genode/repos/base-nova/include/base/ipc_msgbuf.h
2014-05-27 11:14:41 +02:00

413 lines
10 KiB
C++

/*
* \brief IPC message buffer layout for NOVA
* \author Norman Feske
* \author Alexander Boettcher
* \date 2009-10-02
*
* On NOVA, we use IPC to transmit plain data and for capability delegation
* and capability translation.
* Therefore the message buffer contains three categories of payload. The
* capability-specific part are the members '_snd_pt*' (sending capability
* selectors) and '_rcv_pt*' (receiving capability selectors).
*/
/*
* Copyright (C) 2009-2013 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU General Public License version 2.
*/
#ifndef _INCLUDE__BASE__IPC_MSGBUF_H_
#define _INCLUDE__BASE__IPC_MSGBUF_H_
/* NOVA includes */
#include <nova/syscalls.h>
#include <nova/util.h>
namespace Genode {
class Msgbuf_base
{
public:
enum {
MAX_CAP_ARGS_LOG2 = 2,
MAX_CAP_ARGS = 1 << MAX_CAP_ARGS_LOG2
};
protected:
size_t _size;
/**
* Number of portal-capability selectors to send
*/
size_t _snd_pt_sel_cnt;
/**
* Portal capability selectors to delegate
*/
Native_capability _snd_pt_sel [MAX_CAP_ARGS];
/**
* Base of portal receive window
*/
addr_t _rcv_pt_base;
struct {
addr_t sel;
bool del;
} _rcv_pt_sel [MAX_CAP_ARGS];
enum { FREE_INVALID, FREE_SEL, UNUSED_CAP, USED_CAP }
_rcv_pt_cap_free [MAX_CAP_ARGS];
/**
* Read counter for unmarshalling portal capability
* selectors
*/
unsigned short _rcv_pt_sel_cnt;
unsigned short _rcv_pt_sel_max;
unsigned short _rcv_wnd_log2;
char _msg_start[]; /* symbol marks start of message */
public:
enum { INVALID_INDEX = ~0UL };
/**
* Constructor
*/
Msgbuf_base()
: _rcv_pt_base(INVALID_INDEX), _rcv_wnd_log2(MAX_CAP_ARGS_LOG2)
{
rcv_reset();
snd_reset();
}
~Msgbuf_base()
{
rcv_reset();
}
/*
* Begin of actual message buffer
*/
char buf[];
/**
* Return size of message buffer
*/
inline size_t size() const { return _size; }
/**
* Return address of message buffer
*/
inline void *addr() { return &_msg_start[0]; }
/**
* Reset portal capability selector payload
*/
inline void snd_reset() {
for (unsigned i = 0; i < MAX_CAP_ARGS; i++) {
+_snd_pt_sel[i];
_snd_pt_sel[i] = Native_capability();
}
_snd_pt_sel_cnt = 0;
}
/**
* Append portal capability selector to message buffer
*/
inline bool snd_append_pt_sel(Native_capability const &cap)
{
if (_snd_pt_sel_cnt >= MAX_CAP_ARGS - 1)
return false;
_snd_pt_sel[_snd_pt_sel_cnt++ ] = cap;
return true;
}
/**
* Return number of marshalled portal-capability
* selectors
*/
inline size_t snd_pt_sel_cnt() const
{
return _snd_pt_sel_cnt;
}
/**
* Return portal capability selector
*
* \param i index (0 ... 'pt_sel_cnt()' - 1)
* \return portal-capability range descriptor
*
* The returned object could be a null cap. Use
* is_null method to check for it.
*/
Nova::Obj_crd snd_pt_sel(addr_t i, bool &trans_map) const
{
if (i >= _snd_pt_sel_cnt)
return Nova::Obj_crd();
trans_map = _snd_pt_sel[i].trans_map();
return Nova::Obj_crd(_snd_pt_sel[i].local_name(), 0,
_snd_pt_sel[i].dst().rights());
}
/**
* Request current portal-receive window
*/
addr_t rcv_pt_base() const { return _rcv_pt_base; }
/**
* Set log2 number of capabilities to be received during reply of
* a IPC call.
