From b71f3a68e2b67c2a26be0a528482fd99a089af3f Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Thu, 10 Sep 2020 15:13:38 -0700 Subject: [PATCH] disas: Cleanup plugin_disas MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Do not retain a GString in thread-local storage. Allocate a new one and free it on every invocation. Do not g_strdup the result; return the buffer from the GString. Do not use warn_report. Using cs_disasm allocated memory via the &insn parameter, but that was never freed. Use cs_disasm_iter so that we use the memory that we've already allocated, and so that we only try to disassemble one insn, as desired. Do not allocate 1k to hold the bytes for a single instruction. Reviewed-by: Alex Bennée Signed-off-by: Richard Henderson --- disas.c | 55 +++++++++++++++++++------------------------------------ 1 file changed, 19 insertions(+), 36 deletions(-) diff --git a/disas.c b/disas.c index 8d1403dedc..54a540180f 100644 --- a/disas.c +++ b/disas.c @@ -493,13 +493,12 @@ 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; + /* We abuse the FILE parameter to pass a GString. */ + GString *s = (GString *)stream; int initial_len = s->len; + va_list va; va_start(va, fmt); g_string_append_vprintf(s, fmt, va); @@ -519,28 +518,20 @@ static void plugin_print_address(bfd_vma addr, struct disassemble_info *info) static bool cap_disas_plugin(disassemble_info *info, uint64_t pc, size_t size) { - uint8_t cap_buf[1024]; + uint8_t cap_buf[64]; + const uint8_t *cbuf = cap_buf; 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); + assert(size < sizeof(cap_buf)); + target_read_memory(pc, cap_buf, size, 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"); + if (cs_disasm_iter(handle, &cbuf, &size, &pc, cap_insn)) { + GString *s = (GString *)info->stream; + g_string_printf(s, "%s %s", cap_insn->mnemonic, cap_insn->op_str); } cs_close(&handle); @@ -555,34 +546,26 @@ bool cap_disas_plugin(disassemble_info *info, uint64_t pc, size_t size) */ char *plugin_disas(CPUState *cpu, uint64_t addr, size_t size) { - int count; CPUDebug s; - GString *ds = g_string_set_size(&plugin_disas_output, 0); - - g_assert(ds == &plugin_disas_output); + GString *ds = g_string_new(NULL); initialize_debug_target(&s, cpu); s.info.fprintf_func = plugin_printf; + s.info.stream = (FILE *)ds; /* abuse this slot */ s.info.buffer_vma = addr; s.info.buffer_length = size; s.info.print_address_func = plugin_print_address; if (s.info.cap_arch >= 0 && cap_disas_plugin(&s.info, addr, size)) { - return g_strdup(ds->str); + ; /* done */ + } else if (s.info.print_insn) { + s.info.print_insn(addr, &s.info); + } else { + ; /* cannot disassemble -- return empty string */ } - 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); + /* Return the buffer, freeing the GString container. */ + return g_string_free(ds, false); } /* Disassemble this for me please... (debugging). */