From: Christoph Lameter (Ampere) <cl@linux.com>
Date: Thu, 7 Dec 2023 04:11:49 +0000 (-0800)
Subject: ARM64: Revive cpu tracking in mm_struct
X-Git-Url: https://gentwo.org/gitweb/?a=commitdiff_plain;h=699cfefdfd493bdb590232a1a20f14cb6b7f041b;p=linux%2F.git

ARM64: Revive cpu tracking in mm_struct

ARM64 used to have the ability to track which cpu has
used an address space (mm_struct). The cpumask stored in
the mm_struct is currently unused. So what is needed is still
there from the core kernel.

Revert the removal patch and update it to work with the current kernel source.

Signed-off-by: Christoph Lameter (Ampere) <cl@linux.com>
---

diff --git a/arch/arm64/include/asm/tlbbatch.h b/arch/arm64/include/asm/tlbbatch.h
index fedb0b87b8db..3d4d04b38e3c 100644
--- a/arch/arm64/include/asm/tlbbatch.h
+++ b/arch/arm64/include/asm/tlbbatch.h
@@ -3,10 +3,11 @@
 #define _ARCH_ARM64_TLBBATCH_H
 
 struct arch_tlbflush_unmap_batch {
-	/*
-	 * For arm64, HW can do tlb shootdown, so we don't
-	 * need to record cpumask for sending IPI
-	 */
+        /*
+         * Each bit set is a CPU that potentially has a TLB entry for one of
+         * the PFNs being flushed..
+         */
+        struct cpumask cpumask;
 };
 
 #endif /* _ARCH_ARM64_TLBBATCH_H */
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 417a8a86b2db..fb9b9c56a1a8 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -369,6 +369,7 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p)
 
 	init_bootcpu_ops();
 	smp_init_cpus();
+	cpumask_set_cpu(smp_processor_id(), mm_cpumask(&init_mm));
 	smp_build_mpidr_hash();
 
 	/* Init percpu seeds for random tags after cpus are set up. */
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index defbab84e9e5..175e93caaf72 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -213,6 +213,7 @@ asmlinkage notrace void secondary_start_kernel(void)
 	 */
 	mmgrab(mm);
 	current->active_mm = mm;
+	cpumask_set_cpu(cpu, mm_cpumask(mm));
 
 	/*
 	 * TTBR0 is only used for the identity mapping at this stage. Make it
@@ -321,6 +322,11 @@ int __cpu_disable(void)
 	 */
 	irq_migrate_all_off_this_cpu();
 
+	/*
+	 * Remove this CPU from the vm mask set of all processes
+	 */
+	clear_tasks_mm_cpumask(cpu);
+
 	return 0;
 }
 
diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c
index 5a06d05251eb..71c7a2ac6add 100644
--- a/arch/arm64/mm/context.c
+++ b/arch/arm64/mm/context.c
@@ -209,6 +209,7 @@ static u64 new_context(struct mm_struct *mm)
 set_asid:
 	__set_bit(asid, asid_map);
 	cur_idx = asid;
+	cpumask_clear(mm_cpumask(mm));
 	return asid2ctxid(asid, generation);
 }
 
@@ -261,6 +262,7 @@ void check_and_switch_context(struct mm_struct *mm)
 switch_mm_fastpath:
 
 	arm64_apply_bp_hardening();
+	cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm));
 
 	/*
 	 * Defer TTBR0_EL1 setting for user threads to uaccess_enable() when