on the epc instruction. The epc instruction, given the permissions
of the page in which the epc is located, allows the privilege level
to be increased with little or no overhead. The previous privilege
level is recorded in the current frame marker and is restored by
a regular (function) return.
Since the epc instruction has to live in a page with non-standard
properties, we hardwire a "gateway" page in the address space. The
address of the gateway page is exported to userland in ar.k7. This
allows us to rewire the page without breaking the ABI.
The syscall stubs in libc are regular function calls that slightly
differ from the normal runtime. The difference is mostly to simplify
the stubs themselves by by moving some of the logic to the kernel.
The libc stubs call into the gateway page (offset 0), from where the
kernel trampolines to the code that sets up a minimal trapframe and
arranges to execute from the kernel stack.
The way back is basicly the same. The kernel returns to the gateway
page, whereby privilege is dropped, and jumps back to the syscall
stub.
Only the special registers are saved in the trapframe. None of the
scratch registers are preserved and since the kernel follows the
same runtime model, none of the preserved registers are saved.
Future enhancements can include the implementation of lightweight
syscalls, where kernel functions are performed without setting up
a trapframe. Good candidates are the *context syscalls for example.
Now that there's a gateway page from which code can be executed in
a non-privileged context, we also have the ideal place to put the
signal trampolines. By moving the signal trampolines from the user
stack to the gateway page, we open up the doors to unexecutable
stacks. The gateway page contains signal trampolines for both the
"legacy" break-based syscall code and the new and improved epc-
based syscall code.
Approved: re@ (blanket)
available by Hewlett-Packard under the MIT license. The unwinder is
small, clean and fast and needed little adaptation for use in the
kernel.
This import has embedded in it the changes needed to make it build
in a kernel environment.
To optimize the common case, the kernel will minimize the number
of registers saved by not saving the preserved registers. In case
access to preserved registers is needed (signal handling, ptrace)
the kernel will unwind to the context of the syscall or exception.
For this we need an unwinder.
Approved by: re (blanket)
server, map it to EAGAIN locally rather than EACCES. The NLM spec
indicates the DENIED corresponds to lock contention, not a permission
failure. This fixes O_EXLOCK/O_SHLOCK with O_NONBLOCK, which would
previously give a permission error, which in turn fixes things
like mailq(8) and lockf(1) over NFS.
Approved by: scottl (re)
Reviewed by: truckman, Andrew P Lentvorski, Jr. <bsder@allcaps.org>
Idea from: truckman
one or more actions in the list. This makes constructs like:
attach 10 {
// echo "Driver $device_name attached"
};
to be accepted by the parser. It will be treated as if the user had
entered:
// attach 10 {
// echo "Driver $device_name attached"
// };
(eg totally ignored).
Approved by: re@ (rwatson)
load_gs() calls into a single place that is less likely to go wrong.
Eliminate the per-process context switching of MSR_GSBASE, because it
should be constant for a single cpu. Instead, save/restore it during
the loading of the new %gs selector for the new process.
Approved by: re (amd64/* blanket)
has requested the lock in a non-blocking form, instead returning an
immediate failure. This appears to help reduce one of my "locks get
lost" symptoms involving lockf(1), which attempts a non-blocking lock
attempt before actually blocking on the lock. At this point the client
still gets back EACCES, which is an issue we're still working.
Approved by: re (scottl)
Submitted by: Andrew P. Lentvorski, Jr. <bsder@allcaps.org>
has already been registered with ATAPI/CAM (else there is nothing
to do). atapi_cam_reinit_bus may be called before the bus is
registered if an ATAPI command times out during the boot sequence.
PR: i386/51421
Reviewed by: roberto
Approved by: re (rwatson)
MFC after: 1 week
from the NFS server, following contention on a lock by this or another
client, immediately notify the waiting process that the lock has been
granted via a wakeup. Without this change, the client rpc.lockd will
not wakeup the waiting process until it next re-polls the lock (sometime
in the next ten seconds), which can lead to marked latency across all
potential lockers, as the lock is held by the client for the duration.
Approved by: re (scottl)
Submitted by: truckman
Reviewed by: Andrew P. Lentvorski, Jr <bsder@allcaps.org>
stolen from the ia64/ia32 code (indeed there was a repocopy), but I've
redone the MD parts and added and fixed a few essential syscalls. It
is sufficient to run i386 binaries like /bin/ls, /usr/bin/id (dynamic)
and p4. The ia64 code has not implemented signal delivery, so I had
to do that.
Before you say it, yes, this does need to go in a common place. But
we're in a freeze at the moment and I didn't want to risk breaking ia64.
I will sort this out after the freeze so that the common code is in a
common place.
On the AMD64 side, this required adding segment selector context switch
support and some other support infrastructure. The %fs/%gs etc code
is hairy because loading %gs will clobber the kernel's current MSR_GSBASE
setting. The segment selectors are not used by the kernel, so they're only
changed at context switch time or when changing modes. This still needs
to be optimized.
Approved by: re (amd64/* blanket)
- Move struct sigacts out of the u-area and malloc() it using the
M_SUBPROC malloc bucket.
- Add a small sigacts_*() API for managing sigacts structures: sigacts_alloc(),
sigacts_free(), sigacts_copy(), sigacts_share(), and sigacts_shared().
- Remove the p_sigignore, p_sigacts, and p_sigcatch macros.
- Add a mutex to struct sigacts that protects all the members of the struct.
- Add sigacts locking.
- Remove Giant from nosys(), kill(), killpg(), and kern_sigaction() now
that sigacts is locked.
- Several in-kernel functions such as psignal(), tdsignal(), trapsignal(),
and thread_stopped() are now MP safe.
Reviewed by: arch@
Approved by: re (rwatson)
don't add the current time to it, but leave it as clear so that when the
timer is disabled, the it_value is always clear.
Reviewed by: bde
Approved by: re (rwatson)
Those who really need this information can find it in the include file.
* Include a succinct description of the st_birthtime field.
Approved by: re (bmah)
desired buffer is found at one of the roots more than 60% of the time.
Thus, checking both roots before performing either splay eliminates
unnecessary splays on the first tree splayed.
Approved by: re (jhb)
- hosts_ctl(3), hosts_access(3), request_init(3),
request_set(3).
PR: docs/52000
Submitted by: Simon L. Nielsen <simon@nitro.dk>
Approved and Reviewed by: des (mentor), re (scottl)
was obtained from [1], with heavy editing, and ammending text for some of
the ioctls.
All ioctls (in sys/agpio.h) are now documented.
PR: docs/50503
Original patch by: Alex Semenyaka <alexs@snark.ratmir.ru> [1]
Content approved by:
- Eric Anholt <anholt@FreeBSD.ORG>
- Matthew N. Dodd <mdodd@FreeBSD.ORG> (cursory review)
Approved and Reviewed by: des (mentor), re (scottl)
etc.) from the application namespace for programs that use pam_ssh(8).
Use #defines to avoid changing the actual source code.
Approved by: re (rwatson)
