Re: [PATCH bpf] bpf: Fix fexit trampoline.

[patchwork-bot+netdevbpf@kernel.org]

Hello:

This patch was applied to bpf/bpf.git (refs/heads/master):

On Tue, 16 Mar 2021 14:00:07 -0700 you wrote:
> From: Alexei Starovoitov <ast@kernel.org>
> 
> The fexit/fmod_ret programs can be attached to kernel functions that can sleep.
> The synchronize_rcu_tasks() will not wait for such tasks to complete.
> In such case the trampoline image will be freed and when the task
> wakes up the return IP will point to freed memory causing the crash.
> Solve this by adding percpu_ref_get/put for the duration of trampoline
> and separate trampoline vs its image life times.
> The "half page" optimization has to be removed, since
> first_half->second_half->first_half transition cannot be guaranteed to
> complete in deterministic time. Every trampoline update becomes a new image.
> The image with fmod_ret or fexit progs will be freed via percpu_ref_kill and
> call_rcu_tasks. Together they will wait for the original function and
> trampoline asm to complete. The trampoline is patched from nop to jmp to skip
> fexit progs. They are freed independently from the trampoline. The image with
> fentry progs only will be freed via call_rcu_tasks_trace+call_rcu_tasks which
> will wait for both sleepable and non-sleepable progs to complete.
> 
> [...]

Here is the summary with links:
  - [bpf] bpf: Fix fexit trampoline.
    https://git.kernel.org/bpf/bpf/c/e21aa341785c

You are awesome, thank you!
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