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#include "frida-gum.h"
#include "config.h"
#include "debug.h"
#include "prefetch.h"
#include "ranges.h"
#include "unistd.h"
extern uint8_t *__afl_area_ptr;
extern u32 __afl_map_size;
uint64_t __thread previous_pc = 0;
GumAddress current_log_impl = GUM_ADDRESS(0);
static gboolean tracing = false;
static gboolean optimize = false;
static gboolean strict = false;
#if defined(__x86_64__)
static const guint8 afl_log_code[] = {
0x9c, /* pushfq */
0x50, /* push rax */
0x51, /* push rcx */
0x52, /* push rdx */
0x48, 0x8d, 0x05, 0x27,
0x00, 0x00, 0x00, /* lea rax, sym._afl_area_ptr_ptr */
0x48, 0x8b, 0x00, /* mov rax, qword [rax] */
0x48, 0x8b, 0x00, /* mov rax, qword [rax] */
0x48, 0x8d, 0x0d, 0x22,
0x00, 0x00, 0x00, /* lea rcx, sym.previous_pc */
0x48, 0x8b, 0x11, /* mov rdx, qword [rcx] */
0x48, 0x8b, 0x12, /* mov rdx, qword [rdx] */
0x48, 0x31, 0xfa, /* xor rdx, rdi */
0xfe, 0x04, 0x10, /* inc byte [rax + rdx] */
0x48, 0xd1, 0xef, /* shr rdi, 1 */
0x48, 0x8b, 0x01, /* mov rax, qword [rcx] */
0x48, 0x89, 0x38, /* mov qword [rax], rdi */
0x5a, /* pop rdx */
0x59, /* pop rcx */
0x58, /* pop rax */
0x9d, /* popfq */
0xc3, /* ret */
/* Read-only data goes here: */
/* uint8_t** afl_area_ptr_ptr */
/* uint64_t* afl_prev_loc_ptr */
};
void instrument_coverage_optimize(const cs_insn * instr,
GumStalkerOutput *output) {
guint64 current_pc = instr->address;
guint64 area_offset = (current_pc >> 4) ^ (current_pc << 8);
area_offset &= MAP_SIZE - 1;
GumX86Writer *cw = output->writer.x86;
if (current_log_impl == 0 ||
!gum_x86_writer_can_branch_directly_between(cw->pc, current_log_impl) ||
!gum_x86_writer_can_branch_directly_between(cw->pc + 128,
current_log_impl)) {
gconstpointer after_log_impl = cw->code + 1;
gum_x86_writer_put_jmp_near_label(cw, after_log_impl);
current_log_impl = cw->pc;
gum_x86_writer_put_bytes(cw, afl_log_code, sizeof(afl_log_code));
uint8_t **afl_area_ptr_ptr = &__afl_area_ptr;
uint64_t *afl_prev_loc_ptr = &previous_pc;
gum_x86_writer_put_bytes(cw, (const guint8 *)&afl_area_ptr_ptr,
sizeof(afl_area_ptr_ptr));
gum_x86_writer_put_bytes(cw, (const guint8 *)&afl_prev_loc_ptr,
sizeof(afl_prev_loc_ptr));
gum_x86_writer_put_label(cw, after_log_impl);
}
gum_x86_writer_put_lea_reg_reg_offset(cw, GUM_REG_RSP, GUM_REG_RSP,
-GUM_RED_ZONE_SIZE);
gum_x86_writer_put_push_reg(cw, GUM_REG_RDI);
gum_x86_writer_put_mov_reg_address(cw, GUM_REG_RDI, area_offset);
gum_x86_writer_put_call_address(cw, current_log_impl);
gum_x86_writer_put_pop_reg(cw, GUM_REG_RDI);
gum_x86_writer_put_lea_reg_reg_offset(cw, GUM_REG_RSP, GUM_REG_RSP,
GUM_RED_ZONE_SIZE);
}
#elif defined(__aarch64__)
static const guint8 afl_log_code[] = {
// __afl_area_ptr[current_pc ^ previous_pc]++;
// previous_pc = current_pc >> 1;
0xE1, 0x0B, 0xBF, 0xA9, // stp x1, x2, [sp, -0x10]!
0xE3, 0x13, 0xBF, 0xA9, // stp x3, x4, [sp, -0x10]!
