void
x86_page_fault_exception(struct iframe* frame)
{
Thread* thread = thread_get_current_thread();
addr_t cr2 = x86_read_cr2();
addr_t newip;
if (debug_debugger_running()) {
// If this CPU or this thread has a fault handler, we're allowed to be
// here.
if (thread != NULL) {
cpu_ent* cpu = &gCPU[smp_get_current_cpu()];
if (cpu->fault_handler != 0) {
debug_set_page_fault_info(cr2, frame->ip,
(frame->error_code & 0x2) != 0
? DEBUG_PAGE_FAULT_WRITE : 0);
frame->ip = cpu->fault_handler;
frame->bp = cpu->fault_handler_stack_pointer;
return;
}
if (thread->fault_handler != 0) {
kprintf("ERROR: thread::fault_handler used in kernel "
"debugger!\n");
debug_set_page_fault_info(cr2, frame->ip,
(frame->error_code & 0x2) != 0
? DEBUG_PAGE_FAULT_WRITE : 0);
frame->ip = reinterpret_cast<uintptr_t>(thread->fault_handler);
return;
}
}
// otherwise, not really
panic("page fault in debugger without fault handler! Touching "
"address %p from ip %p\n", (void*)cr2, (void*)frame->ip);
return;
} else if ((frame->flags & 0x200) == 0) {
// interrupts disabled
// If a page fault handler is installed, we're allowed to be here.
// TODO: Now we are generally allowing user_memcpy() with interrupts
// disabled, which in most cases is a bug. We should add some thread
// flag allowing to explicitly indicate that this handling is desired.
uintptr_t handler = reinterpret_cast<uintptr_t>(thread->fault_handler);
if (thread && thread->fault_handler != 0) {
if (frame->ip != handler) {
frame->ip = handler;
return;
}
// The fault happened at the fault handler address. This is a
// certain infinite loop.
panic("page fault, interrupts disabled, fault handler loop. "
"Touching address %p from ip %p\n", (void*)cr2,
(void*)frame->ip);
}
// If we are not running the kernel startup the page fault was not
// allowed to happen and we must panic.
panic("page fault, but interrupts were disabled. Touching address "
"%p from ip %p\n", (void*)cr2, (void*)frame->ip);
return;
} else if (thread != NULL && thread->page_faults_allowed < 1) {
panic("page fault not allowed at this place. Touching address "
"%p from ip %p\n", (void*)cr2, (void*)frame->ip);
return;
}
enable_interrupts();
vm_page_fault(cr2, frame->ip,
(frame->error_code & 0x2)!= 0, // write access
(frame->error_code & 0x10) != 0, // instruction fetch
(frame->error_code & 0x4) != 0, // userland
&newip);
if (newip != 0) {
// the page fault handler wants us to modify the iframe to set the
// IP the cpu will return to this ip
frame->ip = newip;
}
}
extern "C" void
arch_arm_data_abort(struct iframe *frame)
{
Thread *thread = thread_get_current_thread();
bool isUser = (frame->spsr & 0x1f) == 0x10;
addr_t far = arm_get_far();
bool isWrite = true;
addr_t newip = 0;
#ifdef TRACE_ARCH_INT
print_iframe("Data Abort", frame);
dprintf("FAR: %08lx, thread: %s\n", far, thread->name);
#endif
IFrameScope scope(frame);
if (debug_debugger_running()) {
// If this CPU or this thread has a fault handler, we're allowed to be
// here.
if (thread != NULL) {
cpu_ent* cpu = &gCPU[smp_get_current_cpu()];
if (cpu->fault_handler != 0) {
debug_set_page_fault_info(far, frame->pc,
isWrite ? DEBUG_PAGE_FAULT_WRITE : 0);
frame->svc_sp = cpu->fault_handler_stack_pointer;
frame->pc = cpu->fault_handler;
return;
}
if (thread->fault_handler != 0) {
kprintf("ERROR: thread::fault_handler used in kernel "
"debugger!\n");
debug_set_page_fault_info(far, frame->pc,
isWrite ? DEBUG_PAGE_FAULT_WRITE : 0);
frame->pc = thread->fault_handler;
return;
}
}
// otherwise, not really
panic("page fault in debugger without fault handler! Touching "
"address %p from pc %p\n", (void *)far, (void *)frame->pc);
return;
} else if ((frame->spsr & (1 << 7)) != 0) {
// interrupts disabled
// If a page fault handler is installed, we're allowed to be here.
// TODO: Now we are generally allowing user_memcpy() with interrupts
// disabled, which in most cases is a bug. We should add some thread
// flag allowing to explicitly indicate that this handling is desired.
if (thread && thread->fault_handler != 0) {
if (frame->pc != thread->fault_handler) {
frame->pc = thread->fault_handler;
return;
}
// The fault happened at the fault handler address. This is a
// certain infinite loop.
panic("page fault, interrupts disabled, fault handler loop. "
"Touching address %p from pc %p\n", (void*)far,
(void*)frame->pc);
}
// If we are not running the kernel startup the page fault was not
// allowed to happen and we must panic.
panic("page fault, but interrupts were disabled. Touching address "
"%p from pc %p\n", (void *)far, (void *)frame->pc);
return;
} else if (thread != NULL && thread->page_faults_allowed < 1) {
panic("page fault not allowed at this place. Touching address "
"%p from pc %p\n", (void *)far, (void *)frame->pc);
return;
}
enable_interrupts();
vm_page_fault(far, frame->pc, isWrite, false, isUser, &newip);
if (newip != 0) {
// the page fault handler wants us to modify the iframe to set the
// IP the cpu will return to to be this ip
frame->pc = newip;
}
}
