[PATCH v10 09/27] powerpc: ability to create execute-disabled pkeys

[Ram Pai]

powerpc has hardware support to disable execute on a pkey.
This patch enables the ability to create execute-disabled
keys.

Signed-off-by: Ram Pai <linux...@us.ibm.com>
---
 arch/powerpc/include/uapi/asm/mman.h |    6 ++++++
 arch/powerpc/mm/pkeys.c              |   16 ++++++++++++++++
 2 files changed, 22 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/include/uapi/asm/mman.h 
b/arch/powerpc/include/uapi/asm/mman.h
index e63bc37..65065ce 100644
--- a/arch/powerpc/include/uapi/asm/mman.h
+++ b/arch/powerpc/include/uapi/asm/mman.h
@@ -30,4 +30,10 @@
 #define MAP_STACK      0x20000         /* give out an address that is best 
suited for process/thread stacks */
 #define MAP_HUGETLB    0x40000         /* create a huge page mapping */
 
+/* Override any generic PKEY permission defines */
+#define PKEY_DISABLE_EXECUTE   0x4
+#undef PKEY_ACCESS_MASK
+#define PKEY_ACCESS_MASK       (PKEY_DISABLE_ACCESS |\
+                               PKEY_DISABLE_WRITE  |\
+                               PKEY_DISABLE_EXECUTE)
 #endif /* _UAPI_ASM_POWERPC_MMAN_H */
diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c
index eca04cd..39e9814 100644
--- a/arch/powerpc/mm/pkeys.c
+++ b/arch/powerpc/mm/pkeys.c
@@ -29,6 +29,14 @@ int pkey_initialize(void)
        int os_reserved, i;
 
        /*
+        * We define PKEY_DISABLE_EXECUTE in addition to the arch-neutral
+        * generic defines for PKEY_DISABLE_ACCESS and PKEY_DISABLE_WRITE.
+        * Ensure that the bits a distinct.
+        */
+       BUILD_BUG_ON(PKEY_DISABLE_EXECUTE &
+                    (PKEY_DISABLE_ACCESS | PKEY_DISABLE_WRITE));
+
+       /*
         * Disable the pkey system till everything is in place. A subsequent
         * patch will enable it.
         */
@@ -181,10 +189,18 @@ int __arch_set_user_pkey_access(struct task_struct *tsk, 
int pkey,
                                unsigned long init_val)
 {
        u64 new_amr_bits = 0x0ul;
+       u64 new_iamr_bits = 0x0ul;
 
        if (!is_pkey_enabled(pkey))
                return -EINVAL;
 
+       if (init_val & PKEY_DISABLE_EXECUTE) {
+               if (!pkey_execute_disable_supported)
+                       return -EINVAL;
+               new_iamr_bits |= IAMR_EX_BIT;
+       }
+       init_iamr(pkey, new_iamr_bits);
+
        /* Set the bits we need in AMR: */
        if (init_val & PKEY_DISABLE_ACCESS)
                new_amr_bits |= AMR_RD_BIT | AMR_WR_BIT;
-- 
1.7.1