Re: [RFC PATCH v1 18/28] prctl: arch-agnostic prtcl for indirect branch tracking

On Tue, Feb 06, 2024 at 04:13:39PM +0000, Mark Brown wrote:

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.

Got it, makes sense.