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-rw-r--r--Documentation/admin-guide/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/hugetlbpage-radix.c2
-rw-r--r--arch/powerpc/mm/mmap.c4
-rw-r--r--arch/powerpc/mm/slice.c2
-rw-r--r--arch/s390/mm/mmap.c4
-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
23 files changed, 152 insertions, 163 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 0f5c3b4347c6..7737ab5d04b2 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3811,6 +3811,13 @@
expediting. Set to zero to disable automatic
expediting.
+ 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 3e25e8d6486b..2e13683dfb24 100644
--- a/arch/arc/mm/mmap.c
+++ b/arch/arc/mm/mmap.c
@@ -65,7 +65,7 @@ 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 2239fde10b80..f0701d8d24df 100644
--- a/arch/arm/mm/mmap.c
+++ b/arch/arm/mm/mmap.c
@@ -90,7 +90,7 @@ 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;
}
@@ -141,7 +141,7 @@ 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 da82c25301e7..46aa289c5102 100644
--- a/arch/frv/mm/elf-fdpic.c
+++ b/arch/frv/mm/elf-fdpic.c
@@ -75,7 +75,7 @@ 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 64dd8bdd92c3..28adeabe851f 100644
--- a/arch/mips/mm/mmap.c
+++ b/arch/mips/mm/mmap.c
@@ -93,7 +93,7 @@ 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 e5288638a1d9..378a754ca186 100644
--- a/arch/parisc/kernel/sys_parisc.c
+++ b/arch/parisc/kernel/sys_parisc.c
@@ -90,7 +90,7 @@ 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;
@@ -117,9 +117,10 @@ 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;
}
@@ -143,7 +144,7 @@ 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;
@@ -177,9 +178,11 @@ 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/hugetlbpage-radix.c b/arch/powerpc/mm/hugetlbpage-radix.c
index 6575b9aabef4..a12e86395025 100644
--- a/arch/powerpc/mm/hugetlbpage-radix.c
+++ b/arch/powerpc/mm/hugetlbpage-radix.c
@@ -68,7 +68,7 @@ radix__hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
addr = ALIGN(addr, huge_page_size(h));
vma = find_vma(mm, addr);
if (mm->task_size - len >= addr &&
- (!vma || addr + len <= vma->vm_start))
+ (!vma || addr + len <= vm_start_gap(vma)))
return addr;
}
/*
diff --git a/arch/powerpc/mm/mmap.c b/arch/powerpc/mm/mmap.c
index 9dbd2a733d6b..0ee6be4f1ba4 100644
--- a/arch/powerpc/mm/mmap.c
+++ b/arch/powerpc/mm/mmap.c
@@ -112,7 +112,7 @@ radix__arch_get_unmapped_area(struct file *filp, unsigned long addr,
addr = PAGE_ALIGN(addr);
vma = find_vma(mm, addr);
if (mm->task_size - len >= addr && addr >= mmap_min_addr &&
- (!vma || addr + len <= vma->vm_start))
+ (!vma || addr + len <= vm_start_gap(vma)))
return addr;
}
@@ -157,7 +157,7 @@ radix__arch_get_unmapped_area_topdown(struct file *filp,
addr = PAGE_ALIGN(addr);
vma = find_vma(mm, addr);
if (mm->task_size - len >= addr && addr >= mmap_min_addr &&
- (!vma || addr + len <= vma->vm_start))
+ (!vma || addr + len <= vm_start_gap(vma)))
return addr;
}
diff --git a/arch/powerpc/mm/slice.c b/arch/powerpc/mm/slice.c
index 966b9fccfa66..45f6740dd407 100644
--- a/arch/powerpc/mm/slice.c
+++ b/arch/powerpc/mm/slice.c
@@ -99,7 +99,7 @@ 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/s390/mm/mmap.c b/arch/s390/mm/mmap.c
index b017daed6887..b854b1da281a 100644
--- a/arch/s390/mm/mmap.c
+++ b/arch/s390/mm/mmap.c
@@ -101,7 +101,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
addr = PAGE_ALIGN(addr);
vma = find_vma(mm, addr);
if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
- (!vma || addr + len <= vma->vm_start))
+ (!vma || addr + len <= vm_start_gap(vma)))
goto check_asce_limit;
}
@@ -151,7 +151,7 @@ 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 && addr >= mmap_min_addr &&
- (!vma || addr + len <= vma->vm_start))
+ (!vma || addr + len <= vm_start_gap(vma)))
goto check_asce_limit;
}
diff --git a/arch/sh/mm/mmap.c b/arch/sh/mm/mmap.c
index 08e7af0be4a7..6a1a1297baae 100644
--- a/arch/sh/mm/mmap.c
+++ b/arch/sh/mm/mmap.c
@@ -64,7 +64,7 @@ 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;
}
@@ -114,7 +114,7 @@ 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 ef4520efc813..043544d0cda3 100644
--- a/arch/sparc/kernel/sys_sparc_64.c
+++ b/arch/sparc/kernel/sys_sparc_64.c
@@ -120,7 +120,7 @@ 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;
}
@@ -183,7 +183,7 @@ 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 7c29d38e6b99..88855e383b34 100644
--- a/arch/sparc/mm/hugetlbpage.c
+++ b/arch/sparc/mm/hugetlbpage.c
@@ -120,7 +120,7 @@ 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/tile/mm/hugetlbpage.c b/arch/tile/mm/hugetlbpage.c
index cb10153b5c9f..03e5cc4e76e4 100644
--- a/arch/tile/mm/hugetlbpage.c
+++ b/arch/tile/mm/hugetlbpage.c
@@ -233,7 +233,7 @@ 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 207b8f2582c7..213ddf3e937d 100644
--- a/arch/x86/kernel/sys_x86_64.c
+++ b/arch/x86/kernel/sys_x86_64.c
@@ -144,7 +144,7 @@ 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;
}
@@ -187,7 +187,7 @@ 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 302f43fd9c28..adad702b39cd 100644
--- a/arch/x86/mm/hugetlbpage.c
+++ b/arch/x86/mm/hugetlbpage.c
@@ -148,7 +148,7 @@ 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 06937928cb72..74afbf02d07e 100644
--- a/arch/xtensa/kernel/syscall.c
