powerpc/mm: Invalidate subpage_prot() system call on radix platforms

Radix enabled platforms don't support subpage_prot() system calls. But
at present the system call goes through without an error and fails
later on while validating expected subpage accesses. Lets not allow
the system call on powerpc radix platforms to begin with to prevent
this confusion in user space.

Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/mm/subpage-prot.c b/arch/powerpc/mm/subpage-prot.c
index 781532d7bc4d29683ab2ac72cff6f0ad7d4d01f4..f14a07c2fb9030aa7d350a4a3977d83d22fff983 100644 (file)
--- a/arch/powerpc/mm/subpage-prot.c
+++ b/arch/powerpc/mm/subpage-prot.c
@@ -195,6 +195,9 @@ long sys_subpage_prot(unsigned long addr, unsigned long len, u32 __user *map)
        unsigned long next, limit;
        int err;
 
+       if (radix_enabled())
+               return -ENOENT;
+
        /* Check parameters */
        if ((addr & ~PAGE_MASK) || (len & ~PAGE_MASK) ||
            addr >= mm->task_size || len >= mm->task_size ||