Affected files:
include/mips_param.h, include/pcb.h,
mips/locore_mips1.S, mips/locore_mips3.S,
mips/mips_machdep.c, mips/vm_machdep.c
Issue:
So far, NetBSD/mips has not successfully got rid of fixed-address
kernel stack. USPACE (two 4KB pages) of each process has two distinct
KSEG2 addresses, both refer to a single physical storage; one address
for fixed range [ UADDR .. KERNELSTACK ), and another for "normal" KSEG2
address which was allocated by kernel memory manager and unique to each
others of processes.
"Doubly mapped" USPACE complicates context switch. Both address ranges
have to be managed with a special care of "wired" TLB entries which
are never replaced until next context switch to ensure no TLB miss for
USPACE access. It's equally crumbersome that MIPS processor's cache
machinary gets be confused about USPACE contents because there are two
distinct KSEG2 addresses to manipulate one physical storage.
Solution:
Purge KERNELSTACK constant for kernel stack pointer and replace
it with process unique values. Kernel stack bottom is located at
'curproc->p_addr + USPACE'. Context switch is simplified as it unloads
half of TLB hardwiring burden. It just manages the unique KSEG2 address
of each USPACE to be wired. As the side effect, switch_exit() has no
MIPS processor ISA dependent code anymore. It switchs kernel stack to
proc0's USPACE which has KSEG0 address and no need of TLB entry.
* Extensive use of 'genassym.cf'
To hide target port dependent and/or processor register size dependent
constants from assembler routines, 'genassym.cf' now has an extentive
set of definitions for various constants and offset values of
structural objects. This change will contribute possible NetBSD/mips64
portability too.
* Separation and rename of locore_r2000/_r4000.S
Those files are now indepedent standalones from locore.S to ease
maintainance works, and renamed to match MIPS processor ISA version.
* Changes in kernel mode exception handlers
Kernel mode exception handlers hold exception contexts by pushing a
certain set of register values on stack for resuming kernel mode
processing. This context is now represented with 'struct trapframe',
which is smaller than full scale (user mode) exception context 'struct
frame'. Stack consumption of kernel mode exception services is now
similar to 4.4BSD/mips.
* Relocation of exception frame
User mode context 'struct frame' is moved to the very bottom of kernel
stack at 'curproc->p_addr + USPACE - sizeof(struct frame)' This change
saves a bit of instructions on every return to user processes as it
eliminates reference to global variable 'curpcb' each time.
* Refurblished DDB backtrace routine
It's a growing concern to maintain stacktrace() code correctly. It
could be simplified by enforcing special arrangements for some of
obscure locore routines which violate usual coding conventions.
New backtrace code searchs for certain instructions peculiar to any of
function tails. Specifically, "jr ra" for normal function returns, "jr
k0" for MIPS1 exception handlers and "eret" for MIPS3 handlers.
* Support for 64-bit safe user code
Affected Files:
${ARCH}/include/pubassym.cf lib/libc/arch/mips/gen/*setjmp*
include/setjmp.h mips/include/[lots] mips/mips/[lots]
Solution:
We define macros REG_L/REG_S and SZREG for loading and storing
registers and for the size of registers. The exact meaning
of these is controlled by a macro (currently _MIPS64) which
allows one to treat the registers as either 32-bit or 64-bit.
There are data types mips_reg_t and mips_fpreg_t which represent
the true register sizes, and avoid confusing register_t.
We needed a way to dynamically gen the structure sizes of things
like sigcontext for setjmp.h, so we defined a pubassym.cf for
libc routines like setjmp and longjmp.
NetBSD/mips allows ${ARCH}'s to be defined which preserve
all 64-bits of registers across user context switches. There
are still a few niceties to clean up for kernel mode context
switches.
* Support for QED 52xx processors
Affected Files:
mips/locore_mips3.S mips/pmap.c include/locore.h
Issue:
The QED 52xx family of processors are targeted at low cost
embedded systems, (i.e. CPUs ~$30) for systems like routers, printers,
etc. We have added preliminary support for some of the idiosyncrasies
of this processor, e.g. no L2 cache, etc. More work needs to be
done here because with a modest 2-way L1 cache, some of the rampant
flushing has significant performance implications. However,
it doesn't crash, which is a start.
