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Thu, 9 Jan 2025 15:54:11 -0500 (EST) X-Mailer: MessagingEngine.com Webmail Interface MIME-Version: 1.0 Date: Thu, 09 Jan 2025 21:53:51 +0100 From: "Arnd Bergmann" To: "Maciej W. Rozycki" , "Eric W. Biederman" Cc: "John Paul Adrian Glaubitz" , "Richard Henderson" , "Matt Turner" , "Kees Cook" , "Paul E. McKenney" , linux-alpha@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Michael Cree" , "Sam James" , "Geert Uytterhoeven" , "Michael Karcher" , "Chris Hofstaedtler" , util-linux@vger.kernel.org, linux-mips@vger.kernel.org, loongarch@lists.linux.dev Message-Id: In-Reply-To: References: <20250103140148.370368-1-glaubitz@physik.fu-berlin.de> <24f03227-1b55-4e50-b6e9-7ac74fda2602@app.fastmail.com> <678ee681-12c3-4e79-a04b-495daf343846@app.fastmail.com> <82d33a2d-dffe-4268-a175-4536b3f9c07f@app.fastmail.com> <87ed1cufj1.fsf@email.froward.int.ebiederm.org> Subject: Re: [PATCH] alpha: Fix personality flag propagation across an exec Content-Type: text/plain Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: B98024000A X-Rspamd-Server: rspam12 X-Stat-Signature: 3om6yq5qxr7boknb7aphnpsbcprs5s97 X-Rspam-User: X-HE-Tag: 1736456054-346784 X-HE-Meta: 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 cH62zFYg 6kxyx7uGTfOVRc6QoNMFUdWIYWTId6sT53FwxGlRZzt9EwNwJGEGr2aZ+h27F+ptzX/3BG85nL/qilwy1W7VcaAuXS0F9v+KoRU38T3nOQhnkF7lIz6FqR7iU9WkNJADDzxZhdSh6PMh2/fygmNecOPEopxZJM3i6QEQL2Nz8avFs1H9JkURJntqaIA== 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: On Thu, Jan 9, 2025, at 21:10, Maciej W. Rozycki wrote: > On Thu, 9 Jan 2025, Eric W. Biederman wrote: > >> > So, this would be the 100% correct for alpha then which would not loose >> > any functionality even for 32-bit binaries? >> >> I don't think it is correct to think about 32-bit binaries on alpha. >> >> Alpha never had a 32bit instruction set. But at some point it looks >> like binaries that could not handle more than 31 bits of address >> space got ported and someone implemented a work-around. I guess this >> is the --taso option that Arnd mentioned. > > This also saves some code space in non-PIE and plain static executables > as it takes fewer machine instructions to load a 64-bit address that is > known beforehand to be a sign-extended 32-bit value. > > This is similar to the MIPS n32 ABI, which also implies a 32-bit address > space while still using 64-bit registers for everything, starting from > stack slots (it's also ILP32 with the `long long' C data type only making > proper use of the full width of the CPU registers, while Alpha's --taso > ABI is I believe IP32 (?) with the plain `long' C data type still 64-bit, > just as with the regular LP64 ABI). I'm pretty sure it's still LP64 on Alpha Linux with gcc. There is an -mpointer-size=32 option in gcc for VMS, but I don't see anything like that in Linux. The only thing that is implemented here is the option for the linker that sets the EF_ALPHA_32BIT bit, but none of the code generation takes advantage of the upper bits being zero. Arnd