Capstone assumes any unknown instruction is 2 bytes.
Instead, use the ilen field in the first two bits of
the instruction to stay in sync with the insn stream.
Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
---
disas.c | 37 +++++++++++++++++++++++++++++++++++++
1 file changed, 37 insertions(+)
diff --git a/disas.c b/disas.c
index 51c71534a3..2a000cbeb0 100644
--- a/disas.c
+++ b/disas.c
@@ -178,6 +178,39 @@ static int print_insn_od_target(bfd_vma pc,
disassemble_info *info)
to share this across calls and across host vs target disassembly. */
static __thread cs_insn *cap_insn;
+/*
+ * The capstone library always skips 2 bytes for S390X.
+ * This is less than ideal, since we can tell from the first two bits
+ * the size of the insn and thus stay in sync with the insn stream.
+ */
+static size_t CAPSTONE_API
+cap_skipdata_s390x_cb(const uint8_t *code, size_t code_size,
+ size_t offset, void *user_data)
+{
+ size_t ilen;
+
+ /* See get_ilen() in target/s390x/internal.h. */
+ switch (code[offset] >> 6) {
+ case 0:
+ ilen = 2;
+ break;
+ case 1:
+ case 2:
+ ilen = 4;
+ break;
+ default:
+ ilen = 6;
+ break;
+ }
+
+ return ilen;
+}
+
+static const cs_opt_skipdata cap_skipdata_s390x = {
+ .mnemonic = ".byte",
+ .callback = cap_skipdata_s390x_cb
+};
+
/* Initialize the Capstone library. */
/* ??? It would be nice to cache this. We would need one handle for the
host and one for the target. For most targets we can reset specific
@@ -208,6 +241,10 @@ static cs_err cap_disas_start(disassemble_info *info, csh
*handle)
/* "Disassemble" unknown insns as ".byte W,X,Y,Z". */
cs_option(*handle, CS_OPT_SKIPDATA, CS_OPT_ON);
+ if (info->cap_arch == CS_ARCH_SYSZ) {
+ cs_option(*handle, CS_OPT_SKIPDATA_SETUP,
+ (uintptr_t)&cap_skipdata_s390x);
+ }
/* Allocate temp space for cs_disasm_iter. */
if (cap_insn == NULL) {
--
2.17.1
