index : meta-agl	albacore blowfish chinook dab eel flounder guppy halibut icefish jellyfish koi lamprey marlin master needlefish next octopus pike quillback ricefish sandbox/YAMAGUCHINaoto/rk3588-nanopc-t6 sandbox/hauvolecong/spec4808 sandbox/jsmoeller/canbusfd sandbox/jsmoeller/cleanup sandbox/jsmoeller/lamprey sandbox/jsmoeller/next-riscv-EW24 sandbox/jsmoeller/qt6 sandbox/jsmoeller/rmappfw sandbox/nguyentanloc27/S4SK-dev sandbox/nguyentanloc27/spec4808
	meta-agl layer (core AGL)	Grokmirror user

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path: root/meta-agl-bsp

Age	Commit message (Collapse)	Author	Files	Lines
2016-05-01	Allow meta-agl-bsp to dynamically include recipes on demand	Jan-Simon Möller	2	-3/+5
	This changeset introduces an improved handling of the recipe inclusion mechanism that allows us to conditionally include fixes for bsp's once (and only once) they are activated. This overcomes the need to use BB_DANGLINGAPPENDS_WARNONLY = 1 that was introduced in changeset 5527. Thus it can be removed again. Change-Id: I7ea10748e3015e781f1e96cfc01ac54e83d0cd5a Signed-off-by: Jan-Simon Möller <jsmoeller@linuxfoundation.org>
2016-05-01	Introduce TI DRA7 vayu and cleanup template files	Jan-Simon Möller	2	-0/+30
	This changeset introduces the TI 'vayu' board. We need to adapt the provided bsp layer 'meta-ti' as it is only at YP 1.8 fido right now. Two changes are needed/known: a) BBMASK eudev bbappend (local.conf.sample) b) apply patch for gcc5 to u-boot-ti-staging On top thie changeset also does janitorial work on the templates: - conf-notes is now in a folder common and symlinked - layer additions have been sync'ed - file layout sync'ed with templates in meta-agl-demo Change-Id: Ib52a9252800d54d5105ac1f5354ad3a3b014188f Signed-off-by: Jan-Simon Möller <jsmoeller@linuxfoundation.org>
2016-01-21	Update build configurations for Mesa	Tadao Tanikawa	2	-20/+5
	No longer Gallium EGL driver (gallium-egl) is needed. Change-Id: Ic3d9abc1c3c0a25a3d4ec9daa330646b8c86e291 Signed-off-by: Tadao Tanikawa <tanikawa.tadao@jp.panasonic.com>
2016-01-21	Update linux kernel for QEMUx86-64 and Minnowboard MAX	Tadao Tanikawa	2	-2/+4
	Update linux kernel for QEMUx86-64 and Minnowboard MAX to compatile with YP 2.0 jethro's. - On QEMU in jethro, mouse not work with linux-3.17 - KVM becomes avairable when CPU support it E.g. command lines to run qemu with kvm and serial console $ cd tmp/deploy/images/qemux86-64 $ runqemu bzImage-qemux86-64.bin \ agl-demo-platform-qemux86-64.ext4 \ qemuparams="-m 512 -usbdevice tablet" serial kvm Change-Id: Ia35b8d5e25c03094994041eaf399b8476e6a6b6c Signed-off-by: Tadao Tanikawa <tanikawa.tadao@jp.panasonic.com>
2016-01-15	Support MinnowBoard MAX	Tadao Tanikawa	4	-0/+6
	To configure for MinnowBoard MAX, use 'intel-corei7-64' as MACHINE. E.g. set up build environment by meta-agl's script: $ source meta-agl/script/envsetup.sh intel-corei7-64 [build-dir] There are instructions to write image into SD card and boot system at "http://elinux.org/Minnowboard:MinnowMaxYoctoProject". Change-Id: I19062482848bb6157791ab698bf92984e24a6d9a Signed-off-by: Tadao Tanikawa <tanikawa.tadao@jp.panasonic.com>
2016-01-13	QEMU kernel: add and fix fanotify API (SPEC-89)	Manuel Bachmann	3	-1/+213
	fanotify API is currently enabled on meta-renesas kernel, and is required by our LTP tests (see mention on https://jira.automotivelinux.org/browse/SPEC-89), but was not available on QEMU kernel. This creates a gap which may break client applications. We also add the patch to fix issue described at https://jira.automotivelinux.org/browse/SPEC-89. Change-Id: Ic201eec7d91553db75f5a5783c47fe1a7d8f7c86 Signed-off-by: Manuel Bachmann <mbc@iot.bzh>
2015-10-22	Provide Wayland FITS, disabled by default	Manuel Bachmann	2	-0/+7
	Wayland FITS is a functional integration test suite for Wayland/Weston. It consists in 2 components : a Weston plugin, and a "wfits" binary used to run tests. The tests themselves simulate user interaction with surfaces and windows, using virtual keyboard/mouse/touchscreen drivers. The recipe was recently submitted to the official "meta-openembedded" layer, and can be found here : http://lists.openembedded.org/pipermail/openembedded-devel/ 2015-September/103511.html The package will not be built unless the user explicitly adds "wayland-fits" to his "conf/local.conf" file. QEMU needs the "uinput" driver available on startup, so we always build it, but only install it if the package has been selected. Change-Id: Ib6045007f6c7e1e22b48607a66930ce341c58002 Signed-off-by: Manuel Bachmann <mbc@iot.bzh>
2015-09-22	Support QEMU build on Poky > 1.7 (weston, gallium-egl)	Manuel Bachmann	2	-1/+4
	Allow to build newer versions of Weston. "gallium-egl" disappeared from Poky > 1.7 (because it disappeared from upstream Mesa, too). Still try to detect and build it if it exists, but do not fail otherwise. Change-Id: I01c3988e2da6a4fe66a80e5a5b1262cc6c1da727 Signed-off-by: Manuel Bachmann <manuel.bachmann@iot.bzh>
2015-07-22	Support wayland/weson with GSES on emulated machine, QEMU(x86-64)	Tadao Tanikawa	3	-0/+25
	To boot weston image on emulated machine QEMU, a new sub-layer `meta-agl-bsp` is added. When bitbake agl-image-weston or agl-image-ivi With this layer, weston GLES can run on QEMU with GLES support. Signed-off-by: Tadao Tanikawa <tanikawa.tadao@jp.panasonic.com>

