void pg_miss(void)
{
FAR struct tcb_s *ftcb = (FAR struct tcb_s*)g_readytorun.head;
FAR struct tcb_s *wtcb;
/* Sanity checking
*
* ASSERT if the currently executing task is the page fill worker thread.
* The page fill worker thread is how the page fault is resolved and
* all logic associated with the page fill worker must be "locked" and
* always present in memory.
*/
pglldbg("Blocking TCB: %p PID: %d\n", ftcb, ftcb->pid);
DEBUGASSERT(g_pgworker != ftcb->pid);
/* Block the currently executing task
* - Call up_block_task() to block the task at the head of the ready-
* to-run list. This should cause an interrupt level context switch
* to the next highest priority task.
* - The blocked task will be marked with state TSTATE_WAIT_PAGEFILL
* and will be retained in the g_waitingforfill prioritized task list.
*/
up_block_task(ftcb, TSTATE_WAIT_PAGEFILL);
/* Boost the page fill worker thread priority.
* - Check the priority of the task at the head of the g_waitingforfill
* list. If the priority of that task is higher than the current
* priority of the page fill worker thread, then boost the priority
* of the page fill worker thread to that priority.
*/
wtcb = sched_gettcb(g_pgworker);
DEBUGASSERT(wtcb != NULL);
if (wtcb->sched_priority < ftcb->sched_priority)
{
/* Reprioritize the page fill worker thread */
pgllvdbg("New worker priority. %d->%d\n",
wtcb->sched_priority, ftcb->sched_priority);
sched_setpriority(wtcb, ftcb->sched_priority);
}
/* Signal the page fill worker thread.
* - Is there a page fill pending? If not then signal the worker
* thread to start working on the queued page fill requests.
*/
if (!g_pftcb)
{
pglldbg("Signaling worker. PID: %d\n", g_pgworker);
kill(g_pgworker, SIGWORK);
}
}
static inline void pg_fillcomplete(void)
{
/* Call up_unblocktask(g_pftcb) to make the task that just
* received the fill ready-to-run.
*/
pglldbg("Restarting TCB: %p\n", g_pftcb);
up_unblock_task(g_pftcb);
}
static void pg_callback(FAR struct tcb_s *tcb, int result)
{
/* Verify that g_pftcb is non-NULL */
pgllvdbg("g_pftcb: %p\n", g_pftcb);
if (g_pftcb)
{
FAR struct tcb_s *htcb = (FAR struct tcb_s *)g_waitingforfill.head;
FAR struct tcb_s *wtcb = sched_gettcb(g_pgworker);
/* Find the higher priority between the task waiting for the fill to
* complete in g_pftcb and the task waiting at the head of the
* g_waitingforfill list. That will be the priority of he highest
* priority task waiting for a fill.
*/
int priority = g_pftcb->sched_priority;
if (htcb && priority < htcb->sched_priority)
{
priority = htcb->sched_priority;
}
/* If this higher priority is higher than current page fill worker
* thread, then boost worker thread's priority to that level. Thus,
* the page fill worker thread will always run at the priority of
* the highest priority task that is waiting for a fill.
*/
if (priority > wtcb->sched_priority)
{
pgllvdbg("New worker priority. %d->%d\n",
wtcb->sched_priority, priority);
sched_setpriority(wtcb, priority);
}
/* Save the page fill result (don't permit the value -EBUSY) */
if (result == -EBUSY)
{
result = -ENOSYS;
}
g_fillresult = result;
}
/* Signal the page fill worker thread (in any event) */
pglldbg("Signaling worker. PID: %d\n", g_pgworker);
kill(g_pgworker, SIGWORK);
}
int up_fillpage(FAR struct tcb_s *tcb, FAR void *vpage, up_pgcallback_t pg_callback)
{
pglldbg("TCB: %p vpage: %d far: %08x\n", tcb, vpage, tcb->xcp.far);
DEBUGASSERT(tcb->xcp.far >= PG_PAGED_VBASE && tcb->xcp.far < PG_PAGED_VEND);
#if defined(CONFIG_PAGING_BINPATH)
# error "File system-based paging must always be implemented with blocking calls"
#elif defined(CONFIG_PAGING_M25PX) || defined(CONFIG_PAGING_AT45DB)
# error "SPI FLASH paging must always be implemented with blocking calls"
#else
# warning "Not implemented"
#endif
return -ENOSYS;
}
int pg_worker(int argc, char *argv[])
{
irqstate_t flags;
/* Loop forever -- Notice that interrupts will be disable at all times that
* this thread runs. That is so that we con't lose signals or have
* asynchronous page faults.
