linux-kernel - [PATCH v13 3/3] mm, powerpc, x86: introduce an additional vma bit for powerpc pkey

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Date:   Fri,  4 May 2018 14:59:42 -0700
From:   Ram Pai <linuxram@...ibm.com>
To:     mpe@...erman.id.au, mingo@...hat.com, akpm@...ux-foundation.org
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-mm@...ck.org, x86@...nel.org,
        linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org,
        dave.hansen@...el.com, benh@...nel.crashing.org, paulus@...ba.org,
        khandual@...ux.vnet.ibm.com, aneesh.kumar@...ux.vnet.ibm.com,
        bsingharora@...il.com, hbabu@...ibm.com, mhocko@...nel.org,
        bauerman@...ux.vnet.ibm.com, ebiederm@...ssion.com,
        linuxram@...ibm.com, corbet@....net, arnd@...db.de
Subject: [PATCH v13 3/3] mm, powerpc, x86: introduce an additional vma bit for powerpc pkey

Only 4bits are allocated in the vma flags to hold 16 keys. This is
sufficient on x86. PowerPC supports 32 keys, which needs 5bits.
Allocate an  additional bit.

cc: Dave Hansen <dave.hansen@...el.com>
cc: Michael Ellermen <mpe@...erman.id.au>
cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
cc: Andrew Morton <akpm@...ux-foundation.org>
Reviewed-by: Ingo Molnar <mingo@...nel.org>
Acked-by: Balbir Singh <bsingharora@...il.com>
Signed-off-by: Ram Pai <linuxram@...ibm.com>
---
 fs/proc/task_mmu.c |    1 +
 include/linux/mm.h |    8 +++++++-
 2 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 0c9e392..3ddddc7 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -679,6 +679,7 @@ static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma)
 		[ilog2(VM_PKEY_BIT1)]	= "",
 		[ilog2(VM_PKEY_BIT2)]	= "",
 		[ilog2(VM_PKEY_BIT3)]	= "",
+		[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 c6a6f24..cca67d1 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -230,10 +230,16 @@ extern int overcommit_kbytes_handler(struct ctl_table *, int, void __user *,
 
 #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 */
+/* Protection key is a 4-bit value on x86 and 5-bit value on ppc64   */
+# 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
+#if defined(CONFIG_PPC)
+# define VM_PKEY_BIT4	VM_HIGH_ARCH_4
+#else 
+# define VM_PKEY_BIT4	0
+#endif
 #endif /* CONFIG_ARCH_HAS_PKEYS */
 
 #if defined(CONFIG_X86)
-- 
1.7.1