a pv chain was being traversed while interrupts were
fully enabled in pmap_remove_all ... this is bogus, and
has been fixed in pmap.c. (sorry for adding the splimp)
Description:
The integer overflow instruction (into) and the interrupt instruction with
value 4 (int #4) both give rise to SIGBUS signals rather than SIGFPE. The
problem is that overflow is a trap not a fault (unlike the BOUND instruction).
following is a summary:
1) increased object cache back up to a more reasonable value.
2) removed old & bogus cruft from machdep.c (clearseg, copyseg,
physcopyseg, etc).
3) inlined many functions in pmap.c
4) changed "load_cr3(rcr3())" into tlbflush() and made tlbflush inline
assembly.
5) changed the way that modified pages are tracked - now vm_page struct
is kept updated directly - no more scanning page tables.
6) removed lots of unnecessary spl's
7) removed old unused functions from pmap.c
8) removed all use of page_size, page_shift, page_mask variables - replaced
with PAGE_ constants.
9) moved trunc/round_page, atop, ptoa, out of vm_param.h and into i386/
include/param.h, and optimized them.
10) numerous changes to sys/vm/ swap_pager, vnode_pager, pageout, fault
code to improve performance. LRU algorithm modified to be more
effective, read ahead/behind values tuned for better performance,
etc, etc...
problem with some chipsets (UMC) remapping the 'hole' memory even when
you've got 16MB. People were led to believe that since there was only
16MB of memory in the machine, that they were okay wrt the ISA DMA
limit. This hack simply causes the extra memory to be ignored if it
appears around the 16MB limit.
* Removed pmap_is_wired
* added extra cli/sti protection in idle (swtch.s)
* slight code improvement in trap.c
* added lots of comments
* improved paging and other algorithms in VM system
Changed the output of the isa probe routine, that only devices, that
have an IO address and are smaller than 0x100 to be on the motherboard.
The seagate SCSI adapter is an example of a card, that doesn't have
an IO address and works only memory mapped.
a binary link-kit. Make all non-optional options (pagers, procfs) standard,
and update LINT to reflect new symtab requirements.
NB: -Wtraditional will henceforth be forgotten. This editing pass was
primarily intended to detect any constructions where the old code might
have been relying on traditional C semantics or syntax. These were all
fixed, and the result of fixing some of them means that -Wall is now a
realistic possibility within a few weeks.
John Dyson to make it reliably work under FreeBSD.
2) Added and enabled PROCFS in the GENERICxx and LINT kernels.
3) New execve() from me. Still work to be done here, but this version
works well and is needed before other changes can be made. For
a description of the design behind this, see freebsd-arch or
ask me.
4) Rewrote stack fault code; made user stack VM grow as needed rather
than all up front; improves performance a little and reduces
process memory requirements.
5) Incorporated fix from Gene Stark to fault/wire a user page table
page to fix a problem in copyout. This is a temporary fix and
is not appropriate for pageable page tables. For a description
of the problem, see Gene's post to the freebsd-hackers mailing
list.
6) Tighten up vm_page struct to reduce memory requirements for it. ifdef
pager page lock code as it's not being used currently.
7) Introduced new element to vmspace struct - vm_minsaddr; initial
(minimum) stack address. Compliment to vm_maxsaddr.
8) Added a panic if the allocation for process u-pages fails.
9) Improve performance and accuracy of kernel profiling by putting in
a little inline assembly instead of spl().
10) Made serial console with sio driver work. Still has problems with
serial input, but is almost useable.
11) Added -Bstatic to SYSTEM_LD in Makefile.i386 so that kernels will
build properly with the new ld.
The following patch adds the addr argument to signal handlers.
The kernel with the patch is no more and no less in compliance or in
violation of POSIX and ANSI C than the kernel before the patch.
The added functionality this addr argument provides is quite useful. It
enables an entire class of algorithms which use mprotect to trace memory
references. Beside garbage collectors, I have heard of this technique being
applied to debuggers and profilers. The only benchmarking I've performed is
using akcl to compile maxima: without the kernel patch, it takes 7 hours to
compile maxima, while with stratified garbage collection, it only takes 50
minutes.
Basically, I can't think of a reason not to add the addr argument and there
is a compelling need for it.
If you find the patch acceptable, please let me know so I can send my
FreeBSD akcl config files to wfs for inclusion in the core akcl release.
