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Date: Sat, 2 Mar 2024 22:49:32 +0100
From: Oleg Nesterov <oleg@redhat.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Jiri Olsa <olsajiri@gmail.com>, yunwei356@gmail.com,
	Andrii Nakryiko <andrii.nakryiko@gmail.com>,
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Subject: Re: [LSF/MM/BPF TOPIC] faster uprobes
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X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.8

On 03/02, Alexei Starovoitov wrote:
>
> I suspect it's all working fine already.
> Only x86 is using single byte uprobe.
> All other archs are using 2 or 4 byte.

Yes, so we have UPROBE_SWBP_INSN_SIZE

> So replacing an insn or two with a call should work.

Please note that  __uprobe_register(offset) fails if
!IS_ALIGNED(offset, UPROBE_SWBP_INSN_SIZE)

Not to mention that if "call" replaces 2 insns we have another problem:
what if another consumer wants to probe the 2ns insn ?

but perhaps (quite possibly) I misunderstand you.

Oleg.