net: bpf: arm: make hole-faulting more robust

[linux-2.6-block.git] / arch / arm / net / bpf_jit_32.h

diff --git a/arch/arm/net/bpf_jit_32.h b/arch/arm/net/bpf_jit_32.h
index afb84621ff6f210eb390c37fdd929c66cc32cbb3..b2d7d92859d37e11c31f54c751a1cb78c419713b 100644 (file)
--- a/arch/arm/net/bpf_jit_32.h
+++ b/arch/arm/net/bpf_jit_32.h
@@ -114,6 +114,20 @@
 
 #define ARM_INST_UMULL         0x00800090
 
+/*
+ * Use a suitable undefined instruction to use for ARM/Thumb2 faulting.
+ * We need to be careful not to conflict with those used by other modules
+ * (BUG, kprobes, etc) and the register_undef_hook() system.
+ *
+ * The ARM architecture reference manual guarantees that the following
+ * instruction space will produce an undefined instruction exception on
+ * all CPUs:
+ *
+ * ARM:   xxxx 0111 1111 xxxx xxxx xxxx 1111 xxxx      ARMv7-AR, section A5.4
+ * Thumb: 1101 1110 xxxx xxxx                          ARMv7-M, section A5.2.6
+ */
+#define ARM_INST_UDF           0xe7fddef1
+
 /* register */
 #define _AL3_R(op, rd, rn, rm) ((op ## _R) | (rd) << 12 | (rn) << 16 | (rm))
 /* immediate */