9eef39d68a
Supervisor Mode Access Prevention (SMAP) is an x86 CPU feature that prevents the kernel from accessing userspace memory. With SMAP enabled, trying to read/write a userspace memory address while in the kernel will now generate a page fault. Since it's sometimes necessary to read/write userspace memory, there are two new instructions that quickly switch the protection on/off: STAC (disables protection) and CLAC (enables protection.) These are exposed in kernel code via the stac() and clac() helpers. There's also a SmapDisabler RAII object that can be used to ensure that you don't forget to re-enable protection before returning to userspace code. THis patch also adds copy_to_user(), copy_from_user() and memset_user() which are the "correct" way of doing things. These functions allow us to briefly disable protection for a specific purpose, and then turn it back on immediately after it's done. Going forward all kernel code should be moved to using these and all uses of SmapDisabler are to be considered FIXME's. Note that we're not realizing the full potential of this feature since I've used SmapDisabler quite liberally in this initial bring-up patch. |
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SerenityOS
Graphical Unix-like operating system for x86 computers.
About
SerenityOS is a love letter to '90s user interfaces with a custom Unix-like core. It flatters with sincerity by stealing beautiful ideas from various other systems.
Roughly speaking, the goal is a marriage between the aesthetic of late-1990s productivity software and the power-user accessibility of late-2000s *nix. This is a system by me, for me, based on the things I like.
If you like some of the same things, you are welcome to join the project. It would be great to one day change the above to say "this is a system by us, for us, based on the things we like." :^)
I regularly post raw hacking sessions and demos on my YouTube channel.
Sometimes I write about the system on my github.io blog.
I'm also on Patreon and GitHub Sponsors if you would like to show some support that way.
Screenshot
Current features (all under development, some more mature than others)
- Pre-emptive multitasking
- Multithreading
- Compositing window server
- IPv4 networking with ARP, TCP, UDP and ICMP
- ext2 filesystem
- Unix-like libc and userland
- POSIX signals
- Shell with pipes and I/O redirection
- mmap()
- Purgeable memory
- /proc filesystem
- Local sockets
- Pseudoterminals (with /dev/pts filesystem)
- Filesystem notifications
- JSON framework
- Low-level utility library (LibCore)
- Mid-level 2D graphics library (LibDraw)
- High-level GUI library (LibGUI)
- HTML/CSS engine
- Web browser
- C++ IDE
- Sampling profiler with GUI
- Emojis (UTF-8)
- HTTP downloads
- SoundBlaster 16 driver
- Software-mixing sound daemon
- WAV playback
- Simple desktop piano/synthesizer
- Visual GUI design tool
- PNG format support
- Text editor
- IRC client
- Simple painting application
- DNS lookup
- Desktop games: Minesweeper and Snake
- Color theming
- Ports system (needs more packages!)
- Other stuff I can't think of right now...
How do I build and run this?
See the SerenityOS build instructions
Wanna talk?
Come chat with us in #serenityos on the Freenode IRC network.
Author
- Andreas Kling - awesomekling
Contributors
(And many more!) Feel free to append yourself here if you've made some sweet contributions. :)
License
SerenityOS is licensed under a 2-clause BSD license.