Prevent speculative execution past ERET ...

Even though ERET always causes a jump to another address, aarch64 CPUs
speculatively execute following instructions as if the ERET
instruction was not a jump instruction.
The speculative execution does not cross privilege-levels (to the jump
target as one would expect), but it continues on the kernel privilege
level as if the ERET instruction did not change the control flow -
thus execution anything that is accidentally linked after the ERET
instruction. Later, the results of this speculative execution are
always architecturally discarded, however they can leak data using
microarchitectural side channels. This speculative execution is very
reliable (seems to be unconditional) and it manages to complete even
relatively performance-heavy operations (e.g. multiple dependent
fetches from uncached memory).

This was fixed in Linux, FreeBSD, OpenBSD and Optee OS:
https://github.com/torvalds/linux/commit/679db70801da9fda91d26caf13bf5b5ccc74e8e8
https://github.com/freebsd/freebsd/commit/29fb48ace4186a41c409fde52bcf4216e9e50b61
https://github.com/openbsd/src/commit/3a08873ece1cb28ace89fd65e8f3c1375cc98de2
https://github.com/OP-TEE/optee_os/commit/abfd092aa19f9c0251e3d5551e2d68a9ebcfec8a

It is demonstrated in a SafeSide example:
https://github.com/google/safeside/blob/master/demos/eret_hvc_smc_wrapper.cc
https://github.com/google/safeside/blob/master/kernel_modules/kmod_eret_hvc_smc/eret_hvc_smc_module.c

Signed-off-by: Anthony Steinhauser <asteinhauser@google.com>
Change-Id: Iead39b0b9fb4b8d8b5609daaa8be81497ba63a0f

Apply compile-time check for AArch64-only cores ...

Some cores support only AArch64 mode. In those cores, only a limited
subset of the AArch32 system registers are implemented. Hence, if TF-A
is supposed to run on AArch64-only cores, it must be compiled with
CTX_INCLUDE_AARCH32_REGS=0.

Currently, the default settings for compiling TF-A are with the AArch32
system registers included. So, if we compile TF-A the default way and
attempt to run it on an AArch64-only core, we only get a runtime panic.

Now a compile-time check has been added to ensure that this flag has the
appropriate value when AArch64-only cores are included in the build.

Change-Id: I298ec550037fafc9347baafb056926d149197d4c
Signed-off-by: John Tsichritzis <john.tsichritzis@arm.com>

Merge changes from topic "sm/fix_a76_errata" into integration ...

* changes:
  Workaround for cortex-A76 errata 1286807
  Cortex-A76: workarounds for errata 1257314, 1262606, 1262888, 1275112

Workaround for cortex-A76 errata 1286807 ...

The workaround for Cortex-A76 errata #1286807 is implemented
in this patch.

Change-Id: I6c15af962ac99ce223e009f6d299cefb41043bed
Signed-off-by: Soby Mathew <soby.mathew@arm.com>

Cortex-A76: workarounds for errata 1257314, 1262606, 1262888, 1275112 ...

The workarounds for errata 1257314, 1262606, 1262888 and 1275112 are
added to the Cortex-A76 cpu specific file. The workarounds are disabled
by default and have to be explicitly enabled by the platform integrator.

Change-Id: I70474927374cb67725f829d159ddde9ac4edc343
Signed-off-by: Soby Mathew <soby.mathew@arm.com>

Add compile-time errors for HW_ASSISTED_COHERENCY flag ...

This patch fixes this issue:
https://github.com/ARM-software/tf-issues/issues/660

The introduced changes are the following:

1) Some cores implement cache coherency maintenance operation on the
hardware level. For those cores, such as - but not only - the DynamIQ
cores, it is mandatory that TF-A is compiled with the
HW_ASSISTED_COHERENCY flag. If not, the core behaviour at runtime is
unpredictable. To prevent this, compile time checks have been added and
compilation errors are generated, if needed.

2) To enable this change for FVP, a logical separation has been done for
the core libraries. A system cannot contain cores of both groups, i.e.
cores that manage coherency on hardware and cores that don't do it. As
such, depending on the HW_ASSISTED_COHERENCY flag, FVP includes the
libraries only of the relevant cores.

3) The neoverse_e1.S file has been added to the FVP sources.

Change-Id: I787d15819b2add4ec0d238249e04bf0497dc12f3
Signed-off-by: John Tsichritzis <john.tsichritzis@arm.com>

DSU: Implement workaround for errata 798953 ...

Under certain near idle conditions, DSU may miss response transfers on
the ACE master or Peripheral port, leading to deadlock. This workaround
disables high-level clock gating of the DSU to prevent this.

Change-Id: I820911d61570bacb38dd325b3519bc8d12caa14b
Signed-off-by: Louis Mayencourt <louis.mayencourt@arm.com>

Cortex-A76: Optimize CVE_2018_3639 workaround ...

Switched from a static check to a runtime assert to make sure a
workaround is implemented for CVE_2018_3639.

This allows platforms that know they have the SSBS hardware workaround
in the CPU to compile out code under DYNAMIC_WORKAROUND_CVE_2018_3639.

The gain in memory size without the dynamic workaround is 4KB in bl31.

Change-Id: I61bb7d87c59964b0c7faac5d6bc7fc5c4651cbf3
Signed-off-by: Ambroise Vincent <ambroise.vincent@arm.com>

Cortex-A76: fix spelling ...

