| Message ID | 20180808123934.17450-5-alex.bennee@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | add hand-rolled fallback when capstone fails | expand |
Alex Bennée <alex.bennee@linaro.org> writes: > We can abuse the CS_OPT_SKIPDATA by providing a call back when > capstone can't disassemble something. The passing of the string to the > dump function is a little clunky but works. > > Signed-off-by: Alex Bennée <alex.bennee@linaro.org> > --- > disas.c | 30 +++++++++++++++++++++++++++++- > include/disas/bfd.h | 11 ++++++++++- > target/arm/cpu.c | 4 ++++ > 3 files changed, 43 insertions(+), 2 deletions(-) > > diff --git a/disas.c b/disas.c > index 5325b7e6be..dfd2c251c5 100644 > --- a/disas.c > +++ b/disas.c > @@ -178,6 +178,20 @@ 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; > > + > +/* Handle fall-back dissasembly. We don't print here but we do set > + * cap_fallback_str for cap_dump_insn to used*/ > +static size_t cap_disas_fallback(const uint8_t *code, size_t code_size, > + size_t offset, void *user_data) > +{ > + disassemble_info *info = (disassemble_info *) user_data; > + info->cap_fallback_str = g_malloc0(256); > + size_t skip = info->capstone_fallback_func(code + offset, > + info->cap_fallback_str, 256); > + return skip; > +} > + > + > /* 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 > @@ -206,6 +220,14 @@ static cs_err cap_disas_start(disassemble_info *info, csh *handle) > cs_option(*handle, CS_OPT_SYNTAX, CS_OPT_SYNTAX_ATT); > } > > + if (info->capstone_fallback_func) { > + cs_opt_skipdata skipdata = { > + .callback = cap_disas_fallback, > + .user_data = info, This also needs: .mnemonic = "deadbeef", just to stop the capstone skip handling crashing. For some reason this only showed up when I started doing Aarch64-to-Aarch64 testing. > + }; > + cs_option(*handle, CS_OPT_SKIPDATA_SETUP, (size_t) &skipdata); > + } > + > /* "Disassemble" unknown insns as ".byte W,X,Y,Z". */ > cs_option(*handle, CS_OPT_SKIPDATA, CS_OPT_ON); > > @@ -281,7 +303,13 @@ static void cap_dump_insn(disassemble_info *info, cs_insn *insn) > } > > /* Print the actual instruction. */ > - print(info->stream, " %-8s %s\n", insn->mnemonic, insn->op_str); > + if (info->cap_fallback_str) { > + print(info->stream, " %s\n", info->cap_fallback_str); > + g_free(info->cap_fallback_str); > + info->cap_fallback_str = NULL; > + } else { > + print(info->stream, " %-8s %s\n", insn->mnemonic, insn->op_str); > + } > > /* Dump any remaining part of the insn on subsequent lines. */ > for (i = split; i < n; i += split) { > diff --git a/include/disas/bfd.h b/include/disas/bfd.h > index 1f69a6e9d3..9d99bfef48 100644 > --- a/include/disas/bfd.h > +++ b/include/disas/bfd.h > @@ -377,6 +377,12 @@ typedef struct disassemble_info { > int cap_insn_unit; > int cap_insn_split; > > + /* Fallback function to disassemble things capstone can't. */ > + size_t (*capstone_fallback_func) > + (const uint8_t *insn, char *ptr, size_t n); > + > + char *cap_fallback_str; > + > } disassemble_info; > > > @@ -491,7 +497,10 @@ int generic_symbol_at_address(bfd_vma, struct disassemble_info *); > (INFO).bytes_per_chunk = 0, \ > (INFO).display_endian = BFD_ENDIAN_UNKNOWN, \ > (INFO).disassembler_options = NULL, \ > - (INFO).insn_info_valid = 0 > + (INFO).insn_info_valid = 0, \ > + (INFO).capstone_fallback_func = NULL, \ > + (INFO).cap_fallback_str = NULL > + > > #ifndef ATTRIBUTE_UNUSED > #define ATTRIBUTE_UNUSED __attribute__((unused)) > diff --git a/target/arm/cpu.c b/target/arm/cpu.c > index 64a8005a4b..cfefbfb0b9 100644 > --- a/target/arm/cpu.c > +++ b/target/arm/cpu.c > @@ -519,6 +519,10 @@ static void arm_disas_set_info(CPUState *cpu, disassemble_info *info) > info->cap_arch = CS_ARCH_ARM64; > info->cap_insn_unit = 4; > info->cap_insn_split = 4; > + > +#if defined(TARGET_AARCH64) > + info->capstone_fallback_func = do_aarch64_fallback_disassembly; > +#endif > } else { > int cap_mode; > if (env->thumb) { -- Alex Bennée
