CAN stands for Controller Area Network, a broadcast network used
in automation and automotive fields. For example, the NMEA2000 standard
developped for marine devices uses a CAN network as the link layer.
This is an implementation of the linux socketcan API:
https://www.kernel.org/doc/Documentation/networking/can.txt
you can also see can(4).
This adds a new socket family (AF_CAN) and protocol (PF_CAN),
as well as the canconfig(8) utility, used to set timing parameter of
CAN hardware. Also inclued is a driver for the CAN controller
found in the allwinner A20 SoC (I tested it with an Olimex lime2 board,
connected with PIC18-based CAN devices).
There is also the canloop(4) pseudo-device, which allows to use
the socketcan API without CAN hardware.
At this time the CANFD part of the linux socketcan API is not implemented.
Error frames are not implemented either. But I could get the cansend and
canreceive utilities from the canutils package to build and run with minimal
changes. tcpudmp(8) can also be used to record frames, which can be
decoded with etherreal.
use with mprotect(2), but without enabling them immediately.
Extend the mremap(2) interface to allow duplicating mappings, i.e.
create a second range of virtual addresses references the same physical
pages. Duplicated mappings can have different effective protections.
Adjust PAX mprotect logic to disallow effective protections of W&X, but
allow one mapping W and another X protections. This obsoletes using
temporary files for purposes like JIT.
Adjust PAX logic for mmap(2) and mprotect(2) to fail if W&X is requested
and not silently drop the X protection.
Improve test cases to ensure correct operation of the changed
interfaces.
Document PT_SETSTEP and PT_CLEARSTEP in ptrace(2).
Try to explain more details of PT_SYSCALL and PT_SYSCALLEMU.
The description of PT_*STEP has been obtained from FreeBSD.
Sponsored by <The NetBSD Foundation>
Introduce new API for debuggers to allow/prevent execution of the specified
thread.
New ptrace(2) operations:
PT_RESUME Allow execution of a specified thread, change its state
from suspended to continued. The addr argument is unused.
The data argument specifies the LWP ID.
This call is equivalent to _lwp_continue(2) called by a
traced process. This call does not change the general
process state from stopped to continued.
PT_SUSPEND Prevent execution of a specified thread, change its state
from continued to suspended. The addr argument is unused.
The data argument specifies the requested LWP ID.
This call is equivalent to _lwp_suspend(2) called by a
traced process. This call does not change the general
process state from continued to stopped.
This interface is modeled after FreeBSD, however with NetBSD specific arguments
passed to ptrace(2) -- FreeBSD passes only thread id, NetBSD passes process and
thread id.
Extend PT_LWPINFO operation in ptrace(2) to report suspended threads. In the
ptrace_lwpinfo structure in pl_event next to PL_EVENT_NONE and PL_EVENT_SIGNAL
add new value PL_EVENT_SUSPENDED.
Add new errno(2) value EDEADLK that might be returned by ptrace(2). It prevents
dead-locking in a scenario of resuming a process or thread that is prevented
from execution. This fixes bug that old API was vulnerable to this scenario.
Kernel bump delayed till introduction of PT_GETDBREGS/PT_SETDBREGS soon.
Add new ATF tests:
- resume1
Verify that a thread can be suspended by a debugger and later
resumed by the debugger
- suspend1
Verify that a thread can be suspended by a debugger and later
resumed by a tracee
- suspend2
Verify that the while the only thread within a process is
suspended, the whole process cannot be unstopped
Sponsored by <The NetBSD Foundation>
Add new interface to add ability to get/set signal mask of a tracee.
It has been inspired by Linux PTRACE_GETSIGMASK and PTRACE_SETSIGMASK, but
adapted for NetBSD API.
This interface is used for checkpointing software to set/restore context
of a process including signal mask like criu or just to track this property
in reverse-execution software like Record and Replay Framework (rr).
Add new ATF tests for this interface
====================================
getsigmask1:
Verify that plain PT_SET_SIGMASK can be called
getsigmask2:
Verify that PT_SET_SIGMASK reports correct mask from tracee
setsigmask1:
Verify that plain PT_SET_SIGMASK can be called with empty mask
setsigmask2:
Verify that sigmask is preserved between PT_GET_SIGMASK and
PT_SET_SIGMASK
setsigmask3:
Verify that sigmask is preserved between PT_GET_SIGMASK, process
resumed and PT_SET_SIGMASK
setsigmask4:
Verify that new sigmask is visible in tracee
Kernel ABI bump delayed as there are more interfaces to come in ptrace(2).
Sponsored by <The NetBSD Foundation>
accept4 is a syscall in Linux, FreeBSD and OpenBSD. It is used in
LLVM, zeromq, and probably others. paccept is a superset of it.
adding it to libc ensures it is used by programs and prevents the
need to define the same wrapper in every program.
The original exect(2) from BSD4.2 was enabling bit for tracing
(single-step mode) and calling execve(2). The purpose of it was to generate
a signal for a tracer once the application will change its image to a new
program.
This approach no longer works as:
- exect(2) traces (single-steps) libc and it requires hundreds or
thousands steps before entering a new image
- it's vax and x86 specific code
- this functionality has been moved to the kernel - once a process is
traced it will generate SIGTRAP with si_code TRAP_EXEC and route it to
its debugger
- the side effects and unportability make this interface unusable
- there are no known users of this interface
- it apparently never worked better since day0 of NetBSD ("day0 bug")
Users are requested to move to other execve(2) variants. Calling current
execve(2) as it is the most similar behavior to this one from BSD4.2.
Discussed several times on mailing lists and in PR/51700.
Add warning to exect(3) telling about marking this function obsolete.
This function is prepared to be removed in next libc major bump.
Sponsored by <The NetBSD Foundation>
PTRACE_VFORK - report vfork(2)-like operations and trace child
PTRACE_VFORK_DONE - report unblocking the parent after vfork(2)-like call
Note that PTRACE_VFORK is currently unimplemented and returns ENOTSUP.
Sponsored by <The NetBSD Foundation>
wiz