Unicorn CPU emulator framework (ARM, AArch64, M68K, Mips, Sparc, X86)
Go to file
Emilio G. Cota f66e74d65b
tcg: consistently access cpu->tb_jmp_cache atomically
Some code paths can lead to atomic accesses racing with memset()
on cpu->tb_jmp_cache, which can result in torn reads/writes
and is undefined behaviour in C11.

These torn accesses are unlikely to show up as bugs, but from code
inspection they seem possible. For example, tb_phys_invalidate does:
/* remove the TB from the hash list */
h = tb_jmp_cache_hash_func(tb->pc);
CPU_FOREACH(cpu) {
if (atomic_read(&cpu->tb_jmp_cache[h]) == tb) {
atomic_set(&cpu->tb_jmp_cache[h], NULL);
}
}
Here atomic_set might race with a concurrent memset (such as the
ones scheduled via "unsafe" async work, e.g. tlb_flush_page) and
therefore we might end up with a torn pointer (or who knows what,
because we are under undefined behaviour).

This patch converts parallel accesses to cpu->tb_jmp_cache to use
atomic primitives, thereby bringing these accesses back to defined
behaviour. The price to pay is to potentially execute more instructions
when clearing cpu->tb_jmp_cache, but given how infrequently they happen
and the small size of the cache, the performance impact I have measured
is within noise range when booting debian-arm.

Note that under "safe async" work (e.g. do_tb_flush) we could use memset
because no other vcpus are running. However I'm keeping these accesses
atomic as well to keep things simple and to avoid confusing analysis
tools such as ThreadSanitizer.

Backports commit f3ced3c59287dabc253f83f0c70aa4934470c15e from qemu
2018-03-03 21:12:36 -05:00
bindings link to Crystal binding 2017-12-23 00:26:40 +08:00
docs Added note about installing tests dependencies on Mac OS X. Added note about tests failing when required architecture support is disabled in build. (#908) 2017-10-12 19:56:00 +08:00
include util: add cacheinfo 2018-03-03 16:58:28 -05:00
msvc qapi: Update scripts to commit 01b2ffcedd94ad7b42bc870e4c6936c87ad03429 2018-03-03 18:32:12 -05:00
qemu tcg: consistently access cpu->tb_jmp_cache atomically 2018-03-03 21:12:36 -05:00
samples Fixed register mistake in comments (#894) 2017-09-17 16:40:01 +07:00
tests add 64-bit test demonstrating setting MSRs and FS/GS segments (#901) 2017-09-29 04:26:23 +08:00
.appveyor.yml MSYS test (#852) 2017-06-25 10:11:35 +08:00
.gitignore arm64eb: add support for ARM64 big endian. 2017-04-24 23:30:01 +08:00
.travis.yml use new travis osx image and brew (#935) 2018-01-05 10:29:49 +08:00
AUTHORS.TXT import 2015-08-21 15:04:50 +08:00
Brewfile Update Brewfile 2017-09-30 17:36:44 +07:00
ChangeLog update ChangeLog 2017-04-20 13:28:02 +08:00
config.mk Fix document file extension 2016-08-08 17:33:49 +09:00
COPYING import 2015-08-21 15:04:50 +08:00
COPYING.LGPL2 LGPL2 for all header files under include/unicorn/ 2017-12-16 10:08:42 +08:00
COPYING_GLIB glib_compat: add COPYING_GLIB 2016-12-27 10:15:08 +08:00
CREDITS.TXT update CREDITS.TXT 2017-04-25 12:56:47 +08:00
install-cmocka-linux.sh Start moving examples in S files (#851) 2017-06-25 10:14:22 +08:00
list.c callback to count number of instructions in uc_emu_start() should be executed first. fix #727 2017-06-16 13:22:38 +08:00
make.sh Added MSVC support for arm64eb. 2017-04-25 14:23:58 +10:00
Makefile crypto: introduce new module for computing hash digests 2018-02-17 15:23:17 -05:00
msvc.bat add msvc.bat 2017-04-21 15:35:40 +08:00
pkgconfig.mk bump extra version to 2 2017-04-21 15:30:40 +08:00
README.md add Clojure 2017-12-23 00:32:33 +08:00
uc.c Move target-* CPU file into a target/ folder 2018-03-01 22:50:58 -05:00
windows_export.bat Make the call out to visual studio extremely resilient 2017-01-02 03:32:48 -08:00

Unicorn Engine

Join the chat at https://gitter.im/unicorn-engine/chat

Build Status Build status

Unicorn is a lightweight, multi-platform, multi-architecture CPU emulator framework based on QEMU.

Unicorn offers some unparalleled features:

  • Multi-architecture: ARM, ARM64 (ARMv8), M68K, MIPS, SPARC, and X86 (16, 32, 64-bit)
  • Clean/simple/lightweight/intuitive architecture-neutral API
  • Implemented in pure C language, with bindings for Crystal, Clojure, Visual Basic, Perl, Rust, Ruby, Python, Java, .NET, Go, Delphi/Free Pascal and Haskell.
  • Native support for Windows & *nix (with Mac OSX, Linux, *BSD & Solaris confirmed)
  • High performance via Just-In-Time compilation
  • Support for fine-grained instrumentation at various levels
  • Thread-safety by design
  • Distributed under free software license GPLv2

Further information is available at http://www.unicorn-engine.org

License

This project is released under the GPL license.

Compilation & Docs

See docs/COMPILE.md file for how to compile and install Unicorn.

More documentation is available in docs/README.md.

Contact

Contact us via mailing list, email or twitter for any questions.

Contribute

If you want to contribute, please pick up something from our Github issues.

We also maintain a list of more challenged problems in a TODO list.

CREDITS.TXT records important contributors of our project.