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[209.85.208.178]) by smtp.gmail.com with ESMTPSA id q7sm1440980lfr.16.2020.09.04.11.42.58 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 04 Sep 2020 11:42:59 -0700 (PDT) Received: by mail-lj1-f178.google.com with SMTP id w3so9129163ljo.5 for ; Fri, 04 Sep 2020 11:42:58 -0700 (PDT) X-Received: by 2002:a2e:84d6:: with SMTP id q22mr3675523ljh.70.1599244978377; Fri, 04 Sep 2020 11:42:58 -0700 (PDT) MIME-Version: 1.0 References: <20200903142242.925828-1-hch@lst.de> <20200904060024.GA2779810@gmail.com> <20200904175823.GA500051@localhost.localdomain> In-Reply-To: <20200904175823.GA500051@localhost.localdomain> From: Linus Torvalds Date: Fri, 4 Sep 2020 11:42:42 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: remove the last set_fs() in common code, and remove it for x86 and powerpc v3 To: Alexey Dobriyan Cc: Ingo Molnar , Christoph Hellwig , Al Viro , Michael Ellerman , "the arch/x86 maintainers" , Luis Chamberlain , Kees Cook , Linux Kernel Mailing List , linux-fsdevel , linux-arch , linuxppc-dev Content-Type: text/plain; charset="UTF-8" Sender: linux-arch-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org On Fri, Sep 4, 2020 at 10:58 AM Alexey Dobriyan wrote: > > set_fs() is older than some kernel hackers! > > $ cd linux-0.11/ > $ find . -type f -name '*.h' | xargs grep -e set_fs -w -n -A3 Oh, it's older than that. It was there (as set_fs) in 0.10, and may even predate that. But sadly, I don't have tar-balls for 0.02 and 0.03, so can't check. The actual use of %fs as the user space segment is already there in 0.01, but there was no 'set_fs()'. That was a simpler and more direct time, and "get_fs()" looked like this back then: #define _fs() ({ \ register unsigned short __res; \ __asm__("mov %%fs,%%ax":"=a" (__res):); \ __res;}) and all the setting was basically part of the kernel entry asm and. Lovely. Linus