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From:   Will Deacon <will@kernel.org>
To:     linux-arm-kernel@lists.infradead.org
Cc:     linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
        Will Deacon <will@kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Marc Zyngier <maz@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Morten Rasmussen <morten.rasmussen@arm.com>,
        Qais Yousef <qais.yousef@arm.com>,
        Suren Baghdasaryan <surenb@google.com>,
        Quentin Perret <qperret@google.com>, Tejun Heo <tj@kernel.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Ingo Molnar <mingo@redhat.com>,
        Juri Lelli <juri.lelli@redhat.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Daniel Bristot de Oliveira <bristot@redhat.com>,
        Valentin Schneider <valentin.schneider@arm.com>,
        kernel-team@android.com
Subject: [PATCH v8 13/19] arm64: Implement task_cpu_possible_mask()
Date:   Wed,  2 Jun 2021 17:47:13 +0100
Message-Id: <20210602164719.31777-14-will@kernel.org>
In-Reply-To: <20210602164719.31777-1-will@kernel.org>
References: <20210602164719.31777-1-will@kernel.org>
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Provide an implementation of task_cpu_possible_mask() so that we can
prevent 64-bit-only cores being added to the 'cpus_mask' for compat
tasks on systems with mismatched 32-bit support at EL0,

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
 arch/arm64/include/asm/mmu_context.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h
index d3cef9133539..bb9b7510f334 100644
--- a/arch/arm64/include/asm/mmu_context.h
+++ b/arch/arm64/include/asm/mmu_context.h
@@ -231,6 +231,19 @@ switch_mm(struct mm_struct *prev, struct mm_struct *next,
 	update_saved_ttbr0(tsk, next);
 }
 
+static inline const struct cpumask *
+task_cpu_possible_mask(struct task_struct *p)
+{
+	if (!static_branch_unlikely(&arm64_mismatched_32bit_el0))
+		return cpu_possible_mask;
+
+	if (!is_compat_thread(task_thread_info(p)))
+		return cpu_possible_mask;
+
+	return system_32bit_el0_cpumask();
+}
+#define task_cpu_possible_mask	task_cpu_possible_mask
+
 void verify_cpu_asid_bits(void);
 void post_ttbr_update_workaround(void);
 
-- 
2.32.0.rc0.204.g9fa02ecfa5-goog