Messages in this thread | | | Date | Fri, 29 Oct 2021 11:08:35 +0100 | From | "Russell King (Oracle)" <> | Subject | Re: [PATCH v2 1/2] arch/Kconfig: Make CONFIG_CPU_SPECTRE available for all architectures |
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On Thu, Oct 28, 2021 at 12:36:58PM -0700, Pawan Gupta wrote: > Isn't ARM already using CPU_SPECTRE for selecting things: > > config HARDEN_BRANCH_PREDICTOR > bool "Harden the branch predictor against aliasing attacks" if EXPERT > depends on CPU_SPECTRE > > This was the whole motivation for doing the same for x86. > > Adding a condition for all architectures is also okay, but its going to > a little messier: > > config BPF_UNPRIV_DEFAULT_OFF > default y if X86 || ARM || ...
It doesn't have to be (but sadly we end up repeating "DEFAULT"):
config BPF_UNPRIV_DEFAULT_OFF_DEFAULT bool
config BPF_UNPRIV_DEFAULT_OFF bool "Disable unprivileged BPF by default" default BPF_UNPRIV_DEFAULT_OFF_DEFAULT
Then architectures can select BPF_UNPRIV_DEFAULT_OFF_DEFAULT if they wish this to be defaulted to "yes".
However, please note that this has limited use given that the BPF_UNPRIV_DEFAULT_OFF option has been around for a while now. Any existing configuration that mentions this symbol will override any default specified in the Kconfig files if the option is user-visible.
So, IMHO, defaults need to be set correctly from the point in time that the option is introduced.
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