On Wed, Oct 18, 2017 at 02:24:03PM +1100, Balbir Singh wrote:

On Fri,  8 Sep 2017 15:44:53 -0700
Ram Pai [off-list ref] wrote:

quoted

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

Signed-off-by: Ram Pai <redacted>
---
 arch/powerpc/include/asm/pkeys.h |    1 +
 arch/powerpc/mm/pkeys.c          |   46 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h
index 133f8c4..5a83ed7 100644
--- a/arch/powerpc/include/asm/pkeys.h
+++ b/arch/powerpc/include/asm/pkeys.h

@@ -26,6 +26,7 @@
 #define arch_max_pkey()  pkeys_total
 #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
 
 #define pkey_alloc_mask(pkey) (0x1 << pkey)
 

diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c
index ebc9e84..178aa33 100644
--- a/arch/powerpc/mm/pkeys.c
+++ b/arch/powerpc/mm/pkeys.c

@@ -59,3 +59,49 @@ void __init pkey_initialize(void)
 	for (i = 2; i < (pkeys_total - os_reserved); i++)
 		initial_allocation_mask &= ~(0x1<<i);
 }
+
+#define PKEY_REG_BITS (sizeof(u64)*8)
+#define pkeyshift(pkey) (PKEY_REG_BITS - ((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));
+

Do we need to check for reserved keys or that is at a layer above?

These routines blindly trust the caller. The assumption is the
system calls which are the gate-keepers for the keys validate
the keys before calling any lower level functions.

quoted

+	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_iamr(old_iamr | new_iamr_bits);

Do we need to check for reserved keys here?

ditto..

quoted

+}
+
+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);
+}

Balbir Singh.

-- 
Ram Pai