To avoid a MAXMACH limit of 32 and make
txtflush into an array for the bitmap.
Provide portable macros for testing and clearing
the bits: needtxtflush(), donetxtflush().
On pc/pc64, define inittxtflush()/settxtflush()
as no-op macros, avoiding the storage overhead of
the txtflush array alltogether.
Previously, mmurelease() was always called with
palloc spinlock held.
This is unneccesary for some mmurelease()
implementations as they wont release pages
to the palloc pool.
This change removes pagechainhead() and
pagechaindone() and replaces them with just
freepages() call, which aquires the palloc
lock internally as needed.
freepages() avoids holding the palloc lock
while walking the linked list of pages,
avoding some lock contention.
devdir internally replicates the qid in ther perm stat field
already and the practice of explicitely passing just causing
confusion when done inconsistently.
- return distinct error message when attempting to create Globalseg with physseg name
- copy directory name to up->genbuf so it stays valid after we unlock(&glogalseglock)
- cleanup wstat() handling, allow changing uid
- make sure global segment size is below SEGMAXSIZE
- move isoverlap() check from globalsegattach() into segattach()
- remove Proc* argument from globalsegattach(), segattach() and isoverlap()
- make Physseg.attr and segattach attr parameter an int for consistency
access to the axi segment hangs the machine when the fpga
is not programmed yet. to prevent access, we introduce a
new SG_FAULT flag, that when set on the Segment.type or
Physseg.attr, causes the fault handler to immidiately
return with an error (as if the segment would not be mapped).
during programming, we temporarily set the SG_FAULT flag
on the axi physseg, flush all processes tlb's that have
the segment mapped and when programming is done, we clear
the flag again.
devproc's procctlmemio() did not handle physical segment
types correctly, as it assumed it can just kmap() the page
in question and write to it. physical segments however
need to be mapped uncached but kmap() will always map
cached as it assumes normal memory. on some machines with
aliasing memory with different cache attributes
leads to undefined behaviour!
we borrow the code from devsegment and provide a generic
segio() function to read and write user segments which
handles all the cases without using kmap by just spawning
a kproc that attaches the segment that needs to be read
from or written to. fault() will setup the right mmu
attributes for us. it will also properly flush pages for
segments that maintain instruction cache when written.
however, tlb's have to be flushed separately.
segio() is used for devsegment and devproc now, which
also allows for simplification of fixfault() as there is no
special error handling case anymore as fixfault() is now
called from faulting process *only*.
reads from /proc/$pid/mem can now span multiple pages.
code like "return g->dlen;" is wrong as we do not hold the
qlock of the global segment. another process could come in
and override g->dlen making us return the wrong byte count.
avoid copying when we already got a kernel address (kernel memory
is the same on processes) which is the case with bread()/bwrite().
this is the same optimization that devsd does.
also avoid allocating/freeing and copying while holding the qlock.
when we copy to/from user memory, we might fault preventing
others from accessing the segment while fault handling is in
progress.
walking the freelist for every page is too slow. as we
are freeing a range, we can do a single pass unlinking all
pages in our range and at the end, check if all pages
where freed, if not put the pages that we did free back
and retry, otherwise we'r done.
fixed segments are continuous in physical memory but
allocated in user pages. unlike shared segments, they
are not allocated on demand but the pages are allocated
on creation time (devsegment). fixed segments are
never swapped out, segfreed or resized and can only be
destroyed as a whole.
the physical base address can be discovered by userspace
reading the ctl file in devsegment.
catch the error() that can be thrown by sleep() and tsleep()
in kprocs.
add missing pexit() calls.
always set the freemem argument to pexit() from kproc otherwise
the process gets added to the broken list.
in devproc status read handler the p->status, p->text and p->user
could overflow the local statbuf buffer as they where copied into
it with code like: memmove(statbuf+someoff, p->text, strlen(p->text)).
now using readstr() which will truncate if the string is too long.
make strncpy() usage consistent, make sure results are always null
terminated.
