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| H A D | cpu_macros.S | ff6f62e105c6553a7b64a8c3c2165b53f7250300 Tue Feb 12 11:25:02 UTC 2019 Antonio Nino Diaz <antonio.ninodiaz@arm.com> Update macro to check need for CVE-2017-5715 mitigation
Armv8.5 introduces the field CSV2 to register ID_AA64PFR0_EL1. It can
have the following 3 values:
- 0: Branch targets trained in one hardware described context may affect
speculative execution in a different hardware described context. In
some CPUs it may be needed to apply mitigations.
- 1: Branch targets trained in one hardware described context can only
affect speculative execution in a different hardware described
context in a hard-to-determine way. No mitigation required.
- 2: Same as 1, but the device is also aware of SCXTNUM_ELx register
contexts. The TF doesn't use the registers, so there is no
difference with 1.
The field CSV2 was originally introduced in the TRM of the Cortex-A76
before the release of the Armv8.5 architecture. That TRM only mentions
the meaning of values 0 and 1. Because of this, the code only checks if
the field has value 1 to know whether to enable or disable the
mitigations.
This patch makes it aware of value 2 as well. Both values 1 and 2
disable the mitigation, and 0 enables it.
Change-Id: I5af33de25a0197c98173f52c6c8c77b51a51429f
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
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