diff --git a/disas.c b/disas.c index 5325b7e6be..dfd2c251c5 100644 --- a/disas.c +++ b/disas.c @@ -178,6 +178,20 @@ 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; + +/* Handle fall-back dissasembly. We don't print here but we do set + * cap_fallback_str for cap_dump_insn to used*/ +static size_t cap_disas_fallback(const uint8_t *code, size_t code_size, + size_t offset, void *user_data) +{ + disassemble_info *info = (disassemble_info *) user_data; + info->cap_fallback_str = g_malloc0(256); + size_t skip = info->capstone_fallback_func(code + offset, + info->cap_fallback_str, 256); + return skip; +} + + /* 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 @@ -206,6 +220,14 @@ static cs_err cap_disas_start(disassemble_info *info, csh *handle) cs_option(*handle, CS_OPT_SYNTAX, CS_OPT_SYNTAX_ATT); } + if (info->capstone_fallback_func) { + cs_opt_skipdata skipdata = { + .callback = cap_disas_fallback, + .user_data = info, + }; + cs_option(*handle, CS_OPT_SKIPDATA_SETUP, (size_t) &skipdata); + } + /* "Disassemble" unknown insns as ".byte W,X,Y,Z". */ cs_option(*handle, CS_OPT_SKIPDATA, CS_OPT_ON); @@ -281,7 +303,13 @@ static void cap_dump_insn(disassemble_info *info, cs_insn *insn) } /* Print the actual instruction. */ - print(info->stream, " %-8s %s\n", insn->mnemonic, insn->op_str); + if (info->cap_fallback_str) { + print(info->stream, " %s\n", info->cap_fallback_str); + g_free(info->cap_fallback_str); + info->cap_fallback_str = NULL; + } else { + print(info->stream, " %-8s %s\n", insn->mnemonic, insn->op_str); + } /* Dump any remaining part of the insn on subsequent lines. */ for (i = split; i < n; i += split) { diff --git a/include/disas/bfd.h b/include/disas/bfd.h index 1f69a6e9d3..9d99bfef48 100644 --- a/include/disas/bfd.h +++ b/include/disas/bfd.h @@ -377,6 +377,12 @@ typedef struct disassemble_info { int cap_insn_unit; int cap_insn_split; + /* Fallback function to disassemble things capstone can't. */ + size_t (*capstone_fallback_func) + (const uint8_t *insn, char *ptr, size_t n); + + char *cap_fallback_str; + } disassemble_info; @@ -491,7 +497,10 @@ int generic_symbol_at_address(bfd_vma, struct disassemble_info *); (INFO).bytes_per_chunk = 0, \ (INFO).display_endian = BFD_ENDIAN_UNKNOWN, \ (INFO).disassembler_options = NULL, \ - (INFO).insn_info_valid = 0 + (INFO).insn_info_valid = 0, \ + (INFO).capstone_fallback_func = NULL, \ + (INFO).cap_fallback_str = NULL + #ifndef ATTRIBUTE_UNUSED #define ATTRIBUTE_UNUSED __attribute__((unused)) diff --git a/target/arm/cpu.c b/target/arm/cpu.c index 64a8005a4b..cfefbfb0b9 100644 --- a/target/arm/cpu.c +++ b/target/arm/cpu.c @@ -519,6 +519,10 @@ static void arm_disas_set_info(CPUState *cpu, disassemble_info *info) info->cap_arch = CS_ARCH_ARM64; info->cap_insn_unit = 4; info->cap_insn_split = 4; + +#if defined(TARGET_AARCH64) + info->capstone_fallback_func = do_aarch64_fallback_disassembly; +#endif } else { int cap_mode; if (env->thumb) {
We can abuse the CS_OPT_SKIPDATA by providing a call back when capstone can't disassemble something. The passing of the string to the dump function is a little clunky but works. Signed-off-by: Alex Bennée <alex.bennee@linaro.org> --- disas.c | 30 +++++++++++++++++++++++++++++- include/disas/bfd.h | 11 ++++++++++- target/arm/cpu.c | 4 ++++ 3 files changed, 43 insertions(+), 2 deletions(-) -- 2.17.1