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[135.19.110.125]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8828652c882sm87366046d6.32.2025.11.16.21.13.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 16 Nov 2025 21:13:17 -0800 (PST) From: Jonathan Marek To: linux-arm-kernel@lists.infradead.org Cc: Catalin Marinas , Will Deacon , James Morse , Douglas Anderson , Trilok Soni , shechenglong , Kuninori Morimoto , Shameer Kolothum , linux-kernel@vger.kernel.org (open list) Subject: [PATCH] arm64: proton-pack: Fix hard lockup when !MITIGATE_SPECTRE_BRANCH_HISTORY Date: Mon, 17 Nov 2025 00:12:08 -0500 Message-ID: <20251117051211.16108-1-jonathan@marek.ca> X-Mailer: git-send-email 2.51.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The "drop print" commit removed the whole branch and not just the print. For some ARM64 cpus, this leads to hard lockup when CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY is not enabled. Fixes: 62e72463ca71 ("arm64: proton-pack: Drop print when !CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY") --- arch/arm64/kernel/proton-pack.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/arm64/kernel/proton-pack.c b/arch/arm64/kernel/proton-pack.c index c7d70d04c164c..80a580e019c50 100644 --- a/arch/arm64/kernel/proton-pack.c +++ b/arch/arm64/kernel/proton-pack.c @@ -1032,6 +1032,8 @@ void spectre_bhb_enable_mitigation(const struct arm64_cpu_capabilities *entry) if (arm64_get_spectre_v2_state() == SPECTRE_VULNERABLE) { /* No point mitigating Spectre-BHB alone. */ + } else if (!IS_ENABLED(CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY)) { + /* Do nothing */ } else if (supports_ecbhb(SCOPE_LOCAL_CPU)) { state = SPECTRE_MITIGATED; set_bit(BHB_HW, &system_bhb_mitigations); -- 2.51.0