[RFC,v2,2/2] Architecture defined limit on memory region random shift.

Commit Message

[e-mail] March 22, 2018, 4:36 p.m. UTC

Signed-off-by: Ilya Smith <[e-mail]>
---
 arch/alpha/kernel/osf_sys.c         | 1 +
 arch/arc/mm/mmap.c                  | 1 +
 arch/arm/mm/mmap.c                  | 2 ++
 arch/frv/mm/elf-fdpic.c             | 1 +
 arch/ia64/kernel/sys_ia64.c         | 1 +
 arch/ia64/mm/hugetlbpage.c          | 1 +
 arch/metag/mm/hugetlbpage.c         | 1 +
 arch/mips/mm/mmap.c                 | 1 +
 arch/parisc/kernel/sys_parisc.c     | 2 ++
 arch/powerpc/mm/hugetlbpage-radix.c | 1 +
 arch/powerpc/mm/mmap.c              | 2 ++
 arch/powerpc/mm/slice.c             | 2 ++
 arch/s390/mm/mmap.c                 | 2 ++
 arch/sh/mm/mmap.c                   | 2 ++
 arch/sparc/kernel/sys_sparc_32.c    | 1 +
 arch/sparc/kernel/sys_sparc_64.c    | 2 ++
 arch/sparc/mm/hugetlbpage.c         | 2 ++
 arch/tile/mm/hugetlbpage.c          | 2 ++
 arch/x86/kernel/sys_x86_64.c        | 4 ++++
 arch/x86/mm/hugetlbpage.c           | 4 ++++
 fs/hugetlbfs/inode.c                | 1 +
 include/linux/mm.h                  | 1 +
 mm/mmap.c                           | 3 ++-
 23 files changed, 39 insertions(+), 1 deletion(-)

Comments

Andrew Morton March 22, 2018, 8:54 p.m. UTC | #1

Please add changelogs.  An explanation of what a "limit on memory
region random shift" is would be nice ;) Why does it exist, why are we
doing this, etc.  Surely there's something to be said - at present this
is just a lump of random code?



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[e-mail] March 23, 2018, 5:49 p.m. UTC | #2

> On 22 Mar 2018, at 23:54, Andrew Morton <[e-mail]> wrote:
> 
> 
> Please add changelogs.  An explanation of what a "limit on memory
> region random shift" is would be nice ;) Why does it exist, why are we
> doing this, etc.  Surely there's something to be said - at present this
> is just a lump of random code?
> 
> 
> 
Sorry, my bad. The main idea of this limit is to decrease possible memory 
fragmentation. This is not so big problem on 64bit process, but really big for 
32 bit processes since may cause failure memory allocation. To control memory 
fragmentation and protect 32 bit systems (or architectures) this limit was 
introduce by this patch. It could be also moved to CONFIG_ as well.--
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Patch

diff --git a/arch/alpha/kernel/osf_sys.c b/arch/alpha/kernel/osf_sys.c
index fa1a392..0ab9f31 100644
--- a/arch/alpha/kernel/osf_sys.c
+++ b/arch/alpha/kernel/osf_sys.c
@@ -1301,6 +1301,7 @@  arch_get_unmapped_area_1(unsigned long addr, unsigned long len,
 	info.high_limit = limit;
 	info.align_mask = 0;
 	info.align_offset = 0;
+	info.random_shift = 0;
 	return vm_unmapped_area(&info);
 }
 
diff --git a/arch/arc/mm/mmap.c b/arch/arc/mm/mmap.c
index 2e13683..45225fc 100644
--- a/arch/arc/mm/mmap.c
+++ b/arch/arc/mm/mmap.c
@@ -75,5 +75,6 @@  arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	info.high_limit = TASK_SIZE;
 	info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
 	info.align_offset = pgoff << PAGE_SHIFT;
+	info.random_shift = 0;
 	return vm_unmapped_area(&info);
 }
diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
index eb1de66..1eb660c 100644
--- a/arch/arm/mm/mmap.c
+++ b/arch/arm/mm/mmap.c
@@ -101,6 +101,7 @@  arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	info.high_limit = TASK_SIZE;
 	info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
 	info.align_offset = pgoff << PAGE_SHIFT;
+	info.random_shift = 0;
 	return vm_unmapped_area(&info);
 }
 
