linux-kernel - [RFC v6 15/62] powerpc: helper functions to initialize AMR, IAMR and UMOR registers

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Date:   Sat, 15 Jul 2017 20:56:17 -0700
From:   Ram Pai <linuxram@...ibm.com>
To:     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, linux-kselftest@...r.kernel.org
Cc:     benh@...nel.crashing.org, paulus@...ba.org, mpe@...erman.id.au,
        khandual@...ux.vnet.ibm.com, aneesh.kumar@...ux.vnet.ibm.com,
        bsingharora@...il.com, dave.hansen@...el.com, hbabu@...ibm.com,
        linuxram@...ibm.com, arnd@...db.de, akpm@...ux-foundation.org,
        corbet@....net, mingo@...hat.com, mhocko@...nel.org
Subject: [RFC v6 15/62] powerpc: helper functions to initialize AMR, IAMR and UMOR registers

Introduce helper functions that can initialize the bits in the AMR,
IAMR and UMOR register; the bits that correspond to the given pkey.

Signed-off-by: Ram Pai <linuxram@...ibm.com>
---
 arch/powerpc/include/asm/pkeys.h |    1 +
 arch/powerpc/mm/pkeys.c          |   44 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h
index 09b268e..4327842 100644
--- a/arch/powerpc/include/asm/pkeys.h
+++ b/arch/powerpc/include/asm/pkeys.h
@@ -5,6 +5,7 @@
 #define arch_max_pkey()  32
 #define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2 | \
 				VM_PKEY_BIT3 | VM_PKEY_BIT4)
+#define AMR_BITS_PER_PKEY 2
 /*
  * Bits are in BE format.
  * NOTE: key 31, 1, 0 are not used.
diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c
index c3acee1..04ee361 100644
--- a/arch/powerpc/mm/pkeys.c
+++ b/arch/powerpc/mm/pkeys.c
@@ -16,3 +16,47 @@
 #include <linux/pkeys.h>                /* PKEY_*                       */
 
 bool pkey_inited;
+#define pkeyshift(pkey) ((arch_max_pkey()-pkey-1) * AMR_BITS_PER_PKEY)
+
+static inline void init_amr(int pkey, u8 init_bits)
+{
+	u64 new_amr_bits = (((u64)init_bits & 0x3UL) << pkeyshift(pkey));
+	u64 old_amr = read_amr() & ~((u64)(0x3ul) << pkeyshift(pkey));
+
+	write_amr(old_amr | new_amr_bits);
+}
+
+static inline void init_iamr(int pkey, u8 init_bits)
+{
+	u64 new_iamr_bits = (((u64)init_bits & 0x3UL) << pkeyshift(pkey));
+	u64 old_iamr = read_iamr() & ~((u64)(0x3ul) << pkeyshift(pkey));
+
+	write_amr(old_iamr | new_iamr_bits);
+}
+
+static void pkey_status_change(int pkey, bool enable)
+{
+	u64 old_uamor;
+
+	/* reset the AMR and IAMR bits for this key */
+	init_amr(pkey, 0x0);
+	init_iamr(pkey, 0x0);
+
+	/* enable/disable key */
+	old_uamor = read_uamor();
+	if (enable)
+		old_uamor |= (0x3ul << pkeyshift(pkey));
+	else
+		old_uamor &= ~(0x3ul << pkeyshift(pkey));
+	write_uamor(old_uamor);
+}
+
+void __arch_activate_pkey(int pkey)
+{
+	pkey_status_change(pkey, true);
+}
+
+void __arch_deactivate_pkey(int pkey)
+{
+	pkey_status_change(pkey, false);
+}
-- 
1.7.1