linux-kernel - [tip:mm/pkeys] mm/core, x86/mm/pkeys: Store protection bits in high VMA flags

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Message-ID: <tip-63c17fb8e5a46a16e10e82005748837fd11a2024@git.kernel.org>
Date:	Thu, 18 Feb 2016 12:19:03 -0800
From:	tip-bot for Dave Hansen <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	hpa@...or.com, bp@...en8.de, torvalds@...ux-foundation.org,
	tglx@...utronix.de, xiexiuqi@...wei.com, koct9i@...il.com,
	kirill.shutemov@...ux.intel.com, mingo@...nel.org,
	vdavydov@...allels.com, valentinrothberg@...il.com,
	dan.j.williams@...el.com, oleg@...hat.com, peterz@...radead.org,
	linux-kernel@...r.kernel.org, dave.hansen@...ux.intel.com,
	jack@...e.cz, brgerst@...il.com, riel@...hat.com,
	sasha.levin@...cle.com, vbabka@...e.cz, dvlasenk@...hat.com,
	mgorman@...e.de, mhocko@...e.com, akpm@...ux-foundation.org,
	luto@...capital.net, dave@...1.net
Subject: [tip:mm/pkeys] mm/core, x86/mm/pkeys:
  Store protection bits in high VMA flags

Commit-ID:  63c17fb8e5a46a16e10e82005748837fd11a2024
Gitweb:     http://git.kernel.org/tip/63c17fb8e5a46a16e10e82005748837fd11a2024
Author:     Dave Hansen <dave.hansen@...ux.intel.com>
AuthorDate: Fri, 12 Feb 2016 13:02:08 -0800
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Thu, 18 Feb 2016 09:31:50 +0100

mm/core, x86/mm/pkeys: Store protection bits in high VMA flags

vma->vm_flags is an 'unsigned long', so has space for 32 flags
on 32-bit architectures.  The high 32 bits are unused on 64-bit
platforms.  We've steered away from using the unused high VMA
bits for things because we would have difficulty supporting it
on 32-bit.

Protection Keys are not available in 32-bit mode, so there is
no concern about supporting this feature in 32-bit mode or on
32-bit CPUs.

This patch carves out 4 bits from the high half of
vma->vm_flags and allows architectures to set config option
to make them available.

Sparse complains about these constants unless we explicitly
call them "UL".

Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Dan Williams <dan.j.williams@...el.com>
Cc: Dave Hansen <dave@...1.net>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Jan Kara <jack@...e.cz>
Cc: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@...il.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Mel Gorman <mgorman@...e.de>
Cc: Michal Hocko <mhocko@...e.com>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Rik van Riel <riel@...hat.com>
Cc: Sasha Levin <sasha.levin@...cle.com>
Cc: Valentin Rothberg <valentinrothberg@...il.com>
Cc: Vladimir Davydov <vdavydov@...allels.com>
Cc: Vlastimil Babka <vbabka@...e.cz>
Cc: Xie XiuQi <xiexiuqi@...wei.com>
Cc: linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.org
Link: http://lkml.kernel.org/r/20160212210208.81AF00D5@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/Kconfig   |  1 +
 include/linux/mm.h | 11 +++++++++++
 mm/Kconfig         |  3 +++
 3 files changed, 15 insertions(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 3632cdd..fb2ebeb 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -155,6 +155,7 @@ config X86
 	select VIRT_TO_BUS
 	select X86_DEV_DMA_OPS			if X86_64
 	select X86_FEATURE_NAMES		if PROC_FS
+	select ARCH_USES_HIGH_VMA_FLAGS		if X86_INTEL_MEMORY_PROTECTION_KEYS
 
 config INSTRUCTION_DECODER
 	def_bool y
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 4c73178..54d173b 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -170,6 +170,17 @@ extern unsigned int kobjsize(const void *objp);
 #define VM_NOHUGEPAGE	0x40000000	/* MADV_NOHUGEPAGE marked this vma */
 #define VM_MERGEABLE	0x80000000	/* KSM may merge identical pages */
 
+#ifdef CONFIG_ARCH_USES_HIGH_VMA_FLAGS
+#define VM_HIGH_ARCH_BIT_0	32	/* bit only usable on 64-bit architectures */
+#define VM_HIGH_ARCH_BIT_1	33	/* bit only usable on 64-bit architectures */
+#define VM_HIGH_ARCH_BIT_2	34	/* bit only usable on 64-bit architectures */
+#define VM_HIGH_ARCH_BIT_3	35	/* bit only usable on 64-bit architectures */
+#define VM_HIGH_ARCH_0	BIT(VM_HIGH_ARCH_BIT_0)
+#define VM_HIGH_ARCH_1	BIT(VM_HIGH_ARCH_BIT_1)
+#define VM_HIGH_ARCH_2	BIT(VM_HIGH_ARCH_BIT_2)
+#define VM_HIGH_ARCH_3	BIT(VM_HIGH_ARCH_BIT_3)
+#endif /* CONFIG_ARCH_USES_HIGH_VMA_FLAGS */
+
 #if defined(CONFIG_X86)
 # define VM_PAT		VM_ARCH_1	/* PAT reserves whole VMA at once (x86) */
 #elif defined(CONFIG_PPC)
diff --git a/mm/Kconfig b/mm/Kconfig
index 03cbfa0..6cf4399 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -669,3 +669,6 @@ config ZONE_DEVICE
 
 config FRAME_VECTOR
 	bool
+
+config ARCH_USES_HIGH_VMA_FLAGS
+	bool