@@ -152,6 +153,7 @@  arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	info.high_limit = mm->mmap_base;
 	info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
 	info.align_offset = pgoff << PAGE_SHIFT;
+	info.random_shift = 0;
 	addr = vm_unmapped_area(&info);
 
 	/*
diff --git a/arch/frv/mm/elf-fdpic.c b/arch/frv/mm/elf-fdpic.c
index 46aa289..a2ce2ce 100644
--- a/arch/frv/mm/elf-fdpic.c
+++ b/arch/frv/mm/elf-fdpic.c
@@ -86,6 +86,7 @@  unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi
 	info.high_limit = (current->mm->start_stack - 0x00200000);
 	info.align_mask = 0;
 	info.align_offset = 0;
+	info.random_shift = 0;
 	addr = vm_unmapped_area(&info);
 	if (!(addr & ~PAGE_MASK))
 		goto success;
diff --git a/arch/ia64/kernel/sys_ia64.c b/arch/ia64/kernel/sys_ia64.c
index 085adfc..15fa4fb 100644
--- a/arch/ia64/kernel/sys_ia64.c
+++ b/arch/ia64/kernel/sys_ia64.c
@@ -64,6 +64,7 @@  arch_get_unmapped_area (struct file *filp, unsigned long addr, unsigned long len
 	info.high_limit = TASK_SIZE;
 	info.align_mask = align_mask;
 	info.align_offset = 0;
+	info.random_shift = 0;
 	return vm_unmapped_area(&info);
 }
 
diff --git a/arch/ia64/mm/hugetlbpage.c b/arch/ia64/mm/hugetlbpage.c
index d16e419..ec7822d 100644
--- a/arch/ia64/mm/hugetlbpage.c
+++ b/arch/ia64/mm/hugetlbpage.c
@@ -162,6 +162,7 @@  unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr, u
 	info.high_limit = HPAGE_REGION_BASE + RGN_MAP_LIMIT;
 	info.align_mask = PAGE_MASK & (HPAGE_SIZE - 1);
 	info.align_offset = 0;
+	info.random_shift = 0;
 	return vm_unmapped_area(&info);
 }
 
diff --git a/arch/metag/mm/hugetlbpage.c b/arch/metag/mm/hugetlbpage.c
index 012ee4c..babd325 100644
--- a/arch/metag/mm/hugetlbpage.c
+++ b/arch/metag/mm/hugetlbpage.c
@@ -191,6 +191,7 @@  hugetlb_get_unmapped_area_new_pmd(unsigned long len)
 	info.high_limit = TASK_SIZE;
 	info.align_mask = PAGE_MASK & HUGEPT_MASK;
 	info.align_offset = 0;
+	info.random_shift = 0;
 	return vm_unmapped_area(&info);
 }
 
diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c
index 33d3251..5a3d384 100644
--- a/arch/mips/mm/mmap.c
+++ b/arch/mips/mm/mmap.c
@@ -122,6 +122,7 @@  static unsigned long arch_get_unmapped_area_common(struct file *filp,
 	info.flags = 0;
 	info.low_limit = mm->mmap_base;
 	info.high_limit = TASK_SIZE;
+	info.random_shift = 0;
 	return vm_unmapped_area(&info);
 }
 
diff --git a/arch/parisc/kernel/sys_parisc.c b/arch/parisc/kernel/sys_parisc.c
index 378a754..abf4b05 100644
--- a/arch/parisc/kernel/sys_parisc.c
+++ b/arch/parisc/kernel/sys_parisc.c
@@ -130,6 +130,7 @@  unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	info.high_limit = mmap_upper_limit();
 	info.align_mask = last_mmap ? (PAGE_MASK & (SHM_COLOUR - 1)) : 0;
 	info.align_offset = shared_align_offset(last_mmap, pgoff);
+	info.random_shift = 0;
 	addr = vm_unmapped_area(&info);
 
