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Filename : kretprobe.stp
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// kretprobe data tapset
// Copyright (C) 2009, 2011 Red Hat Inc.
//
// This file is part of systemtap, and is free software.  You can
// redistribute it and/or modify it under the terms of the GNU General
// Public License (GPL); either version 2, or (at your option) any
// later version.


// This is an internally-used tapset for sharing data between kretprobe
// entry / return handlers.  See the function
//   dwarf_var_expanding_visitor::gen_kretprobe_saved_return
// for details.
//
// Note, invalid calls are silently ignored...

%{
static void *
_kretprobe_data(struct kretprobe_instance *pi, size_t offset, size_t length)
{
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,25)
	size_t end = offset + length;
	if (end > offset && pi && end <= pi->rp->data_size)
		return &pi->data[offset];
#endif
	return NULL;
}
%}

function _get_kretprobe_long:long(i:long) %{ /* pure */
    if (CONTEXT->probe_type == stp_probe_type_kretprobe) {
	size_t offset = STAP_ARG_i * sizeof(int64_t);
	const int64_t *data = _kretprobe_data(CONTEXT->ips.krp.pi, offset, sizeof(int64_t));
	STAP_RETVALUE = data ? *data : 0;
    }
%}

function _set_kretprobe_long(i:long, value:long) %{ /* impure */
    if (CONTEXT->probe_type == stp_probe_type_kretprobe) {
	size_t offset = STAP_ARG_i * sizeof(int64_t);
	int64_t *data = _kretprobe_data(CONTEXT->ips.krp.pi, offset, sizeof(int64_t));
	if (data)
		*data = STAP_ARG_value;
    }
%}

function _get_kretprobe_string:string(i:long) %{ /* pure */
    if (CONTEXT->probe_type == stp_probe_type_kretprobe) {
	size_t offset = CONTEXT->ips.krp.pi_longs * sizeof(int64_t) +
			STAP_ARG_i * MAXSTRINGLEN;
	const char *data = _kretprobe_data(CONTEXT->ips.krp.pi, offset, MAXSTRINGLEN);
	strlcpy(STAP_RETVALUE, data ?: "", MAXSTRINGLEN);
    }
%}

function _set_kretprobe_string(i:long, value:string) %{ /* impure */ /* unmodified-fnargs */
    if (CONTEXT->probe_type == stp_probe_type_kretprobe) {
	size_t offset = CONTEXT->ips.krp.pi_longs * sizeof(int64_t) +
			STAP_ARG_i * MAXSTRINGLEN;
	char *data = _kretprobe_data(CONTEXT->ips.krp.pi, offset, MAXSTRINGLEN);
	if (data)
		strlcpy(data, STAP_ARG_value, MAXSTRINGLEN);
    }
%}