*
* All interrupt logic as well as all page fill worker thread logic must
* be locked in memory. Therefore, keeping interrupts disabled here
* should prevent any concurrent page faults. Any page faults or page
* fill completions should occur while this thread sleeps.
*/
pglldbg("Started\n");
flags = irqsave();
for (;;)
{
/* Wait awhile. We will wait here until either the configurable timeout
* elapses or until we are awakened by a signal (which terminates the
* usleep with an EINTR error). Note that interrupts will be re-enabled
* while this task sleeps.
*
* The timeout is a failsafe that will handle any cases where a single
* is lost (that would really be a bug and shouldn't happen!) and also
* supports timeouts for case of non-blocking, asynchronous fills.
*/
usleep(CONFIG_PAGING_WORKPERIOD);
/* The page fill worker thread will be awakened on one of three conditions:
*
* - When signaled by pg_miss(), the page fill worker thread will be awakenend,
* - if CONFIG_PAGING_BLOCKINGFILL is not defined, from pg_callback()
* after completing a page fill, or
* - On a configurable timeout expires with no activity.
*
* Interrupts are still disabled.
*/
#ifndef CONFIG_PAGING_BLOCKINGFILL
/* For the non-blocking up_fillpage(), the page fill worker thread will detect
* that the page fill is complete when it is awakened with g_pftcb non-NULL
* and fill completion status from pg_callback.
*/
if (g_pftcb != NULL)
{
/* If it is a real page fill completion event, then the result of the page
* fill will be in g_fillresult and will not be equal to -EBUSY.
*/
if (g_fillresult != -EBUSY)
{
/* Any value other than OK, brings the system down */
ASSERT(g_fillresult == OK);
/* Handle the successful page fill complete event by restarting the
* task that was blocked waiting for this page fill.
*/
pglldbg("Restarting TCB: %p\n", g_pftcb);
up_unblock_task(g_pftcb);;
/* Yes .. Start the next asynchronous fill. Check the return
* value to see a fill was actually started (false means that
* no fill was started).
*/
pgllvdbg("Calling pg_startfill\n");
if (!pg_startfill())
{
/* No fill was started. This can mean only that all queued
* page fill actions have and been completed and there is
* nothing more to do.
*/
pgllvdbg("Call pg_alldone()\n");
pg_alldone();
}
}
/* If a configurable timeout period expires with no page fill completion
* event, then declare a failure.
*/
#ifdef CONFIG_PAGING_TIMEOUT_TICKS
else
{
lldbg("Timeout!\n");
ASSERT(clock_systimer() - g_starttime < CONFIG_PAGING_TIMEOUT_TICKS);
}
#endif
}
/* Otherwise, this might be a page fill initiation event. When
* awakened from pg_miss(), no fill will be in progress and
* g_pftcb will be NULL.
*/
else
{
/* Are there tasks blocked and waiting for a fill? If so,
* pg_startfill() will start the asynchronous fill (and set
* g_pftcb).
*/
pgllvdbg("Calling pg_startfill\n");
(void)pg_startfill();
}
#else
/* Are there tasks blocked and waiting for a fill? Loop until all
* pending fills have been processed.
*/
for (;;)
{
/* Yes .. Start the fill and block until the fill completes.
* Check the return value to see a fill was actually performed.
* (false means that no fill was perforemd).
*/
pgllvdbg("Calling pg_startfill\n");
if (!pg_startfill())
{
/* Break out of the loop -- there is nothing more to do */
break;
}
/* Handle the page fill complete event by restarting the
* task that was blocked waiting for this page fill. In the
* non-blocking fill case, the page fill worker thread will
* know that the page fill is complete when pg_startfill()
* returns true.
