Commit graph

10 commits

Author SHA1 Message Date
Tomas Hruby
391fd926ff TASK_PRIVILEGE and level0() removed
- there are no tasks running, we don't need TASK_PRIVILEGE priviledge anymore

- as there is no ring 1 anymore, there is no need for level0() to call sensitive
  code from ring 1 in ring 0

- 286 related macros removed as clean up
2010-02-09 15:23:31 +00:00
Tomas Hruby
728f0f0c49 Removal of the system task
* Userspace change to use the new kernel calls

	- _taskcall(SYSTASK...) changed to _kernel_call(...)

	- int 32 reused for the kernel calls

	- _do_kernel_call() to make the trap to kernel

	- kernel_call() to make the actuall kernel call from C using
	  _do_kernel_call()

	- unlike ipc call the kernel call always succeeds as kernel is
	  always available, however, kernel may return an error

* Kernel side implementation of kernel calls

	- the SYSTEm task does not run, only the proc table entry is
	  preserved

	- every data_copy(SYSTEM is no data_copy(KERNEL

	- "locking" is an empty operation now as everything runs in
	  kernel

	- sys_task() is replaced by kernel_call() which copies the
	  message into kernel, dispatches the call to its handler and
	  finishes by either copying the results back to userspace (if
	  need be) or by suspending the process because of VM

	- suspended processes are later made runnable once the memory
	  issue is resolved, picked up by the scheduler and only at
	  this time the call is resumed (in fact restarted) which does
	  not need to copy the message from userspace as the message
	  is already saved in the process structure.

	- no ned for the vmrestart queue, the scheduler will restart
	  the system calls

	- no special case in do_vmctl(), all requests remove the
	  RTS_VMREQUEST flag
2010-02-09 15:20:09 +00:00
Tomas Hruby
b14a86ca5c Sys calls are called ipc calls now
- the syscalls are pretty much just ipc calls, however, sendrec() is
  used to implement system task (sys) calls

- sendrec() won't be used anymore for this, therefore ipc calls will
  become pure ipc calls
2010-02-09 15:13:07 +00:00
Kees van Reeuwijk
b67f788eea Removed a number of useless #includes 2010-01-26 10:59:01 +00:00
Kees van Reeuwijk
a7cee5bec4 Removed unused symbols.
Minor cleanups.
2010-01-22 22:01:08 +00:00
Tomas Hruby
5efa92f754 NMI watchdog is an awesome feature for debugging locked up kernels.
There is not that much use for it on a single CPU, however, deadlock
between kernel and system task can be delected. Or a runaway loop.

If a kernel gets locked up the timer interrupts don't occure (as all
interrupts are disabled in kernel mode). The only chance is to
interrupt the kernel by a non-maskable interrupt.

This patch generates NMIs using performance counters. It uses the most
widely available performace counters. As the performance counters are 
highly model-specific this patch is not guaranteed to work on every
machine.  Unfortunately this is also true for KVM :-/ On the other
hand adding this feature for other models is not extremely difficult
and the framework makes it hopefully easy enough.

Depending on the frequency of the CPU an NMI is generated at most
about every 0.5s If the cpu's speed is less then 2Ghz it is generated
at most every 1s. In general an NMI is generated much less often as
the performance counter counts down only if the cpu is not idle.
Therefore the overhead of this feature is fairly minimal even if the
load is high.

Uppon detecting that the kernel is locked up the kernel dumps the 
state of the kernel registers and panics.

Local APIC must be enabled for the watchdog to work.

The code is _always_ compiled in, however, it is only enabled if  
watchdog=<non-zero> is set in the boot monitor.

One corner case is serial console debugging. As dumping a lot of stuff
to the serial link may take a lot of time, the watchdog does not 
detect lockups during this time!!! as it would result in too many
false positives. 10 nmi have to be handled before the lockup is
detected. This means something between ~5s to 10s.

Another corner case is that the watchdog is enabled only after the
paging is enabled as it would be pure madness to try to get it right.
2010-01-16 20:53:55 +00:00
Tomas Hruby
42c13951a7 APIC disabled if CPU lacks TSC
- we cannot calibrate local APIC timer in such a case

- fixes possible uninitialized variable problem during calibration if no TSC
2010-01-13 18:22:41 +00:00
Kees van Reeuwijk
ad4c0ff698 Fixed a bug in apic.c that broke lapic_stop_timer().
Fixed bugs in liveupdate.c that rendered load_state_info() meaningless.
More informative error message in do_config() in service.c.
2010-01-13 14:44:19 +00:00
Kees van Reeuwijk
d8f3af3672 Fixed a typing bug.
More explicit type conversion from virual to physical bytes.
Bracket negative #defines for extra paranoia.
Added a forgotten 'void' to a function.
2010-01-06 08:23:14 +00:00
Tomas Hruby
8a44a44cb9 Local APIC
- local APIC timer used as the source of time

- PIC is still used as the hw interrupt controller as we don't have
  enough info without ACPI or MPS to set up IO APICs

- remapping of APIC when switching paging on, uses the new mechanism
  to tell VM what phys areas to map in kernel's virtual space

- one more step to SMP

based on code by Arun C.
2009-11-16 21:41:44 +00:00