Provide an implementation of arch_cpu_allowed_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,
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
---
arch/arm64/include/asm/mmu_context.h | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h
index 0672236e1aea..54fc469e7db9 100644
--- a/arch/arm64/include/asm/mmu_context.h
+++ b/arch/arm64/include/asm/mmu_context.h
@@ -251,6 +251,18 @@ switch_mm(struct mm_struct *prev, struct mm_struct *next,
#define deactivate_mm(tsk,mm) do { } while (0)
#define activate_mm(prev,next) switch_mm(prev, next, current)
+static inline const struct cpumask *arch_cpu_allowed_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 arch_cpu_allowed_mask arch_cpu_allowed_mask
+
void verify_cpu_asid_bits(void);
void post_ttbr_update_workaround(void);
--
2.29.2.299.gdc1121823c-goog
