Messages in this thread Patch in this message | | | Subject | [PATCH 13/37] x86, pkeys: store protection in high VMA flags | From | Dave Hansen <> | Date | Mon, 16 Nov 2015 19:35:28 -0800 |
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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 _
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