[PATCH V1 0/3] perf/x86/intel: Add Branch Monitoring support

[Megha Dey]

This patchset adds support for Intel's branch monitoring feature. This
feature uses heuristics to detect the occurrence of an ROP(Return Oriented
Programming) or ROP like(JOP: Jump oriented programming) attack. These
heuristics are based off certain performance monitoring statistics,
measured dynamically over a short configurable window period. ROP is a
malware trend in which the attacker can compromise a return pointer held
on the stack to redirect execution to a different desired instruction.

Currently, only the Cannonlake family of Intel processors support this
feature. This feature is enabled by CONFIG_PERF_EVENTS_INTEL_BM.

Once the kernel is compiled with CONFIG_PERF_EVENTS_INTEL_BM=y on a
Cannonlake system, the following perf events are added which can be viewed
with perf list:
  intel_bm/branch-misp/                              [Kernel PMU event]
  intel_bm/call-ret/                                 [Kernel PMU event]
  intel_bm/far-branch/                               [Kernel PMU event]
  intel_bm/indirect-branch-misp/                     [Kernel PMU event]
  intel_bm/ret-misp/                                 [Kernel PMU event]
  intel_bm/rets/                                     [Kernel PMU event]

A perf-based kernel driver has been used to monitor the occurrence of
one of the 6 branch monitoring events. There are 2 counters that each
can select between one of these events for evaluation over a specified
instruction window size (0 to 1023). For each counter, a threshold value
(0 to 127) can be configured to set a point at which an interrupt is
generated. Each task can monitor a maximum of 2 events at any given time.

Apart from the kernel driver, this patchset adds CPUID of Cannonlake
processors to Intel family list and the Documentation/x86/intel_bm.txt
file with some information about Intel Branch monitoring.

Changes V0->V1:
1. Used the 'is_sampling_event' function 
2. Added support to monitor 2 events for every task
3. Corrected typos
4. Added a lock to prevent race condition in concurrent perf_event_open()s
5. Got rid of start()/stop() and added its functionality in add()/del()
6. Removed read() callback as it was not doing anything.
6. Removed code for sampling events as we do not support sampling.
7. Added 'id' member to hw_perf_event::intel_bm to track which counter the
event is using.
8. Moved MSR accesses to the add()/del() callbacks

Megha Dey (3):
  x86/cpu/intel: Add Cannonlake to Intel family
  perf/x86/intel/bm.c: Add Intel Branch Monitoring support
  x86, bm: Add documentation on Intel Branch Monitoring

 Documentation/x86/intel_bm.txt      | 216 +++++++++++++
 arch/x86/events/Kconfig             |  10 +
 arch/x86/events/intel/Makefile      |   2 +
 arch/x86/events/intel/bm.c          | 618 ++++++++++++++++++++++++++++++++++++
 arch/x86/include/asm/intel-family.h |   2 +
 arch/x86/include/asm/msr-index.h    |   5 +
 arch/x86/include/asm/processor.h    |   4 +
 include/linux/perf_event.h          |   9 +-
 kernel/events/core.c                |  16 +
 9 files changed, 881 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/x86/intel_bm.txt
 create mode 100644 arch/x86/events/intel/bm.c

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1.9.1