. restore state depends on how saving of state was done;
also remember trap style in sig context
. actually set and restore TRACEBIT with new trap styles;
have to remove it once process enters kernel though, done
in debug trap exception handler
. introduce MF_STEP that makes arch-specific code
turn on trace bit instead of setting TRACEBIT directly,
a bit more arch-friendly and avoids keeping precious
state in per-process PSW arch-dependently
state is usually not in p_reg any more with sysenter/syscall trap entries,
so when saving/restarting do_ipc invocations the state has to be remembered
explicitly.
The 'trap style' variable records how a process has trapped into the
kernel (hardware/software interrupt, or one of the other trap
instructions). KTS_NONE indicates the process isn't trapped into the
kernel at all and is useful for sanity checking. The KTS_NONE reset was
inadvertently removed while removing some debugging code and this commit
restores it.
When processes have entered the kernel with one of the new
trap modes, %ebp is not valid, used for stacktraces, so we
need an alternative way to retrieve it to make the stacktraces
valid again.
upgrade to NetBSD CVS release from 2012/10/17 12:00:00 UTC
Makefiles updates to imporve portability
Made sure to be consistent in the usage of braces/parenthesis at
least on a per file basis. For variables, it is recommended to
continue to use braces.
The tested targets are the followgin ones:
* tools
* distribution
* sets
* release
The remaining NetBSD targets have not been disabled nor tested
*at all*. Try them at your own risk, they may reboot the earth.
For all compliant Makefiles, objects and generated files are put in
MAKEOBJDIR, which means you can now keep objects between two branch
switching. Same for DESTDIR, please refer to build.sh options.
Regarding new or modifications of Makefiles a few things:
* Read share/mk/bsd.README
* If you add a subdirectory, add a Makefile in it, and have it called
by the parent through the SUBDIR variable.
* Do not add arbitrary inclusion which crosses to another branch of
the hierarchy; If you can't do without it, put a comment on why.
If possible, do not use inclusion at all.
* Use as much as possible the infrastructure, it is here to make
life easier, do not fight it.
Sets and package are now used to track files.
We have one set called "minix", composed of one package called "minix-sys"
Bumping libc files for unsupported architectures, to simplify merging.
A bunch of small fixes:
* in libutil update
* the macro in endian.h
* some undefined types due to clear separation from host.
* Fix a warning for cdbr.c
Some modification which were required for the new build system:
* inclusion path for const.h in sconst, still hacky
* Removed default malloc.c which conflicts on some occasions.
. Check if we have the right number of boot modules
. Check if the ELF parsing of VM actually succeeded
Both these are root causes of less-than-obvious other
errors/asserts a little further down the line; uncovered
while experimenting with booting by iPXE, specifically
(a) iPXE having a 8-multiboot-modules limit and
(b) trying to boot a gzipped VM.
. add cpufeature detection of both
. use it for both ipc and kernelcall traps, using a register
for call number
. SYSENTER/SYSCALL does not save any context, therefore userland
has to save it
. to accomodate multiple kernel entry/exit types, the entry
type is recorded in the process struct. hitherto all types
were interrupt (soft int, exception, hard int); now SYSENTER/SYSCALL
is new, with the difference that context is not fully restored
from proc struct when running the process again. this can't be
done as some information is missing.
. complication: cases in which the kernel has to fully change
process context (i.e. sigreturn). in that case the exit type
is changed from SYSENTER/SYSEXIT to soft-int (i.e. iret) and
context is fully restored from the proc struct. this does mean
the PC and SP must change, as the sysenter/sysexit userland code
will otherwise try to restore its own context. this is true in the
sigreturn case.
. override all usage by setting libc_ipc=1
. only reference single pages in process data structures
to simplify page faults, copy-on-write, etc.
. this breaks the secondary cache for objects that are
not one-page-sized; restored in a next commit
Coverity was flagging a recursive include between kernel.h and
cpulocals.h. As cpulocals.h also included proc.h, we can move that
include statement into kernel.h, and clean up the source files'
include statements accordingly.
. map all objects named usermapped_*.o with globally visible
pages; usermapped_glo_*.o with the VM 'global' bit on, i.e.
permanently in tlb (very scarce resource!)
