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>

diff --git a/arch/arm/kernel/kprobes-thumb.c b/arch/arm/kernel/kprobes-thumb.c
index e496948fefac4493323ddf25aeee8a9f1685b1fc..997fc6d59a4099c2e61331602e41046414a0a221 100644 (file)
--- 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
 };