Solution:
A routine for flushing the cache based on virtual addresses was added;
a routine which deals with the two-way set associativity of the
5230 L1 cache was added, accomodations to 5230's instruction hazards
were added.
* TLB Miss code for mips3/mips4 processors cleaned up significantly.
Affected Files:
mips/locore_mips3.S mips/vm_machdep.c include/locore.h mips_machdep.c
Issue:
The TLB Miss handler exceeded the allowed size, which wasn't
a problem because there was no handler for when the processor
was in 64-bit mode. The handler for invalid TLB exceptions
also appears to have much vestigial code, which made it
difficult to understand.
Solution:
Use the XCONTEXT register to store a pointer to the segment
map table, this coupled with removing some dead code allows
the handlers to fit.
decoupled from long or int or long long. Define macros in asm.h to facilitate
choosing these on a port by port basis.
* Create <machine/pubassym.h> mechanism to allow jmp_buf structure size
to be calculated at system build time.
* Define _MIPS_BSD_SIM macro which specifies what calling style is appropritae
for the architecture. For 64-bit oriented systems set the Status Register
to allow 64-bit instructions.
* Remove UADDR related macros because kernel U structure is now mapped
normally.
* Separate cpu.h into cpu.h and cpuarch.h to keep things neat.
* Add support for QED 52xx processors
- Don't make a reference of curproc when it has NULL value. It causes
double fault upon a fatal panic ocation.
- Macro FETCH_INSTRUCTION() took a value of address 0.
-
UVM relies on pmap modules keeping track of modified/referenced bits
after a page has been removed from all mappings. So *dont* clear
PV_REFERENCED or PV_MODIFIED flags in pmap_remove().
either OP_JR function code or *OP_JALR* function code (not OP_JAL opcode).
insn_unconditional_flow_transfer() was to read an unintialized variable.
Those MD DDB routines seems not useful work so far.
- returned EOPNOTSUPP rather than -1.
- no check for negative offset.
many of these fix potential security problems in these drivers.
XXX XXX XXX
the d_mmap cdev routine should be changed to have a prototype like:
paddr_t (*d_mmap) __P((dev_t, off_t, int));
by someone!
Track page modification status in the PV entry like the alpha, and let
pmap_is_modified() return current status back to the VM system. UVM now
works reliably.
Garbage collect the old pmap_attribute[] stuff.
- cpu_set_kpc() now takes void *arg third argument, passed to the
entry point.
- cpu_fork() allows parent to be non-curproc iff parent is proc0.
When forking non-curproc, assume its state has already been saved.
- Adjust various pieces of machine-dependent code to account of all of this.
* commit isapnpvar.h changes required for ARC to support plain isa.
* fixup mistake over mips/include/cpuregs.h.
* mips/mips_machdep.c:
set L2 cache-size for arc, cleanup use of L2cache present
vs L2 cache-size variables. check for no L2 cache on kernels
configured to require one. misc cleanups.
* mips/mpis/trap.c: more locore stack-traceback label cleanup.
XXX Locore callbacks for mips3, mips4, r4600 cacheflush need more work.
Adds (most) support for ARC platform to port-independent mips code.
Some changes (e.g., clean up of overlapping CPU/FPU ids) inspired by
comparison to the OpenBSD 2.1 codebase of Soda's ARC port.
Open issues:
* Still no support for r4600 or mipsIV CPUs with two-way L1 cache.
Code derived from Per Fogelstrom's OpenBSD source doesn't work
on mips3 pmaxes with L2 cache.
* Still some port-specific #ifdefs, for interrupt enable and
pmax L2 cache-size. Needs more thought, but overlaps with
work-in-progress by Tohru and Tsubai on spl()s and related stuff.
u-area in machine-dependent code. Instead, call exit2() to schedule
the reaper to free them for us, once it is safe to do so (i.e. we are
no longer running on the dead proc's vmspace and stack).
- bump cpu_model[] length as the longest name occupies over 30 characters.
- place machine_arch[] beside machine[] for clearity.
- nuke useless #include directives.