The old 386BSD config files there won't work on either NetBSD or FreeBSD.
Subject: Page fault in PTE area fails in copyout
Index: sys/i386/i386/trap.c FreeBSD-1.0.2
Description:
Reading files of several megabytes into Emacs, or many small
files all at once, would fail with "IO error - bad address".
Repeat-By:
The bug can be exercised by a test program that malloc()'s
a 5MB chunk of memory, and then, without accessing the memory
first, filling it with data from a file using read().
(I read 64k chunks from /dev/wd0d into successive 64k regions
of the 5MB chunk.) The read() will fail with EFAULT at the first
virtual address boundary that is a multiple of 0x400000.
Fix:
The problem was code in sys/i386/i386/trap.c that tries to
figure out what kind of trap occurred and to handle it appropriately.
It was interpreting any page fault with virtual address
>= vm->vm_maxsaddr as being a user stack segment fault.
In fact, addresses >= USRSTACK are in the user structure/PTE area,
and if they are handled as stack faults, the proper PTE will
not be paged in when it is supposed to be. This situation comes
up in copyout() and copyoutstr(), if PTE's are accessed for the
first time ever. The page fault on accessing the nonexistent PTE
is mishandled as a stack fault, and then the fault that occurs on
the subsequent access to the page itself causes copyout to fail
with EFAULT.
when the machine panics.
i386/i386/locore.s:
1) got rid of most .set directives that were being used like
#define's, and replaced them with appropriate #define's in
the appropriate header files (accessed via genassym).
2) added comments to header inclusions and global definitions,
and global variables
3) replaced some hardcoded constants with cpp defines (such as
PDESIZE and others)
4) aligned all comments to the same column to make them easier to
read
5) moved macro definitions for ENTRY, ALIGN, NOP, etc. to
/sys/i386/include/asmacros.h
6) added #ifdef BDE_DEBUGGER around all of Bruce's debugger code
7) added new global '_KERNend' to store last location+1 of kernel
8) cleaned up zeroing of bss so that only bss is zeroed
9) fix zeroing of page tables so that it really does zero them all
- not just if they follow the bss.
10) rewrote page table initialization code so that 1) works correctly
and 2) write protects the kernel text by default
11) properly initialize the kernel page directory, upages, p0stack PT,
and page tables. The previous scheme was more than a bit
screwy.
12) change allocation of virtual area of IO hole so that it is
fixed at KERNBASE + 0xa0000. The previous scheme put it
right after the kernel page tables and then later expected
it to be at KERNBASE +0xa0000
13) change multiple bogus settings of user read/write of various
areas of kernel VM - including the IO hole; we should never
be accessing the IO hole in user mode through the kernel
page tables
14) split kernel support routines such as bcopy, bzero, copyin,
copyout, etc. into a seperate file 'support.s'
15) split swtch and related routines into a seperate 'swtch.s'
16) split routines related to traps, syscalls, and interrupts
into a seperate file 'exception.s'
17) remove some unused global variables from locore that got
inserted by Garrett when he pulled them out of some .h
files.
i386/isa/icu.s:
1) clean up global variable declarations
2) move in declaration of astpending and netisr
i386/i386/pmap.c:
1) fix calculation of virtual_avail. It previously was calculated
to be right in the middle of the kernel page tables - not
a good place to start allocating kernel VM.
2) properly allocate kernel page dir/tables etc out of kernel map
- previously only took out 2 pages.
i386/i386/machdep.c:
1) modify boot() to print a warning that the system will reboot in
PANIC_REBOOT_WAIT_TIME amount of seconds, and let the user
abort with a key on the console. The machine will wait for
ever if a key is typed before the reboot. The default is
15 seconds, but can be set to 0 to mean don't wait at all,
-1 to mean wait forever, or any positive value to wait for
that many seconds.
2) print "Rebooting..." just before doing it.
kern/subr_prf.c:
1) remove PANICWAIT as it is deprecated by the change to machdep.c
i386/i386/trap.c:
1) add table of trap type strings and use it to print a real trap/
panic message rather than just a number. Lot's of work to
be done here, but this is the first step. Symbolic traceback
is in the TODO.
i386/i386/Makefile.i386:
1) add support in to build support.s, exception.s and swtch.s
...and various changes to various header files to make all of the
above happen.
