Give the plugins access to the QEMU dissasembler so they don't have to re-invent the wheel. We generate a warning when there are spare bytes in the decode buffer. This is usually due to the front end loading in more bytes than decoded.
Signed-off-by: Alex Bennée <alex.ben...@linaro.org> Reviewed-by: Richard Henderson <richard.hender...@linaro.org> --- v5 - fix plugin_printf to use vprintf with va - use __thread storage for string - only decode single instruction for bfd case - don't assert, warn_report when we have spare bytes in insn buffer v6 - checkpatch fixes --- disas.c | 110 +++++++++++++++++++++++++++++++++++ include/disas/disas.h | 2 + include/qemu/qemu-plugin.h | 9 +++ plugins/api.c | 9 ++- plugins/qemu-plugins.symbols | 1 + 5 files changed, 130 insertions(+), 1 deletion(-) diff --git a/disas.c b/disas.c index 3e2bfa572b..3937da6157 100644 --- a/disas.c +++ b/disas.c @@ -418,6 +418,7 @@ static bool cap_disas_monitor(disassemble_info *info, uint64_t pc, int count) # define cap_disas_target(i, p, s) false # define cap_disas_host(i, p, s) false # define cap_disas_monitor(i, p, c) false +# define cap_disas_plugin(i, p, c) false #endif /* CONFIG_CAPSTONE */ /* Disassemble this for me please... (debugging). */ @@ -475,6 +476,115 @@ void target_disas(FILE *out, CPUState *cpu, target_ulong code, } } +static __thread GString plugin_disas_output; + +static int plugin_printf(FILE *stream, const char *fmt, ...) +{ + va_list va; + GString *s = &plugin_disas_output; + int initial_len = s->len; + + va_start(va, fmt); + g_string_append_vprintf(s, fmt, va); + va_end(va); + + return s->len - initial_len; +} + +static void plugin_print_address(bfd_vma addr, struct disassemble_info *info) +{ + /* does nothing */ +} + + +#ifdef CONFIG_CAPSTONE +/* Disassemble a single instruction directly into plugin output */ +static +bool cap_disas_plugin(disassemble_info *info, uint64_t pc, size_t size) +{ + uint8_t cap_buf[1024]; + csh handle; + cs_insn *insn; + size_t csize = 0; + int count; + GString *s = &plugin_disas_output; + + if (cap_disas_start(info, &handle) != CS_ERR_OK) { + return false; + } + insn = cap_insn; + + size_t tsize = MIN(sizeof(cap_buf) - csize, size); + const uint8_t *cbuf = cap_buf; + target_read_memory(pc, cap_buf, tsize, info); + + count = cs_disasm(handle, cbuf, size, 0, 1, &insn); + + if (count) { + g_string_printf(s, "%s %s", insn->mnemonic, insn->op_str); + } else { + g_string_printf(s, "cs_disasm failed"); + } + + cs_close(&handle); + return true; +} +#endif + +/* + * We should only be dissembling one instruction at a time here. If + * there is left over it usually indicates the front end has read more + * bytes than it needed. + */ +char *plugin_disas(CPUState *cpu, uint64_t addr, size_t size) +{ + CPUClass *cc = CPU_GET_CLASS(cpu); + int count; + CPUDebug s; + GString *ds = g_string_set_size(&plugin_disas_output, 0); + + g_assert(ds == &plugin_disas_output); + + INIT_DISASSEMBLE_INFO(s.info, NULL, plugin_printf); + + s.cpu = cpu; + s.info.read_memory_func = target_read_memory; + s.info.buffer_vma = addr; + s.info.buffer_length = size; + s.info.print_address_func = plugin_print_address; + s.info.cap_arch = -1; + s.info.cap_mode = 0; + s.info.cap_insn_unit = 4; + s.info.cap_insn_split = 4; + +#ifdef TARGET_WORDS_BIGENDIAN + s.info.endian = BFD_ENDIAN_BIG; +#else + s.info.endian = BFD_ENDIAN_LITTLE; +#endif + + if (cc->disas_set_info) { + cc->disas_set_info(cpu, &s.info); + } + + if (s.info.cap_arch >= 0 && cap_disas_plugin(&s.info, addr, size)) { + return g_strdup(ds->str); + } + + if (s.info.print_insn == NULL) { + s.info.print_insn = print_insn_od_target; + } + + count = s.info.print_insn(addr, &s.info); + + /* The decoder probably read more than it needed it's not critical */ + if (count < size) { + warn_report("%s: %zu bytes left over", __func__, size - count); + } + + return g_strdup(ds->str); +} + /* Disassemble this for me please... (debugging). */ void disas(FILE *out, void *code, unsigned long size) { diff --git a/include/disas/disas.h b/include/disas/disas.h index ba47e9197c..36c33f6f19 100644 --- a/include/disas/disas.h +++ b/include/disas/disas.h @@ -14,6 +14,8 @@ void target_disas(FILE *out, CPUState *cpu, target_ulong code, void monitor_disas(Monitor *mon, CPUState *cpu, target_ulong pc, int nb_insn, int is_physical); +char *plugin_disas(CPUState *cpu, uint64_t addr, size_t size); + /* Look up symbol for debugging purpose. Returns "" if unknown. */ const char *lookup_symbol(target_ulong orig_addr); #endif diff --git a/include/qemu/qemu-plugin.h b/include/qemu/qemu-plugin.h index 784f1dfc3d..ddf267fbfe 100644 --- a/include/qemu/qemu-plugin.h +++ b/include/qemu/qemu-plugin.h @@ -351,6 +351,15 @@ qemu_plugin_register_vcpu_syscall_ret_cb(qemu_plugin_id_t id, qemu_plugin_vcpu_syscall_ret_cb_t cb); +/** + * qemu_plugin_insn_disas() - return disassembly string for instruction + * @insn: instruction reference + * + * Returns an allocated string containing the disassembly + */ + +char *qemu_plugin_insn_disas(const struct qemu_plugin_insn *insn); + /** * qemu_plugin_vcpu_for_each() - iterate over the existing vCPU * @id: plugin ID diff --git a/plugins/api.c b/plugins/api.c index 33dac8e790..5adc4d25a1 100644 --- a/plugins/api.c +++ b/plugins/api.c @@ -39,7 +39,8 @@ #include "cpu.h" #include "sysemu/sysemu.h" #include "tcg/tcg.h" -#include "trace/mem-internal.h" /* mem_info macros */ +#include "exec/exec-all.h" +#include "disas/disas.h" #include "plugin.h" #ifndef CONFIG_USER_ONLY #include "qemu/plugin-memory.h" @@ -212,6 +213,12 @@ void *qemu_plugin_insn_haddr(const struct qemu_plugin_insn *insn) return insn->haddr; } +char *qemu_plugin_insn_disas(const struct qemu_plugin_insn *insn) +{ + CPUState *cpu = current_cpu; + return plugin_disas(cpu, insn->vaddr, insn->data->len); +} + /* * The memory queries allow the plugin to query information about a * memory access. diff --git a/plugins/qemu-plugins.symbols b/plugins/qemu-plugins.symbols index 40c0d1abd2..267ec381b4 100644 --- a/plugins/qemu-plugins.symbols +++ b/plugins/qemu-plugins.symbols @@ -25,6 +25,7 @@ qemu_plugin_insn_size; qemu_plugin_insn_vaddr; qemu_plugin_insn_haddr; + qemu_plugin_insn_disas; qemu_plugin_mem_size_shift; qemu_plugin_mem_is_sign_extended; qemu_plugin_mem_is_big_endian; -- 2.20.1