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[209.85.128.175]) by smtp.gmail.com with ESMTPSA id 00721157ae682-6eace8f0a81sm30869837b3.45.2024.11.13.05.55.14 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 13 Nov 2024 05:55:15 -0800 (PST) Received: by mail-yw1-f175.google.com with SMTP id 00721157ae682-6e35bf59cf6so7562687b3.0 for ; Wed, 13 Nov 2024 05:55:14 -0800 (PST) X-Forwarded-Encrypted: i=1; AJvYcCVwVGGjihV3rzXEniuqNcTyWdu18yIzuLcgw56jddFF5AfNt0/gBgfZZ3g8RHuY+vPPNODpKZVI5Q==@kvack.org X-Received: by 2002:a05:690c:74ca:b0:6db:da0e:d166 with SMTP id 00721157ae682-6eade45bda3mr168692847b3.12.1731506114746; Wed, 13 Nov 2024 05:55:14 -0800 (PST) MIME-Version: 1.0 References: <8bbfe73f7f1ef9f1a4674d963d1c4e8181f33341.camel@sipsolutions.net> In-Reply-To: From: Geert Uytterhoeven Date: Wed, 13 Nov 2024 14:55:02 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [RFC PATCH v2 02/13] x86/um: nommu: elf loader for fdpic To: Hajime Tazaki Cc: johannes@sipsolutions.net, linux-um@lists.infradead.org, ricarkol@google.com, Liam.Howlett@oracle.com, ebiederm@xmission.com, kees@kernel.org, viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Greg Ungerer , Rich Felker Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: cbshay1ebjabfebsc1nn8r76xiw98yc4 X-Rspam-User: X-Rspamd-Queue-Id: 30ADF140003 X-Rspamd-Server: rspam02 X-HE-Tag: 1731506088-439693 X-HE-Meta: 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 0ZfReSbp DByihtISyeriJi1Dvyv6X2/UAkVCnZ6k/cVIULqjcFHuo8varUTVVygUQupywND0zEUQSr9w8T9QQIdxSfoaH286re/feGkYPdrecBxtGZD/dgYTJuY+kpYyJ87VjP/OO6l365/8qM0h1PJHAzGLN6DaaPNHfUtbV1Y411qRqlYoNlW9P9+p6UQ6KxKxtwIiIZ+dGnnjA0tXizZBcJ/abxKCAvXreUyCp6Ei9vKRG/5hSQ5NTN65iMrflqXOXu7a+PXYQZ4mDVpBB/eB/kLfXNSXkSB8f3/2NJpJvYYO1BrCJ7lad7ITpF6iO9u/ndWzXzmT3DKm5N+G5sNoyvjawMijm58XUsHdxx+nG+T7WZ4peihT39dXrvH/QvfGBDg26D1moJ+SDP/vjWBHzOzUnjc/7Wz5hcCPk8fLugiW/mJiWmFPfggClTJBvi6KhWvUR6S/AIsUplYRoeOg= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Tazaki-san, On Wed, Nov 13, 2024 at 2:17=E2=80=AFPM Hajime Tazaki = wrote: > On Wed, 13 Nov 2024 19:27:08 +0900, > Geert Uytterhoeven wrote: > > On Wed, Nov 13, 2024 at 9:37=E2=80=AFAM Johannes Berg wrote: > > > On Wed, 2024-11-13 at 09:36 +0100, Johannes Berg wrote: > > > > On Wed, 2024-11-13 at 09:19 +0100, Geert Uytterhoeven wrote: > > > > > > > > > > > > > - depends on ARM || ((M68K || RISCV || SUPERH || XTEN= SA) && !MMU) > > > > > > > > + depends on ARM || ((M68K || RISCV || SUPERH || UML = || XTENSA) && !MMU) > > > > > > > > > > > > > > s/UML/X86/? > > > > > > > > > > > > I guess the fdpic loader can be used to X86, but this patchset = only > > > > > > adds UML to be able to select it. I intended to add UML into n= ommu > > > > > > family. > > > > > > > > > > While currently x86-nommu is supported for UML only, this is real= ly > > > > > x86-specific. I still hope UML will get support for other archite= ctures > > > > > one day, at which point a dependency on UML here will become wron= g... > > > > > > > > > > > > > X86 isn't set for UML, X64_32 and X64_64 are though. > > > > > > > > Given that the no-MMU UM support even is 64-bit only, that probably > > > > should then really be (UML && X86_64). > > > > > > > > But it already has !MMU, so can't be selected otherwise, and it see= ms > > > > that non-X86 UML > > > > > > ... would require far more changes in all kinds of places, so not sur= e > > > I'd be too concerned about it here. > > > > OK, up to you... > > Indeed, this particular patch [02/13] intends to support the fdpic > loader under the condition 1) x86_64 ELF binaries (w/ PIE), 2) on UML, > 3) and with) !MMU configured. Given that situation, the strict check > should be like: > > depends on ARM || ((M68K || RISCV || SUPERH || (UML && X86_64) || XTEN= SA) && !MMU) > > (as Johannes mentioned). > > on the other hand, the fdpic loader works (afaik) on MMU environment so, > > depends on ARM || (UML && X86_64) || ((M68K || RISCV || SUPERH || XTEN= SA) && !MMU) > > should also works, but this might be too broad for this patchset (and > not sure if this makes a new use case). AFAIK that depends on the architecture's MMU context structure, cfr. the comment in commit 782f4c5c44e7d99d ("m68knommu: allow elf_fdpic loader to be selected"), which restricts it to nommu on m68k. If it does work on X86_64, you can drop the dependency on UML, and we're (almost) back to my initial comment ;-) > anyway, thank you for the comment. > # I really wanted to have comments from nommu folks. I've added some in CC... Gr{oetje,eeting}s, Geert --=20 Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k= .org In personal conversations with technical people, I call myself a hacker. Bu= t when I'm talking to journalists I just say "programmer" or something like t= hat. -- Linus Torvalds