/* Dwarfless register access for s390x */

global _reg_offsets, _stp_regs_registered

function _stp_register_regs() {
	/* Same order as pt_regs */
	_reg_offsets["args"] = 0
	_reg_offsets["psw.mask"] = 8
	_reg_offsets["psw.addr"] = 16
	_reg_offsets["r0"] = 24
	_reg_offsets["r1"] = 32
	_reg_offsets["r2"] = 40
	_reg_offsets["r3"] = 48
	_reg_offsets["r4"] = 56
	_reg_offsets["r5"] = 64
	_reg_offsets["r6"] = 72
	_reg_offsets["r7"] = 80
	_reg_offsets["r8"] = 88
	_reg_offsets["r9"] = 96
	_reg_offsets["r10"] = 104
	_reg_offsets["r11"] = 112
	_reg_offsets["r12"] = 120
	_reg_offsets["r13"] = 128
	_reg_offsets["r14"] = 136
	_reg_offsets["r15"] = 144

	_reg_offsets["orig_gpr2"] = 152
	_reg_offsets["ilc"] = 160
	_reg_offsets["trap"] = 162

	/*
	 * If we ever need to support s390 (31-bit arch), we can
	 * get to the register offsets by using just a
	 * reg32_offset = _reg_offsets["reg"]/2
	 * or somesuch
	 */
	_stp_regs_registered = 1
}


/*
 * Though the flag says 31bit, asm-s390/thread_info.h comment
 * says "32bit process"
 */
function probing_32bit_app() %{ /* pure */
	if (CONTEXT->regs)
		THIS->__retvalue = (user_mode(CONTEXT->regs) &&
				test_tsk_thread_flag(current, TIF_31BIT));
	else
		THIS->__retvalue = 0;
%}

function _stp_probing_kernel: long () %{ /* pure */
	THIS->__retvalue = !user_mode(CONTEXT->regs);
%}

function _stp_get_register_by_offset:long (offset:long) %{ /* pure */
	long value;
	if (!CONTEXT->regs) {
		CONTEXT->last_error = "No registers available in this context";
		return;
	}
	if (THIS->offset < 0 || THIS->offset > sizeof(struct pt_regs) - sizeof(unsigned short)) {
		snprintf(CONTEXT->error_buffer, sizeof(CONTEXT->error_buffer),
				"Bad register offset: %lld", THIS->offset);
		CONTEXT->last_error = CONTEXT->error_buffer;
		return;
	}

	if (THIS->offset < sizeof(struct pt_regs) - 2 * sizeof(unsigned short))
		memcpy(&value, ((char *)CONTEXT->regs) + THIS->offset,
				sizeof(value));
	else {
		/* ilc or trap */
		unsigned short us_value;
		memcpy(&us_value, ((char *)CONTEXT->regs) + THIS->offset,
				sizeof(us_value));
		value = us_value;	// not sign-extended
	}
	THIS->__retvalue = value;
%}

function _stp_sign_extend32:long (value:long) {
	if (value & 0x80000000)
		value |= (0xffffffff << 32)
	return value
}

function _stp_register:long (name:string, sign_extend:long) {
	if (!registers_valid()) {
		error("cannot access CPU registers in this context")
		return 0
	}
	if (!_stp_regs_registered)
		_stp_register_regs()
	offset = _reg_offsets[name]
	if (offset == 0 && !(name in _reg_offsets)) {
		error("Unknown register: " . name)
		return 0
	}
	value = _stp_get_register_by_offset(offset)
	if (probing_32bit_app()) {
		if (sign_extend)
			value = _stp_sign_extend32(value)
		else
			value &= 0xffffffff
	}
	return value
}

/* Return the named register value as a signed value. */
function register:long (name:string) {
	return _stp_register(name, 1)
}

/*
 * Return the named register value as an unsigned value.  Specifically,
 * don't sign-extend the register value when promoting it to 64 bits.
 */
function u_register:long (name:string) {
	return _stp_register(name, 0)
}

/*
 * Return the value of function arg #argnum (1=first arg).
 * If truncate=1, mask off the top 32 bits.
 * If sign_extend=1 and (truncate=1 or the probepoint we've hit is in a
 * 32-bit app), sign-extend the 32-bit value.
 *
 * We don't yet support extracting arg #6 and beyond, which are passed
 * on stack
 */
function _stp_arg:long (argnum:long, sign_extend:long, truncate:long) {
	val = 0
	if (argnum < 1 || argnum > 5) {
		error(sprintf("Cannot access arg(%d)", argnum))
		return 0
	}

	if (argnum == 1)
		val = u_register("r2")
	else if (argnum == 2)
		val = u_register("r3")
	else if (argnum == 3)
		val = u_register("r4")
	else if (argnum == 4)
		val = u_register("r5")
	else (argnum == 5)
		val = u_register("r6")

	if (truncate) {
		if (sign_extend)
			val = _stp_sign_extend32(val)
		else
			/* High bits may be garbage. */
			val = (val & 0xffffffff);
	}
	return val;
}

/* Return the value of function arg #argnum (1=first arg) as a signed int. */
function int_arg:long (argnum:long) {
	return _stp_arg(argnum, 1, 1)
}

/* Return the value of function arg #argnum (1=first arg) as an unsigned int. */
function uint_arg:long (argnum:long) {
	return _stp_arg(argnum, 0, 1)
}

function long_arg:long (argnum:long) {
	return _stp_arg(argnum, 1, 0)
}

function ulong_arg:long (argnum:long) {
	return _stp_arg(argnum, 0, 0)
}

function longlong_arg:long (argnum:long) {
	if (probing_32bit_app()) {
		/* TODO verify if this is correct for 31bit apps */
		highbits = _stp_arg(argnum, 0, 1)
		lowbits = _stp_arg(argnum+1, 0, 1)
		return ((highbits << 32) | lowbits)
	} else
		return _stp_arg(argnum, 0, 0)
}

function ulonglong_arg:long (argnum:long) {
	return longlong_arg(argnum)
}

function pointer_arg:long (argnum:long) {
	return _stp_arg(argnum, 0, 0)
}

function s32_arg:long (argnum:long) {
	return int_arg(argnum)
}

function u32_arg:long (argnum:long) {
	return uint_arg(argnum)
}

function s64_arg:long (argnum:long) {
	return longlong_arg(argnum)
}

function u64_arg:long (argnum:long) {
	return ulonglong_arg(argnum)
}

function asmlinkage() %{ /* pure */ %}

function fastcall() %{ /* pure */ %}

function regparm() %{
	snprintf(CONTEXT->error_buffer, sizeof(CONTEXT->error_buffer),
		"regparm is invalid on s390.");
	CONTEXT->last_error = CONTEXT->error_buffer;
%}