static void
signal(void *unused, uintptr_t arg, struct pbuf *pbuf)
{
debug("Signal function called\n");
L4_Msg_t msg;
L4_MsgClear(&msg);
L4_MsgLoad(&msg);
L4_MsgTag_t tag = L4_Send((L4_ThreadId_t) arg);
if (L4_IpcFailed(tag))
{
L4_Word_t ec = L4_ErrorCode();
printf("%s: IPC error\n", __FUNCTION__);
sos_print_error(ec);
assert(!(ec & 1));
}
call_pbuf = pbuf;
}
/*
* Init function to initialise the page table entries
*/
L4_Word_t
pager_init(L4_Word_t low, L4_Word_t high)
{
//The frames have been used to set up page table entries as well
page_table = (sos_PTE*) low;
// Use a simple algaebric formula to calculate optimum size of page table for the
// amount of memory available
//new_low points to the memory to be used now, memory low -> new_low is the pagetable
new_low = ((double)high*sizeof(sos_PTE)+PAGESIZE*(double)low)/
(double)(PAGESIZE+sizeof(sos_PTE));
// align it
new_low = (new_low/PAGESIZE)*PAGESIZE + PAGESIZE;
numPTE = (high-new_low)/PAGESIZE;
printf("low: %lx new_low: %lx high: %lx numPTE: %d \n", low, new_low, high, numPTE);
//printf("value of swap memory %p \n",swap_table);
// initialize the empty page table.
for (int i = 0; i < numPTE; i++)
{
page_table[i].tid = L4_nilthread;
page_table[i].referenced = 0;
page_table[i].dirty = 0;
page_table[i].being_updated = 0;
page_table[i].error_in_transfer = 0;
page_table[i].pinned = 0;
}
for(int i=0;i<MAX_SWAP_ENTRIES;i++) {
swap_table[i].tid = L4_nilthread;
swap_table[i].offset = PTE_SENTINEL;
//Initially all entries are free so each points to the next one in the table
swap_table[i].next_free = i+1;
}
// add a guard page against stack overflows and let it map to 0
L4_Word_t guardPage = 0x7000000;
L4_PhysDesc_t phys = L4_PhysDesc(0, L4_DefaultMemory);
L4_Fpage_t targetFpage = L4_FpageLog2(guardPage, 12);
L4_Set_Rights(&targetFpage, L4_Readable);
if ( !L4_MapFpage(L4_Myself(), targetFpage, phys) ) {
sos_print_error(L4_ErrorCode());
printf(" Can't map guard page\n");
}
return new_low;
}
/*
* Function invoked by roottask on pagefault
*/
int
pager(L4_ThreadId_t tid, L4_Msg_t *msgP)
{
send = 1;
// Get the faulting address
L4_Word_t addr = L4_MsgWord(msgP, 0);
L4_Word_t physicalAddress = 0;
L4_Word_t permission = 0;
L4_MsgTag_t tag;
// Alignment
addr = (addr / PAGESIZE)*PAGESIZE;
tag = L4_MsgMsgTag(msgP);
L4_Word_t access_type = L4_Label(tag) & 0x07;
//printf("pager invoked addr=%lx by %lx %lx for access 0x%lx\n", addr,L4_ThreadNo(tid),tid.raw,access_type);
// Construct fpage IPC message
L4_Fpage_t targetFpage = L4_FpageLog2(addr, 12);
if(VIRTUAL(addr))
{
if(addr >= BASE_CODE_SEGMENT_ADDRESS) {
//Code segment
int inPage = isInPage(tid,targetFpage);
if(inPage == -1) {
//It should be in page table so this should not happen
printf("Panic !!! Cannot load the code segment");
} else {
physicalAddress = new_low + inPage*PAGESIZE;
permission = L4_FullyAccessible;
}
} else {
//Heap and stack
int inPage = isInPage(tid, targetFpage);
if (inPage == -1)
{
//We need to check if the page is in swap
inPage = isInSwap(tid,targetFpage);
mapAddress(tid, targetFpage,inPage);
//We dont need to map any addresses here as mapAddresses maps the addresses
return send;
} else {
physicalAddress = new_low+inPage*PAGESIZE;
targetFpage = page_table[inPage].pageNo;
page_table[inPage].referenced = 1;
if(access_type & L4_Writable) {
//We now need to set the dirty bit and provide read write access
page_table[inPage].dirty = 1;
permission = L4_ReadWriteOnly;
} else {
permission = L4_Readable;
}
}
}
} else {
// we need to map physical addresses 1:1
physicalAddress = addr;
if(addr < new_low) {
// This is beyond the low memory range ie the page table
// and some other addresses which is below the low range
permission = L4_FullyAccessible;
} else {
// This would be the code segment between the new_low and high
permission = L4_Readable;
}
}
L4_Set_Rights(&targetFpage,permission);
L4_PhysDesc_t phys = L4_PhysDesc(physicalAddress, L4_DefaultMemory);
if ( !L4_MapFpage(tid, targetFpage, phys) ) {
sos_print_error(L4_ErrorCode());
printf(" Can't map page at %lx\n", addr);
}
return send;
}