- small scale cleanup in vm_machdep.c
address on 2 architectures anyhow. Also, move the definition of the `label_t'
type inside _KERNEL protection, since it is specific to the in-kernel
setjmp()/longjmp() implementations.
as with user-land programs, include files are installed by each directory
in the tree that has includes to install. (This allows more flexibility
as to what gets installed, makes 'partial installs' easier, and gives us
more options as to which machines' includes get installed at any given
time.) The old SYS_INCLUDES={symlinks,copies} behaviours are _both_
still supported, though at least one bug in the 'symlinks' case is
fixed by this change. Include files can't be build before installation,
so directories that have includes as targets (e.g. dev/pci) have to move
those targets into a different Makefile.
there is one. The Mach VM system seems to take care of this, so it
hasn't knowingly caused a problem. UVM does change mappings without
removing the current mapping, and will pmap_page_protect() hangs
if pmap_enter() doesn't remove the previous mapping.
prototype declearation for method to override wbflush() callback
vector with model-specific code. Used on DEC r2000a machines with
writebuffers which indicate writebuffer drain via cp0 usability bit.
read and write compare register (controls cycle-driven periodic interrupt).
Use cycle counter for microsecond time on mips3, but for now only on
3min motherboards (5000/150). the MAXINE baseboard microsecond
counter is more stable and I don't ave no 5000/260 to test.
XXX clkread() is a mess, it should be rewritten.
XXX should add nanotime() to give inkernel nanosecond resolution,
and then microtime() reworked to use nanotime().
interrupt-callout vector from mips locore dispatch code to port code.
* Move branch-emulation declaration to mips/include/trap.h.
* Garbage-collect pmax/pmax/trap.h.
Not needed now pmax/pmax_trap.c is gone, and after above tidy-up.
common place:
- allocsys(), which computes space for and assigns addresses
to kernel data structures at boot time.
- mips_init_msgbuf(), which initializes the error message
buffer at the end of core.
- mips_init_proc0(), which initializes the U-area for proc0
and nullproc.
didn't make it in. Aproved by Jonathan and tested here at Stanford.
While I'm here, add conditional prototypes for clnlintr() and nsintr()
so that NS and ISO will compile correctly.
to the TLB dump routines arguements. Machines would die horibbly when
trying to dump the TLB entries in DDB. Also don't explicitly "page" the
output, since db_printf takes care of that.
if the break instruction is still there. This works around a problem with
the software single step in DDB not recognizing the temporary breakpoint
set to emulate the single step.
- fix _C_LABEL so that it actually works.
- make __RENAME use _C_LABEL.
- fix __RENAME so that it expects an unquoted argument.
- fix __indr_reference and __warn_references so that they
supply their own final semicolon.
- define __warn_references to nothing if not GNU C (required
by the way it's used).
The __warn_references semicolon change has to be made
so that __warn_references can be defined into nothing.
(A ; all by itself isn't a great idea.) The __indr_reference
change was made for consistency.
From /sys/news3400/news3400/locore.s, with id
@(#)locore.s 8.3 (Berkeley) 9/23/93
Kazumasa Utashiro notes that the pmax cacheflush routines don't work:
#ifndef NOTDEF /* I don't know why Ralph's code doesn't work. KU:XXX */
It's because pmax hardware wries the COP0 bit to external branch
logic. news3400s don't, and so the bc0f loop fails. It will also
fail on some other models of pmax, but we dont' support them.
Surround the relevant framgents in locore_r200.S with "#ifdef pmax".
Longer-term, the cacheflush entry in the locore callback may have
to be a CPU baseboard-specific entry, not just CPU-version specific.
(_BYTE_ORDER, _BIG_ENDIAN, _LITTLE_ENDIAN).
Define old names from the ANSI ones if not _POSIX_SOURCE.
* Define _QUAD_HIGHWORD and _QUAD_LOWWORD properly when
_BYTE_ORDER == _BIG_ENDIAN.
Only assembly version for i386 bswap16 and bswap32 for now (bswap64 uses
bswap32). Contribution of assembly versions of these are welcome.
Add byte-swapping of ext2fs metadata for big-endian systems.
Tested on i386 and sparc.
castor