From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from wxsgout04.xfusion.com (wxsgout04.xfusion.com [36.139.87.180]) (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 55741EEBA for ; Mon, 20 Oct 2025 15:08:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=36.139.87.180 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760972907; cv=none; b=Otvl78dLt82qEi6uQCgzus8zMJMRdpTIRk0oNPfFMymF/i3W39m3T3bSiCb3SWLzeXWhJlPwRkLzpBG3oKZr/7eEFp9F9GSgn9vP2wAXg07xe2LlMFqWcVXGclBv24n9vffLi/9gNrJs5t2kqegyWnZIHQCVp9pYXTOoF9ZPZgE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760972907; c=relaxed/simple; bh=BcRZ6hb4eWUgJMud/DQ/wdKbE9i3yZNlpMW21cd/wUg=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=HEOZP43uQHBZK6coRr7zJiOC4JWvHWdp7N3F9JwTM48cmGevRm/iW6R1EpGCUKI5pbqODMsvx8KN+FnXviexU7HMjTQweAO3rAicKPxh165XmbCgm4lFH382j3wLULZFlk68Ya5xd89l5jb3AaiztIMbNzkthiFfSoqMM5QzufU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=xfusion.com; spf=pass smtp.mailfrom=xfusion.com; arc=none smtp.client-ip=36.139.87.180 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=xfusion.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=xfusion.com Received: from wuxpheds03048.xfusion.com (unknown [10.32.143.30]) by wxsgout04.xfusion.com (SkyGuard) with ESMTPS id 4cqyxl3NzQzBC2xT; Mon, 20 Oct 2025 22:49:31 +0800 (CST) Received: from DESKTOP-Q8I2N5U.xfusion.com (10.82.130.100) by wuxpheds03048.xfusion.com (10.32.143.30) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_RSA_WITH_AES_128_CBC_SHA256) id 15.2.2562.20; Mon, 20 Oct 2025 22:51:41 +0800 From: shechenglong To: CC: , , , , , , , shechenglong Subject: [PATCH v2 2/2] cpu: fix hard lockup triggered by printk calls within scheduling context Date: Mon, 20 Oct 2025 22:51:17 +0800 Message-ID: <20251020145118.1306-3-shechenglong@xfusion.com> X-Mailer: git-send-email 2.38.0.windows.1 In-Reply-To: <20251020145118.1306-1-shechenglong@xfusion.com> References: <20250918064907.1832-1-shechenglong@xfusion.com> <20251020145118.1306-1-shechenglong@xfusion.com> Reply-To: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain X-ClientProxiedBy: wuxpheds03045.xfusion.com (10.32.131.99) To wuxpheds03048.xfusion.com (10.32.143.30) relocate the printk() calls from spectre_v4_mitigations_off() and=0D spectre_v2_mitigations_off() into setup_system_capabilities() function,=0D preventing hard lockups that occur when printk() is invoked from scheduler = context.=0D =0D Link: https://patchwork.kernel.org/project/linux-arm-kernel/patch/202509180= 64907.1832-1-shechenglong@xfusion.com/=0D Suggested-by: Mark Rutland =0D Suggested-by: Catalin Marinas =0D Suggested-by: Will Deacon =0D Signed-off-by: shechenglong =0D ---=0D arch/arm64/include/asm/spectre.h | 2 ++=0D arch/arm64/kernel/cpufeature.c | 7 ++++++-=0D arch/arm64/kernel/proton-pack.c | 28 ++++++++++++++--------------=0D 3 files changed, 22 insertions(+), 15 deletions(-)=0D =0D diff --git a/arch/arm64/include/asm/spectre.h b/arch/arm64/include/asm/spec= tre.h=0D index 8fef12626090..f244b52fb123 100644=0D --- a/arch/arm64/include/asm/spectre.h=0D +++ b/arch/arm64/include/asm/spectre.h=0D @@ -118,5 +118,7 @@ void spectre_bhb_patch_wa3(struct alt_instr *alt,=0D void spectre_bhb_patch_clearbhb(struct alt_instr *alt,=0D __le32 *origptr, __le32 *updptr, int nr_ins= t);=0D =0D +void spectre_print_disabled_mitigations(void);=0D +=0D #endif /* __ASSEMBLY__ */=0D #endif /* __ASM_SPECTRE_H */=0D diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.