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From 0558b5c626426017848d9f3b7af380494c3deece Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jan-Simon=20M=C3=B6ller?= <jsmoeller@linuxfoundation.org>
Date: Tue, 27 Jun 2017 22:46:11 +0200
Subject: [PATCH 1/3] [SEC][Backport] mm: larger stack guard gap, between vmas
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This change backports
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/patch/?id=1ad9a25dd06fda9bdc27875e1cedb8277accb212

Signed-off-by: Jan-Simon Möller <jsmoeller@linuxfoundation.org>
---
 Documentation/kernel-parameters.txt |   7 ++
 arch/arc/mm/mmap.c                  |   2 +-
 arch/arm/mm/mmap.c                  |   4 +-
 arch/frv/mm/elf-fdpic.c             |   2 +-
 arch/mips/mm/mmap.c                 |   2 +-
 arch/powerpc/mm/slice.c             |   2 +-
 arch/sh/mm/mmap.c                   |   4 +-
 arch/sparc/kernel/sys_sparc_64.c    |   4 +-
 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           |   2 +-
 arch/xtensa/kernel/syscall.c        |   2 +-
 fs/hugetlbfs/inode.c                |   2 +-
 fs/proc/task_mmu.c                  |   4 -
 include/linux/mm.h                  |  53 ++++++------
 mm/memory.c                         |  49 -----------
 mm/mmap.c                           | 168 ++++++++++++++++++++----------------
 18 files changed, 144 insertions(+), 171 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 9859ddf..09924a9 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2884,6 +2884,13 @@ 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 2e06d56..cf4ae69 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 5ef506c..984509e 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 836f147..efa59f1 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 7e5fe27..0bb4295 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/powerpc/mm/slice.c b/arch/powerpc/mm/slice.c
index 7ce9cf3..887365a 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 6777177..7df7d59 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 2daaaa6..79b981e 100644
--- a/arch/sparc/kernel/sys_sparc_64.c
+++ b/arch/sparc/kernel/sys_sparc_64.c
@@ -119,7 +119,7 @@ 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;
 	}
 
@@ -182,7 +182,7 @@ 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 d2b5944..ce49370 100644
--- a/arch/sparc/mm/hugetlbpage.c
+++ b/arch/sparc/mm/hugetlbpage.c
@@ -118,7 +118,7 @@ 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 650ccff..c75eac7 100644
--- a/arch/tile/mm/hugetlbpage.c
+++ b/arch/tile/mm/hugetlbpage.c
@@ -297,7 +297,7 @@ 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 30277e2..d050393 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 ae1aa71..6adf3d9 100644
--- a/arch/x86/mm/hugetlbpage.c
+++ b/arch/x86/mm/hugetlbpage.c
@@ -341,7 +341,7 @@ 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 5d3f7a1..1ff0b92 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 4e5f332..db7d89c 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -169,7 +169,7 @@ 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 65fc60a..a5884ed 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -279,11 +279,7 @@ 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_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
 			start,
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 263b405..294a6b1 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1056,34 +1056,6 @@ int set_page_dirty(struct page *page);
 int set_page_dirty_lock(struct page *page);
 int clear_page_dirty_for_io(struct page *page);
 
-/* 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);
 
@@ -1609,6 +1581,7 @@ unsigned long ra_submit(struct file_ra_state *ra,
 			struct address_space *mapping,
 			struct file *filp);
 
+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);
 
@@ -1637,6 +1610,30 @@ 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/memory.c b/mm/memory.c
index 3a3f316..06bbba9 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1654,12 +1654,6 @@ no_page_table:
 	return page;
 }
 
