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Subject[PATCH v9 08/51] powerpc: implementation for arch_set_user_pkey_access()
Date
This patch provides the detailed implementation for
a user to allocate a key and enable it in the hardware.

It provides the plumbing, but it cannot be used till
the system call is implemented. The next patch will
do so.

Reviewed-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
---
arch/powerpc/include/asm/pkeys.h | 6 ++++-
arch/powerpc/mm/pkeys.c | 40 ++++++++++++++++++++++++++++++++++++++
2 files changed, 45 insertions(+), 1 deletions(-)

diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h
index 0d00a54..652c750 100644
--- a/arch/powerpc/include/asm/pkeys.h
+++ b/arch/powerpc/include/asm/pkeys.h
@@ -139,10 +139,14 @@ static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma,
return 0;
}

+extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
+ unsigned long init_val);
static inline int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
unsigned long init_val)
{
- return 0;
+ if (static_branch_likely(&pkey_disabled))
+ return -EINVAL;
+ return __arch_set_user_pkey_access(tsk, pkey, init_val);
}

static inline void pkey_mm_init(struct mm_struct *mm)
diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c
index f3bf661..4a01c2f 100644
--- a/arch/powerpc/mm/pkeys.c
+++ b/arch/powerpc/mm/pkeys.c
@@ -9,6 +9,7 @@
* (at your option) any later version.
*/

+#include <asm/mman.h>
#include <linux/pkeys.h>

DEFINE_STATIC_KEY_TRUE(pkey_disabled);
@@ -17,6 +18,9 @@
u32 initial_allocation_mask; /* Bits set for reserved keys */

#define AMR_BITS_PER_PKEY 2
+#define AMR_RD_BIT 0x1UL
+#define AMR_WR_BIT 0x2UL
+#define IAMR_EX_BIT 0x1UL
#define PKEY_REG_BITS (sizeof(u64)*8)
#define pkeyshift(pkey) (PKEY_REG_BITS - ((pkey+1) * AMR_BITS_PER_PKEY))

@@ -102,6 +106,20 @@ static inline void write_uamor(u64 value)
mtspr(SPRN_UAMOR, value);
}

+static bool is_pkey_enabled(int pkey)
+{
+ u64 uamor = read_uamor();
+ u64 pkey_bits = 0x3ul << pkeyshift(pkey);
+ u64 uamor_pkey_bits = (uamor & pkey_bits);
+
+ /*
+ * Both the bits in UAMOR corresponding to the key should be set or
+ * reset.
+ */
+ WARN_ON(uamor_pkey_bits && (uamor_pkey_bits != pkey_bits));
+ return !!(uamor_pkey_bits);
+}
+
static inline void init_amr(int pkey, u8 init_bits)
{
u64 new_amr_bits = (((u64)init_bits & 0x3UL) << pkeyshift(pkey));
@@ -144,3 +162,25 @@ void __arch_deactivate_pkey(int pkey)
{
pkey_status_change(pkey, false);
}
+
+/*
+ * Set the access rights in AMR IAMR and UAMOR registers for @pkey to that
+ * specified in @init_val.
+ */
+int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
+ unsigned long init_val)
+{
+ u64 new_amr_bits = 0x0ul;
+
+ if (!is_pkey_enabled(pkey))
+ return -EINVAL;
+
+ /* Set the bits we need in AMR: */
+ if (init_val & PKEY_DISABLE_ACCESS)
+ new_amr_bits |= AMR_RD_BIT | AMR_WR_BIT;
+ else if (init_val & PKEY_DISABLE_WRITE)
+ new_amr_bits |= AMR_WR_BIT;
+
+ init_amr(pkey, new_amr_bits);
+ return 0;
+}
--
1.7.1
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