From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mslow3.mail.gandi.net (mslow3.mail.gandi.net [217.70.178.249]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B2D4E2D59FA for ; Tue, 17 Feb 2026 08:07:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.70.178.249 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771315651; cv=none; b=Nd17vQFP6IkUPVry5F2PzQ7Ox9SCUzNcP5mbGoa0618he021/5WJZxAK4DlOsaJFy2h/izX1x4BqSPNTuQ9wCaSQlLqfcZGan7nJsDS2ECIbr7Fr48+MDxhFSkQFSAk7Ht3mVdUYJj70DRFm82H9HRdfnrcPjXu+YBlIemoV+1Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771315651; c=relaxed/simple; bh=lgzape97VBTSH8g4Sn4ffM5oBqcg2AeUOu2+qSZoYfA=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=lsflFpyy1+T8qM7o6/DEVdkX4X+BpBpyyawYYp+05ydfzeZdAa7KF3d/uSh446INDdiXpkPAlgh/3SimW55Gc9NvTyM2YI+vmGaI2sOCZ1zl3l6bHWuUfCgq9lYeFFkDr+IPSxZwH9v8UNCLiYzGUYNCTskweEJEWa3AvSn7p44= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=xenomai.org; spf=pass smtp.mailfrom=xenomai.org; dkim=pass (2048-bit key) header.d=xenomai.org header.i=@xenomai.org header.b=fDID5y3T; arc=none smtp.client-ip=217.70.178.249 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=xenomai.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=xenomai.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=xenomai.org header.i=@xenomai.org header.b="fDID5y3T" Received: from relay1-d.mail.gandi.net (relay1-d.mail.gandi.net [IPv6:2001:4b98:dc4:8::221]) by mslow3.mail.gandi.net (Postfix) with ESMTP id 1ECD65813BA for ; Tue, 17 Feb 2026 08:00:33 +0000 (UTC) Received: by mail.gandi.net (Postfix) with ESMTPSA id E9A474326D; Tue, 17 Feb 2026 08:00:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=xenomai.org; s=gm1; t=1771315225; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=PW/Y8yXp1o00s+IcJf8yi0FZtw2FljC7Pv+blsrlbt4=; b=fDID5y3T5U1jHcGXA4z64sYAuk4JIzec+u1Wrbw0W675RTxkeJBGEoX9TEFXdml3pZHEzY ipxDcwztjFctsvIVkCX8q4nhxXQ83Cb84eSa6NW3AQRfhWvZ5l4tBFPqwa8vKFY8vcG0Hk NgpUv9r4+aTFQTVf9ADV/uq7bEs1kft9I+3HuBNdSVf0fHKnu8Sze7CdeWomZsOrGHq5qi HSvdR+nhZognxIhpC6y4YzLWC6m2Qz7ElEUMikAzwDei8tDmdsXtT+Yla9Y+NH2U469Yi9 CTveHWqFs2GU7Xnr4fOvFUfpAAYf7Fo9nxc6Isv7w8DTja1ispX9g1x634q/YA== From: Philippe Gerum To: Florian Bezdeka Cc: Xenomai , Jan Kiszka Subject: Re: [PATCH Dovetail 2/2] arm64: irq_pipeline: Fix the demotion checks for el0 and el1 IRQs In-Reply-To: <20260216-wip-flo-v6-19-dovetail-rebase-v1-2-5c36863cba17@siemens.com> (Florian Bezdeka's message of "Mon, 16 Feb 2026 20:05:26 +0100") References: <20260216-wip-flo-v6-19-dovetail-rebase-v1-0-5c36863cba17@siemens.com> <20260216-wip-flo-v6-19-dovetail-rebase-v1-2-5c36863cba17@siemens.com> User-Agent: mu4e 1.12.12; emacs 30.2 Date: Tue, 17 Feb 2026 09:00:17 +0100 Message-ID: <87jywbajfy.fsf@xenomai.org> Precedence: bulk X-Mailing-List: xenomai@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-GND-Sasl: rpm@xenomai.org X-GND-State: clean X-GND-Score: -100 X-GND-Cause: