENT;
if (*flags & FOLL_WRITE)
fault_flags |= FAULT_FLAG_WRITE;
if (nonblocking)
diff --git a/mm/memory.c b/mm/memory.c
index 4e03447b1ef2..ea9698d1b865 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2589,40 +2589,6 @@ out_release:
}
/*
- * This is like a special single-page "expand_{down|up}wards()",
- * except we must first make sure that 'address{-|+}PAGE_SIZE'
- * doesn't hit another vma.
- */
-static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
-{
- address &= PAGE_MASK;
- if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
- struct vm_area_struct *prev = vma->vm_prev;
-
- /*
- * Is there a mapping abutting this one below?
- *
- * That's only ok if it's the same stack mapping
- * that has gotten split..
- */
- if (prev && prev->vm_end == address)
- return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
-
- return expand_downwards(vma, address - PAGE_SIZE);
- }
- if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
- struct vm_area_struct *next = vma->vm_next;
-
- /* As VM_GROWSDOWN but s/below/above/ */
- if (next && next->vm_start == address + PAGE_SIZE)
- return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
-
- return expand_upwards(vma, address + PAGE_SIZE);
- }
- return 0;
-}
-
-/*
* We enter with non-exclusive mmap_sem (to exclude vma changes,
* but allow concurrent faults), and pte mapped but not yet locked.
* We return with mmap_sem still held, but pte unmapped and unlocked.
@@ -2641,10 +2607,6 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
if (vma->vm_flags & VM_SHARED)
return VM_FAULT_SIGBUS;
- /* Check if we need to add a guard page to the stack */
- if (check_stack_guard_page(vma, address) < 0)
- return VM_FAULT_SIGSEGV;
-
/* Use the zero-page for reads */
if (!(flags & FAULT_FLAG_WRITE)) {
entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
diff --git a/mm/mmap.c b/mm/mmap.c
index b49641901093..9c6c7524b42d 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -266,6 +266,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
unsigned long rlim, retval;
unsigned long newbrk, oldbrk;
struct mm_struct *mm = current->mm;
+ struct vm_area_struct *next;
unsigned long min_brk;
bool populate;
@@ -311,7 +312,8 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
}
/* Check against existing mmap mappings. */
- if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
+ next = find_vma(mm, oldbrk);
+ if (next && newbrk + PAGE_SIZE > vm_start_gap(next))
goto out;
/* Ok, looks good - let it rip. */
@@ -334,10 +336,22 @@ out:
static long vma_compute_subtree_gap(struct vm_area_struct *vma)
{
- unsigned long max, subtree_gap;
- max = vma->vm_start;
- if (vma->vm_prev)
- max -= vma->vm_prev->vm_end;
+ unsigned long max, prev_end, subtree_gap;
+
+ /*
+ * Note: in the rare case of a VM_GROWSDOWN above a VM_GROWSUP, we
+ * allow two stack_guard_gaps between them here, and when choosing
+ * an unmapped area; whereas when expanding we only require one.
+ * That's a little inconsistent, but keeps the code here simpler.
+ */
+ max = vm_start_gap(vma);
+ if (vma->vm_prev) {
+ prev_end = vm_end_gap(vma->vm_prev);
+ if (max > prev_end)
+ max -= prev_end;
+ else
+ max = 0;
+ }
if (vma->vm_rb.rb_left) {
subtree_gap = rb_entry(vma->vm_rb.rb_left,
struct vm_area_struct, vm_rb)->rb_subtree_gap;
@@ -426,7 +440,7 @@ static void validate_mm(struct mm_struct *mm)
anon_vma_unlock_read(anon_vma);
}
- highest_address = vma->vm_end;
+ highest_address = vm_end_gap(vma);
vma = vma->vm_next;
i++;
}
@@ -594,7 +608,7 @@ void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
if (vma->vm_next)
vma_gap_update(vma->vm_next);
else
- mm->highest_vm_end = vma->vm_end;
+ mm->highest_vm_end = vm_end_gap(vma);
/*
* vma->vm_prev wasn't known when we followed the rbtree to find the
@@ -846,7 +860,7 @@ again: remove_next = 1 + (end > next->vm_end);
