https://github.com/softdevteam/user_rdpmc

Enable RDPMC from Linux userspace.
https://github.com/softdevteam/user_rdpmc

Last synced: 6 days ago
JSON representation

Enable RDPMC from Linux userspace.

• Host: GitHub
• URL: https://github.com/softdevteam/user_rdpmc
• Owner: softdevteam
• License: other
• Created: 2016-08-23T15:53:40.000Z (about 8 years ago)
• Default Branch: master
• Last Pushed: 2016-08-23T16:24:50.000Z (about 8 years ago)
• Last Synced: 2024-04-24T03:43:51.222Z (7 months ago)
• Language: C
• Homepage:
• Size: 7.81 KB
• Stars: 8
• Watchers: 8
• Forks: 2
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

README

        
The user_rdpmc Linux Kernel Module

==================================

A simple Linux kernel module which, when loaded, allows ring 3 (userspace)

programs to use the `RDPMC` assembler instruction by flipping the `PMC` flag in

the `CR4` register.

This module only makes sense on an x86 machine.

Building

--------

Install Linux kernel headers and run `make`.

The build currently assumes a Debian Linux system. You may have to tweak some

paths in the Makefile for other distributions.

Using

-----

First run the `test_rdpmc` program and check that the program crashes, thus

confirming that the userspace cannot invoke `RDPMC`.

Insert the module with `sudo insmod user_rdpmc.ko`. The dmesg buffer should

then display a message similar to:

```

[ 5016.743382] Enabling RDPMC from ring 3 for 4 CPUs

```

Now if you re-run the test program, it should not crash. Userspace can now

invoke `RDPMC`.

If you remove the `user_rdpmc` module, userspace is then denied use of `RDPMC`.