From f9d7b4610c82104c07202a6557bae7228e45c6ca Mon Sep 17 00:00:00 2001 From: notaz Date: Mon, 2 Nov 2015 00:48:43 +0200 Subject: [PATCH] translate: handle yet another prologue/epilogue --- tools/translate.c | 141 ++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 119 insertions(+), 22 deletions(-) diff --git a/tools/translate.c b/tools/translate.c index 79413a2..eacb0e0 100644 --- a/tools/translate.c +++ b/tools/translate.c @@ -1956,7 +1956,7 @@ static int stack_frame_access(struct parsed_op *po, snprintf(buf, buf_size, "%sap", cast); return -1; } - ferr(po, "offset %d (%s,%d) doesn't map to any arg\n", + ferr(po, "offset 0x%x (%s,%d) doesn't map to any arg\n", offset, bp_arg, arg_i); } if (ofs_reg[0] != 0) @@ -4146,9 +4146,72 @@ static void eliminate_seh_calls(int opcnt) eliminate_seh_finally(opcnt); } +// check for prologue of many pushes and epilogue with pops +static void check_simple_sequence(int opcnt, int *fsz) +{ + int found = 0; + int seq_len; + int seq_p; + int seq[4]; + int reg; + int i, j; + + for (i = 0; i < opcnt && i < ARRAY_SIZE(seq); i++) { + if (ops[i].op != OP_PUSH || ops[i].operand[0].type != OPT_REG) + break; + reg = ops[i].operand[0].reg; + if (reg != xBX && reg != xSI && reg != xDI && reg != xBP) + break; + for (j = 0; j < i; j++) + if (seq[j] == reg) + break; + if (j != i) + // probably something else is going on here + break; + seq[i] = reg; + } + seq_len = i; + if (seq_len == 0) + return; + + for (; i < opcnt && seq_len > 0; i++) { + if (!(ops[i].flags & OPF_TAIL)) + continue; + + for (j = i - 1, seq_p = 0; j >= 0 && seq_p < seq_len; j--) { + if (ops[j].op != OP_POP || ops[j].operand[0].type != OPT_REG) + break; + if (ops[j].operand[0].reg != seq[seq_p]) + break; + seq_p++; + } + found = seq_len = seq_p; + } + if (!found) + return; + + for (i = 0; i < seq_len; i++) + ops[i].flags |= OPF_RMD | OPF_DONE | OPF_NOREGS; + + for (; i < opcnt && seq_len > 0; i++) { + if (!(ops[i].flags & OPF_TAIL)) + continue; + + for (j = i - 1, seq_p = 0; j >= 0 && seq_p < seq_len; j--) { + ops[j].flags |= OPF_RMD | OPF_DONE | OPF_NOREGS; + seq_p++; + } + } + + // unlike pushes after sub esp, + // IDA treats pushed like this as part of var area + *fsz += seq_len * 4; +} + static int scan_prologue(int i, int opcnt, int *ecx_push, int *esp_sub) { - int j; + const char *name; + int j, len, ret; for (; i < opcnt; i++) if (!(ops[i].flags & OPF_DONE)) @@ -4175,6 +4238,19 @@ static int scan_prologue(int i, int opcnt, int *ecx_push, int *esp_sub) *esp_sub = 1; break; } + if (ops[i].op == OP_LEA && ops[i].operand[0].reg == xSP + && ops[i].operand[1].type == OPT_REGMEM + && IS_START(ops[i].operand[1].name, "esp-")) + { + name = ops[i].operand[1].name; + ret = sscanf(name, "esp-%x%n", &j, &len); + ferr_assert(&ops[i], ret == 1 && len == strlen(name)); + g_stack_fsz += j; + ops[i].flags |= OPF_RMD | OPF_DONE | OPF_NOREGS; + i++; + *esp_sub = 1; + break; + } if (ops[i].op == OP_MOV && ops[i].operand[0].reg == xAX && ops[i].operand[1].type == OPT_CONST) { @@ -4201,7 +4277,8 @@ static void scan_prologue_epilogue(int opcnt, int *stack_align) { int ecx_push = 0, esp_sub = 0, pusha = 0; int sandard_epilogue; - int found; + int found, ret, len; + int push_fsz = 0; int i, j, l; if (g_seh_found == 2) { @@ -4325,6 +4402,7 @@ static void scan_prologue_epilogue(int opcnt, int *stack_align) } // non-bp frame + check_simple_sequence(opcnt, &push_fsz); i = scan_prologue(0, opcnt, &ecx_push, &esp_sub); if (ecx_push && !esp_sub) { @@ -4389,6 +4467,12 @@ static void scan_prologue_epilogue(int opcnt, int *stack_align) } } + for (; j >= 0; j--) { + if ((ops[j].flags & (OPF_RMD | OPF_DONE | OPF_NOREGS)) != + (OPF_RMD | OPF_DONE | OPF_NOREGS)) + break; + } + if (ecx_push > 0 && !esp_sub) { for (l = 0; l < ecx_push && j >= 0; l++) { if (ops[j].op == OP_POP && IS(opr_name(&ops[j], 0), "ecx")) @@ -4422,28 +4506,37 @@ static void scan_prologue_epilogue(int opcnt, int *stack_align) } if (esp_sub) { - if (ops[j].op != OP_ADD - || !IS(opr_name(&ops[j], 0), "esp") - || ops[j].operand[1].type != OPT_CONST) + if (ops[j].op == OP_ADD + && IS(opr_name(&ops[j], 0), "esp") + && ops[j].operand[1].type == OPT_CONST) { - if (i < opcnt && ops[i].op == OP_CALL - && ops[i].pp != NULL && ops[i].pp->is_noreturn) - { - // noreturn tailcall with no epilogue - i++; - found = 1; - continue; - } - ferr(&ops[j], "'add esp' expected\n"); - } - - if (ops[j].operand[1].val < g_stack_fsz) - ferr(&ops[j], "esp adj is too low (need %d)\n", g_stack_fsz); + if (ops[j].operand[1].val < g_stack_fsz) + ferr(&ops[j], "esp adj is too low (need %d)\n", g_stack_fsz); - ops[j].operand[1].val -= g_stack_fsz; // for stack arg scanner - if (ops[j].operand[1].val == 0) + ops[j].operand[1].val -= g_stack_fsz; // for stack arg scanner + if (ops[j].operand[1].val == 0) + ops[j].flags |= OPF_RMD | OPF_DONE | OPF_NOREGS; + found = 1; + } + else if (ops[j].op == OP_LEA && ops[j].operand[0].reg == xSP + && ops[j].operand[1].type == OPT_REGMEM + && IS_START(ops[j].operand[1].name, "esp+")) + { + const char *name = ops[j].operand[1].name; + ret = sscanf(name, "esp+%x%n", &l, &len); + ferr_assert(&ops[j], ret == 1 && len == strlen(name)); + ferr_assert(&ops[j], l <= g_stack_fsz); ops[j].flags |= OPF_RMD | OPF_DONE | OPF_NOREGS; - found = 1; + found = 1; + } + else if (i < opcnt && ops[i].op == OP_CALL + && ops[i].pp != NULL && ops[i].pp->is_noreturn) + { + // noreturn tailcall with no epilogue + found = 1; + } + else + ferr(&ops[j], "'add esp' expected\n"); } i++; @@ -4452,6 +4545,10 @@ static void scan_prologue_epilogue(int opcnt, int *stack_align) if (!found) ferr(ops, "missing esp epilogue\n"); } + + if (g_stack_fsz != 0) + // see check_simple_sequence + g_stack_fsz += push_fsz; } // find an instruction that changed opr before i op -- 2.39.2