The 'phandle-array' type is a bit ambiguous. It can be either just an
array of phandles or an array of phandles plus args. Many schemas for
phandle-array properties aren't clear in the schema which case applies
though the description usually describes it.
The array of phandles case boils down to needing:
items:
maxItems: 1
The phandle plus args cases should typically take this form:
items:
- items:
- description: A phandle
- description: 1st arg cell
- description: 2nd arg cell
With this change, some examples need updating so that the bracketing of
property values matches the schema.
Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Vinod Koul <vkoul@kernel.org>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Georgi Djakov <djakov@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Mark Brown <broonie@kernel.org>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Acked-by: Stephen Boyd <sboyd@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Marc Kleine-Budde <mkl@pengutronix.de>
Link: https://lore.kernel.org/r/20220119015038.2433585-1-robh@kernel.org
The CLKSCREW attack [0] exposed security vulnerabilities in energy management
implementations where untrusted software had direct access to clock and
voltage hardware controls. In this attack, the malicious software was able to
place the platform into unsafe overclocked or undervolted configurations. Such
configurations then enabled the injection of predictable faults to reveal
secrets.
Many Arm-based systems used to or still use voltage regulator and clock
frameworks in the kernel. These frameworks allow callers to independently
manipulate frequency and voltage settings. Such implementations can render
systems susceptible to this form of attack.
Attacks such as CLKSCREW are now being mitigated by not having direct and
independent control of clock and voltage in the kernel and moving that
control to a trusted entity, such as the SCP firmware or secure world
firmware/software which are to perform sanity checking on the requested
performance levels, thereby preventing any attempted malicious programming.
With the advent of such an abstraction, there is a need to replace the
generic clock and regulator bindings used by such devices with a generic
performance domains bindings.
[0] https://www.usenix.org/conference/usenixsecurity17/technical-sessions/presentation/tang
Cc: Rob Herring <robh+dt@kernel.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