gggruggvucftvghtrhhoucdtuddrgeefgedrtddtgddvudelvdefucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecuifetpfffkfdpucggtfgfnhhsuhgsshgtrhhisggvnecuuegrihhlohhuthemuceftddunecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjughrpefhvfevufgjfhgffffkgggtsehttdertddtredtnecuhfhrohhmpefrhhhilhhiphhpvgcuifgvrhhumhcuoehrphhmseigvghnohhmrghirdhorhhgqeenucggtffrrghtthgvrhhnpedvlefhvdehkeduheevleegiedtueejgfekhfeijeefvdeijeekgeeigfejhfekgeenucfkphepvdgrtddumegvtdgrmedulegsmeeftggutdemleeklegrmeehtgegsgemsgejfhhfmegsrghfnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehinhgvthepvdgrtddumegvtdgrmedulegsmeeftggutdemleeklegrmeehtgegsgemsgejfhhfmegsrghfpdhhvghlohepphihrhhopdhmrghilhhfrhhomheprhhpmhesgigvnhhomhgrihdrohhrghdpqhhiugepgfelteegjeegfedvieffpdhmohguvgepshhmthhpohhuthdpnhgspghrtghpthhtohepfedprhgtphhtthhopehjrghnrdhkihhsiihkrgesshhivghmvghnshdrtghomhdprhgtphhtthhopeigvghnohhmrghisehlihhsthhsrdhlihhnuhigrdguvghvpdhrtghpthhtohepfhhlohhrihgrnhdrsggviiguvghkrgesshhivghmvghnshdrtghomh Florian Bezdeka writes: > While reviewing some of the low level pipeline code I realized that > the checks for task demotion are wrong on arm64. > > el0: The demotion check was missing in the oob case. We have to check > for running_inband() only as user_mode(regs) will always be true. > We are serving an IRQ over el0, so application / user mode. > > el1: The demotion check was unnecessary and "inactive" as > user_mode(regs) is never true on el1, we are serving an IRQ over > kernel mode. > If the demotion happens from el1, you still want to check for a rescheduling opportunity (i.e. kernel preemption case). > Signed-off-by: Florian Bezdeka > --- > arch/arm64/kernel/entry-common.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c > index 07fa70713ce04eaf3df9223354babcecde923280..9c99eb3d18c459a90e1f7ce4e4c307e235e457a2 100644 > --- a/arch/arm64/kernel/entry-common.c > +++ b/arch/arm64/kernel/entry-common.c > @@ -73,6 +73,10 @@ static noinstr void arm64_pipeline_el0_irq(struct pt_regs *regs, > do_interrupt_handler(regs, handler); > /* Done, unwind now. */ > handle_irq_pipelined_finish(prevd, regs); > + if (running_inband()) { > + stall_inband_nocheck(); > + irqentry_exit_to_user_mode(regs); > + } > instrumentation_end(); > arm64_exit_to_user_mode(regs); > } > @@ -90,10 +94,6 @@ static noinstr void arm64_pipeline_el1_irq(struct pt_regs *regs, > prevd = handle_irq_pipelined_prepare(regs); > do_interrupt_handler(regs, handler); > handle_irq_pipelined_finish(prevd, regs); > - if (running_inband() && user_mode(regs)) { > - stall_inband_nocheck(); > - irqentry_exit_to_user_mode(regs); > - } > instrumentation_end(); > mte_check_tfsr_exit(); > return; diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c index e0227d467cef4..770fc4059e083 100644 --- a/arch/arm64/kernel/entry-common.c +++ b/arch/arm64/kernel/entry-common.c @@ -90,10 +90,8 @@ static noinstr void arm64_pipeline_el1_irq(struct pt_regs *regs, prevd = handle_irq_pipelined_prepare(regs); do_interrupt_handler(regs, handler); handle_irq_pipelined_finish(prevd, regs); - if (running_inband() && user_mode(regs)) { - stall_inband_nocheck(); - irqentry_exit_to_user_mode(regs); - } + if (running_inband()) + goto out_irqentry; instrumentation_end(); mte_check_tfsr_exit(); return; @@ -109,6 +107,7 @@ static noinstr void arm64_pipeline_el1_irq(struct pt_regs *regs, trace_hardirqs_on(); unstall_inband_nocheck(); handle_irq_pipelined_finish(prevd, regs); +out_irqentry: stall_inband_nocheck(); trace_hardirqs_off(); instrumentation_end(); -- Philippe.