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SubjectRe: [RFC v4 01/17] mm: introduce an additional vma bit for powerpc pkey
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On Tue, 2017-06-27 at 03:11 -0700, Ram Pai wrote:
> Currently there are only 4bits in the vma flags to support 16 keys
> on x86. powerpc supports 32 keys, which needs 5bits. This patch
> introduces an addition bit in the vma flags.
>
> Signed-off-by: Ram Pai <linuxram@us.ibm.com>
> ---
> fs/proc/task_mmu.c | 6 +++++-
> include/linux/mm.h | 18 +++++++++++++-----
> 2 files changed, 18 insertions(+), 6 deletions(-)
>
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index f0c8b33..2ddc298 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -666,12 +666,16 @@ static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma)
> [ilog2(VM_MERGEABLE)] = "mg",
> [ilog2(VM_UFFD_MISSING)]= "um",
> [ilog2(VM_UFFD_WP)] = "uw",
> -#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
> +#ifdef CONFIG_ARCH_HAS_PKEYS
> /* These come out via ProtectionKey: */
> [ilog2(VM_PKEY_BIT0)] = "",
> [ilog2(VM_PKEY_BIT1)] = "",
> [ilog2(VM_PKEY_BIT2)] = "",
> [ilog2(VM_PKEY_BIT3)] = "",
> +#endif /* CONFIG_ARCH_HAS_PKEYS */
> +#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
> + /* Additional bit in ProtectionKey: */
> + [ilog2(VM_PKEY_BIT4)] = "",
> #endif

Not sure why these are linked with smap bits, but I guess the keys live
in the Supervisor Mode Access Prevention area?

Balbir Singh.

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