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