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Subject[RFC v6 17/62] 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.

Signed-off-by: Ram Pai <linuxram@us.ibm.com>
---
arch/powerpc/include/asm/pkeys.h | 10 +++++++++-
arch/powerpc/mm/pkeys.c | 27 +++++++++++++++++++++++++++
2 files changed, 36 insertions(+), 1 deletions(-)

diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h
index 7f5c21d..1943e6b 100644
--- a/arch/powerpc/include/asm/pkeys.h
+++ b/arch/powerpc/include/asm/pkeys.h
@@ -3,6 +3,10 @@

extern bool pkey_inited;
#define arch_max_pkey() 32
+#define AMR_RD_BIT 0x1UL
+#define AMR_WR_BIT 0x2UL
+#define IAMR_EX_BIT 0x1UL
+#define AMR_BITS_PER_PKEY 2
#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
@@ -113,10 +117,14 @@ 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 (!pkey_inited)
+ return -1;
+ 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 04ee361..98d0391 100644
--- a/arch/powerpc/mm/pkeys.c
+++ b/arch/powerpc/mm/pkeys.c
@@ -17,6 +17,10 @@

bool pkey_inited;
#define pkeyshift(pkey) ((arch_max_pkey()-pkey-1) * AMR_BITS_PER_PKEY)
+static bool is_pkey_enabled(int pkey)
+{
+ return !!(read_uamor() & (0x3ul << pkeyshift(pkey)));
+}

static inline void init_amr(int pkey, u8 init_bits)
{
@@ -60,3 +64,26 @@ void __arch_deactivate_pkey(int pkey)
{
pkey_status_change(pkey, false);
}
+
+/*
+ * set the access right in AMR IAMR and UAMOR register
+ * 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 -1;
+
+ /* 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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