*/
pgllvdbg("Restarting TCB: %p\n", g_pftcb);
up_unblock_task(g_pftcb);;
}
/* All queued fills have been processed */
pgllvdbg("Call pg_alldone()\n");
pg_alldone();
#endif
}
return OK; /* To keep some compilers happy */
}
static inline bool pg_startfill(void)
{
FAR void *vpage;
int result;
/* Remove the TCB at the head of the g_waitfor fill list and check if there
* is any task waiting for a page fill. pg_dequeue will handle this (plus
* some cornercases) and will true if the next page TCB was successfully
* dequeued.
*/
if (pg_dequeue())
{
/* Call up_allocpage(tcb, &vpage). This architecture-specific function will
* set aside page in memory and map to virtual address (vpage). If all
* available pages are in-use (the typical case), this function will select
* a page in-use, un-map it, and make it available.
*/
pgllvdbg("Call up_allocpage(%p)\n", g_pftcb);
result = up_allocpage(g_pftcb, &vpage);
DEBUGASSERT(result == OK);
/* Start the fill. The exact way that the fill is started depends upon
* the nature of the architecture-specific up_fillpage() function -- Is it
* a blocking or a non-blocking call?
*/
#ifdef CONFIG_PAGING_BLOCKINGFILL
/* If CONFIG_PAGING_BLOCKINGFILL is defined, then up_fillpage is blocking
* call. In this case, up_fillpage() will accept only (1) a reference to
* the TCB that requires the fill. Architecture-specific context information
* within the TCB will be sufficient to perform the fill. And (2) the
* (virtual) address of the allocated page to be filled. The resulting
* status of the fill will be provided by return value from up_fillpage().
*/
pgllvdbg("Call up_fillpage(%p)\n", g_pftcb);
result = up_fillpage(g_pftcb, vpage);
DEBUGASSERT(result == OK);
#else
/* If CONFIG_PAGING_BLOCKINGFILL is defined, then up_fillpage is non-blocking
* call. In this case up_fillpage() will accept an additional argument: The page
* fill worker thread will provide a callback function, pg_callback.
*
* Calling up_fillpage will start an asynchronous page fill. pg_callback
* ill be called when the page fill is finished (or an error occurs). This
* This callback will probably from interrupt level.
*/
pgllvdbg("Call up_fillpage(%p)\n", g_pftcb);
result = up_fillpage(g_pftcb, vpage, pg_callback);
DEBUGASSERT(result == OK);
/* Save the time that the fill was started. These will be used to check for
* timeouts.
*/
#ifdef CONFIG_PAGING_TIMEOUT_TICKS
g_starttime = clock_systimer();
#endif
/* Return and wait to be signaled for the next event -- the fill completion
* event. While the fill is in progress, other tasks may execute. If
* another page fault occurs during this time, the faulting task will be
* blocked, its TCB will be added (in priority order) to g_waitingforfill
* and the priority of the page worker task may be boosted. But no action
* will be taken until the current page fill completes. NOTE: The IDLE task
* must also be fully locked in memory. The IDLE task cannot be blocked. It
* the case where all tasks are blocked waiting for a page fill, the IDLE
* task must still be available to run.
*/
#endif /* CONFIG_PAGING_BLOCKINGFILL */
return true;
}
pglldbg("Queue empty\n");
return false;
}
static inline bool pg_dequeue(void)
{
/* Loop until either (1) the TCB of a task that requires a fill is found, OR
* (2) the g_watingforfill list becomes empty.
*/
do
{
/* Remove the TCB from the head of the list (if any) */
g_pftcb = (FAR struct tcb_s *)dq_remfirst((dq_queue_t*)&g_waitingforfill);
pgllvdbg("g_pftcb: %p\n", g_pftcb);
if (g_pftcb != NULL)
{
/* Call the architecture-specific function up_checkmapping() to see if
* the page fill still needs to be performed. In certain conditions,
* the page fault may occur on several threads for the same page and
* be queues multiple times. In this corner case, the blocked task will
* simply be restarted.
*/
if (!up_checkmapping(g_pftcb))
{
/* This page needs to be filled. pg_miss bumps up
* the priority of the page fill worker thread as each
* TCB is added to the g_waitingforfill list. So we
* may need to also drop the priority of the worker
* thread as the next TCB comes off of the list.
*
* If wtcb->sched_priority > CONFIG_PAGING_DEFPRIO,
* then the page fill worker thread is executing at
* an elevated priority that may be reduced.
