From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792696563; b=HfAyZa+alXaQN+LNDIUfFeD++cMlKDv0VoR7Y6nc7yOtsQRUB0Zt92AZ2JPUrLxebeQ4 tfQxwZO8TdK3C7R3tVuyTEmdkghq/MweXyOK1kq9kwpwdTcomaOlskGMylmFpKC3Vck3h z7VtBm4AzcI3ETrdeVk45lCqc78yAgJwsKB12vpyB4oipuOetEw7UPUveuJVnp0nYwvqY pn6iflOxu9mOkNlbT8npwKzGhI7lsQ3FL6LuaYicgIC8uZdFZ2krzZ1i522d5hDkalPfs ezoxAUE7hOVhKWgLkh7SFFZt+ZRDWvpnp4YHvmoNbg7cihyg3H6JSSzgNMoCPLnmggQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792696563; h=Received:DKIM-Signature:From:To:Cc:Subject:In-Reply-To:References: Date:Message-ID:MIME-Version:Content-Type:Content-Transfer-Encoding; bh=zfF/h5yN+JN0JXoERjM1UOmD6YL51qlegqbjQ5IjJaw=; b=yisF+d1m+E7vIaljbDjCjb0bCmnmDMdBaP77FAtYOJI5F4AW59kGTAfzdgUZyttgnngP UWsXOnMn1hev1UdKAVdfYsp2V81KRKVqzJA363Aaa0jZggJynSp8bEijV3RulrzC6Gcr5 MtObWINWwc2qwa83rAWXzqmjoa/BGUDrRQkqrAzaGdAjz5bfefKxm80EUOixHrWqHVakj 9fwoj+5ad03k1egP2xLmuS5Hab+GF6cXb85K4fi4QBGYltjTTmkDEZboU1b7YZnMAaWjY H38MR8iPMSHWjiptHGGp3k2YRVghrQBzRPbNVqTh/rMpoB+DwBTJ4zaJjAdZ6KNMSKQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=N5BvSZtD; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 45C86606A31A; Thu, 22 Oct 2026 19:16:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=N5BvSZtD Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2CE1F1F01825; Thu, 22 Oct 2026 19:16:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792696563; bh=zfF/h5yN+JN0JXoERjM1UOmD6YL51qlegqbjQ5IjJaw=; h=From:To:Cc:Subject:In-Reply-To:References:Date; b=N5BvSZtDsOnevI6N7z+hpnuDFwgb+Za20bBfcyPl1zdZ/RUM/vhVGgooCl8EukmyB v951DfxEQIGKmPlqDa47vEV9oOJpjd3jTdFHzFJ8cGbv5Ec+77S428dvBazQLk752d 8oijRTx04uvdE5t0WJ3hFRzAydPhPUU1uC5jEb9/jBb3UCG/5+2vXEPMQ0qv3aaJy/ fDrmEd5ydsQk2Juig/QI4K6qM7Xm060UN2bTZPYYJFIjTdDkBvnz/aEeUGpDN6dDMG QYnQUY/lk7t3H2ZOK5q9Ex67PolYwOb50JpOTpWf5Zn6NIH8OuYBLaiHmJRlGX+jMg L4eC2BtuFHQ4g== From: Thomas Gleixner To: Sebastian Andrzej Siewior Cc: LKML , Peter Zijlstra , Michael Ellerman , Shrikanth Hegde , linuxppc-dev@lists.ozlabs.org, Kees Cook , Huacai Chen , loongarch@lists.linux.dev, Paul Walmsley , Palmer Dabbelt , linux-riscv@lists.infradead.org, Sven Schnelle , linux-s390@vger.kernel.org, x86@kernel.org, Mark Rutland , Jinjie Ruan , Andy Lutomirski , Oleg Nesterov , Richard Henderson , Russell King , Catalin Marinas , Guo Ren , Geert Uytterhoeven , Thomas Bogendoerfer , Helge Deller , Yoshinori Sato , Richard Weinberger , Chris Zankel , linux-arm-kernel@lists.infradead.org, linux-alpha@vger.kernel.org, linux-csky@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linux-sh@vger.kernel.org, linux-um@lists.infradead.org, Arnd Bergmann , Vineet Gupta , Will Deacon , Brian Cain , Michal Simek , Dinh Nguyen , "David S. Miller" , Andreas Larsson , linux-snps-arc@lists.infradead.org, linux-hexagon@vger.kernel.org, linux-openrisc@vger.kernel.org, sparclinux@vger.kernel.org, linux-arch@vger.kernel.org, Michal =?utf-8?Q?Such=C3=A1nek?