= c=0D index 5ed401ff79e3..6836e314fd30 100644=0D --- a/arch/arm64/kernel/cpufeature.c=0D +++ b/arch/arm64/kernel/cpufeature.c=0D @@ -94,7 +94,7 @@=0D #include =0D #include =0D #include =0D -=0D +#include =0D /* Kernel representation of AT_HWCAP and AT_HWCAP2 */=0D static DECLARE_BITMAP(elf_hwcap, MAX_CPU_FEATURES) __read_mostly;=0D =0D @@ -3875,6 +3875,11 @@ static void __init setup_system_capabilities(void)=0D */=0D if (system_uses_ttbr0_pan())=0D pr_info("emulated: Privileged Access Never (PAN) using TTBR= 0_EL1 switching\n");=0D +=0D + /*=0D + * Report Spectre mitigations status.=0D + */=0D + spectre_print_disabled_mitigations();=0D }=0D =0D void __init setup_system_features(void)=0D diff --git a/arch/arm64/kernel/proton-pack.c b/arch/arm64/kernel/proton-pac= k.c=0D index d833b7c1bba8..386f986e6b5d 100644=0D --- a/arch/arm64/kernel/proton-pack.c=0D +++ b/arch/arm64/kernel/proton-pack.c=0D @@ -91,12 +91,7 @@ early_param("nospectre_v2", parse_spectre_v2_param);=0D =0D static bool spectre_v2_mitigations_off(void)=0D {=0D - bool ret =3D __nospectre_v2 || cpu_mitigations_off();=0D -=0D - if (ret)=0D - pr_info_once("spectre-v2 mitigation disabled by command lin= e option\n");=0D -=0D - return ret;=0D + return __nospectre_v2 || cpu_mitigations_off();=0D }=0D =0D static const char *get_bhb_affected_string(enum mitigation_state bhb_state= )=0D @@ -421,13 +416,8 @@ early_param("ssbd", parse_spectre_v4_param);=0D */=0D static bool spectre_v4_mitigations_off(void)=0D {=0D - bool ret =3D cpu_mitigations_off() ||=0D + return cpu_mitigations_off() ||=0D __spectre_v4_policy =3D=3D SPECTRE_V4_POLICY_MITIGATION_= DISABLED;=0D -=0D - if (ret)=0D - pr_info_once("spectre-v4 mitigation disabled by command-lin= e option\n");=0D -=0D - return ret;=0D }=0D =0D /* Do we need to toggle the mitigation state on entry to/exit from the ker= nel? */=0D @@ -1042,8 +1032,6 @@ void spectre_bhb_enable_mitigation(const struct arm64= _cpu_capabilities *entry)=0D =0D if (arm64_get_spectre_v2_state() =3D=3D SPECTRE_VULNERABLE) {=0D /* No point mitigating Spectre-BHB alone. */=0D - } else if (cpu_mitigations_off() || __nospectre_bhb) {=0D - pr_info_once("spectre-bhb mitigation disabled by command li= ne option\n");=0D } else if (supports_ecbhb(SCOPE_LOCAL_CPU)) {=0D state =3D SPECTRE_MITIGATED;=0D set_bit(BHB_HW, &system_bhb_mitigations);=0D @@ -1197,3 +1185,15 @@ void unpriv_ebpf_notify(int new_state)=0D pr_err("WARNING: %s", EBPF_WARN);=0D }=0D #endif=0D +=0D +void spectre_print_disabled_mitigations(void)=0D +{=0D + if (spectre_v2_mitigations_off())=0D + pr_info("spectre-v2 mitigation disabled by command-line opt= ion\n");=0D +=0D + if (spectre_v4_mitigations_off())=0D + pr_info("spectre-v4 mitigation disabled by command-line opt= ion\n");=0D +=0D + if (__nospectre_bhb || cpu_mitigations_off())=0D + pr_info("spectre-bhb mitigation disabled by command-line op= tion\n");=0D +}=0D --=0D 2.33.0=0D