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[209.85.208.174]) by smtp.gmail.com with ESMTPSA id a12sm3340661ljk.48.2020.01.30.10.03.11 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 30 Jan 2020 10:03:11 -0800 (PST) Received: by mail-lj1-f174.google.com with SMTP id w1so4371428ljh.5 for ; Thu, 30 Jan 2020 10:03:11 -0800 (PST) X-Received: by 2002:a2e:580c:: with SMTP id m12mr3650122ljb.150.1580407390980; Thu, 30 Jan 2020 10:03:10 -0800 (PST) MIME-Version: 1.0 References: <20200128165906.GA67781@gmail.com> <20200129132618.GA30979@zn.tnic> <20200129170725.GA21265@agluck-desk2.amr.corp.intel.com> <20200129183404.GB30979@zn.tnic> <20200130085134.GB6684@zn.tnic> <20200130173910.GK6684@zn.tnic> In-Reply-To: <20200130173910.GK6684@zn.tnic> From: Linus Torvalds Date: Thu, 30 Jan 2020 10:02:54 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [GIT PULL] x86/asm changes for v5.6 To: Borislav Petkov Cc: "Luck, Tony" , Ingo Molnar , Linux Kernel Mailing List , Thomas Gleixner , Borislav Petkov , Peter Zijlstra , Andrew Morton 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 30, 2020 at 9:39 AM Borislav Petkov wrote: > > Yeah, makes sense. It would help if one slaps a relative JMP as *not* > the first insn in an alternatives replacement and the build to warn that > it can't work. Maybe with the exception that a short conditional jump inside the alternative code itself is fine. Because a branch-over inside the alternative sequence (or a loop - think inline cmpxchg loop or whatever) would be fine, since it's unaffected by code placement. Linus