= , Jonathan Corbet , linux-doc@vger.kernel.org, "H. Peter Anvin" Subject: Re: [patch 16/18] x86/entry: Get rid of the sys_ni_syscall() indirection In-Reply-To: <20261022142425.3Wx-RrU5@linutronix.de> References: <20260707181957.433213175@kernel.org> <20260707190254.493733289@kernel.org> <20261022142425.3Wx-RrU5@linutronix.de> Date: Thu, 22 Oct 2026 21:15:59 +0200 Message-ID: <87fqxx1r80.ffs@fw13> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On Thu, Oct 22 2026 at 16:24, Sebastian Andrzej Siewior wrote: > On 2026-07-07 21:07:01 [+0200], Thomas Gleixner wrote: >> Invoking sys_ni_syscall() from a code path, which already knows that the >> syscall number is invalid just to assign -ENOSYS to regs->ax is a pointl= ess >> exercise. It's even redundant as the low level entry code already has set >> regs->ax to -ENOSYS on entry. >>=20 >> Remove the extra conditionals and the function calls. > > Since this patch, tools/testing/selftests/x86/syscall_numbering_64 > throws in this: > |[RUN] Running tests under ptrace: modifying the default return > |[RUN] Checking system calls with msb =3D 0 (0x0) > |[RUN] Checking some common syscalls as 64 bit > |[OK] x64 syscall 0:0 returned 0 as expected > |[OK] x64 syscall 0:1 returned 0 as expected > |[RUN] Checking some 64-bit only syscalls as 64 bit > |[OK] x64 syscall 0:19 returned 0 as expected > |[OK] x64 syscall 0:20 returned 0 as expected > |[RUN] Checking out of range system calls > |[FAIL] x32 syscall 0:-64 returned -9999, but it should = have returned -ENOSYS > =E2=80=A6 > |[FAIL] x32 syscall 0:-2 returned -9999, but it should h= ave returned -ENOSYS > |[FAIL] x32 syscalls 0:-64..-2 had 63 failure > |[OK] x32 syscall 0:-1 returned MODIFIED_BY_PTRACE as expe= cted > |[FAIL] x64 syscall 0:1073741760 returned -9999, but it = should have returned -ENOSYS > =E2=80=A6 > |[FAIL] x64 syscall 0:1073741823 returned -9999, but it = should have returned -ENOSYS > |[FAIL] x64 syscalls 0:1073741760..1073741823 had 64 failure > |[FAIL] x64 syscall 0:-64 returned -9999, but it should = have returned -ENOSYS > =E2=80=A6 > |[FAIL] x64 syscall 0:547 returned -9999, but it should = have returned -ENOSYS > |[FAIL] x64 syscalls 0:512..547 had 36 failure > |[RUN] Checking some common syscalls as x32 > |[OK] x32 syscall 0:0 returned 0 as expected > =E2=80=A6 > |[RUN] Checking out of range system calls > |[FAIL] x32 syscall 1:-64 returned -9999, but it should = have returned -ENOSYS > |[FAIL] x32 syscalls 1:-64..-2 had 63 failure > |[OK] x32 syscall 1:-1 returned MODIFIED_BY_PTRACE as expe= cted > |[FAIL] x64 syscall 1:1073741760 returned -9999, but it = should have returned -ENOSYS > =E2=80=A6 > > and so on=E2=80=A6 The test has > > | #define MODIFIED_BY_PTRACE -9999 > > and the ptracer modifies the return code. However not always. Not sure > if this was indeed a pointless exercise or not. Hrmm. That's weird. Let me have a look.