Before reserving address space in SYS_EXEC verify that ELF address
space is actually loadable. For example when trying to execute the
kernel binary in userspace, binarys address space would overlap with
current kernel address space. Now kernel won't crash anymore and
will just send SIGKILL to the process calling exec*().
Every inode holds a weak pointer to shared file data. This contains
physical addresses of pages for inode file data. Physical addresses
are allocated and read on demand.
When last shared mapping is unmapped. The inodes shared data is freed
and written to the inode.
MemoryBackedRegion now inherits from this and is used for private
anonymous mappigs. This will make shared mappings and file backed
mappings much easier to implement.
All executable files are now read from disk and paged on demand.
This was a big rewrite of the old ELF library but in the end
everything seems much cleaner, since all the old functionality was
not actually needed for execution.
I have to do some measurements, but I feel like memory usage dropped
quite a bit after this change.
Userspace programs can call tty_ctrl() to disable/enable tty from
handling input and displaying output.
This API is probably going to change in the future to ioctl calls
but I'm not sure how ioctl is used and what functionality should it
have. I decided to create whole new function and syscall for now.
Next I will expose framebuffer in /dev/fb0 and then I can start work
on graphical environment! :D
We now validate pointers passed by the user, to forbid arbitary
memory read/write. Now the user is only allowed to pass in pointers
in their own mapped memory space (or null).
I could delete the whole FixedWidthAllocator as it was now obsolete.
GeneralAllocator is still used by kmalloc. Kmalloc cannot actually
use it since, GeneralAllocator depends on SpinLock and kmalloc runs
without interrupts.
I have no idea why I had made PATH environment variable parsing
to be part of the kernel. Now the shell does the parsing and
environment syscall is no longer needed.
When we want to kill a process, we mark its threads as Terminating
or Terminated. If the thread is in critical section that has to be
finished, it will be in Terminating state until done. Once Scheduler
is trying to execute Terminated thread it will instead delete it.
Once processes last thread is marked Terminated, the processes will
turn it into a cleanup thread, that will allow blocks and memory
cleanup to be done.
Bananymous
Bananymous