From: Dave Hansen <dave.han...@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.han...@linux.intel.com>
Reviewed-by: Thomas Gleixner <t...@linutronix.de>
---
b/arch/x86/Kconfig | 1 +
b/include/linux/mm.h | 11 +++++++++++
b/mm/Kconfig | 3 +++
3 files changed, 15 insertions(+)
diff -puN arch/x86/Kconfig~pkeys-06-eat-high-vma-flags arch/x86/Kconfig
--- a/arch/x86/Kconfig~pkeys-06-eat-high-vma-flags 2016-01-06
15:50:06.481195258 -0800
+++ b/arch/x86/Kconfig 2016-01-06 15:50:06.488195574 -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-06-eat-high-vma-flags include/linux/mm.h
--- a/include/linux/mm.h~pkeys-06-eat-high-vma-flags 2016-01-06
15:50:06.482195303 -0800
+++ b/include/linux/mm.h 2016-01-06 15:50:06.489195619 -0800
@@ -158,6 +158,17 @@ 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_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 -puN mm/Kconfig~pkeys-06-eat-high-vma-flags mm/Kconfig
--- a/mm/Kconfig~pkeys-06-eat-high-vma-flags 2016-01-06 15:50:06.484195393
-0800
+++ b/mm/Kconfig 2016-01-06 15:50:06.489195619 -0800
@@ -668,3 +668,6 @@ config ZONE_DEVICE
config FRAME_VECTOR
bool
+
+config ARCH_USES_HIGH_VMA_FLAGS
+ bool
_
--
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