 found_addr:
@@ -192,6 +193,7 @@  arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	info.high_limit = mm->mmap_base;
 	info.align_mask = last_mmap ? (PAGE_MASK & (SHM_COLOUR - 1)) : 0;
 	info.align_offset = shared_align_offset(last_mmap, pgoff);
+	info.random_shift = 0;
 	addr = vm_unmapped_area(&info);
 	if (!(addr & ~PAGE_MASK))
 		goto found_addr;
diff --git a/arch/powerpc/mm/hugetlbpage-radix.c b/arch/powerpc/mm/hugetlbpage-radix.c
index 2486bee..1d61a88 100644
--- a/arch/powerpc/mm/hugetlbpage-radix.c
+++ b/arch/powerpc/mm/hugetlbpage-radix.c
@@ -87,6 +87,7 @@  radix__hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 	info.high_limit = mm->mmap_base + (high_limit - DEFAULT_MAP_WINDOW);
 	info.align_mask = PAGE_MASK & ~huge_page_mask(h);
 	info.align_offset = 0;
+	info.random_shift = 0;
 
 	return vm_unmapped_area(&info);
 }
diff --git a/arch/powerpc/mm/mmap.c b/arch/powerpc/mm/mmap.c
index d503f34..7fe98c7 100644
--- a/arch/powerpc/mm/mmap.c
+++ b/arch/powerpc/mm/mmap.c
@@ -136,6 +136,7 @@  radix__arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	info.low_limit = mm->mmap_base;
 	info.high_limit = high_limit;
 	info.align_mask = 0;
+	info.random_shift = 0;
 
 	return vm_unmapped_area(&info);
 }
@@ -180,6 +181,7 @@  radix__arch_get_unmapped_area_topdown(struct file *filp,
 	info.low_limit = max(PAGE_SIZE, mmap_min_addr);
 	info.high_limit = mm->mmap_base + (high_limit - DEFAULT_MAP_WINDOW);
 	info.align_mask = 0;
+	info.random_shift = 0;
 
 	addr = vm_unmapped_area(&info);
 	if (!(addr & ~PAGE_MASK))
diff --git a/arch/powerpc/mm/slice.c b/arch/powerpc/mm/slice.c
index 23ec2c5..2005845 100644
--- a/arch/powerpc/mm/slice.c
+++ b/arch/powerpc/mm/slice.c
@@ -284,6 +284,7 @@  static unsigned long slice_find_area_bottomup(struct mm_struct *mm,
 	info.length = len;
 	info.align_mask = PAGE_MASK & ((1ul << pshift) - 1);
 	info.align_offset = 0;
+	info.random_shift = 0;
 
 	addr = TASK_UNMAPPED_BASE;
 	/*
@@ -330,6 +331,7 @@  static unsigned long slice_find_area_topdown(struct mm_struct *mm,
 	info.length = len;
 	info.align_mask = PAGE_MASK & ((1ul << pshift) - 1);
 	info.align_offset = 0;
+	info.random_shift = 0;
 
