From 591721d73cf017a5e44b0efbfb5c14449b13e87c Mon Sep 17 00:00:00 2001 From: notaz Date: Sun, 2 Feb 2014 04:33:30 +0200 Subject: [PATCH] scas, DF, more pop stack adjust, etc.. --- tools/translate.c | 198 +++++++++++++++++++++++++++++++++++++++------- 1 file changed, 168 insertions(+), 30 deletions(-) diff --git a/tools/translate.c b/tools/translate.c index eeea0ac..5e68bda 100644 --- a/tools/translate.c +++ b/tools/translate.c @@ -41,6 +41,7 @@ enum op_flags { OPF_REPNZ = (1 << 9), /* rep is repne/repnz */ OPF_FARG = (1 << 10), /* push collected as func arg (no reuse) */ OPF_EBP_S = (1 << 11), /* ebp used as scratch here, not BP */ + OPF_DF = (1 << 12), /* DF flag set */ }; enum op_op { @@ -48,6 +49,7 @@ enum op_op { OP_NOP, OP_PUSH, OP_POP, + OP_LEAVE, OP_MOV, OP_LEA, OP_MOVZX, @@ -57,6 +59,9 @@ enum op_op { OP_STOS, OP_MOVS, OP_CMPS, + OP_SCAS, + OP_STD, + OP_CLD, OP_RET, OP_ADD, OP_SUB, @@ -398,7 +403,7 @@ static const char *parse_stack_el(const char *name, char *extra_reg) // must be a number after esp+, already converted to 0x.. s = name + 4; if (!('0' <= *s && *s <= '9')) { - aerr("%s nan?\n", __func__); + aerr("%s nan?\n", __func__); return NULL; } if (s[0] == '0' && s[1] == 'x') @@ -711,6 +716,7 @@ static const struct { { "nop", OP_NOP, 0, 0, 0 }, { "push", OP_PUSH, 1, 1, 0 }, { "pop", OP_POP, 1, 1, OPF_DATA }, + { "leave",OP_LEAVE, 0, 0, OPF_DATA }, { "mov" , OP_MOV, 2, 2, OPF_DATA }, { "lea", OP_LEA, 2, 2, OPF_DATA }, { "movzx",OP_MOVZX, 2, 2, OPF_DATA }, @@ -726,6 +732,11 @@ static const struct { { "cmpsb",OP_CMPS, 0, 0, OPF_DATA|OPF_FLAGS }, { "cmpsw",OP_CMPS, 0, 0, OPF_DATA|OPF_FLAGS }, { "cmpsd",OP_CMPS, 0, 0, OPF_DATA|OPF_FLAGS }, + { "scasb",OP_SCAS, 0, 0, OPF_DATA|OPF_FLAGS }, + { "scasw",OP_SCAS, 0, 0, OPF_DATA|OPF_FLAGS }, + { "scasd",OP_SCAS, 0, 0, OPF_DATA|OPF_FLAGS }, + { "std", OP_STD, 0, 0, OPF_DATA }, // special flag + { "cld", OP_CLD, 0, 0, OPF_DATA }, { "add", OP_ADD, 2, 2, OPF_DATA|OPF_FLAGS }, { "sub", OP_SUB, 2, 2, OPF_DATA|OPF_FLAGS }, { "and", OP_AND, 2, 2, OPF_DATA|OPF_FLAGS }, @@ -883,13 +894,14 @@ static void parse_op(struct parsed_op *op, char words[16][256], int wordc) break; case OP_STOS: + case OP_SCAS: if (op->operand_cnt != 0) break; - if (IS(words[op_w], "stosb")) + if (words[op_w][4] == 'b') lmod = OPLM_BYTE; - else if (IS(words[op_w], "stosw")) + else if (words[op_w][4] == 'w') lmod = OPLM_WORD; - else if (IS(words[op_w], "stosd")) + else if (words[op_w][4] == 'd') lmod = OPLM_DWORD; op->operand_cnt = 3; setup_reg_opr(&op->operand[0], xDI, lmod, &op->regmask_src); @@ -1476,7 +1488,7 @@ static void check_label_read_ref(struct parsed_op *po, const char *name) } static char *out_src_opr(char *buf, size_t buf_size, - struct parsed_op *po, struct parsed_opr *popr, const char *cast, + struct parsed_op *po, struct parsed_opr *popr, const char *cast, int is_lea) { char tmp1[256], tmp2[256]; @@ -2036,6 +2048,52 @@ static int scan_for_pop_ret(int i, int opcnt, const char *reg, return found ? 