Re: [RFC v5 11/38] mm: introduce an additional vma bit for powerpc pkey
From: Dave Hansen <hidden>
Date: 2017-07-11 18:11:06
Also in:
linux-arch, linux-mm, lkml
On 07/05/2017 02:21 PM, Ram Pai wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- 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
I'd probably just leave the #ifdef out and eat the byte or whatever of storage that this costs us on x86.
quoted hunk ↗ jump to hunk
}; size_t i;diff --git a/include/linux/mm.h b/include/linux/mm.h index 7cb17c6..3d35bcc 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h@@ -208,21 +208,29 @@ extern int overcommit_kbytes_handler(struct ctl_table *, int, void __user *, #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_BIT_4 36 /* bit only usable on 64-bit arch */
Please just copy the above lines.
#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) +#define VM_HIGH_ARCH_4 BIT(VM_HIGH_ARCH_BIT_4) #endif /* CONFIG_ARCH_USES_HIGH_VMA_FLAGS */ -#if defined(CONFIG_X86) -# define VM_PAT VM_ARCH_1 /* PAT reserves whole VMA at once (x86) */ -#if defined (CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS) +#ifdef CONFIG_ARCH_HAS_PKEYS # define VM_PKEY_SHIFT VM_HIGH_ARCH_BIT_0 -# define VM_PKEY_BIT0 VM_HIGH_ARCH_0 /* A protection key is a 4-bit value */ +# define VM_PKEY_BIT0 VM_HIGH_ARCH_0 # define VM_PKEY_BIT1 VM_HIGH_ARCH_1 # define VM_PKEY_BIT2 VM_HIGH_ARCH_2 # define VM_PKEY_BIT3 VM_HIGH_ARCH_3 -#endif +#endif /* CONFIG_ARCH_HAS_PKEYS */
We have the space here, so can we just say that it's 4-bits on x86 and 5 on ppc?
+#if defined(CONFIG_PPC64_MEMORY_PROTECTION_KEYS) +# define VM_PKEY_BIT4 VM_HIGH_ARCH_4 /* additional key bit used on ppc64 */ +#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
Why bother #ifdef'ing a #define?
+#if defined(CONFIG_X86) +# define VM_PAT VM_ARCH_1 /* PAT reserves whole VMA at once (x86) */ #elif defined(CONFIG_PPC) # define VM_SAO VM_ARCH_1 /* Strong Access Ordering (powerpc) */ #elif defined(CONFIG_PARISC)