parisc: Enable KASLR

Add missing code for userspace executable address randomization, e.g.
applications compiled with the gcc -pie option.

Signed-off-by: Helge Deller <deller@gmx.de>

4 files changed, 14 insertions, 18 deletions

diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index a14b86587013..3a71f38cdc05 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -7,6 +7,7 @@ config PARISC
         select HAVE_FUNCTION_GRAPH_TRACER
         select HAVE_SYSCALL_TRACEPOINTS
         select ARCH_WANT_FRAME_POINTERS
+        select ARCH_HAS_ELF_RANDOMIZE
         select RTC_CLASS
         select RTC_DRV_GENERIC
         select INIT_ALL_POSSIBLE
diff --git a/arch/parisc/include/asm/elf.h b/arch/parisc/include/asm/elf.h
index 78c9fd32c554..a6b2a421571e 100644
--- a/arch/parisc/include/asm/elf.h
+++ b/arch/parisc/include/asm/elf.h
@@ -348,9 +348,10 @@ struct pt_regs;	/* forward declaration... */
 
 #define ELF_HWCAP       0
 
-#define STACK_RND_MASK  (is_32bit_task() ? \
-                                0x7ff >> (PAGE_SHIFT - 12) : \
-                                0x3ffff >> (PAGE_SHIFT - 12))
+/* Masks for stack and mmap randomization */
+#define BRK_RND_MASK    (is_32bit_task() ? 0x07ffUL : 0x3ffffUL)
+#define MMAP_RND_MASK   (is_32bit_task() ? 0x1fffUL : 0x3ffffUL)
+#define STACK_RND_MASK  MMAP_RND_MASK
 
 struct mm_struct;
 extern unsigned long arch_randomize_brk(struct mm_struct *);
diff --git a/arch/parisc/kernel/process.c b/arch/parisc/kernel/process.c
index 40639439d8b3..ea6603ee8d24 100644
--- a/arch/parisc/kernel/process.c
+++ b/arch/parisc/kernel/process.c
@@ -276,11 +276,7 @@ void *dereference_function_descriptor(void *ptr)
 
 static inline unsigned long brk_rnd(void)
 {
-        /* 8MB for 32bit, 1GB for 64bit */
-        if (is_32bit_task())
-                return (get_random_int() & 0x7ffUL) << PAGE_SHIFT;
-        else
-                return (get_random_int() & 0x3ffffUL) << PAGE_SHIFT;
+        return (get_random_int() & BRK_RND_MASK) << PAGE_SHIFT;
 }
 
 unsigned long arch_randomize_brk(struct mm_struct *mm)
diff --git a/arch/parisc/kernel/sys_parisc.c b/arch/parisc/kernel/sys_parisc.c
index 0a393a04e891..a81e177cac7b 100644
--- a/arch/parisc/kernel/sys_parisc.c
+++ b/arch/parisc/kernel/sys_parisc.c
@@ -225,19 +225,17 @@ static unsigned long mmap_rnd(void)
 {
         unsigned long rnd = 0;
 
-        /*
-        *  8 bits of randomness in 32bit mmaps, 20 address space bits
-        * 28 bits of randomness in 64bit mmaps, 40 address space bits
-        */
-        if (current->flags & PF_RANDOMIZE) {
-                if (is_32bit_task())
-                        rnd = get_random_int() % (1<<8);
-                else
-                        rnd = get_random_int() % (1<<28);
-        }
+        if (current->flags & PF_RANDOMIZE)
+                rnd = get_random_int() & MMAP_RND_MASK;
+
         return rnd << PAGE_SHIFT;
 }
 
+unsigned long arch_mmap_rnd(void)
+{
+        return (get_random_int() & MMAP_RND_MASK) << PAGE_SHIFT;
+}
+
 static unsigned long mmap_legacy_base(void)
 {
         return TASK_UNMAPPED_BASE + mmap_rnd();