[PATCH v6 0/6] x86/arch_prctl Add ARCH_[GET|SET]_CPUID for controlling the CPUID instruction

From	Kyle Huey <me@kylehuey.com>
Newsgroups	linux.kernel
Subject	[PATCH v6 0/6] x86/arch_prctl Add ARCH_[GET\|SET]_CPUID for controlling the CPUID instruction
Date	2016-09-27 00:00 +0200
Message-ID	<slM6l-JE-5@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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rr (http://rr-project.org/), a userspace record-and-replay reverse-
execution debugger, would like to trap and emulate the CPUID instruction.
This would allow us to a) mask away certain hardware features that rr does
not support (e.g. RDRAND) and b) enable trace portability across machines
by providing constant results.

Newer Intel CPUs (Ivy Bridge and later) can fault when CPUID is executed at
CPL > 0.  Expose this capability to userspace as a new pair of arch_prctls,
ARCH_GET_CPUID and ARCH_SET_CPUID, with two values, ARCH_CPUID_ENABLE and
ARCH_CPUID_SIGSEGV.

The following changes have been made since v5:

Patch 3:
- do_arch_prctl is again do_arch_prctl_common

Patch 6:
- Added static qualifiers on get/set_cpuid_mode
- Braced ifs in disable/enable_cpuid
- Renamed arch_post_exec to arch_setup_new_exec

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[PATCH v6 0/6] x86/arch_prctl Add ARCH_[GET|SET]_CPUID for controlling the CPUID instruction Kyle Huey <me@kylehuey.com> - 2016-09-27 00:00 +0200
  [PATCH v6 5/6] x86/cpufeature: Detect CPUID faulting support Kyle Huey <me@kylehuey.com> - 2016-09-27 00:00 +0200
  [PATCH v6 4/6] x86/syscalls/32: Wire up arch_prctl on x86-32 Kyle Huey <me@kylehuey.com> - 2016-09-27 00:00 +0200
  [PATCH v6 1/6] x86/arch_prctl/64: Use SYSCALL_DEFINE2 to define sys_arch_prctl Kyle Huey <me@kylehuey.com> - 2016-09-27 00:00 +0200
  [PATCH v6 3/6] x86/arch_prctl: Add do_arch_prctl_common Kyle Huey <me@kylehuey.com> - 2016-09-27 00:00 +0200
  [PATCH v6 6/6] x86/arch_prctl: Add ARCH_[GET|SET]_CPUID Kyle Huey <me@kylehuey.com> - 2016-09-27 00:00 +0200
  [PATCH v6 2/6] x86/arch_prctl/64: Rename do_arch_prctl to do_arch_prctl_64 Kyle Huey <me@kylehuey.com> - 2016-09-27 00:00 +0200

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