*
* If wtcb->sched_priority > g_pftcb->sched_priority
* then the page fill worker thread is executing at
* a higher priority than is appropriate for this
* fill (this priority can get re-boosted by pg_miss()
* if a new higher priority fill is required).
*/
FAR struct tcb_s *wtcb = (FAR struct tcb_s *)g_readytorun.head;
if (wtcb->sched_priority > CONFIG_PAGING_DEFPRIO &&
wtcb->sched_priority > g_pftcb->sched_priority)
{
/* Don't reduce the priority of the page fill
* worker thread lower than the configured
* minimum.
*/
int priority = g_pftcb->sched_priority;
if (priority < CONFIG_PAGING_DEFPRIO)
{
priority = CONFIG_PAGING_DEFPRIO;
}
/* Reduce the priority of the page fill worker thread */
pgllvdbg("New worker priority. %d->%d\n",
wtcb->sched_priority, priority);
sched_setpriority(wtcb, priority);
}
/* Return with g_pftcb holding the pointer to
* the TCB associated with task that requires the page fill.
*/
return true;
}
/* The page need by this task has already been mapped into the
* virtual address space -- just restart it.
*/
pglldbg("Restarting TCB: %p\n", g_pftcb);
up_unblock_task(g_pftcb);
}
}
while (g_pftcb != NULL);
return false;
}
uint32_t *arm_dataabort(uint32_t *regs, uint32_t dfar, uint32_t dfsr)
{
DFAR struct tcb_s *tcb = (DFAR struct tcb_s *)g_readytorun.head;
uint32_t *savestate;
/* Save the saved processor context in current_regs where it can be accessed
* for register dumps and possibly context switching.
*/
savestate = (uint32_t*)current_regs;
current_regs = regs;
/* In the NuttX on-demand paging implementation, only the read-only, .text
* section is paged. However, the ARM compiler generated PC-relative data
* fetches from within the .text sections. Also, it is customary to locate
* read-only data (.rodata) within the same section as .text so that it
* does not require copying to RAM. Misses in either of these case should
* cause a data abort.
*
* We are only interested in data aborts due to page translations faults.
* Sections should already be in place and permissions should already be
* be set correctly (to read-only) so any other data abort reason is a
* fatal error.
*/
pglldbg("DFSR: %08x DFAR: %08x\n", dfsr, dfar);
if ((dfsr & FSR_MASK) != FSR_PAGE)
{
goto segfault;
}
/* Check the (virtual) address of data that caused the data abort. When
* the exception occurred, this address was provided in the DFAR register.
* (It has not yet been saved in the register context save area).
*/
pgllvdbg("VBASE: %08x VEND: %08x\n", PG_PAGED_VBASE, PG_PAGED_VEND);
if (dfar < PG_PAGED_VBASE || dfar >= PG_PAGED_VEND)
{
goto segfault;
}
/* Save the offending data address as the fault address in the TCB of
* the currently task. This fault address is also used by the prefetch
* abort handling; this will allow common paging logic for both
* prefetch and data aborts.
*/
tcb->xcp.dfar = regs[REG_R15];
/* Call pg_miss() to schedule the page fill. A consequences of this
* call are:
*
* (1) The currently executing task will be blocked and saved on
* on the g_waitingforfill task list.
* (2) An interrupt-level context switch will occur so that when
* this function returns, it will return to a different task,
* most likely the page fill worker thread.
* (3) The page fill worker task has been signalled and should
* execute immediately when we return from this exception.
*/
pg_miss();
/* Restore the previous value of current_regs. NULL would indicate that
* we are no longer in an interrupt handler. It will be non-NULL if we
* are returning from a nested interrupt.
*/
current_regs = savestate;
return regs;
segfault:
lldbg("Data abort. PC: %08x DFAR: %08x DFSR: %08x\n",
regs[REG_PC], dfar, dfsr);
PANIC();
return regs; /* To keep the compiler happy */
}
uint32_t *arm_prefetchabort(uint32_t *regs, uint32_t ifar, uint32_t ifsr)
{
uint32_t *savestate;
/* Save the saved processor context in current_regs where it can be accessed
* for register dumps and possibly context switching.
*/
savestate = (uint32_t *)current_regs;
current_regs = regs;
/* Get the (virtual) address of instruction that caused the prefetch abort.
