From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EFC452500DE for ; Tue, 14 Jan 2025 11:21:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736853714; cv=none; b=o0yFilVdxhcVCCK2H+nKp0Yh5TIJ8JL2SwSX3TYh2r/M4GBXXk2OUlME7FxvnouJSeu4ObUhvXvLhcnkx48CvekYU8BwtxkoCQi7FDOS4StlsKr56r3h3FmB+G0LUllEcxW/Wd+yO5a/DoFtImK2ENztpDWoK47u5y83NtRaS6k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736853714; c=relaxed/simple; bh=5JFAfkPR+Ike3FMmbmMZs5Ka5jUJg7zx9lp5Nr+ajQo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=EscD9cbvEwh2MXJYaD8pxHh29S29UYPZO5XhvjDojZh/cUdyaABlKCX9zg0merohptbx/XeJJPL3LRolcAq0MIXUyoWfhGDL6dC1GwODKi5ZblvPmJ0+xWKtrZHAjEQ923l5XyeTh0p+85XjqoygH6woenUjOVuok7fj94WXYKk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=iWgxlCQu; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="iWgxlCQu" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1736853711; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=gKIV4YzdGrCw0FjbYvth1lwU1z2n2sZ8xFygOnMWM/Q=; b=iWgxlCQui7p8H+QLBZiT4TZ9Jx+EMxnBhgaxk8PVORHrf9BpH5hKIXLgcIVP8kNOyFVJdh plIUcrhNysdReJEPXlq7NTwev8ZpQNDI+eqW5tHgb3v4Ay8HMVpw43TCW9Vru8Fhodj0EY UB/E/uWHQAY0vFPr5giFOP8BEeQapvk= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-68-MOulm-YXPBixk34LJI9Atw-1; Tue, 14 Jan 2025 06:21:44 -0500 X-MC-Unique: MOulm-YXPBixk34LJI9Atw-1 X-Mimecast-MFC-AGG-ID: MOulm-YXPBixk34LJI9Atw Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 3656D195605E; Tue, 14 Jan 2025 11:21:41 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.226.88]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id C67BB3003FD1; Tue, 14 Jan 2025 11:21:33 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Tue, 14 Jan 2025 12:21:16 +0100 (CET) Date: Tue, 14 Jan 2025 12:21:07 +0100 From: Oleg Nesterov To: Masami Hiramatsu Cc: Jiri Olsa , Aleksa Sarai , Eyal Birger , linux-kernel , linux-trace-kernel@vger.kernel.org, BPF-dev-list , Song Liu , Yonghong Song , John Fastabend , peterz@infradead.org, tglx@linutronix.de, bp@alien8.de, x86@kernel.org, linux-api@vger.kernel.org, Andrii Nakryiko , Daniel Borkmann , Alexei Starovoitov , Andrii Nakryiko , "rostedt@goodmis.org" , rafi@rbk.io, Shmulik Ladkani Subject: Re: Crash when attaching uretprobes to processes running in Docker Message-ID: <20250114112106.GC19816@redhat.com> References: <20250110.152323-sassy.torch.lavish.rent-vKX3ul5B3qyi@cyphar.com> <20250114190521.0b69a1af64cac41106101154@kernel.org> Precedence: bulk X-Mailing-List: linux-api@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250114190521.0b69a1af64cac41106101154@kernel.org> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 On 01/14, Masami Hiramatsu wrote: > > On Tue, 14 Jan 2025 10:22:20 +0100 > Jiri Olsa wrote: > > > @@ -418,6 +439,9 @@ SYSCALL_DEFINE0(uretprobe) > > regs->r11 = regs->flags; > > regs->cx = regs->ip; > > > > + /* zero rbx to signal trampoline that uretprobe syscall was executed */ > > + regs->bx = 0; > > Can we just return -ENOSYS as like as other syscall instead of > using rbx as a side channel? > We can carefully check the return address is not -ERRNO when set up > and reserve the -ENOSYS for this use case. Not sure I understand... But please not that the uretprobed function can return any value including -ENOSYS, and this is what sys_uretprobe() has to return. Oleg.