netdev - Re: [PATCH 0/2] bpf: Yet another approach to fix the BPF dispatcher thing

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Message-ID: <Y2PU01h0hy+6dI0J@krava>
Date:   Thu, 3 Nov 2022 15:48:51 +0100
From:   Jiri Olsa <olsajiri@...il.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     olsajiri@...il.com, ast@...nel.org, daniel@...earbox.net,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        bpf@...r.kernel.org, bjorn@...nel.org, toke@...hat.com,
        David.Laight@...lab.com, rostedt@...dmis.org
Subject: Re: [PATCH 0/2] bpf: Yet another approach to fix the BPF dispatcher
 thing

On Thu, Nov 03, 2022 at 01:00:12PM +0100, Peter Zijlstra wrote:
> Hi!
> 
> Even thought the __attribute__((patchable_function_entry())) solution to the
> BPF dispatcher woes works, it turns out to not be supported by the whole range
> of ageing compilers we support. Specifically this attribute seems to be GCC-8
> and later.
> 
> This is another approach -- using static_call() to rewrite the dispatcher
> function. I've compile tested this on:
> 
>   x86_64  (inline static-call support)
>   i386    (out-of-line static-call support)
>   aargh64 (no static-call support)
> 
> A previous version was tested and found working by Bjorn.
> 
> It is split in two patches; first reverting the current approach and then
> introducing the new for ease of review.
> 

Acked-by: Jiri Olsa <jolsa@...nel.org>
Tested-by: Jiri Olsa <jolsa@...nel.org>

thanks,
jirka