0 : -1; } +static void scan_propagate_df(int i, int opcnt) +{ + struct parsed_op *po = &ops[i]; + int j; + + for (; i < opcnt; i++) { + po = &ops[i]; + if (po->flags & OPF_DF) + return; // already resolved + po->flags |= OPF_DF; + + if (po->op == OP_CALL) + ferr(po, "call with DF set?\n"); + + if (po->flags & OPF_JMP) { + if (po->btj != NULL) { + // jumptable + for (j = 0; j < po->btj->count; j++) + scan_propagate_df(po->btj->d[j].bt_i, opcnt); + return; + } + + if (po->bt_i < 0) { + ferr(po, "dead branch\n"); + return; + } + + if (po->flags & OPF_CC) + scan_propagate_df(po->bt_i, opcnt); + else + i = po->bt_i - 1; + continue; + } + + if (po->flags & OPF_TAIL) + break; + + if (po->op == OP_CLD) { + po->flags |= OPF_RMD; + return; + } + } + + ferr(po, "missing DF clear?\n"); +} + // is operand 'opr' modified by parsed_op 'po'? static int is_opr_modified(const struct parsed_opr *opr, const struct parsed_op *po) @@ -2268,7 +2326,7 @@ static int scan_for_esp_adjust(int i, int opcnt, int *adj) } } - if (*adj == 4 && first_pop >= 0 && ops[first_pop].op == OP_POP + if (*adj <= 8 && first_pop >= 0 && ops[first_pop].op == OP_POP && ops[first_pop].operand[0].type == OPT_REG && ops[first_pop].operand[0].reg == xCX) { @@ -2832,8 +2890,11 @@ static void gen_func(FILE *fout, FILE *fhdr, const char *funcn, int opcnt) if (i == opcnt && (ops[i - 1].flags & OPF_JMP) && found) break; - if (ops[i - 1].op == OP_POP && IS(opr_name(&ops[i - 1], 0), "ebp")) + if ((ops[i - 1].op == OP_POP && IS(opr_name(&ops[i - 1], 0), "ebp")) + || ops[i - 1].op == OP_LEAVE) + { ops[i - 1].flags |= OPF_RMD; + } else if (!(g_ida_func_attr & IDAFA_NORETURN)) ferr(&ops[i - 1], "'pop ebp' expected\n"); @@ -2844,8 +2905,11 @@ static void gen_func(FILE *fout, FILE *fhdr, const char *funcn, int opcnt) { ops[i - 2].flags |= OPF_RMD; } - else if (!(g_ida_func_attr & IDAFA_NORETURN)) + else if (ops[i - 1].op != OP_LEAVE + && !(g_ida_func_attr & IDAFA_NORETURN)) + { ferr(&ops[i - 2], "esp restore expected\n"); + } if (ecx_push && ops[i - 3].op == OP_POP && IS(opr_name(&ops[i - 3], 0), "ecx")) @@ -3073,9 +3137,20 @@ tailcall: tmpname, pp->argc_stack * 4, j); ops[ret].flags |= OPF_RMD; - // a bit of a hack, but deals with use of - // single adj for multiple calls - ops[ret].operand[1].val -= j; + if (ops[ret].op == OP_POP && j > 4) { + // deal with multi-pop stack adjust + j = pp->argc_stack; + while (ops[ret].op == OP_POP && j > 0 && ret < opcnt) { + ops[ret].flags |= OPF_RMD; + j--; + ret++; + } + } + else { + // a bit of a hack, but deals with use of + // single adj for multiple calls + ops[ret].operand[1].val -= j; + } } else if (pp->is_vararg) ferr(po, "missing esp_adjust for vararg func '%s'\n", @@ -3094,6 +3169,7 @@ tailcall: // pass4: // - find POPs for PUSHes, rm both + // - scan for STD/CLD, propagate DF // - scan for all used registers // - find flag set ops for their users // - do unreselved calls @@ -3146,6 +3222,11 @@ tailcall: } } + if (po->op == OP_STD) { + po->flags |= OPF_DF | OPF_RMD; + scan_propagate_df(i + 1, opcnt); + } + regmask_now = po->regmask_src | po->regmask_dst; if (regmask_now & (1 << xBP)) { if (g_bp_frame && !(po->flags & OPF_EBP_S)) { @@ -3178,11 +3259,15 @@ tailcall: // to get nicer code, we try to delay test and cmp; // if we can't because of operand modification, or if we - // have math op, or branch, make it calculate flags explicitly - if (tmp_op->op == OP_TEST || tmp_op->op == OP_CMP) { + // have arith op, or branch, make it calculate flags explicitly + if (tmp_op->op == OP_TEST || tmp_op->op == OP_CMP) + { if (branched || scan_for_mod(tmp_op, setters[j] + 1, i, 0) >= 0) pfomask = 1 << pfo; } + else if (tmp_op->op == OP_SCAS) { + pfomask = 1 << pfo; + } else if (tmp_op->op == OP_CMPS) { pfomask = 1 << PFO_Z; } @@ -3205,6 +3290,9 @@ tailcall: if (po->op == OP_ADC || po->op == OP_SBB) cmp_result_vars |= 1 << PFO_C; } + else if (po->op == OP_CMPS || po->op == OP_SCAS) { + cmp_result_vars |= 1 << PFO_Z; + } else if (po->op == OP_MUL || (po->op == OP_IMUL && po->operand_cnt == 1)) { @@ -3567,53 +3655,54 @@ tailcall: break; case OP_STOS: - // assumes DF=0 assert_operand_cnt(3); if (po->flags & OPF_REP) { - fprintf(fout, " for (; ecx != 0; ecx--, edi += %d)\n", + fprintf(fout, " for (; ecx != 0; ecx--, edi %c= %d)\n", + (po->flags & OPF_DF) ? '-' : '+', lmod_bytes(po, po->operand[0].lmod)); fprintf(fout, " %sedi = eax;", lmod_cast_u_ptr(po, po->operand[0].lmod)); strcpy(g_comment, "rep stos"); } else { - fprintf(fout, " %sedi = eax; edi += %d;", + fprintf(fout, " %sedi = eax; edi %c= %d;", lmod_cast_u_ptr(po, po->operand[0].lmod), + (po->flags & OPF_DF) ? '-' : '+', lmod_bytes(po, po->operand[0].lmod)); strcpy(g_comment, "stos"); } break; case OP_MOVS: - // assumes DF=0 assert_operand_cnt(3); j = lmod_bytes(po, po->operand[0].lmod); strcpy(buf1, lmod_cast_u_ptr(po, po->operand[0].lmod)); + l = (po->flags & OPF_DF) ? '-' : '+'; if (po->flags & OPF_REP) { fprintf(fout, - " for (; ecx != 0; ecx--, edi += %d, esi += %d)\n", - j, j); + " for (; ecx != 0; ecx--, edi %c= %d, esi %c= %d)\n", + l, j, l, j); fprintf(fout, " %sedi = %sesi;", buf1, buf1); strcpy(g_comment, "rep movs"); } else { - fprintf(fout, " %sedi = %sesi; edi += %d; esi += %d;", - buf1, buf1, j, j); + fprintf(fout, " %sedi = %sesi; edi %c= %d; esi %c= %d;", + buf1, buf1, l, j, l, j); strcpy(g_comment, "movs"); } break; case OP_CMPS: - // assumes DF=0 // repe ~ repeat while ZF=1 assert_operand_cnt(3); j = lmod_bytes(po, po->operand[0].lmod); strcpy(buf1, lmod_cast_u_ptr(po, po->operand[0].lmod)); + l = (po->flags & OPF_DF) ? '-' : '+'; if (po->flags & OPF_REP) { fprintf(fout, - " for (; ecx != 0; ecx--, edi += %d, esi += %d)\n", - j, j); + " for (; ecx != 0; ecx--, edi %c= %d, esi %c= %d)\n", + l, j, l, j); fprintf(fout, " if ((cond_z = (%sedi == %sesi)) %s 0)\n", buf1, buf1, (po->flags & OPF_REPZ) ? "==" : "!