* When the exception occurred, this address was provided in the lr register
* and this value was saved in the context save area as the PC at the
* REG_R15 index.
*
* Check to see if this miss address is within the configured range of
* virtual addresses.
*/
pglldbg("VADDR: %08x VBASE: %08x VEND: %08x\n",
regs[REG_PC], PG_PAGED_VBASE, PG_PAGED_VEND);
if (regs[REG_R15] >= PG_PAGED_VBASE && regs[REG_R15] < PG_PAGED_VEND)
{
/* Save the offending PC as the fault address in the TCB of the currently
* executing task. This value is, of course, already known in regs[REG_R15],
* but saving it in this location will allow common paging logic for both
* prefetch and data aborts.
*/
struct tcb_s *tcb = this_task();
tcb->xcp.far = regs[REG_R15];
/* Call pg_miss() to schedule the page fill. A consequences of this
* call are:
*
* (1) The currently executing task will be blocked and saved on
* on the g_waitingforfill task list.
* (2) An interrupt-level context switch will occur so that when
* this function returns, it will return to a different task,
* most likely the page fill worker thread.
* (3) The page fill worker task has been signalled and should
* execute immediately when we return from this exception.
*/
pg_miss();
/* Restore the previous value of current_regs. NULL would indicate that
* we are no longer in an interrupt handler. It will be non-NULL if we
* are returning from a nested interrupt.
*/
current_regs = savestate;
}
else
{
lldbg("Prefetch abort. PC: %08x IFAR: %08x IFSR: %08x\n",
regs[REG_PC], ifar, ifsr);
PANIC();
}
return regs;
}
int up_fillpage(FAR struct tcb_s *tcb, FAR void *vpage)
{
#if defined(CONFIG_PAGING_BINPATH)
ssize_t nbytes;
off_t offset;
off_t pos;
#elif defined(CONFIG_PAGING_M25PX) || defined(CONFIG_PAGING_AT45DB)
ssize_t nbytes;
off_t offset;
#endif
pglldbg("TCB: %p vpage: %p far: %08x\n", tcb, vpage, tcb->xcp.far);
DEBUGASSERT(tcb->xcp.far >= PG_PAGED_VBASE && tcb->xcp.far < PG_PAGED_VEND);
/* If BINPATH is defined, then it is the full path to a file on a mounted file
* system. In this case initialization will be deferred until the first
* time that up_fillpage() is called. Are we initialized?
*/
#if defined(CONFIG_PAGING_BINPATH)
/* Perform initialization of the paging source device (if necessary) */
lpc31_initsrc();
/* Create an offset into the binary image that corresponds to the
* virtual address. File offset 0 corresponds to PG_LOCKED_VBASE.
*/
offset = (off_t)tcb->xcp.far - PG_LOCKED_VBASE;
/* Seek to that position */
pos = lseek(g_pgsrc.fd, offset, SEEK_SET);
DEBUGASSERT(pos != (off_t)-1);
/* And read the page data from that offset */
nbytes = read(g_pgsrc.fd, vpage, PAGESIZE);
DEBUGASSERT(nbytes == PAGESIZE);
return OK;
#elif defined(CONFIG_PAGING_M25PX) || defined(CONFIG_PAGING_AT45DB) /* !CONFIG_PAGING_BINPATH */
/* Perform initialization of the paging source device (if necessary) */
lpc31_initsrc();
/* Create an offset into the binary image that corresponds to the
* virtual address. File offset 0 corresponds to PG_LOCKED_VBASE.
*/
offset = (off_t)tcb->xcp.far - PG_LOCKED_VBASE + CONFIG_EA3131_PAGING_BINOFFSET;
/* Read the page at the correct offset into the SPI FLASH device */
nbytes = MTD_READ(g_pgsrc.mtd, offset, PAGESIZE, (FAR uint8_t *)vpage);
DEBUGASSERT(nbytes == PAGESIZE);
return OK;
#else /* !CONFIG_PAGING_BINPATH && !CONFIG_PAGING_M25PX && !CONFIG_PAGING_AT45DB */
# warning "Not implemented"
return -ENOSYS;
#endif /* !CONFIG_PAGING_BINPATH && !CONFIG_PAGING_M25PX && !CONFIG_PAGING_AT45DB */
}
