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[v11,10/16] arm64: Implement task_cpu_possible_mask()

Message ID 20210730112443.23245-11-will@kernel.org (mailing list archive)
State New, archived
Headers show
Series Add support for 32-bit tasks on asymmetric AArch32 systems | expand

Commit Message

Will Deacon July 30, 2021, 11:24 a.m. UTC
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(+)
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diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h
index eeb210997149..f4ba93d4ffeb 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);