ARM: kprobes: Decode 16-bit Thumb hint instructions
For hints which may have observable effects, like SEV (send event), we
use kprobe_emulate_none which emulates the hint by executing the
original instruction.
For NOP we simulate the instruction using kprobe_simulate_nop, which
does nothing. As probes execute with interrupts disabled this is also
used for hints which may block for an indefinite time, like WFE (wait
for event).
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 973c3eb..7dcf6df 100644
--- a/arch/arm/kernel/kprobes-thumb.c
+++ b/arch/arm/kernel/kprobes-thumb.c
@@ -26,6 +26,39 @@
*/
#define current_cond(cpsr) ((cpsr >> 12) & 0xf)
+static const union decode_item t16_table_1011[] = {
+ /* Miscellaneous 16-bit instructions */
+
+ /*
+ * If-Then, and hints
+ * 1011 1111 xxxx xxxx
+ */
+
+ /* YIELD 1011 1111 0001 0000 */
+ DECODE_OR (0xffff, 0xbf10),
+ /* SEV 1011 1111 0100 0000 */
+ DECODE_EMULATE (0xffff, 0xbf40, kprobe_emulate_none),
+ /* NOP 1011 1111 0000 0000 */
+ /* WFE 1011 1111 0010 0000 */
+ /* WFI 1011 1111 0011 0000 */
+ DECODE_SIMULATE (0xffcf, 0xbf00, kprobe_simulate_nop),
+ /* Unassigned hints 1011 1111 xxxx 0000 */
+ DECODE_REJECT (0xff0f, 0xbf00),
+
+ DECODE_END
+};
+
+const union decode_item kprobe_decode_thumb16_table[] = {
+
+ /*
+ * Miscellaneous 16-bit instructions
+ * 1011 xxxx xxxx xxxx
+ */
+ DECODE_TABLE (0xf000, 0xb000, t16_table_1011),
+
+ DECODE_END
+};
+
static unsigned long __kprobes thumb_check_cc(unsigned long cpsr)
{
if (unlikely(in_it_block(cpsr)))
@@ -52,7 +85,7 @@
{
asi->insn_singlestep = thumb16_singlestep;
asi->insn_check_cc = thumb_check_cc;
- return INSN_REJECTED;
+ return kprobe_decode_insn(insn, asi, kprobe_decode_thumb16_table, true);
}
enum kprobe_insn __kprobes