vma_gap_update(vma);
if (end_changed) {
if (!next)
- mm->highest_vm_end = end;
+ mm->highest_vm_end = vm_end_gap(vma);
else if (!adjust_next)
vma_gap_update(next);
}
@@ -889,7 +903,7 @@ again: remove_next = 1 + (end > next->vm_end);
else if (next)
vma_gap_update(next);
else
- mm->highest_vm_end = end;
+ VM_WARN_ON(mm->highest_vm_end != vm_end_gap(vma));
}
if (insert && file)
uprobe_mmap(insert);
@@ -1702,7 +1716,7 @@ unsigned long unmapped_area(struct vm_unmapped_area_info *info)
while (true) {
/* Visit left subtree if it looks promising */
- gap_end = vma->vm_start;
+ gap_end = vm_start_gap(vma);
if (gap_end >= low_limit && vma->vm_rb.rb_left) {
struct vm_area_struct *left =
rb_entry(vma->vm_rb.rb_left,
@@ -1713,7 +1727,7 @@ unsigned long unmapped_area(struct vm_unmapped_area_info *info)
}
}
- gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
+ gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
check_current:
/* Check if current node has a suitable gap */
if (gap_start > high_limit)
@@ -1740,8 +1754,8 @@ check_current:
vma = rb_entry(rb_parent(prev),
struct vm_area_struct, vm_rb);
if (prev == vma->vm_rb.rb_left) {
- gap_start = vma->vm_prev->vm_end;
- gap_end = vma->vm_start;
+ gap_start = vm_end_gap(vma->vm_prev);
+ gap_end = vm_start_gap(vma);
goto check_current;
}
}
@@ -1805,7 +1819,7 @@ unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
while (true) {
/* Visit right subtree if it looks promising */
- gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
+ gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
if (gap_start <= high_limit && vma->vm_rb.rb_right) {
struct vm_area_struct *right =
rb_entry(vma->vm_rb.rb_right,
@@ -1818,7 +1832,7 @@ unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
check_current:
/* Check if current node has a suitable gap */
- gap_end = vma->vm_start;
+ gap_end = vm_start_gap(vma);
if (gap_end < low_limit)
return -ENOMEM;
if (gap_start <= high_limit && gap_end - gap_start >= length)
@@ -1844,7 +1858,7 @@ check_current:
struct vm_area_struct, vm_rb);
if (prev == vma->vm_rb.rb_right) {
gap_start = vma->vm_prev ?
- vma->vm_prev->vm_end : 0;
+ vm_end_gap(vma->vm_prev) : 0;
goto check_current;
}
}
@@ -1882,7 +1896,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
unsigned long len, unsigned long pgoff, unsigned long flags)
{
struct mm_struct *mm = current->mm;
- struct vm_area_struct *vma;
+ struct vm_area_struct *vma, *prev;
struct vm_unmapped_area_info info;
if (len > TASK_SIZE - mmap_min_addr)
@@ -1893,9 +1907,10 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
if (addr) {
addr = PAGE_ALIGN(addr);
- vma = find_vma(mm, addr);
+ vma = find_vma_prev(mm, addr, &prev);
if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
- (!vma || addr + len <= vma->vm_start))
+ (!vma || addr + len <= vm_start_gap(vma)) &&
+ (!prev || addr >= vm_end_gap(prev)))
return addr;
}
@@ -1918,7 +1933,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
const unsigned long len, const unsigned long pgoff,
const unsigned long flags)
{
- struct vm_area_struct *vma;
+ struct vm_area_struct *vma, *prev;
struct mm_struct *mm = current->mm;
unsigned long addr = addr0;
struct vm_unmapped_area_info info;
@@ -1933,9 +1948,10 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
/* requesting a specific address */
if (addr) {
addr = PAGE_ALIGN(addr);
- vma = find_vma(mm, addr);
+ vma = find_vma_prev(mm, addr, &prev);
if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
- (!vma || addr + len <= vma->vm_start))
+ (!vma || addr + len <= vm_start_gap(vma)) &&
+ (!prev || addr >= vm_end_gap(prev)))
return addr;
}
@@ -2061,21 +2077,19 @@ find_vma_prev(struct mm_struct *mm, unsigned long addr,
* update accounting. This is shared with both the
* grow-up and grow-down cases.
