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Thu, 9 Jul 2026 15:50:21 +0800 (CST) Received: from dggpemf500011.china.huawei.com (unknown [7.185.36.131]) by mail.maildlp.com (Postfix) with ESMTPS id C128A40537; Thu, 9 Jul 2026 15:59:26 +0800 (CST) Received: from [10.67.109.254] (10.67.109.254) by dggpemf500011.china.huawei.com (7.185.36.131) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Thu, 9 Jul 2026 15:59:22 +0800 Message-ID: Date: Thu, 9 Jul 2026 15:59:21 +0800 X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] syscall_user_dispatch: Introduce ARCH_SUPPORTS_SYSCALL_USER_DISPATCH To: =?UTF-8?Q?Thomas_Wei=C3=9Fschuh?= CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , References: <20260709072803.3843948-1-ruanjinjie@huawei.com> <20260709093404-0b19988f-8d19-4fae-86d8-396aa747307d@linutronix.de> From: Jinjie Ruan In-Reply-To: <20260709093404-0b19988f-8d19-4fae-86d8-396aa747307d@linutronix.de> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.67.109.254] X-ClientProxiedBy: kwepems500002.china.huawei.com (7.221.188.17) To dggpemf500011.china.huawei.com (7.185.36.131) On 7/9/2026 3:36 PM, Thomas Weißschuh wrote: > On Thu, Jul 09, 2026 at 03:28:03PM +0800, Jinjie Ruan wrote: >> Currently, only x86 genuinely implements and supports Syscall User >> Dispatch (SUD). Multiple architectures provide a stub >> arch_syscall_is_vdso_sigreturn() returning 'false' simply to satisfy >> GENERIC_ENTRY compilation, which creates a false impression of feature >> support. >> >> Introduce ARCH_SUPPORTS_SYSCALL_USER_DISPATCH to decouple this mechanism >> from GENERIC_ENTRY. Select it exclusively on x86 and remove the redundant >> stub functions from other architectures. > > Nice, this confused me before. > >> Link: https://lore.kernel.org/linux-arm-kernel/akZgV0Y4YAmB43_g@J2N7QTR9R3.cambridge.arm.com/ >> Cc: Thomas Gleixner >> Cc: Mark Rutland >> Cc: Ada Couprie Diaz >> Cc: Thomas Weißschuh >> Suggested-by: Mark Rutland >> Signed-off-by: Jinjie Ruan >> --- >> arch/Kconfig | 1 + >> arch/loongarch/include/asm/syscall.h | 6 ------ >> arch/powerpc/include/asm/syscall.h | 5 ----- >> arch/riscv/include/asm/syscall.h | 5 ----- >> arch/s390/include/asm/syscall.h | 5 ----- >> arch/x86/Kconfig | 1 + >> 6 files changed, 2 insertions(+), 21 deletions(-) >> >> diff --git a/arch/Kconfig b/arch/Kconfig >> index 0c01521c2f3f..393d0fb75eac 100644 >> --- a/arch/Kconfig >> +++ b/arch/Kconfig >> @@ -116,6 +116,7 @@ config GENERIC_ENTRY >> >> config SYSCALL_USER_DISPATCH >> bool "Syscall User Dispatch" >> + depends on ARCH_SUPPORTS_SYSCALL_USER_DISPATCH > > ARCH_SUPPORTS_SYSCALL_USER_DISPATCH is not declared as a config option, > so the 'select' will not do anything. Needs this: > > config ARCH_SUPPORTS_SYSCALL_USER_DISPATCH > bool Yes, this is missing here. > >> depends on GENERIC_ENTRY >> default y >> help > > (...)