Commit graph

11 commits

Author SHA1 Message Date
Arun Thomas
cbd276e4ce Convert library asm files to GAS syntax 2010-03-03 14:27:30 +00:00
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
5e57818431 copy_msg_from_user() and copy_msg_to_user()
- copies a mesage from/to userspace without need of translating
  addresses

- the assumption is that the address space is installed, i.e. ldt and
  cr3 are loaded correctly

- if a pagefault or a general protection occurs while copying from
  userland to kernel (or vice versa) and error is returned which gives
  the caller a chance to respond in a proper way

- error happens _only_ because of a wrong user pointer if the function
  is used correctly

- if the prerequisites of the function do no hold, the function will
  most likely fail as the user address becomes random
2010-02-09 15:15:45 +00:00
Tomas Hruby
ad9ba944d1 Early address space switch
- switch_address_space() implements a switch of the user address space
  for the destination process

- this makes memory of this process easily accessible, e.g. a pointer
  valid in the userspace can be used with a little complexity to
  access the process's memory

- the switch does not happed only just before we return to userspace,
  however, it happens right after we know which process we are going
  to schedule. This happens before we start processing the misc flags
  of this process so its memory is available

- if the process becomes not runnable while processing the mics flags
  we pick a new process and we switch the address space again which
  introduces possibly a little bit more overhead, however, it is
  hopefully hidden by reducing the overheads when we actually access
  the memory
2010-02-09 15:13:52 +00:00
Tomas Hruby
51065a1b47 Cooments to warn not to use certains instructions
- gas2ack cannot handle all variants of some instructions. Until this issues is
  addressed, this patch places a big warning where appropriate. This code is not
  supposed to change frequently.
2009-12-07 12:01:05 +00:00
Ben Gras
bd42705433 FPU context switching support by Evgeniy Ivanov. 2009-12-02 13:01:48 +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
Tomas Hruby
ad4dcaab71 Idle task never runs
- idle task becomes a pseudo task which is never scheduled. It is never put on
  any run queue and never enters userspace. An entry for this task still remains
  in the process table for time accounting

- Instead of panicing if there is not process to schedule, pick_proc() returns
  NULL which is a signal to put the cpu in an idle state and set everything in
  such a way that after receiving and interrupt it looks like idle task was
  preempted

- idle task is set non-preemptible to avoid handling in the timer interrupt code
  which make userspace scheduling simpler as idle task does not need to be
  handled as a special case.
2009-11-12 08:42:18 +00:00
Tomas Hruby
ebbce7507b Complete ovehaul of mode switching code
- after a trap to kernel, the code automatically switches to kernel
  stack, in the future local to the CPU

- k_reenter variable replaced by a test whether the CS is kernel cs or
  not. The information is passed further if needed. Removes a global
  variable which would need to be cpu local

- no need for global variables describing the exception or trap
  context. This information is kept on stack and a pointer to this
  structure is passed to the C code as a single structure

- removed loadedcr3 variable and its use replaced by reading the %cr3
  register

- no need to redisable interrupts in restart() as they are already
  disabled.

- unified handling of traps that push and don't push errorcode

- removed save() function as the process context is not saved directly
  to process table but saved as required by the trap code. Essentially
  it means that save() code is inlined everywhere not only in the
  exception handling routine

- returning from syscall is more arch independent - it sets the retger
  in C

- top of the x86 stack contains the current CPU id and pointer to the
  currently scheduled process (the one right interrupted) so the mode
  switch code can find where to save the context without need to use
  proc_ptr which will be cpu local in the future and therefore
  difficult to access in assembler and expensive to access in general

- some more clean up of level0 code. No need to read-back the argument
  passed in
  %eax from the proc structure. The mode switch code does not clobber
  %the general registers and hence we can just call what is in %eax

- many assebly macros in sconst.h as they will be reused by the apic
  assembly
2009-11-06 09:08:26 +00:00
Tomas Hruby
cf854041ce Hardware interrupts code path cleanup
- the PIC master and slave irq handlers don't pass the irq hook pointer but just
  the irq number. It gives a little bit more information to the C handler as the
  irq number is not lost

- the irq code path is more achitecture independent. i386 hw interrupts are
  called irq and whereever the code is arch independent enough hw_intr_
  functions are called to mask/unmask interrupts

- the legacy PIC is not the only possible interrupt controller in the x86 world,
  therefore the intr_(un)mask functions were renamed to signal their
  functionality explicitly. APIC will add their own.

- masking and unmasking PIC interrupt lines is removed from assembler and all
  the functionality is rewriten in C and moved to i8259.c

- interrupt handlers have to unmask the interrupt line if all irq handlers are
  done. Assembler does not do it anymore
2009-11-04 13:24:56 +00:00
Tomas Hruby
403764c538 Conversion of kernel assembly from ACK to GNU
- .s files removed and replaced by .S as the .S is a standard extension for assembly that needs preprocessing
2009-10-30 16:00:44 +00:00