From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=217.140.110.172 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794404685; b=AzM7luZWD/8h4lrDvoZP5Gvk1sxRp+Y37sLxIU12w/I4+C2znwjjY43s/UCHUJUdwqFf bPILVfpM/HE5cZDmbsFc96RCpdr1n8kwpDKCC3DnrgV26iG6Y+LCEkko2WKJG6MyNLOqr nV6w/iEXOHWCzbgMof5VclPhnAv+3pwZtuq7R8xHQdYWJwGr1OVsizXW+0ipoL9qpz4Al ISw8nR52SJuxbA43Ws+aHWSSR3hIsSt8foO+Olfcl3ArNcAIDJFPgt6rPE3a2UoG6qtHI 9j+8nQB2er5Iygl+AW4zSl3RI/NybQ+pv+Ks6ub5NvjmO1KvPuGfnilRV4XdEzJyaIA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794404685; h=DMARC-Filter:Received:Received:DKIM-Signature:Message-ID:Date: MIME-Version:User-Agent:Subject:To:Cc:References:Content-Language: From:In-Reply-To:Content-Type:Content-Transfer-Encoding; bh=C/nooMgmJG/3mp0rQ1JdOcq7TiihZwhR9+Lq4gd1ZqA=; b=Bj+vNYYF308rg+ngwzsblP00Nbsoo4frE9ffUMqlR0ncCn/J+8WWdVZAleatPefqxLpR w02mX9G2DsMZjeWvSI0ivbQImPXqwD9FzAOR/wpcItOCaZ1pPbliUgppzZcLRTJwFiSlW jVt7mbcZwTRRD3OuMoSTVl449rjDRW6pRObY1Sb6SpYXNNP4qcutZejk6AOHiuxYuOyuG YqT7TZMWkNKkfW0Ab8/3LIjSqKs6i59oxudNZyCX5Mp15uhq5/saaUd1nQOCa9dLl4trW AiHdzwfiMsq1WswPFXHmDVqJodQY7D3VUS8XMrRsP8ZbWE6VfS8cT6QknvaY6zE8Rxw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass header.d=arm.com header.i=@arm.com header.a=rsa-sha256 header.s=foss header.b=XMZDjw8K; arc=none smtp.remote-ip=217.140.110.172 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 55187606A31C; Wed, 11 Nov 2026 13:44:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 55187606A31C Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.a=rsa-sha256 header.s=foss header.b=XMZDjw8K Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 841C31576; Wed, 11 Nov 2026 05:44:41 -0800 (PST) Received: from [10.0.154.42] (e121487-lin.cambridge.arm.com [10.0.154.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id CC9EA3F673; Wed, 11 Nov 2026 05:44:42 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1794404684; bh=w2VNZqXDGorpHrLLSd9Lolnep92uG7Tj6Jtn26G8qZc=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=XMZDjw8KwZgkZXf/BmInpGUc/Nu/+rD12k7JhOUze6J6Xxre4SfOdq5WVwxjfiWTa 9/eDyVHQTNWpHi+d18HTtRra8Hh3YqU0K4XAOeQV5OSptnSeNSVquJujUod3s+tLxQ jSMziHEiA/pMBzLCDPi5kiv7vPRnqrAFnAB9u5XQ= Message-ID: <282608f5-a13b-4695-aa17-f834bf5d8272@arm.com> Date: Wed, 11 Nov 2026 13:44:40 +0000 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 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] arm64: suspend: Save GCS state over suspend To: Mark Brown , Catalin Marinas , Will Deacon , Mark Rutland , Anshuman Khandual , Joey Gouly Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20261105-arm64-fix-sysreg-suspend-v1-0-f4d9a99fec46@kernel.org> <20261105-arm64-fix-sysreg-suspend-v1-2-f4d9a99fec46@kernel.org> Content-Language: en-GB From: Vladimir Murzin In-Reply-To: <20261105-arm64-fix-sysreg-suspend-v1-2-f4d9a99fec46@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 11/5/26 16:05, Mark Brown wrote: > GCSCRE0_EL1 and GCSPR_EL0 are live registers for EL0 on systems with GCS > but are not saved and restored by cpu_do_suspend()/cpu_do_resume(). This > means that the task that initiated suspend can return to userspace with > UNKNOWN or incorrect values for GCSPR_EL0 and GCSCRE0_EL1 (many fields > in GCSCRE0_EL1 reset to 0). This will in turn lead to ongoing > corruption, including not restoring mode until a task with a different > GCS mode is run. Fix this by saving and restoring the values over > suspend. > > This increases the size of struct cpu_suspend_ctx by 16 bytes. > > Fixes: 5d8b172e7005 ("arm64: Add Kconfig for Guarded Control Stack (GCS)") > Signed-off-by: Mark Brown > Cc: stable@vger.kernel.org > --- > arch/arm64/include/asm/suspend.h | 2 +- > arch/arm64/mm/proc.S | 12 ++++++++++++ > 2 files changed, 13 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/include/asm/suspend.h b/arch/arm64/include/asm/suspend.h > index eb9ce315f146..8e9c97aab15a 100644 > --- a/arch/arm64/include/asm/suspend.h > +++ b/arch/arm64/include/asm/suspend.h > @@ -2,7 +2,7 @@ > #ifndef __ASM_SUSPEND_H > #define __ASM_SUSPEND_H > > -#define NR_CTX_REGS 16 > +#define NR_CTX_REGS 18 > #define NR_CALLEE_SAVED_REGS 12 > > /* > diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S > index 664ea9e3b9ad..99aacf03367d 100644 > --- a/arch/arm64/mm/proc.S > +++ b/arch/arm64/mm/proc.S > @@ -121,6 +121,12 @@ alternative_else_nop_endif > alternative_if ARM64_HAS_S1POE > mrs x2, REG_POR_EL0 > str x2, [x0, #120] > +alternative_else_nop_endif > +alternative_if ARM64_HAS_GCS > + mrs x2, REG_GCSPR_EL0 > + str x2, [x0, #128] > + mrs x2, REG_GCSCRE0_EL1 > + str x2, [x0, #136] Have you considered using stp? > alternative_else_nop_endif > ret > SYM_FUNC_END(cpu_do_suspend) > @@ -168,6 +174,12 @@ alternative_if ARM64_HAS_S1POE > ldr x2, [x0, #120] > msr REG_POR_EL0, x2 > alternative_else_nop_endif > +alternative_if ARM64_HAS_GCS > + ldr x2, [x0, #128] > + msr REG_GCSPR_EL0, x2 > + ldr x2, [x0, #136] > + msr REG_GCSCRE0_EL1, x2 Have you considered using ldp? Cheers Vladimir