Previously during ipc copy, only the currently active task flags were
checked. This means the flags of whoever doing the actual copy was used
in the ipc. Now flags are stored in the ktcb and checked by the copy routine.
Current use of the flags is to determine short/full/extended ipc.
- Added a full ipc send/recv test
- Removed non-zero value checking in r2 for ipc that was there
to catch inadvertent full ipc calls.
- Added correct hanlding for read/write mrs for current status of utcb.
TODO:
- Add mapping of every utcb to every task for privileged access so that
the kernel can access every utcb without switching spaces.
- Removal of same mappings
- Upon thread creation need to copy page tables accordingly i.e.
each task will have its own utcb mapped with USER access, but every
other utcb as kernel access only. Need to handle this case upon page
table copying.
- Added ARM register ipc usage explanation to glue/arm/message.h
- In the current design, the unused r2 register is a system register
that kernel checks for ipc flags such as:
- IPC type: e.g. full or extended.
- In extended IPC, MR index containing message buffer ptr.
- In extended IPC, message size
- KIP's pointer to UTCB seems to work with existing l4lib ipc functions.
- Works up to clone()
- In clone we mmap() the same UTCB on each new thread - excessive.
- Generally during page fault handling, cloned threads may fault on the same page
multiple times even though a single handling would be enough for all of them.
Need to detect and handle this.
Added setting of utcb address to l4_thread_control.
This is going to be moved to exchange_registers() since we need to pass
both the utcb physical and virtual address and exregs fits such context
modification better than thread_control.
Headers 3 headers related to message registers and utcbs are now merged under
utcb.h in libl4. Some message register definitions used by the kernel are now
moved into kernel's glue/message.h. This avoids the duplication of same
definitions. Also the total number of mregs are now determined by arch-specific
kernel header, which is good.
