Blackfin arch: ensure that speculative loads of bad pointers don't cause us to do bad things.

Fix/change formatting of a few more things.

Signed-off-by: Robin Getz <robin.getz@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/arch/blackfin/kernel/fixed_code.S b/arch/blackfin/kernel/fixed_code.S
index d8b1ebc70996..90262691b11a 100644
--- a/arch/blackfin/kernel/fixed_code.S
+++ b/arch/blackfin/kernel/fixed_code.S
@@ -129,4 +129,18 @@ ENTRY(_atomic_xor32)
         rts;
 ENDPROC (_atomic_ior32)
 
+.align 16
+        /*
+         * safe_user_instruction
+         * Four NOPS are enough to allow the pipeline to speculativily load
+         * execute anything it wants. After that, things have gone bad, and
+         * we are stuck - so panic. Since we might be in user space, we can't
+         * call panic, so just cause a unhandled exception, this should cause
+         * a dump of the trace buffer so we can tell were we are, and a reboot
+         */
+ENTRY(_safe_user_instruction)
+        NOP; NOP; NOP; NOP;
+        EXCPT 0x4;
+ENDPROC(_safe_user_instruction)
+
 ENTRY(_fixed_code_end)