ARM: kprobes: Reject 16-bit Thumb SETEND, CPS and BKPT instructions

These are very rare and/or problematic to emulate so we will take the
easy option and disallow probing them (as does the existing ARM
implementation).

Rejecting these instructions doesn't actually require any entries in the
decoding table as it is the default case for instructions which aren't
found.

Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/arm/kernel/kprobes-thumb.c b/arch/arm/kernel/kprobes-thumb.c
index d3133fd2d4e8..554578bc5f09 100644
--- a/arch/arm/kernel/kprobes-thumb.c
+++ b/arch/arm/kernel/kprobes-thumb.c
@@ -373,6 +373,10 @@ static const union decode_item t16_table_1011[] = {
         /* IT                           1011 1111 xxxx xxxx */
         DECODE_CUSTOM   (0xff00, 0xbf00, t16_decode_it),
 
+        /* SETEND                       1011 0110 010x xxxx */
+        /* CPS                          1011 0110 011x xxxx */
+        /* BKPT                         1011 1110 xxxx xxxx */
+        /* And unallocated instructions...                  */
         DECODE_END
 };