From 165eb13e485c5c25c7cb276ac85f788a2bd200cb Mon Sep 17 00:00:00 2001 From: Jonathan Marek Date: Mon, 17 Nov 2025 00:12:08 -0500 Subject: [PATCH] arm64: proton-pack: Fix hard lockup when !MITIGATE_SPECTRE_BRANCH_HISTORY 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") Signed-off-by: Jonathan Marek Signed-off-by: Will Deacon --- 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 c7d70d04c164..80a580e019c5 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); -- 2.47.3