On Mon, Nov 15, 2021 at 10:57 AM Rob Herring [off-list ref] wrote:

On Wed, Oct 27, 2021 at 3:16 PM Rob Herring [off-list ref] wrote:

quoted

The arm64 support departs from the x86 implementation by requiring the user
to explicitly request user access (via attr.config1) and only enables access
for task bound events. Since usage is explicitly requested, access is
enabled at perf_event_open() rather than on mmap() as that greatly
simplifies the implementation. Rather than trying to lock down the access
as the x86 implementation has been doing, we can start with only a limited
use case enabled and later expand it if needed.

I've run this version thru Vince's perf tests[14] with arm64 support added.
I wish I'd found these tests sooner...

This originally resurrected Raphael's series[1] to enable userspace counter
access on arm64. My previous versions are here
[2][3][4][5][6][7][8][9][10][11][12].
A git branch is here[13].

Changes in v12:
 - Zero PMSELR_EL0 when userspace access is enabled
 - Return -EOPNOTSUPP for if h/w doesn't support 64-bit counters

Will, the series rebases cleanly on v5.16-rc1. Please let me know if
you want me to resend.

Peter, Will is waiting on an ack on the core/x86 bits from you.

Ping!

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