+++ b/arch/xtensa/kernel/syscall.c
@@ -88,7 +88,7 @@ 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 dde861387a40..d44f5456eb9b 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -200,7 +200,7 @@ 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 f0c8b33d99b1..520802da059c 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -300,11 +300,7 @@ 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 b892e95d4929..6f543a47fc92 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1393,12 +1393,6 @@ 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 bool vma_is_anonymous(struct vm_area_struct *vma)
{
return !vma->vm_ops;
@@ -1414,28 +1408,6 @@ bool vma_is_shmem(struct vm_area_struct *vma);
static inline bool vma_is_shmem(struct vm_area_struct *vma) { return false; }
#endif
-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);
-}
-
int vma_is_stack_for_current(struct vm_area_struct *vma);
extern unsigned long move_page_tables(struct vm_area_struct *vma,
@@ -2222,6 +2194,7 @@ void page_cache_async_readahead(struct address_space *mapping,
pgoff_t offset,
unsigned long size);
+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);
@@ -2250,6 +2223,30 @@ 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 b3c7214d710d..576c4df58882 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -387,11 +387,6 @@ static int faultin_page(struct task_struct *tsk, struct vm_area_struct *vma,
/* mlock all present pages, but do not fault in new pages */
if ((*flags & (FOLL_POPULATE | FOLL_MLOCK)) == FOLL_MLOCK)
return -ENOENT;
- /* For mm_populate(), just skip the stack guard page. */
- if ((*flags & FOLL_POPULATE) &&
- (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 (*flags & FOLL_REMOTE)
diff --git a/mm/memory.c b/mm/memory.c
index 2e65df1831d9..bb11c474857e 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2855,40 +2855,6 @@ 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.
@@ -2904,10 +2870,6 @@ static int do_anonymous_page(struct vm_fault *vmf)
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, vmf->address) < 0)
- return VM_FAULT_SIGSEGV;
-
/*
* Use pte_alloc() instead of pte_alloc_map(). We can't run
* pte_offset_map() on pmds where a huge pmd might be created
diff --git a/mm/mmap.c b/mm/mmap.c
index f82741e199c0..8e07976d5e47 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -183,6 +183,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
unsigned long retval;
unsigned long newbrk, oldbrk;
struct mm_struct *mm = current->mm;
+ struct vm_area_struct *next;
unsigned long min_brk;
bool populate;
LIST_HEAD(uf);
@@ -229,7 +230,8 @@ 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. */
@@ -253,10 +255,22 @@ 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;
@@ -352,7 +366,7 @@ 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++;
}
@@ -541,7 +555,7 @@ 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
@@ -856,7 +870,7 @@ again:
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);
}
@@ -941,7 +955,7 @@ again:
* mm->highest_vm_end doesn't need any update
* in remove_next == 1 case.
*/
- VM_WARN_ON(mm->highest_vm_end != end);
+ VM_WARN_ON(mm->highest_vm_end != vm_end_gap(vma));
}
}
if (insert && file)
@@ -1787,7 +1801,7 @@ 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,
@@ -1798,7 +1812,7 @@ 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)
@@ -1825,8 +1839,8 @@ 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;
}
}
@@ -1890,7 +1904,7 @@ 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,
@@ -1903,7 +1917,7 @@ 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)
@@ -1929,7 +1943,7 @@ 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;
}
}
@@ -1967,7 +1981,7 @@ 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)
@@ -1978,9 +1992,10 @@ 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;
}
@@ -2003,7 +2018,7 @@ 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;
@@ -2018,9 +2033,10 @@ 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;
}
@@ -2155,21 +2171,19 @@ 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, vma->vm_flags, 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 > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur))
+ if (size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur))
return -ENOMEM;
/* mlock limit tests */
@@ -2207,17 +2221,30 @@ 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 mm_struct *mm = vma->vm_mm;
+ 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;
@@ -2261,7 +2288,7 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
if (vma->vm_next)
vma_gap_update(vma->vm_next);
else
- mm->highest_vm_end = address;
+ mm->highest_vm_end = vm_end_gap(vma);
spin_unlock(&mm->page_table_lock);
perf_event_mmap(vma);
@@ -2282,6 +2309,8 @@ int expand_downwards(struct vm_area_struct *vma,
unsigned long address)
{
struct mm_struct *mm = vma->vm_mm;
+ struct vm_area_struct *prev;
+ unsigned long gap_addr;
int error;
address &= PAGE_MASK;
@@ -2289,6 +2318,17 @@ 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;
@@ -2343,28 +2383,25 @@ 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);
}
@@ -2386,14 +2423,6 @@ 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);
}
@@ -2491,7 +2520,7 @@ 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 2024-11-16 07:24:48 +0000