="); @@ -3624,8 +3713,8 @@ tailcall: } else { fprintf(fout, - " cond_z = (%sedi = %sesi); edi += %d; esi += %d;", - buf1, buf1, j, j); + " cond_z = (%sedi = %sesi); edi %c= %d; esi %c= %d;", + buf1, buf1, l, j, l, j); strcpy(g_comment, "cmps"); } pfomask &= ~(1 << PFO_Z); @@ -3633,6 +3722,36 @@ tailcall: delayed_flag_op = NULL; break; + case OP_SCAS: + // only does ZF (for now) + // repe ~ repeat while ZF=1 + assert_operand_cnt(3); + j = lmod_bytes(po, po->operand[0].lmod); + l = (po->flags & OPF_DF) ? '-' : '+'; + if (po->flags & OPF_REP) { + fprintf(fout, + " for (; ecx != 0; ecx--, edi %c= %d)\n", l, j); + fprintf(fout, + " if ((cond_z = (%seax == %sedi)) %s 0)\n", + lmod_cast_u(po, po->operand[0].lmod), + lmod_cast_u_ptr(po, po->operand[0].lmod), + (po->flags & OPF_REPZ) ? "==" : "!="); + fprintf(fout, + " break;"); + snprintf(g_comment, sizeof(g_comment), "rep%s scas", + (po->flags & OPF_REPZ) ? "e" : "ne"); + } + else { + fprintf(fout, " cond_z = (%seax = %sedi); edi %c= %d;", + lmod_cast_u(po, po->operand[0].lmod), + lmod_cast_u_ptr(po, po->operand[0].lmod), l, j); + strcpy(g_comment, "scas"); + } + pfomask &= ~(1 << PFO_Z); + last_arith_dst = NULL; + delayed_flag_op = NULL; + break; + // arithmetic w/flags case OP_ADD: case OP_SUB: @@ -4001,6 +4120,19 @@ tailcall: fprintf(fout, " s_%s = %s;", buf1, buf1); break; } + else if (ops[i + 1].op == OP_POP + && !(ops[i + 1].flags & OPF_RMD)) + { + // push/pop pair + out_dst_opr(buf1, sizeof(buf1), + &ops[i + 1], &ops[i + 1].operand[0]); + fprintf(fout, " %s = %s;", buf1, + out_src_opr(buf2, sizeof(buf2), po, &po->operand[0], + ops[i + 1].operand[0].is_ptr ? "(void *)" : "", 0)); + + ops[i + 1].flags |= OPF_RMD; + break; + } if (!(g_ida_func_attr & IDAFA_NORETURN)) ferr(po, "stray push encountered\n"); no_output = 1; @@ -4038,10 +4170,16 @@ tailcall: fprintf(fout, "\n"); // some sanity checking - if ((po->flags & OPF_REP) && po->op != OP_STOS - && po->op != OP_MOVS && po->op != OP_CMPS) - ferr(po, "unexpected rep\n"); - if ((po->flags & (OPF_REPZ|OPF_REPNZ)) && po->op != OP_CMPS) + if (po->flags & OPF_REP) { + if (po->op != OP_STOS && po->op != OP_MOVS + && po->op != OP_CMPS && po->op != OP_SCAS) + ferr(po, "unexpected rep\n"); + if (!(po->flags & (OPF_REPZ|OPF_REPNZ)) + && (po->op == OP_CMPS || po->op == OP_SCAS)) + ferr(po, "cmps/scas with plain rep\n"); + } + if ((po->flags & (OPF_REPZ|OPF_REPNZ)) + && po->op != OP_CMPS && po->op != OP_SCAS) ferr(po, "unexpected repz/repnz\n"); if (pfomask != 0) -- 2.39.5