b3c0d957a2
When building with KCOV enabled the compiler will insert function calls to probes allowing us to trace the execution of the kernel from userspace. These probes are on function entry (trace-pc) and on comparison operations (trace-cmp). Userspace can enable the use of these probes on a single kernel thread with an ioctl interface. It can allocate space for the probe with KIOSETBUFSIZE, then mmap the allocated buffer and enable tracing with KIOENABLE, with the trace mode being passed in as the int argument. When complete KIODISABLE is used to disable tracing. The first item in the buffer is the number of trace event that have happened. Userspace can write 0 to this to reset the tracing, and is expected to do so on first use. The format of the buffer depends on the trace mode. When in PC tracing just the return address of the probe is stored. Under comparison tracing the comparison type, the two arguments, and the return address are traced. The former method uses on entry per trace event, while the later uses 4. As such they are incompatible so only a single mode may be enabled. KCOV is expected to help fuzzing the kernel, and while in development has already found a number of issues. It is required for the syzkaller system call fuzzer [1]. Other kernel fuzzers could also make use of it, either with the current interface, or by extending it with new modes. A man page is currently being worked on and is expected to be committed soon, however having the code in the kernel now is useful for other developers to use. [1] https://github.com/google/syzkaller Submitted by: Mitchell Horne <mhorne063@gmail.com> (Earlier version) Reviewed by: kib Testing by: tuexen Sponsored by: DARPA, AFRL Sponsored by: The FreeBSD Foundation (Mitchell Horne) Differential Revision: https://reviews.freebsd.org/D14599 |
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| bin | ||
| cddl | ||
| contrib | ||
| crypto | ||
| etc | ||
| gnu | ||
| include | ||
| kerberos5 | ||
| lib | ||
| libexec | ||
| release | ||
| rescue | ||
| sbin | ||
| secure | ||
| share | ||
| stand | ||
| sys | ||
| targets | ||
| tests | ||
| tools | ||
| usr.bin | ||
| usr.sbin | ||
| .arcconfig | ||
| .arclint | ||
| .gitattributes | ||
| .gitignore | ||
| COPYRIGHT | ||
| LOCKS | ||
| MAINTAINERS | ||
| Makefile | ||
| Makefile.inc1 | ||
| Makefile.libcompat | ||
| Makefile.sys.inc | ||
| ObsoleteFiles.inc | ||
| README | ||
| README.md | ||
| UPDATING | ||
FreeBSD Source:
This is the top level of the FreeBSD source directory. This file
was last revised on:
FreeBSD
FreeBSD is an operating system used to power modern servers, desktops, and embedded platforms. A large community has continually developed it for more than thirty years. Its advanced networking, security, and storage features have made FreeBSD the platform of choice for many of the busiest web sites and most pervasive embedded networking and storage devices.
For copyright information, please see the file COPYRIGHT in this directory. Additional copyright information also exists for some sources in this tree - please see the specific source directories for more information.
The Makefile in this directory supports a number of targets for building components (or all) of the FreeBSD source tree. See build(7), config(8), https://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/makeworld.html, and https://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig.html for more information, including setting make(1) variables.
Source Roadmap:
bin System/user commands.
cddl Various commands and libraries under the Common Development
and Distribution License.
contrib Packages contributed by 3rd parties.
crypto Cryptography stuff (see crypto/README).
etc Template files for /etc.
gnu Various commands and libraries under the GNU Public License.
Please see gnu/COPYING* for more information.
include System include files.
kerberos5 Kerberos5 (Heimdal) package.
lib System libraries.
libexec System daemons.
release Release building Makefile & associated tools.
rescue Build system for statically linked /rescue utilities.
sbin System commands.
secure Cryptographic libraries and commands.
share Shared resources.
stand Boot loader sources.
sys Kernel sources.
sys/<arch>/conf Kernel configuration files. GENERIC is the configuration
used in release builds. NOTES contains documentation of
all possible entries.
tests Regression tests which can be run by Kyua. See tests/README
for additional information.
tools Utilities for regression testing and miscellaneous tasks.
usr.bin User commands.
usr.sbin System administration commands.
For information on synchronizing your source tree with one or more of the FreeBSD Project's development branches, please see:
https://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/current-stable.html