linux-kernel - [PATCH 2/8] mm, powerpc, x86: introduce an additional vma bit for powerpc pkey

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Date:   Wed,  9 May 2018 00:59:42 +1000
From:   Michael Ellerman <mpe@...erman.id.au>
To:     linuxram@...ibm.com
Cc:     mingo@...hat.com, linuxppc-dev@...abs.org, linux-mm@...ck.org,
        x86@...nel.org, linux-kernel@...r.kernel.org, dave.hansen@...el.com
Subject: [PATCH 2/8] mm, powerpc, x86: introduce an additional vma bit for powerpc pkey

From: Ram Pai <linuxram@...ibm.com>

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.

Reviewed-by: Ingo Molnar <mingo@...nel.org>
Acked-by: Balbir Singh <bsingharora@...il.com>
Signed-off-by: Ram Pai <linuxram@...ibm.com>
[mpe: Fold in #if VM_PKEY_BIT4 as noticed by Dave Hansen]
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
---
 fs/proc/task_mmu.c | 3 +++
 include/linux/mm.h | 3 ++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 541392a62608..c2163606e6fb 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -679,6 +679,9 @@ 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)]	= "",
+#if VM_PKEY_BIT4
+		[ilog2(VM_PKEY_BIT4)]	= "",
+#endif
 #endif /* CONFIG_ARCH_HAS_PKEYS */
 	};
 	size_t i;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index c6a6f2492c1b..abfd758ff83a 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -231,9 +231,10 @@ extern unsigned int kobjsize(const void *objp);
 #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_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
+# define VM_PKEY_BIT4	VM_HIGH_ARCH_4
 #endif /* CONFIG_ARCH_HAS_PKEYS */
 
 #if defined(CONFIG_X86)
-- 
2.14.1