// x0 = current_pc
0xc1, 0x01, 0x00, 0x58, // ldr x1, #0x38, =&__afl_area_ptr
0x21, 0x00, 0x40, 0xf9, // ldr x1, [x1] (=__afl_area_ptr)
0xc2, 0x01, 0x00, 0x58, // ldr x2, #0x38, =&previous_pc
0x42, 0x00, 0x40, 0xf9, // ldr x2, [x2] (=previous_pc)
// __afl_area_ptr[current_pc ^ previous_pc]++;
0x42, 0x00, 0x00, 0xca, // eor x2, x2, x0
0x23, 0x68, 0x62, 0xf8, // ldr x3, [x1, x2]
0x63, 0x04, 0x00, 0x91, // add x3, x3, #1
0x23, 0x68, 0x22, 0xf8, // str x3, [x1, x2]
// previous_pc = current_pc >> 1;
0xe0, 0x07, 0x40, 0x8b, // add x0, xzr, x0, LSR #1
0xe2, 0x00, 0x00, 0x58, // ldr x2, #0x1c, =&previous_pc
0x40, 0x00, 0x00, 0xf9, // str x0, [x2]
0xE3, 0x13, 0xc1, 0xA8, // ldp x3, x4, [sp], #0x10
0xE1, 0x0B, 0xc1, 0xA8, // ldp x1, x2, [sp], #0x10
0xC0, 0x03, 0x5F, 0xD6, // ret
// &afl_area_ptr_ptr
// &afl_prev_loc_ptr
};
void instrument_coverage_optimize(const cs_insn * instr,
GumStalkerOutput *output) {
guint64 current_pc = instr->address;
guint64 area_offset = (current_pc >> 4) ^ (current_pc << 8);
area_offset &= MAP_SIZE - 1;
GumArm64Writer *cw = output->writer.arm64;
if (current_log_impl == 0 ||
!gum_arm64_writer_can_branch_directly_between(cw, cw->pc,
current_log_impl) ||
!gum_arm64_writer_can_branch_directly_between(cw, cw->pc + 128,
current_log_impl)) {
gconstpointer after_log_impl = cw->code + 1;
gum_arm64_writer_put_b_label(cw, after_log_impl);
current_log_impl = cw->pc;
gum_arm64_writer_put_bytes(cw, afl_log_code, sizeof(afl_log_code));
uint8_t **afl_area_ptr_ptr = &__afl_area_ptr;
uint64_t *afl_prev_loc_ptr = &previous_pc;
gum_arm64_writer_put_bytes(cw, (const guint8 *)&afl_area_ptr_ptr,
sizeof(afl_area_ptr_ptr));
gum_arm64_writer_put_bytes(cw, (const guint8 *)&afl_prev_loc_ptr,
sizeof(afl_prev_loc_ptr));
gum_arm64_writer_put_label(cw, after_log_impl);
}
gum_arm64_writer_put_stp_reg_reg_reg_offset(
cw, ARM64_REG_LR, ARM64_REG_X0, ARM64_REG_SP, -(16 + GUM_RED_ZONE_SIZE),
GUM_INDEX_PRE_ADJUST);
gum_arm64_writer_put_ldr_reg_u64(cw, ARM64_REG_X0, area_offset);
gum_arm64_writer_put_bl_imm(cw, current_log_impl);
gum_arm64_writer_put_ldp_reg_reg_reg_offset(
cw, ARM64_REG_LR, ARM64_REG_X0, ARM64_REG_SP, 16 + GUM_RED_ZONE_SIZE,
GUM_INDEX_POST_ADJUST);
}
#endif
static void on_basic_block(GumCpuContext *context, gpointer user_data) {
/* Avoid stack operations in potentially performance critical code */
static char buffer[200];
int len;
guint64 current_pc = (guint64)user_data;
if (tracing) {
/* Avoid any functions which may cause an allocation since the target app
* may already be running inside malloc and it isn't designed to be
* re-entrant on a single thread */
len = snprintf(buffer, sizeof(buffer),
"current_pc: 0x%016" G_GINT64_MODIFIER
"x, previous_pc: 0x%016" G_GINT64_MODIFIER "x\n",
current_pc, previous_pc);
write(STDOUT_FILENO, buffer, len + 1);
}
current_pc = (current_pc >> 4) ^ (current_pc << 8);
current_pc &= MAP_SIZE - 1;
__afl_area_ptr[current_pc ^ previous_pc]++;
previous_pc = current_pc >> 1;
}
void instr_basic_block(GumStalkerIterator *iterator, GumStalkerOutput *output,
gpointer user_data) {
const cs_insn *instr;
gboolean begin = TRUE;
while (gum_stalker_iterator_next(iterator, &instr)) {
if (begin) {
prefetch_write((void *)instr->address);
if (!strict || !range_is_excluded((void *)instr->address)) {
if (optimize) {
instrument_coverage_optimize(instr, output);
} else {
gum_stalker_iterator_put_callout(iterator, on_basic_block,
(gpointer)instr->address, NULL);
}
}
begin = FALSE;
}
gum_stalker_iterator_keep(iterator);
}
}
void instrument_init() {
optimize = (getenv("AFL_FRIDA_INST_NO_OPTIMIZE") == NULL);
tracing = (getenv("AFL_FRIDA_INST_TRACE") != NULL);
strict = (getenv("AFL_FRIDA_INST_STRICT") != NULL);
#if !defined(__x86_64__) && !defined(__aarch64__)
optimize = false;
#endif
OKF("Instrumentation - optimize [%c]", optimize ? 'X' : ' ');
OKF("Instrumentation - tracing [%c]", tracing ? 'X' : ' ');
OKF("Instrumentation - strict [%c]", strict ? 'X' : ' ');
if (tracing && optimize) {
FATAL("AFL_FRIDA_INST_OPTIMIZE and AFL_FRIDA_INST_TRACE are incompatible");
}
if (__afl_map_size != 0x10000) {
FATAL("Bad map size: 0x%08x", __afl_map_size);
}
}
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