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[209.85.208.171]) by smtp.gmail.com with ESMTPSA id 10sm11847073ljr.4.2019.01.10.15.10.42 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 10 Jan 2019 15:10:42 -0800 (PST) Received: by mail-lj1-f171.google.com with SMTP id k15-v6so11234815ljc.8 for ; Thu, 10 Jan 2019 15:10:42 -0800 (PST) X-Received: by 2002:a2e:2c02:: with SMTP id s2-v6mr7173902ljs.118.1547161358642; Thu, 10 Jan 2019 15:02:38 -0800 (PST) MIME-Version: 1.0 References: <20190110203023.GL2861@worktop.programming.kicks-ass.net> <20190110205226.iburt6mrddsxnjpk@treble> In-Reply-To: <20190110205226.iburt6mrddsxnjpk@treble> From: Linus Torvalds Date: Thu, 10 Jan 2019 15:02:22 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v3 0/6] Static calls To: Josh Poimboeuf Cc: Peter Zijlstra , "the arch/x86 maintainers" , Linux List Kernel Mailing , Ard Biesheuvel , Andy Lutomirski , Steven Rostedt , Ingo Molnar , Thomas Gleixner , Masami Hiramatsu , Jason Baron , Jiri Kosina , David Laight , Borislav Petkov , Julia Cartwright , Jessica Yu , "H. Peter Anvin" , Nadav Amit , Rasmus Villemoes , Edward Cree , Daniel Bristot de Oliveira Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 10, 2019 at 12:52 PM Josh Poimboeuf wrote: > > Right, emulating a call instruction from the #BP handler is ugly, > because you have to somehow grow the stack to make room for the return > address. Personally I liked the idea of shifting the iret frame by 16 > bytes in the #DB entry code, but others hated it. Yeah, I hated it. But I'm starting to think it's the simplest solution. So still not loving it, but all the other models have had huge issues too. Linus