*/
-static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
+static int acct_stack_growth(struct vm_area_struct *vma,
+ unsigned long size, unsigned long grow)
{
struct mm_struct *mm = vma->vm_mm;
struct rlimit *rlim = current->signal->rlim;
- unsigned long new_start, actual_size;
+ unsigned long new_start;
/* address space limit tests */
if (!may_expand_vm(mm, grow))
return -ENOMEM;
/* Stack limit test */
- actual_size = size;
- if (size && (vma->vm_flags & (VM_GROWSUP | VM_GROWSDOWN)))
- actual_size -= PAGE_SIZE;
- if (actual_size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur))
+ if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur))
return -ENOMEM;
/* mlock limit tests */
@@ -2116,17 +2130,30 @@ static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, uns
*/
int expand_upwards(struct vm_area_struct *vma, unsigned long address)
{
+ struct vm_area_struct *next;
+ unsigned long gap_addr;
int error = 0;
if (!(vma->vm_flags & VM_GROWSUP))
return -EFAULT;
/* Guard against wrapping around to address 0. */
- if (address < PAGE_ALIGN(address+4))
- address = PAGE_ALIGN(address+4);
- else
+ address &= PAGE_MASK;
+ address += PAGE_SIZE;
+ if (!address)
return -ENOMEM;
+ /* Enforce stack_guard_gap */
+ gap_addr = address + stack_guard_gap;
+ if (gap_addr < address)
+ return -ENOMEM;
+ next = vma->vm_next;
+ if (next && next->vm_start < gap_addr) {
+ if (!(next->vm_flags & VM_GROWSUP))
+ return -ENOMEM;
+ /* Check that both stack segments have the same anon_vma? */
+ }
+
/* We must make sure the anon_vma is allocated. */
if (unlikely(anon_vma_prepare(vma)))
return -ENOMEM;
@@ -2167,7 +2194,7 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
if (vma->vm_next)
vma_gap_update(vma->vm_next);
else
- vma->vm_mm->highest_vm_end = address;
+ vma->vm_mm->highest_vm_end = vm_end_gap(vma);
spin_unlock(&vma->vm_mm->page_table_lock);
perf_event_mmap(vma);
@@ -2187,6 +2214,8 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
int expand_downwards(struct vm_area_struct *vma,
unsigned long address)
{
+ struct vm_area_struct *prev;
+ unsigned long gap_addr;
int error;
address &= PAGE_MASK;
@@ -2194,6 +2223,17 @@ int expand_downwards(struct vm_area_struct *vma,
if (error)
return error;
+ /* Enforce stack_guard_gap */
+ gap_addr = address - stack_guard_gap;
+ if (gap_addr > address)
+ return -ENOMEM;
+ prev = vma->vm_prev;
+ if (prev && prev->vm_end > gap_addr) {
+ if (!(prev->vm_flags & VM_GROWSDOWN))
+ return -ENOMEM;
+ /* Check that both stack segments have the same anon_vma? */
+ }
+
/* We must make sure the anon_vma is allocated. */
if (unlikely(anon_vma_prepare(vma)))
return -ENOMEM;
@@ -2245,28 +2285,25 @@ int expand_downwards(struct vm_area_struct *vma,
return error;
}
-/*
- * Note how expand_stack() refuses to expand the stack all the way to
- * abut the next virtual mapping, *unless* that mapping itself is also
- * a stack mapping. We want to leave room for a guard page, after all
- * (the guard page itself is not added here, that is done by the
- * actual page faulting logic)
- *
- * This matches the behavior of the guard page logic (see mm/memory.c:
- * check_stack_guard_page()), which only allows the guard page to be
- * removed under these circumstances.
- */
+/* enforced gap between the expanding stack and other mappings. */
+unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT;
+
+static int __init cmdline_parse_stack_guard_gap(char *p)
+{
+ unsigned long val;
+ char *endptr;
+
+ val = simple_strtoul(p, &endptr, 10);
+ if (!*endptr)
+ stack_guard_gap = val << PAGE_SHIFT;
+
+ return 0;
+}
+__setup("stack_guard_gap=", cmdline_parse_stack_guard_gap);
+
#ifdef CONFIG_STACK_GROWSUP
int expand_stack(struct vm_area_struct *vma, unsigned long address)
{
- struct vm_area_struct *next;
-
- address &= PAGE_MASK;
- next = vma->vm_next;
- if (next && next->vm_start == address + PAGE_SIZE) {
- if (!(next->vm_flags & VM_GROWSUP))
- return -ENOMEM;
- }
return expand_upwards(vma, address);
}
@@ -2288,14 +2325,6 @@ find_extend_vma(struct mm_struct *mm, unsigned long addr)
#else
int expand_stack(struct vm_area_struct *vma, unsigned long address)
{
- struct vm_area_struct *prev;
-
- address &= PAGE_MASK;
- prev = vma->vm_prev;
- if (prev && prev->vm_end == address) {
- if (!(prev->vm_flags & VM_GROWSDOWN))
- return -ENOMEM;
- }
return expand_downwards(vma, address);
}
@@ -2391,7 +2420,7 @@ detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
vma->vm_prev = prev;
vma_gap_update(vma);
} else
- mm->highest_vm_end = prev ? prev->vm_end : 0;
+ mm->highest_vm_end = prev ? vm_end_gap(prev) : 0;
tail_vma->vm_next = NULL;
/* Kill the cache */
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-03 00:08:06 +0000