Merge pull request #1818 from pbeesley-arm/doc-links ...

doc: Fix broken external links

doc: Fix broken external links ...

Using Sphinx linkcheck on the TF-A docs revealed some broken
or permanently-redirected links. These have been updated where
possible.

Change-Id: Ie1fead47972ede3331973759b50ee466264bd2ee
Signed-off-by: Paul Beesley <paul.beesley@arm.com>

Doc: Remove useless escape characters ...

Just like has been done in the porting guide a couple of patches
earlier, kill all escaped underscore characters in all documents.

Change-Id: I7fb5b806412849761d9221a6ce3cbd95ec43d611
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>

Fix broken links in documentation ...

Change-Id: Ic58f88fa4e5fc0004a33357915ff80db30954441
Signed-off-by: John Tsichritzis <john.tsichritzis@arm.com>

DSU erratum 936184 workaround ...

If the system is in near idle conditions, this erratum could cause a
deadlock or data corruption. This patch applies the workaround that
prevents this.

This DSU erratum affects only the DSUs that contain the ACP interface
and it was fixed in r2p0. The workaround is applied only to the DSUs
that are actually affected.

Link to respective Arm documentation:
http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.epm138168/index.html

Change-Id: I033213b3077685130fc1e3f4f79c4d15d7483ec9
Signed-off-by: John Tsichritzis <john.tsichritzis@arm.com>

Add support for dynamic mitigation for CVE-2018-3639 ...

Some CPUS may benefit from using a dynamic mitigation approach for
CVE-2018-3639.  A new SMC interface is defined to allow software
executing in lower ELs to enable or disable the mitigation for their
execution context.

It should be noted that regardless of the state of the mitigation for
lower ELs, code executing in EL3 is always mitigated against
CVE-2018-3639.

NOTE: This change is a compatibility break for any platform using
the declare_cpu_ops_workaround_cve_2017_5715 macro.  Migrate to
the declare_cpu_ops_wa macro instead.

Change-Id: I3509a9337ad217bbd96de9f380c4ff8bf7917013
Signed-off-by: Dimitris Papastamos <dimitris.papastamos@arm.com>

Implement static workaround for CVE-2018-3639 ...

For affected CPUs, this approach enables the mitigation during EL3
initialization, following every PE reset. No mechanism is provided to
disable the mitigation at runtime.

This approach permanently mitigates the entire software stack and no
additional mitigation code is required in other software components.

TF-A implements this approach for the following affected CPUs:

*   Cortex-A57 and Cortex-A72, by setting bit 55 (Disable load pass store) of
    `CPUACTLR_EL1` (`S3_1_C15_C2_0`).

*   Cortex-A73, by setting bit 3 of `S3_0_C15_C0_0` (not documented in the
    Technical Reference Manual (TRM)).

*   Cortex-A75, by setting bit 35 (reserved in TRM) of `CPUACTLR_EL1`
    (`S3_0_C15_C1_0`).

Additionally, a new SMC interface is implemented to allow software
executing in lower ELs to discover whether the system is mitigated
against CVE-2018-3639.

Refer to "Firmware interfaces for mitigating cache speculation
vulnerabilities System Software on Arm Systems"[0] for more
information.

[0] https://developer.arm.com/cache-speculation-vulnerability-firmware-specification

Change-Id: I084aa7c3bc7c26bf2df2248301270f77bed22ceb
Signed-off-by: Dimitris Papastamos <dimitris.papastamos@arm.com>

Fixup SMCCC_FEATURES return value for SMCCC_ARCH_WORKAROUND_1 ...

Only return -1 if the workaround for CVE-2017-5715 is not compiled in.

Change-Id: I1bd07c57d22b4a13cf51b35be141a1f1ffb065ff
Signed-off-by: Dimitris Papastamos <dimitris.papastamos@arm.com>

Update Arm TF references to TF-A ...

Update Arm Trusted Firmware references in the upstream documents to
Trusted Firmware-A (TF-A). This is for consistency with and
disambiguation from Trusted Firmware-M (TF-M).

Also update other Arm trademarks, e.g. ARM->Arm, ARMv8->Armv8-A.

Change-Id: I8bb0e18af29c6744eeea2dc6c08f2c10b20ede22
Signed-off-by: Dan Handley <dan.handley@arm.com>
Signed-off-by: David Cunado <david.cunado@arm.com>

Workaround for CVE-2017-5715 on Cortex A57 and A72 ...

Invalidate the Branch Target Buffer (BTB) on entry to EL3 by disabling
and enabling the MMU.  To achieve this without performing any branch
instruction, a per-cpu vbar is installed which executes the workaround
and then branches off to the corresponding vector entry in the main
vector table.  A side effect of this change is that the main vbar is
configured before any reset handling.  This is to allow the per-cpu
reset function to override the vbar setting.

This workaround is enabled by default on the affected CPUs.

Change-Id: I97788d38463a5840a410e3cea85ed297a1678265
Signed-off-by: Dimitris Papastamos <dimitris.papastamos@arm.com>

Cortex-A72: Implement workaround for erratum 859971 ...

Erratum 855971 applies to revision r0p3 or earlier Cortex-A72 CPUs. The
recommended workaround is to disable instruction prefetch.

Change-Id: I7fde74ee2a8a23b2a8a1891b260f0eb909fad4bf
Signed-off-by: Eleanor Bonnici <Eleanor.bonnici@arm.com>
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>

Cortex-A57: Implement workaround for erratum 859972 ...

Erratum 855972 applies to revision r1p3 or earlier Cortex-A57 CPUs. The
recommended workaround is to disable instruction prefetch.

Change-Id: I56eeac0b753eb1432bd940083372ad6f7e93b16a
Signed-off-by: Eleanor Bonnici <Eleanor.bonnici@arm.com>
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>

Add doc for some Cortex A53 errata workarounds ...

Add documentation for errata 835769 and 843419 workarounds introduced in
commit a94cc37

Fixes ARM-software/tf-issues#504

Change-Id: I7f3db53dfc5f3827b32663f483d3302bc9679b19
Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>

Convert documentation to reStructuredText ...

Due to recent issues in the rendering of the documentation on GitHub and
some long-standing issues like the lack of automatic table of content in
Markdown, the documentation has been converted to reStructuredText.
Basic constructs looks pretty similar to Markdown.

Automatically convert GitHub markdown documentation to reStructuredText
using pandoc.

Change-Id: If20b695acedc6d1b49c8d9fb64efd6b6ba23f4a9
Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>