 	addr = mm->mmap_base;
 	/*
diff --git a/arch/s390/mm/mmap.c b/arch/s390/mm/mmap.c
index 831bdcf..141823f 100644
--- a/arch/s390/mm/mmap.c
+++ b/arch/s390/mm/mmap.c
@@ -95,6 +95,7 @@  arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	info.length = len;
 	info.low_limit = mm->mmap_base;
 	info.high_limit = TASK_SIZE;
+	info.random_shift = 0;
 	if (filp || (flags & MAP_SHARED))
 		info.align_mask = MMAP_ALIGN_MASK << PAGE_SHIFT;
 	else
@@ -146,6 +147,7 @@  arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	info.length = len;
 	info.low_limit = max(PAGE_SIZE, mmap_min_addr);
 	info.high_limit = mm->mmap_base;
+	info.random_shift = 0;
 	if (filp || (flags & MAP_SHARED))
 		info.align_mask = MMAP_ALIGN_MASK << PAGE_SHIFT;
 	else
diff --git a/arch/sh/mm/mmap.c b/arch/sh/mm/mmap.c
index 6a1a129..d9206c2 100644
--- a/arch/sh/mm/mmap.c
+++ b/arch/sh/mm/mmap.c
@@ -74,6 +74,7 @@  unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	info.high_limit = TASK_SIZE;
 	info.align_mask = do_colour_align ? (PAGE_MASK & shm_align_mask) : 0;
 	info.align_offset = pgoff << PAGE_SHIFT;
+	info.random_shift = 0;
 	return vm_unmapped_area(&info);
 }
 
@@ -124,6 +125,7 @@  arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	info.high_limit = mm->mmap_base;
 	info.align_mask = do_colour_align ? (PAGE_MASK & shm_align_mask) : 0;
 	info.align_offset = pgoff << PAGE_SHIFT;
+	info.random_shift = 0;
 	addr = vm_unmapped_area(&info);
 
 	/*
diff --git a/arch/sparc/kernel/sys_sparc_32.c b/arch/sparc/kernel/sys_sparc_32.c
index 990703b7..af664ba3 100644
--- a/arch/sparc/kernel/sys_sparc_32.c
+++ b/arch/sparc/kernel/sys_sparc_32.c
@@ -66,6 +66,7 @@  unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi
 	info.align_mask = (flags & MAP_SHARED) ?
 		(PAGE_MASK & (SHMLBA - 1)) : 0;
 	info.align_offset = pgoff << PAGE_SHIFT;
+	info.random_shift = 0;
 	return vm_unmapped_area(&info);
 }
 
diff --git a/arch/sparc/kernel/sys_sparc_64.c b/arch/sparc/kernel/sys_sparc_64.c
index 55416db..3d12e3d 100644
--- a/arch/sparc/kernel/sys_sparc_64.c
+++ b/arch/sparc/kernel/sys_sparc_64.c
@@ -131,6 +131,7 @@  unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi
 	info.high_limit = min(task_size, VA_EXCLUDE_START);
 	info.align_mask = do_color_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
 	info.align_offset = pgoff << PAGE_SHIFT;
+	info.random_shift = 0;
 	addr = vm_unmapped_area(&info);
 
 	if ((addr & ~PAGE_MASK) && task_size > VA_EXCLUDE_END) {
@@ -194,6 +195,7 @@  arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	info.high_limit = mm->mmap_base;
 	info.align_mask = do_color_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
 	info.align_offset = pgoff << PAGE_SHIFT;
+	info.random_shift = 0;
 	addr = vm_unmapped_area(&info);
 
 	/*
diff --git a/arch/sparc/mm/hugetlbpage.c b/arch/sparc/mm/hugetlbpage.c
index 0112d69..6d0c032 100644
--- a/arch/sparc/mm/hugetlbpage.c
+++ b/arch/sparc/mm/hugetlbpage.c
@@ -43,6 +43,7 @@  static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *filp,
 	info.high_limit = min(task_size, VA_EXCLUDE_START);
 	info.align_mask = PAGE_MASK & ~huge_page_mask(h);
 	info.align_offset = 0;
+	info.random_shift = 0;
 	addr = vm_unmapped_area(&info);
 
 	if ((addr & ~PAGE_MASK) && task_size > VA_EXCLUDE_END) {
@@ -75,6 +76,7 @@  hugetlb_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	info.high_limit = mm->mmap_base;
 	info.align_mask = PAGE_MASK & ~huge_page_mask(h);
 	info.align_offset = 0;
+	info.random_shift = 0;
 	addr = vm_unmapped_area(&info);
 
