linux-kernel - Re: linux-next: manual merge of the tip tree with the bpf-next tree

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Message-ID: <CAADnVQLcNWCsazy4XudB4EPaqvdtea+d8w5q4R5MsvRJ4fmOmA@mail.gmail.com>
Date: Thu, 25 Sep 2025 15:34:15 +0100
From: Alexei Starovoitov <alexei.starovoitov@...il.com>
To: Mark Brown <broonie@...nel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...nel.org>, 
	"H. Peter Anvin" <hpa@...or.com>, Peter Zijlstra <peterz@...radead.org>, 
	Alexei Starovoitov <ast@...nel.org>, Jiri Olsa <jolsa@...nel.org>, 
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, 
	Linux Next Mailing List <linux-next@...r.kernel.org>
Subject: Re: linux-next: manual merge of the tip tree with the bpf-next tree

On Thu, Sep 25, 2025 at 3:06 PM Mark Brown <broonie@...nel.org> wrote:
>
> Hi all,
>
> Today's linux-next merge of the tip tree got a conflict in:
>
>   kernel/events/uprobes.c
>
> between commit:
>
>   4363264111e12 ("uprobe: Do not emulate/sstep original instruction when ip is changed")
>
> from the bpf-next tree and commit:
>
>   ba2bfc97b4629 ("uprobes/x86: Add support to optimize uprobes")
>
> from the tip tree.
>
> I fixed it up (see below) and can carry the fix as necessary. This
> is now fixed as far as linux-next is concerned, but any non trivial
> conflicts should be mentioned to your upstream maintainer when your tree
> is submitted for merging.  You may also want to consider cooperating
> with the maintainer of the conflicting tree to minimise any particularly
> complex conflicts.
>
> diff --cc kernel/events/uprobes.c
> index c2ff256dd6419,996a81080d563..0000000000000
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@@ -2741,13 -2765,9 +2765,16 @@@ static void handle_swbp(struct pt_regs
>
>         handler_chain(uprobe, regs);
>
>  +      /*
>  +       * If user decided to take execution elsewhere, it makes little sense
>  +       * to execute the original instruction, so let's skip it.
>  +       */
>  +      if (instruction_pointer(regs) != bp_vaddr)
>  +              goto out;
>  +
> +       /* Try to optimize after first hit. */
> +       arch_uprobe_optimize(&uprobe->arch, bp_vaddr);
> +
>         if (arch_uprobe_skip_sstep(&uprobe->arch, regs))
>                 goto out;

Yep. That's exactly what we discussed.
I'll mention it in the PR during the merge window.