ARM: kprobes: Reject 16-bit Thumb SVC and UNDEFINED instructions

SVC (SWI) instructions shouldn't occur in kernel code so we don't
need to be able to probe them.

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

1 files changed, 8 insertions, 0 deletions

diff --git a/arch/arm/kernel/kprobes-thumb.c b/arch/arm/kernel/kprobes-thumb.c
index e496948fefac..997fc6d59a40 100644
--- a/arch/arm/kernel/kprobes-thumb.c
+++ b/arch/arm/kernel/kprobes-thumb.c
@@ -464,6 +464,14 @@ const union decode_item kprobe_decode_thumb16_table[] = {
         /* LDM                          1100 1xxx xxxx xxxx */
         DECODE_EMULATE  (0xf000, 0xc000, t16_emulate_loregs_rwflags),
 
+        /*
+         * Conditional branch, and Supervisor Call
+         */
+
+        /* Permanently UNDEFINED        1101 1110 xxxx xxxx */
+        /* SVC                          1101 1111 xxxx xxxx */
+        DECODE_REJECT   (0xfe00, 0xde00),
+
         DECODE_END
 };