*/
void rcv_wnd(unsigned short const caps_log2)
{
if (caps_log2 > MAX_CAP_ARGS_LOG2)
nova_die();
_rcv_wnd_log2 = caps_log2;
}
/**
* Reset portal-capability receive window
*/
void rcv_reset()
{
if (!rcv_invalid()) { rcv_cleanup(false); }
_rcv_pt_sel_cnt = 0;
_rcv_pt_sel_max = 0;
_rcv_pt_base = INVALID_INDEX;
}
/**
* Return received portal-capability selector
*/
void rcv_pt_sel(Native_capability &cap)
{
if (_rcv_pt_sel_cnt >= _rcv_pt_sel_max) {
cap = Native_capability();
return;
}
/* return only received or translated caps */
cap = Native_capability(_rcv_pt_sel[_rcv_pt_sel_cnt++].sel);
}
/**
* Return true if receive window must be re-initialized
*/
bool rcv_invalid() const
{
return _rcv_pt_base == INVALID_INDEX;
}
/**
* Return true if receive window must be re-initialized
*
* After reading portal selectors from the message
* buffer using 'rcv_pt_sel()', we assume that the IDC
* call populated the current receive window with one
* or more portal capabilities.
* To enable the reception of portal capability
* selectors for the next IDC, we need a fresh receive
* window.
*
* \param keep 'true' - Try to keep receive window if
* it's clean.
* 'false' - Free caps of receive window
* because object is freed
* afterwards.
*
* \result 'true' - receive window must be re-initialized
* 'false' - portal selectors has been kept
*/
bool rcv_cleanup(bool keep, unsigned short const new_max = MAX_CAP_ARGS)
{
/* mark used mapped capabilities as used to prevent freeing */
bool reinit = false;
for (unsigned i = 0; i < _rcv_pt_sel_cnt; i++) {
if (!_rcv_pt_sel[i].del)
continue;
/* should never happen */
if (_rcv_pt_sel[i].sel < rcv_pt_base() ||
(_rcv_pt_sel[i].sel >= rcv_pt_base() + MAX_CAP_ARGS))
nova_die();
_rcv_pt_cap_free [_rcv_pt_sel[i].sel - rcv_pt_base()] = USED_CAP;
cap_map()->remove(_rcv_pt_sel[i].sel - rcv_pt_base(), 0);
reinit = true;
}
/* if old receive window was smaller, we need to re-init */
for (unsigned i = 0; !reinit && i < new_max; i++)
if (_rcv_pt_cap_free[i] == FREE_INVALID)
reinit = true;
_rcv_pt_sel_cnt = 0;
_rcv_pt_sel_max = 0;
/* we can keep the cap selectors if none was used */
if (keep && !reinit) {
for (unsigned i = 0; i < MAX_CAP_ARGS; i++) {
/* revoke received caps which are unused */
if (_rcv_pt_cap_free[i] == UNUSED_CAP)
Nova::revoke(Nova::Obj_crd(rcv_pt_base() + i, 0), true);
/* free rest of indexes if new_max is smaller then last window */
if (i >= new_max && _rcv_pt_cap_free[i] == FREE_SEL)
cap_map()->remove(rcv_pt_base() + i, 0, false);
}
return false;
}
/* decrease ref count if valid selector */
for (unsigned i = 0; i < MAX_CAP_ARGS; i++)
if (_rcv_pt_cap_free[i] != FREE_INVALID)
cap_map()->remove(rcv_pt_base() + i, 0, _rcv_pt_cap_free[i] == FREE_SEL);
return true;
}
/**
* Initialize receive window for portal capability
* selectors
*
* \param utcb - UTCB of designated receiver
* thread
* \param rcv_window - If specified - receive exactly
* one capability at the specified
* index of rcv_window
*
* Depending on the 'rcv_invalid', 'rcv_cleanup(true)'
* state of the message buffer and the specified
* rcv_window parameter, this function allocates a
* fresh receive window and clears 'rcv_invalid'.
