[PATCH 1/6] mm: introduce an additional vma bit for powerpc pkey

From: Ram Pai
Date: Fri Sep 15 2017 - 21:21:46 EST


Currently only 4bits are allocated in the vma flags to hold 16
keys. This is sufficient for x86. PowerPC supports 32 keys,
which needs 5bits. This patch allocates an additional bit.

Signed-off-by: Ram Pai <linuxram@xxxxxxxxxx>
---
fs/proc/task_mmu.c | 6 ++++--
include/linux/mm.h | 16 ++++++++++------
2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index b836fd6..cf25306 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -661,13 +661,15 @@ 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
+ /* Additional bit used by ppc64 */
+ [ilog2(VM_PKEY_BIT4)] = "",
+#endif /* CONFIG_ARCH_HAS_PKEYS */
};
size_t i;

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 46b9ac5..6d72ec0 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -208,21 +208,25 @@ 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 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)
+#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_BIT1 VM_HIGH_ARCH_1
+# define VM_PKEY_BIT0 VM_HIGH_ARCH_0 /* A protection key is a 4-bit value */
+# define VM_PKEY_BIT1 VM_HIGH_ARCH_1 /* on x86 and 5-bit value on ppc64 */
# define VM_PKEY_BIT2 VM_HIGH_ARCH_2
# define VM_PKEY_BIT3 VM_HIGH_ARCH_3
-#endif
+# define VM_PKEY_BIT4 VM_HIGH_ARCH_4
+#endif /* CONFIG_ARCH_HAS_PKEYS */
+
+#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)
--
1.7.1