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;
}