*/
bool prepare_rcv_window(Nova::Utcb *utcb,
addr_t rcv_window = INVALID_INDEX)
{
/* open maximal translate window */
utcb->crd_xlt = Nova::Obj_crd(0, ~0UL);
/* use receive window if specified */
if (rcv_window != INVALID_INDEX) {
/* cleanup if receive window already used */
if (!rcv_invalid()) rcv_cleanup(false);
_rcv_pt_base = rcv_window;
/* open receive window */
utcb->crd_rcv = Nova::Obj_crd(rcv_pt_base(), _rcv_wnd_log2);
return true;
}
/* allocate receive window if necessary, otherwise use old one */
if (rcv_invalid() || rcv_cleanup(true, 1U << _rcv_wnd_log2))
{
_rcv_pt_base = cap_map()->insert(_rcv_wnd_log2);
if (_rcv_pt_base == INVALID_INDEX) {
/* no mappings can be received */
utcb->crd_rcv = Nova::Obj_crd();
return false;
}
}
/* open receive window */
utcb->crd_rcv = Nova::Obj_crd(rcv_pt_base(), _rcv_wnd_log2);
return true;
}
/**
* Post IPC processing.
*
* Remember where and which caps have been received
* respectively have been translated.
* The information is required to correctly free
* cap indexes and to revoke unused received caps.
*
* \param utcb UTCB of designated receiver thread
*/
void post_ipc(Nova::Utcb *utcb, addr_t const rcv_window = INVALID_INDEX)
{
using namespace Nova;
unsigned const rcv_items = (utcb->items >> 16) & 0xffffu;
_rcv_pt_sel_max = 0;
_rcv_pt_sel_cnt = 0;
unsigned short const max = 1U << utcb->crd_rcv.order();
if (max > MAX_CAP_ARGS)
nova_die();
for (unsigned short i = 0; i < MAX_CAP_ARGS; i++)
_rcv_pt_cap_free [i] = (i >= max) ? FREE_INVALID : FREE_SEL;
for (unsigned i = 0; i < rcv_items; i++) {
Nova::Utcb::Item * item = utcb->get_item(i);
if (!item)
break;
Nova::Crd cap(item->crd);
/* track which items we got mapped */
if (!cap.is_null() && item->is_del()) {
/* should never happen */
if (cap.base() < rcv_pt_base() ||
(cap.base() >= rcv_pt_base() + max))
nova_die();
_rcv_pt_cap_free [cap.base() - rcv_pt_base()] = UNUSED_CAP;
}
if (_rcv_pt_sel_max >= max) continue;
/* track the order of mapped and translated items */
if (cap.is_null()) {
_rcv_pt_sel[_rcv_pt_sel_max].sel = INVALID_INDEX;
_rcv_pt_sel[_rcv_pt_sel_max++].del = false;
} else {
_rcv_pt_sel[_rcv_pt_sel_max].sel = cap.base();
_rcv_pt_sel[_rcv_pt_sel_max++].del = item->is_del();
}
}
/*
* If a specific rcv_window has been specified,
* (see prepare_rcv_window) then the caller want to take care
* about freeing the * selector. Make the _rcv_pt_base invalid
* so that it is not cleanup twice.
*/
if (rcv_window != INVALID_INDEX)
_rcv_pt_base = INVALID_INDEX;
}
};
template <unsigned BUF_SIZE>
class Msgbuf : public Msgbuf_base
{
public:
char buf[BUF_SIZE];
Msgbuf() { _size = BUF_SIZE; }
};
}
#endif /* _INCLUDE__BASE__IPC_MSGBUF_H_ */