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>
This patch also fixes the assumption that the counters are disabled on
the resume path. This is incorrect as the AMU counters are enabled
early in the CPU reset function before `cpuamu_context_restore()`
runs.
Change-Id: I38a94eb166a523f00de18e86860434ffccff2131
Signed-off-by: Dimitris Papastamos <dimitris.papastamos@arm.com>
The Cortex A75 has 5 AMU counters. The first three counters are fixed
and the remaining two are programmable.
A new build option is introduced, `ENABLE_AMU`. When set, the fixed
counters will be enabled for use by lower ELs. The programmable
counters are currently disabled.
Change-Id: I4bd5208799bb9ed7d2596e8b0bfc87abbbe18740
Signed-off-by: Dimitris Papastamos <dimitris.papastamos@arm.com>
Both Cortex-A75 and Cortex-A55 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 considerably
simpler.
Change-Id: I68b30e6e1ebe7c041d5e67f39c59f08575fc7ecc
Co-authored-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
Dimitris Papastamos
David Wang