 	/*
diff --git a/arch/tile/mm/hugetlbpage.c b/arch/tile/mm/hugetlbpage.c
index 0986d42..2b3a9b6 100644
--- a/arch/tile/mm/hugetlbpage.c
+++ b/arch/tile/mm/hugetlbpage.c
@@ -176,6 +176,7 @@  static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
 	info.high_limit = TASK_SIZE;
 	info.align_mask = PAGE_MASK & ~huge_page_mask(h);
 	info.align_offset = 0;
+	info.random_shift = 0;
 	return vm_unmapped_area(&info);
 }
 
@@ -193,6 +194,7 @@  static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
 	info.high_limit = current->mm->mmap_base;
 	info.align_mask = PAGE_MASK & ~huge_page_mask(h);
 	info.align_offset = 0;
+	info.random_shift = 0;
 	addr = vm_unmapped_area(&info);
 
 	/*
diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c
index 676774b..0eda047 100644
--- a/arch/x86/kernel/sys_x86_64.c
+++ b/arch/x86/kernel/sys_x86_64.c
@@ -163,6 +163,8 @@  arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	info.high_limit = end;
 	info.align_mask = 0;
 	info.align_offset = pgoff << PAGE_SHIFT;
+	info.random_shift = in_compat_syscall() ?
+		256 : 0x1000000;
 	if (filp) {
 		info.align_mask = get_align_mask();
 		info.align_offset += get_align_bits();
@@ -224,6 +226,8 @@  arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 
 	info.align_mask = 0;
 	info.align_offset = pgoff << PAGE_SHIFT;
+	info.random_shift = in_compat_syscall() ?
+		256 : 0x1000000;
 	if (filp) {
 		info.align_mask = get_align_mask();
 		info.align_offset += get_align_bits();
diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c
index 00b2966..f4f6436 100644
--- a/arch/x86/mm/hugetlbpage.c
+++ b/arch/x86/mm/hugetlbpage.c
@@ -97,6 +97,8 @@  static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
 
 	info.align_mask = PAGE_MASK & ~huge_page_mask(h);
 	info.align_offset = 0;
+	info.random_shift = in_compat_syscall() ?
+		256 : 0x1000000;
 	return vm_unmapped_area(&info);
 }
 
@@ -121,6 +123,8 @@  static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
 
 	info.align_mask = PAGE_MASK & ~huge_page_mask(h);
 	info.align_offset = 0;
+	info.random_shift = in_compat_syscall() ?
+		256 : 0x1000000;
 	addr = vm_unmapped_area(&info);
 
 	/*
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 8fe1b0a..83e962e 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -200,6 +200,7 @@  hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 	info.high_limit = TASK_SIZE;
 	info.align_mask = PAGE_MASK & ~huge_page_mask(h);
 	info.align_offset = 0;
+	info.random_shift = 0;
 	return vm_unmapped_area(&info);
 }
 #endif
diff --git a/include/linux/mm.h b/include/linux/mm.h
index c716257..f869e6d 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2252,6 +2252,7 @@  struct vm_unmapped_area_info {
 	unsigned long high_limit;
 	unsigned long align_mask;
 	unsigned long align_offset;
+	unsigned long random_shift;
 };
 
 #ifndef CONFIG_MMU
diff --git a/mm/mmap.c b/mm/mmap.c
index ba9cebb..425fa09 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1938,7 +1938,7 @@  unsigned long unmapped_area_random(struct vm_unmapped_area_info *info)
 	if (gap_end ==  gap_start)
 		return gap_start;
 	addr = entropy[1] % (min((gap_end - gap_start) >> PAGE_SHIFT,
-							 0x10000UL));
+							 info->random_shift));
 	addr = gap_end - (addr << PAGE_SHIFT);
 	addr += (info->align_offset - addr) & info->align_mask;
 	return addr;
@@ -2186,6 +2186,7 @@  arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	info.low_limit = mm->mmap_base;
 	info.high_limit = TASK_SIZE;
 	info.align_mask = 0;
+	info.random_shift = 0;
 	return vm_unmapped_area(&info);
 }
 #endif