PR10299: Basic documentation for the changes to embedded-C argument access.

[systemtap.git] / tapset / arm / registers.stp

/* Dwarfless register access for arm */

global _reg_offsets, _stp_regs_registered

function _stp_register_regs() {

	/* Same order as pt_regs */
	_reg_offsets["r0"] =  0		_reg_offsets["a1"] =  0
	_reg_offsets["r1"] =  4		_reg_offsets["a2"] =  4
	_reg_offsets["r2"] =  8		_reg_offsets["a3"] =  8
	_reg_offsets["r3"] = 12		_reg_offsets["a4"] =  12
	_reg_offsets["r4"] = 16		_reg_offsets["v1"] =  16
	_reg_offsets["r5"] = 20		_reg_offsets["v2"] =  20
	_reg_offsets["r6"] = 24		_reg_offsets["v3"] =  24
	_reg_offsets["r7"] = 28		_reg_offsets["v4"] =  28
	_reg_offsets["r8"] = 32		_reg_offsets["v5"] =  32
	_reg_offsets["r9"] = 36  	_reg_offsets["v6"] =  36
	_reg_offsets["r10"] = 40	_reg_offsets["v7"] =  40
	_reg_offsets["fp"] = 44		_reg_offsets["v8"] =  44
	_reg_offsets["ip"] = 48
	_reg_offsets["sp"] = 52
	_reg_offsets["lr"] = 56
	_reg_offsets["pc"] = 60
	_reg_offsets["cpsr"] = 64
	_reg_offsets["orig_r0"] = 68

	_stp_regs_registered = 1
}

function _stp_get_register_by_offset:long (offset:long) %{ /* pure */
	long value;
	struct pt_regs *regs;
	if (CONTEXT->probe_flags & _STP_PROBE_STATE_USER_MODE) {
		regs = CONTEXT->uregs;
	} else {
		regs = CONTEXT->kregs;
	}
	if (!regs) {
		CONTEXT->last_error = "No registers available in this context";
		return;
	}
	if (THIS->offset < 0 || THIS->offset > sizeof(struct pt_regs) - sizeof(long)) {
		snprintf(CONTEXT->error_buffer, sizeof(CONTEXT->error_buffer),
				"Bad register offset: %lld", THIS->offset);
		CONTEXT->last_error = CONTEXT->error_buffer;
		return;
	}
	memcpy(&value, ((char *)regs) + THIS->offset, sizeof(value));
	THIS->__retvalue = value;
%}

function _stp_probing_kernel:long () {
	return !user_mode();
}

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

/*
 * 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 register(name) & 0xffffffff;
}

/* Return the value of function arg #argnum (1=first arg) as a signed value.
 *
 * We don't yet support extracting arg #5 and beyond, which are passed
 * on stack
 */
function _stp_arg:long (argnum:long) {
	val = 0
	if (argnum < 1 || argnum > 4) {
		error(sprintf("Cannot access arg(%d)", argnum))
		return 0
	}

	if (argnum == 1)
		val = register("r0")
	else if (argnum == 2)
		val = register("r1")
	else if (argnum == 3)
		val = register("r2")
	else if (argnum == 4)
		val = register("r3")

	return val;
}

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

/* Return the value of function arg #argnum as an unsigned int. */
function uint_arg:long (argnum:long) {
	return _stp_arg(argnum) & 0xffffffff;
}

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

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

function longlong_arg:long (argnum:long) {
	/*
	 * TODO: If argnum == nr_regarg, gcc puts the whole 64-bit arg
	 * on the stack.
	 */
	lowbits = uint_arg(argnum)
	highbits = uint_arg(argnum+1)
	return ((highbits << 32) | lowbits)
}

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

function pointer_arg:long (argnum:long) {
	return ulong_arg(argnum)
}

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(n:long) %{
	snprintf(CONTEXT->error_buffer, sizeof(CONTEXT->error_buffer),
		"regparm is invalid on arm.");
	CONTEXT->last_error = CONTEXT->error_buffer;
%}