ZZSTATUS ZzBuildHalfTrampoline(ZzInterceptorBackend *self, ZzHookFunctionEntry *entry) {
zbyte temp_code_slice_data[256] = {0};
ZzArm64Writer *arm64_writer = NULL;
ZzCodeSlice *code_slice = NULL;
ZzArm64HookFunctionEntryBackend *entry_backend = (ZzArm64HookFunctionEntryBackend *)entry->backend;
ZZSTATUS status = ZZ_SUCCESS;
zaddr target_addr = (zaddr)entry->target_ptr;
arm64_writer = &self->arm64_writer;
zz_arm64_writer_reset(arm64_writer, temp_code_slice_data);
/* prepare 2 stack space: 1. next_hop 2. entry arg */
zz_arm64_writer_put_sub_reg_reg_imm(arm64_writer, ZZ_ARM64_REG_SP, ZZ_ARM64_REG_SP, 2 * 0x8);
zz_arm64_writer_put_ldr_b_reg_address(arm64_writer, ZZ_ARM64_REG_X17, (zaddr)entry);
zz_arm64_writer_put_str_reg_reg_offset(arm64_writer, ZZ_ARM64_REG_X17, ZZ_ARM64_REG_SP, 0x0);
/* jump to half thunk */
zz_arm64_writer_put_ldr_br_reg_address(arm64_writer, ZZ_ARM64_REG_X17, (zaddr)self->half_thunk);
/* code patch */
code_slice = zz_code_patch_arm64_writer(arm64_writer, self->allocator, 0, 0);
if (code_slice)
entry->on_half_trampoline = code_slice->data;
else
return ZZ_FAILED;
return status;
}
ZZSTATUS ZzBuildEnterTrampoline(ZzInterceptorBackend *self, ZzHookFunctionEntry *entry) {
zbyte temp_code_slice_data[256] = {0};
ZzArm64Writer *arm64_writer = NULL;
ZzCodeSlice *code_slice = NULL;
ZzArm64HookFunctionEntryBackend *entry_backend = (ZzArm64HookFunctionEntryBackend *)entry->backend;
ZZSTATUS status = ZZ_SUCCESS;
zaddr target_addr = (zaddr)entry->target_ptr;
arm64_writer = &self->arm64_writer;
zz_arm64_writer_reset(arm64_writer, temp_code_slice_data);
/* prepare 2 stack space: 1. next_hop 2. entry arg */
zz_arm64_writer_put_sub_reg_reg_imm(arm64_writer, ZZ_ARM64_REG_SP, ZZ_ARM64_REG_SP, 2 * 0x8);
zz_arm64_writer_put_ldr_b_reg_address(arm64_writer, ZZ_ARM64_REG_X17, (zaddr)entry);
zz_arm64_writer_put_str_reg_reg_offset(arm64_writer, ZZ_ARM64_REG_X17, ZZ_ARM64_REG_SP, 0x0);
/* jump to enter thunk */
zz_arm64_writer_put_ldr_br_reg_address(arm64_writer, ZZ_ARM64_REG_X17, (zaddr)self->enter_thunk);
/* code patch */
code_slice = zz_code_patch_arm64_writer(arm64_writer, self->allocator, 0, 0);
if (code_slice)
entry->on_enter_trampoline = code_slice->data;
else
return ZZ_FAILED;
/* debug log */
if (ZzIsEnableDebugMode()) {
char buffer[1024] = {};
sprintf(buffer + strlen(buffer), "%s\n", "ZzBuildEnterTrampoline:");
sprintf(buffer + strlen(buffer),
"LogInfo: on_enter_trampoline at %p, length: %ld. hook-entry: %p. and will jump to enter_thunk(%p).\n",
code_slice->data, code_slice->size, (void *)entry, (void *)self->enter_thunk);
ZzInfoLog("%s", buffer);
}
if (entry_backend->redirect_code_size == ZZ_ARM64_TINY_REDIRECT_SIZE) {
ZzBuildEnterTransferTrampoline(self, entry);
}
free(code_slice);
return status;
}
void zz_arm64_thunker_build_half_thunk(ZzWriter *writer) {
/* save general registers and sp */
zz_arm64_writer_put_bytes(writer, (void *)ctx_save, 23 * 4);
zz_arm64_writer_put_add_reg_reg_imm(writer, ZZ_ARM64_REG_X1, ZZ_ARM64_REG_SP, 8 + CTX_SAVE_STACK_OFFSET + 2 * 8);
/* trick: use the `ctx_save` left [sp]*/
zz_arm64_writer_put_str_reg_reg_offset(writer, ZZ_ARM64_REG_X1, ZZ_ARM64_REG_SP, 0 * 8);
/* alignment padding + dummy PC */
zz_arm64_writer_put_sub_reg_reg_imm(writer, ZZ_ARM64_REG_SP, ZZ_ARM64_REG_SP, 2 * 8);
/* pass enter func args */
/* entry */
zz_arm64_writer_put_ldr_reg_reg_offset(writer, ZZ_ARM64_REG_X0, ZZ_ARM64_REG_SP, 2 * 8 + 8 + CTX_SAVE_STACK_OFFSET);
/* next hop*/
zz_arm64_writer_put_add_reg_reg_imm(writer, ZZ_ARM64_REG_X1, ZZ_ARM64_REG_SP,
2 * 8 + 8 + CTX_SAVE_STACK_OFFSET + 0x8);
/* RegState */
zz_arm64_writer_put_add_reg_reg_imm(writer, ZZ_ARM64_REG_X2, ZZ_ARM64_REG_SP, 2 * 8);
/* caller ret address */
zz_arm64_writer_put_add_reg_reg_imm(writer, ZZ_ARM64_REG_X3, ZZ_ARM64_REG_SP, 2 * 8 + 2 * 8 + 28 * 8 + 8);
/* call function_context_half_invocation */
zz_arm64_writer_put_ldr_blr_b_reg_address(writer, ZZ_ARM64_REG_X17, (zz_addr_t)function_context_half_invocation);
/* alignment padding + dummy PC */
zz_arm64_writer_put_add_reg_reg_imm(writer, ZZ_ARM64_REG_SP, ZZ_ARM64_REG_SP, 2 * 8);
/* restore general registers stack */
zz_arm64_writer_put_bytes(writer, (void *)ctx_restore, 21 * 4);
/* load next hop to x17 */
zz_arm64_writer_put_ldr_reg_reg_offset(writer, ZZ_ARM64_REG_X17, ZZ_ARM64_REG_SP, 0x8);
/* restore next hop and arg stack */
zz_arm64_writer_put_add_reg_reg_imm(writer, ZZ_ARM64_REG_SP, ZZ_ARM64_REG_SP, 2 * 8);
/* jump to next hop */
zz_arm64_writer_put_br_reg(writer, ZZ_ARM64_REG_X17);
}
