lkml.org 
[lkml]   [2015]   [Nov]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Subject[PATCH 13/37] x86, pkeys: store protection in high VMA flags
From
Date

From: Dave Hansen <dave.hansen@linux.intel.com>

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@linux.intel.com>
---

b/arch/x86/Kconfig | 1 +
b/include/linux/mm.h | 7 +++++++
b/mm/Kconfig | 3 +++
3 files changed, 11 insertions(+)

diff -puN arch/x86/Kconfig~pkeys-07-eat-high-vma-flags arch/x86/Kconfig
--- a/arch/x86/Kconfig~pkeys-07-eat-high-vma-flags 2015-11-16 12:35:40.938426022 -0800
+++ b/arch/x86/Kconfig 2015-11-16 12:35:40.945426340 -0800
@@ -152,6 +152,7 @@ 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 -puN include/linux/mm.h~pkeys-07-eat-high-vma-flags include/linux/mm.h
--- a/include/linux/mm.h~pkeys-07-eat-high-vma-flags 2015-11-16 12:35:40.940426113 -0800
+++ b/include/linux/mm.h 2015-11-16 12:35:40.946426385 -0800
@@ -158,6 +158,13 @@ extern unsigned int kobjsize(const void
#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_0 0x100000000UL /* bit only usable on 64-bit architectures */
+#define VM_HIGH_ARCH_1 0x200000000UL /* bit only usable on 64-bit architectures */
+#define VM_HIGH_ARCH_2 0x400000000UL /* bit only usable on 64-bit architectures */
+#define VM_HIGH_ARCH_3 0x800000000UL /* bit only usable on 64-bit architectures */
+#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 -puN mm/Kconfig~pkeys-07-eat-high-vma-flags mm/Kconfig
--- a/mm/Kconfig~pkeys-07-eat-high-vma-flags 2015-11-16 12:35:40.942426204 -0800
+++ b/mm/Kconfig 2015-11-16 12:35:40.947426431 -0800
@@ -668,3 +668,6 @@ config ZONE_DEVICE

config FRAME_VECTOR
bool
+
+config ARCH_USES_HIGH_VMA_FLAGS
+ bool
_

\
 
 \ /
  Last update: 2015-11-17 05:01    [W:0.183 / U:0.060 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site