. added kinfo, machine, kmessages and loadinfo for a start
. modified log, tty to make use of the shared messages struct
. some strncpy/strcpy to strlcpy conversions
. new <minix/param.h> to avoid including other minix headers
that have colliding definitions with library and commands code,
causing parse warnings
. removed some dead code / assignments
adjust the smp booting procedure for segmentless operation. changes are
mostly due to gdt/idt being dependent on paging, because of the high
location, and paging being on much sooner because of that too.
also smaller fixes: redefine DESC_SIZE, fix kernel makefile variable name
(crosscompiling), some null pointer checks that trap now because of a
sparser pagetable, acpi sanity checking
This commit removes all traces of Minix segments (the text/data/stack
memory map abstraction in the kernel) and significance of Intel segments
(hardware segments like CS, DS that add offsets to all addressing before
page table translation). This ultimately simplifies the memory layout
and addressing and makes the same layout possible on non-Intel
architectures.
There are only two types of addresses in the world now: virtual
and physical; even the kernel and processes have the same virtual
address space. Kernel and user processes can be distinguished at a
glance as processes won't use 0xF0000000 and above.
No static pre-allocated memory sizes exist any more.
Changes to booting:
. The pre_init.c leaves the kernel and modules exactly as
they were left by the bootloader in physical memory
. The kernel starts running using physical addressing,
loaded at a fixed location given in its linker script by the
bootloader. All code and data in this phase are linked to
this fixed low location.
. It makes a bootstrap pagetable to map itself to a
fixed high location (also in linker script) and jumps to
the high address. All code and data then use this high addressing.
. All code/data symbols linked at the low addresses is prefixed by
an objcopy step with __k_unpaged_*, so that that code cannot
reference highly-linked symbols (which aren't valid yet) or vice
versa (symbols that aren't valid any more).
. The two addressing modes are separated in the linker script by
collecting the unpaged_*.o objects and linking them with low
addresses, and linking the rest high. Some objects are linked
twice, once low and once high.
. The bootstrap phase passes a lot of information (e.g. free memory
list, physical location of the modules, etc.) using the kinfo
struct.
. After this bootstrap the low-linked part is freed.
. The kernel maps in VM into the bootstrap page table so that VM can
begin executing. Its first job is to make page tables for all other
boot processes. So VM runs before RS, and RS gets a fully dynamic,
VM-managed address space. VM gets its privilege info from RS as usual
but that happens after RS starts running.
. Both the kernel loading VM and VM organizing boot processes happen
using the libexec logic. This removes the last reason for VM to
still know much about exec() and vm/exec.c is gone.
Further Implementation:
. All segments are based at 0 and have a 4 GB limit.
. The kernel is mapped in at the top of the virtual address
space so as not to constrain the user processes.
. Processes do not use segments from the LDT at all; there are
no segments in the LDT any more, so no LLDT is needed.
. The Minix segments T/D/S are gone and so none of the
user-space or in-kernel copy functions use them. The copy
functions use a process endpoint of NONE to realize it's
a physical address, virtual otherwise.
. The umap call only makes sense to translate a virtual address
to a physical address now.
. Segments-related calls like newmap and alloc_segments are gone.
. All segments-related translation in VM is gone (vir2map etc).
. Initialization in VM is simpler as no moving around is necessary.
. VM and all other boot processes can be linked wherever they wish
and will be mapped in at the right location by the kernel and VM
respectively.
Other changes:
. The multiboot code is less special: it does not use mb_print
for its diagnostics any more but uses printf() as normal, saving
the output into the diagnostics buffer, only printing to the
screen using the direct print functions if a panic() occurs.
. The multiboot code uses the flexible 'free memory map list'
style to receive the list of free memory if available.
. The kernel determines the memory layout of the processes to
a degree: it tells VM where the kernel starts and ends and
where the kernel wants the top of the process to be. VM then
uses this entire range, i.e. the stack is right at the top,
and mmap()ped bits of memory are placed below that downwards,
and the break grows upwards.
Other Consequences:
. Every process gets its own page table as address spaces
can't be separated any more by segments.
. As all segments are 0-based, there is no distinction between
virtual and linear addresses, nor between userspace and
kernel addresses.
. Less work is done when context switching, leading to a net
performance increase. (8% faster on my machine for 'make servers'.)
. The layout and configuration of the GDT makes sysenter and syscall
possible.
