From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 445C312CDAE; Tue, 19 Nov 2024 09:13:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732007638; cv=none; b=pb7OzwRN6ssv5GnN1/JSqVDivmKhKJ/gIF0baDkHXA/9DLYhdJMPt4ox3ShcKULEIA0SbsPWmYLuLvtP7ETyxn75yYIPUxPcQTeUUhNFwjOWnTa28trW9gOJnki9MIjB9nYMNJpprk5DwPxA0Zd/v8rQzIjR41xCLJAnqUnEQcQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732007638; c=relaxed/simple; bh=ecTbzJ5AaNWfrV0C1O4VXMVfV5Sfpj63ONG+7CIujDg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=GOjhantewPZ0hRGL4YC1f7Fspzw/Yfh9vjmpSv0KvvAzpEbMQyc5jnfvIQ49tPoAMx7C6DbRr90J8xwBUaZ5vmSA0ABQhBhJ1CQdgzXKeaBIRQm3c2mjsRjRzKnHBUqbK/XjZExY/vjAmqUQ78QJ5JqZqTot9g6jHsED/YzUYQA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=NsNqJwFy; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="NsNqJwFy" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=fl+NTXtpNg4Pp8q2Lsf9iJ/z+achogFWtubvIsHu1dI=; b=NsNqJwFyPpwrWTn1KZS0+oK0VW HQXe0hRFdDH5zdmbQMoDS4arEhib00WDZY0CSkDBwYZh5Y4S1h3frPNXG58jLDaUsBX/jEN/XUb2M aiVi2NF5h5yDj8Zk/JHTOTWS7QxlDVuJSJKt1D1GpdldlMfhKsE7cY0B9DL2dzcI487dlCcIGR4wV JeEbOBX/9FizfuuAE28MoQy919qfM2wYtz9ppQyKLJjKRbKBC4V1/XCYzZLvZo2WY03hexfnA3V1G s2sJgs8CtRmbcD2ZX9UTi0qTamojZfaOVrp0YD6rscnWRsVnUfAnCazeXE2vZ5NTtvMUYCuBbHW4L LOF24LWA==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1tDKIw-00000000KUn-0y7U; Tue, 19 Nov 2024 09:13:50 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 16C3A3006AB; Tue, 19 Nov 2024 10:13:49 +0100 (CET) Date: Tue, 19 Nov 2024 10:13:48 +0100 From: Peter Zijlstra To: Andrii Nakryiko Cc: Jiri Olsa , Oleg Nesterov , Andrii Nakryiko , bpf@vger.kernel.org, Song Liu , Yonghong Song , John Fastabend , Hao Luo , Steven Rostedt , Masami Hiramatsu , Alan Maguire , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: Re: [RFC perf/core 05/11] uprobes: Add mapping for optimized uprobe trampolines Message-ID: <20241119091348.GE11903@noisy.programming.kicks-ass.net> References: <20241105133405.2703607-1-jolsa@kernel.org> <20241105133405.2703607-6-jolsa@kernel.org> <20241105142327.GF10375@noisy.programming.kicks-ass.net> Precedence: bulk X-Mailing-List: linux-trace-kernel@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: On Mon, Nov 18, 2024 at 10:06:51PM -0800, Andrii Nakryiko wrote: > > > Jiri, we could also have an option to support 64-bit call, right? We'd > > > need nop9 for that, but it's an option as well to future-proofing this > > > approach, no? > > > > hm, I don't think there's call with relative 64bit offset > > why do you need a relative, when you have 64 bits? ;) there is a call > to absolute address, no? No, there is not :/ You get to use an indirect call, which means multiple instructions and all the speculation joy. IFF USDT thingies have AX clobbered (I couldn't find in a hurry) then patching the multi instruction thing is relatively straight forward, if they don't, its going to be a pain.