TF-A Documentation: Update Security Advisory TFV-5 (CVE-2017-15031)

This patch updates description of Security Advisory TFV-5.

Change-Id: Ieaee0b51a79843345b1aca5d0e20c4964beb3c95
Signed-off-by: Alexei Fedorov <Alexei.Fedorov@arm.com>

docs/security_advisories/security-advisory-tfv-5.rst

@@ -7,9 +7,9 @@ Advisory TFV-5 (CVE-2017-15031)
 +================+=============================================================+
 | CVE ID         | `CVE-2017-15031`_                                           |
 +----------------+-------------------------------------------------------------+
-| Date           | 02 Oct 2017                                                 |
+| Date           | 02 Oct 2017, updated on 04 Nov 2019                         |
 +----------------+-------------------------------------------------------------+
-| Versions       | All, up to and including v1.4                               |
+| Versions       | All, up to and including v2.1                               |
 | Affected       |                                                             |
 +----------------+-------------------------------------------------------------+
 | Configurations | All                                                         |
@@ -18,8 +18,12 @@ Advisory TFV-5 (CVE-2017-15031)
 | Impact         | Leakage of sensitive secure world timing information        |
 +----------------+-------------------------------------------------------------+
 | Fix Version    | `Pull Request #1127`_ (merged on 18 October 2017)           |
+|                |                                                             |
+|                | `Commit e290a8fcbc`_ (merged on 23 August 2019)             |
+|                |                                                             |
+|                | `Commit c3e8b0be9b`_ (merged on 27 September 2019)          |
 +----------------+-------------------------------------------------------------+
-| Credit         | Arm                                                         |
+| Credit         | Arm, Marek Bykowski                                         |
 +----------------+-------------------------------------------------------------+
 
 The ``PMCR_EL0`` (Performance Monitors Control Register) provides details of the
@@ -28,10 +32,11 @@ implemented, and configures and controls the counters. If the ``PMCR_EL0.DP``
 bit is set to zero, the cycle counter (when enabled) counts during secure world
 execution, even when prohibited by the debug signals.
 
-Since Arm TF does not save and restore ``PMCR_EL0`` when switching between the
+Since TF-A does not save and restore ``PMCR_EL0`` when switching between the
 normal and secure worlds, normal world code can set ``PMCR_EL0.DP`` to zero to
 cause leakage of secure world timing information. This register should be added
-to the list of saved/restored registers.
+to the list of saved/restored registers both when entering EL3 and also
+transitioning to S-EL1.
 
 Furthermore, ``PMCR_EL0.DP`` has an architecturally ``UNKNOWN`` reset value.
 Since Arm TF does not initialize this register, it's possible that on at least
@@ -42,5 +47,11 @@ sensible default values in the secure context.
 The same issue exists for the equivalent AArch32 register, ``PMCR``, except that
 here ``PMCR_EL0.DP`` architecturally resets to zero.
 
+NOTE: The original pull request referenced above only fixed the issue for S-EL1
+whereas the EL3 was fixed in the later commits.
+
 .. _CVE-2017-15031: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-15031
 .. _Pull Request #1127: https://github.com/ARM-software/arm-trusted-firmware/pull/1127
+.. _Commit e290a8fcbc: https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/commit/?id=e290a8fcbc
+.. _Commit c3e8b0be9b: https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/commit/?id=c3e8b0be9b
+