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Date: Tue, 6 Feb 2024 16:13:39 +0000
From: Mark Brown <broonie@kernel.org>
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Subject: Re: [RFC PATCH v1 18/28] prctl: arch-agnostic prtcl for indirect
 branch tracking
Message-ID: <ZcJas4tZNzOJv6hW@finisterre.sirena.org.uk>
References: <20240125062739.1339782-1-debug@rivosinc.com>
 <20240125062739.1339782-19-debug@rivosinc.com>
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On Wed, Jan 24, 2024 at 10:21:43PM -0800, debug@rivosinc.com wrote:

> To allow userspace to enable this feature for itself, following prtcls are
> defined:
>  - PR_GET_INDIR_BR_LP_STATUS: Gets current configured status for indirect branch
>    tracking.
>  - PR_SET_INDIR_BR_LP_STATUS: Sets a configuration for indirect branch tracking
>    Following status options are allowed
>            - PR_INDIR_BR_LP_ENABLE: Enables indirect branch tracking on user
>              thread.
>            - PR_INDIR_BR_LP_DISABLE; Disables indirect branch tracking on user
>              thread.
>  - PR_LOCK_INDIR_BR_LP_STATUS: Locks configured status for indirect branch
>    tracking for user thread.

FWIW the arm64 BTI feature is enabled per page of executable memory
rather than in CPU state so it'd be hard for us to adopt this interface.
I don't think that's a blocker, just noting it.

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