Thread (29 messages) 29 messages, 4 authors, 2020-12-28
STALE1987d
Revisions (3)
  1. v3 [diff vs current]
  2. v4 [diff vs current]
  3. v5 current

[PATCH v5 11/15] arm64: Implement task_cpu_possible_mask()

From: Will Deacon <will@kernel.org>
Date: 2020-12-08 13:30:44
Also in: linux-arch, lkml
Subsystem: arm64 port (aarch64 architecture), the rest · Maintainers: Catalin Marinas, Will Deacon, Linus Torvalds

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,

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 0672236e1aea..a5c917fa49aa 100644
--- a/arch/arm64/include/asm/mmu_context.h
+++ b/arch/arm64/include/asm/mmu_context.h
@@ -251,6 +251,19 @@ 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 *
+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);
 
-- 
2.29.2.576.ga3fc446d84-goog


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