Change-Id: I6adf7c14e8a974a7d40d51615b5e69eab1a7436f
Signed-off-by: Ambroise Vincent <ambroise.vincent@arm.com>

Add workaround for errata 1073348 for Cortex-A76 ...

Concurrent instruction TLB miss and mispredicted return instruction
might fetch wrong instruction stream. Set bit 6 of CPUACTLR_EL1 to
prevent this.

Change-Id: I2da4f30cd2df3f5e885dd3c4825c557492d1ac58
Signed-off-by: Louis Mayencourt <louis.mayencourt@arm.com>

Add workaround for errata 1220197 for Cortex-A76 ...

Streaming store under specific conditions might cause deadlock or data
corruption. Set bit 25:24 of CPUECTLR_EL1, which disables write
streaming to the L2 to prevent this.

Change-Id: Ib5cabb997b35ada78b27e75787afd610ea606dcf
Signed-off-by: Louis Mayencourt <louis.mayencourt@arm.com>

Add workaround for errata 1130799 for Cortex-A76 ...

TLBI VAAE1 or TLBI VAALE1 targeting a page within hardware page
aggregated address translation data in the L2 TLB might cause
corruption of address translation data. Set bit 59 of CPUACTLR2_EL1 to
prevent this.

Change-Id: I59f3edea54e87d264e0794f5ca2a8c68a636e586
Signed-off-by: Louis Mayencourt <louis.mayencourt@arm.com>

Sanitise includes across codebase ...

Enforce full include path for includes. Deprecate old paths.

The following folders inside include/lib have been left unchanged:

- include/lib/cpus/${ARCH}
- include/lib/el3_runtime/${ARCH}

The reason for this change is that having a global namespace for
includes isn't a good idea. It defeats one of the advantages of having
folders and it introduces problems that are sometimes subtle (because
you may not know the header you are actually including if there are two
of them).

For example, this patch had to be created because two headers were
called the same way: e0ea0928d5b7 ("Fix gpio includes of mt8173 platform
to avoid collision."). More recently, this patch has had similar
problems: 46f9b2c3a282 ("drivers: add tzc380 support").

This problem was introduced in commit 4ecca33988b9 ("Move include and
source files to logical locations"). At that time, there weren't too
many headers so it wasn't a real issue. However, time has shown that
this creates problems.

Platforms that want to preserve the way they include headers may add the
removed paths to PLAT_INCLUDES, but this is discouraged.

Change-Id: I39dc53ed98f9e297a5966e723d1936d6ccf2fc8f
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

AArch64: Use SSBS for CVE_2018_3639 mitigation ...

The Armv8.5 extensions introduces PSTATE.SSBS (Speculation Store Bypass
Safe) bit to mitigate against Variant 4 vulnerabilities. Although an
Armv8.5 feature, this can be implemented by CPUs implementing earlier
version of the architecture.

With this patch, when both PSTATE.SSBS is implemented and
DYNAMIC_WORKAROUND_CVE_2018_3639 is active, querying for
SMCCC_ARCH_WORKAROUND_2 via. SMCCC_ARCH_FEATURES call would return 1 to
indicate that mitigation on the PE is either permanently enabled or not
required.

When SSBS is implemented, SCTLR_EL3.DSSBS is initialized to 0 at reset
of every BL stage. This means that EL3 always executes with mitigation
applied.

For Cortex A76, if the PE implements SSBS, the existing mitigation (by
using a different vector table, and tweaking CPU ACTLR2) is not used.

Change-Id: Ib0386c5714184144d4747951751c2fc6ba4242b6
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@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 end_vector_entry assembler macro ...

Check_vector_size checks if the size of the vector fits
in the size reserved for it. This check creates problems in
the Clang assembler. A new macro, end_vector_entry, is added
and check_vector_size is deprecated.

This new macro fills the current exception vector until the next
exception vector. If the size of the current vector is bigger
than 32 instructions then it gives an error.

Change-Id: Ie8545cf1003a1e31656a1018dd6b4c28a4eaf671
Signed-off-by: Roberto Vargas <roberto.vargas@arm.com>

Implement dynamic mitigation for CVE-2018-3639 on Cortex-A76 ...

The Cortex-A76 implements SMCCC_ARCH_WORKAROUND_2 as defined in
"Firmware interfaces for mitigating cache speculation vulnerabilities
System Software on Arm Systems"[0].

Dynamic mitigation for CVE-2018-3639 is enabled/disabled by
setting/clearning bit 16 (Disable load pass store) of `CPUACTLR2_EL1`.

NOTE: The generic code that implements dynamic mitigation does not
currently implement the expected semantics when dispatching an SDEI
event to a lower EL.  This will be fixed in a separate patch.

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

Change-Id: I8fb2862b9ab24d55a0e9693e48e8be4df32afb5a
Signed-off-by: Dimitris Papastamos <dimitris.papastamos@arm.com>

Add support for Cortex-Ares and Cortex-A76 CPUs ...

Both Cortex-Ares and Cortex-A76 CPUs use the ARM DynamIQ Shared Unit
(DSU).  The power-down and power-up sequences are therefore mostly
managed in hardware, and required software operations are simple.

Change-Id: I3a9447b5bdbdbc5ed845b20f6564d086516fa161
Signed-off-by: Isla Mitchell <isla.mitchell@arm.com>