linux-kernel - [PATCH 2/6] mm, x86 : introduce arch_pkeys

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Message-Id: <1505524870-4783-3-git-send-email-linuxram@us.ibm.com>
Date:   Fri, 15 Sep 2017 18:21:06 -0700
From:   Ram Pai <linuxram@...ibm.com>
To:     mpe@...erman.id.au, linuxppc-dev@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        linux-mm@...ck.org, x86@...nel.org, linux-doc@...r.kernel.org
Cc:     arnd@...db.de, akpm@...ux-foundation.org, corbet@....net,
        mingo@...hat.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
Subject: [PATCH 2/6] mm, x86 : introduce arch_pkeys_enabled()

Arch neutral code needs to know if the architecture supports
protection  keys  to  display protection key in smaps. Hence
introducing arch_pkeys_enabled().

This patch also provides x86 implementation for
arch_pkeys_enabled().

Signed-off-by: Ram Pai <linuxram@...ibm.com>
---
 arch/x86/include/asm/pkeys.h |    1 +
 arch/x86/kernel/fpu/xstate.c |    5 +++++
 include/linux/pkeys.h        |    5 +++++
 3 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/pkeys.h b/arch/x86/include/asm/pkeys.h
index b3b09b9..fa82799 100644
--- a/arch/x86/include/asm/pkeys.h
+++ b/arch/x86/include/asm/pkeys.h
@@ -5,6 +5,7 @@
 
 extern int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
 		unsigned long init_val);
+extern bool arch_pkeys_enabled(void);
 
 /*
  * Try to dedicate one of the protection keys to be used as an
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index c24ac1e..df594b8 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -918,6 +918,11 @@ int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
 
 	return 0;
 }
+
+bool arch_pkeys_enabled(void)
+{
+	return boot_cpu_has(X86_FEATURE_OSPKE);
+}
 #endif /* ! CONFIG_ARCH_HAS_PKEYS */
 
 /*
diff --git a/include/linux/pkeys.h b/include/linux/pkeys.h
index a1bacf1..d120810 100644
--- a/include/linux/pkeys.h
+++ b/include/linux/pkeys.h
@@ -34,6 +34,11 @@ static inline int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
 	return 0;
 }
 
+static inline bool arch_pkeys_enabled(void)
+{
+	return false;
+}
+
 static inline void copy_init_pkru_to_fpregs(void)
 {
 }
-- 
1.7.1