-static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
-{
-	return stack_guard_page_start(vma, addr) ||
-	       stack_guard_page_end(vma, addr+PAGE_SIZE);
-}
-
 /**
  * __get_user_pages() - pin user pages in memory
  * @tsk:	task_struct of target task
@@ -1827,11 +1821,6 @@ long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 				int ret;
 				unsigned int fault_flags = 0;
 
-				/* For mlock, just skip the stack guard page. */
-				if (foll_flags & FOLL_MLOCK) {
-					if (stack_guard_page(vma, start))
-						goto next_page;
-				}
 				if (foll_flags & FOLL_WRITE)
 					fault_flags |= FAULT_FLAG_WRITE;
 				if (nonblocking)
@@ -3186,40 +3175,6 @@ 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;
-
-		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;
-
-		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.
@@ -3234,10 +3189,6 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
 
 	pte_unmap(page_table);
 
-	/* Check if we need to add a guard page to the stack */
-	if (check_stack_guard_page(vma, address) < 0)
-		return VM_FAULT_SIGBUS;
-
 	/* 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 8f87b14..cbdac38 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -263,6 +263,7 @@ 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;
 
@@ -308,7 +309,8 @@ 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. */
@@ -331,10 +333,22 @@ 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;
@@ -418,7 +432,7 @@ void validate_mm(struct mm_struct *mm)
 		list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
 			anon_vma_interval_tree_verify(avc);
 		vma_unlock_anon_vma(vma);
-		highest_address = vma->vm_end;
+		highest_address = vm_end_gap(vma);
 		vma = vma->vm_next;
 		i++;
 	}
@@ -586,7 +600,7 @@ 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
@@ -835,7 +849,7 @@ 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);
 		}
@@ -878,7 +892,7 @@ again:			remove_next = 1 + (end > next->vm_end);
 		else if (next)
 			vma_gap_update(next);
 		else
-			mm->highest_vm_end = end;
+			WARN_ON(mm->highest_vm_end != vm_end_gap(vma));
 	}
 	if (insert && file)
 		uprobe_mmap(insert);
@@ -1670,7 +1684,7 @@ 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,
@@ -1681,7 +1695,7 @@ 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)
@@ -1708,8 +1722,8 @@ 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;
 			}
 		}
@@ -1773,7 +1787,7 @@ 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,
@@ -1786,7 +1800,7 @@ 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)
@@ -1812,7 +1826,7 @@ 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;
 			}
 		}
@@ -1850,7 +1864,7 @@ 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)
@@ -1861,9 +1875,10 @@ 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;
 	}
 
@@ -1895,7 +1910,7 @@ 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;
@@ -1910,9 +1925,10 @@ 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;
 	}
 
@@ -2104,32 +2120,40 @@ 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)
 {
-	int error;
+	struct vm_area_struct *next;
+	unsigned long gap_addr;
+	int error = 0;
 
 	if (!(vma->vm_flags & VM_GROWSUP))
 		return -EFAULT;
 
-	/*
-	 * We must make sure the anon_vma is allocated
-	 * so that the anon_vma locking is not a noop.
-	 */
+	/* Guard against wrapping around to address 0. */
+	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;
-	vma_lock_anon_vma(vma);
 
 	/*
 	 * vma->vm_start/vm_end cannot change under us because the caller
 	 * is required to hold the mmap_sem in read mode.  We need the
 	 * anon_vma lock to serialize against concurrent expand_stacks.
-	 * Also guard against wrapping around to address 0.
 	 */
-	if (address < PAGE_ALIGN(address+4))
-		address = PAGE_ALIGN(address+4);
-	else {
-		vma_unlock_anon_vma(vma);
-		return -ENOMEM;
-	}
-	error = 0;
+	vma_lock_anon_vma(vma);
 
 	/* Somebody else might have raced and expanded it already */
 	if (address > vma->vm_end) {
@@ -2160,7 +2184,7 @@ 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);
@@ -2180,27 +2204,36 @@ 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;
 
-	/*
-	 * We must make sure the anon_vma is allocated
-	 * so that the anon_vma locking is not a noop.
-	 */
-	if (unlikely(anon_vma_prepare(vma)))
-		return -ENOMEM;
-
 	address &= PAGE_MASK;
 	error = security_mmap_addr(address);
 	if (error)
 		return error;
 
-	vma_lock_anon_vma(vma);
+	/* 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;
 
 	/*
 	 * vma->vm_start/vm_end cannot change under us because the caller
 	 * is required to hold the mmap_sem in read mode.  We need the
 	 * anon_vma lock to serialize against concurrent expand_stacks.
 	 */
+	vma_lock_anon_vma(vma);
 
 	/* Somebody else might have raced and expanded it already */
 	if (address < vma->vm_start) {
@@ -2242,28 +2275,25 @@ 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);
 }
 
@@ -2285,14 +2315,6 @@ 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);
 }
 
@@ -2389,7 +2411,7 @@ 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;
 	if (mm->unmap_area == arch_unmap_area)
 		addr = prev ? prev->vm_end : mm->mmap_base;
-- 
2.1.4