linux-kernel - [PATCH 5/5] arm64: mm: Add TLB flush trace on context switch

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Date:   Mon, 17 Oct 2022 16:12:58 +0800
From:   y00318929 <yeyunfeng@...wei.com>
To:     <catalin.marinas@....com>, <will@...nel.org>,
        <wangkefeng.wang@...wei.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <yeyunfeng@...wei.com>
Subject: [PATCH 5/5] arm64: mm: Add TLB flush trace on context switch

From: Yunfeng Ye <yeyunfeng@...wei.com>

We do not know how many times the TLB is flushed on context switch.
Adding trace_tlb_flush() in check_and_switch_context() may be useful.

Signed-off-by: Yunfeng Ye <yeyunfeng@...wei.com>
---
 arch/arm64/mm/context.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c
index 0ea3e7485ae7..eab470a97620 100644
--- a/arch/arm64/mm/context.c
+++ b/arch/arm64/mm/context.c
@@ -19,6 +19,8 @@
 #include <asm/smp.h>
 #include <asm/tlbflush.h>
 
+#include <trace/events/tlb.h>
+
 struct asid_bitmap {
 	unsigned long *map;
 	unsigned long nr;
@@ -60,6 +62,8 @@ static DEFINE_STATIC_KEY_FALSE(asid_isolation_enable);
 #define ctxid2asid(asid)	((asid) & ~ASID_MASK)
 #define asid2ctxid(asid, genid)	((asid) | (genid))
 
+#define TLB_FLUSH_ALL		(-1)
+
 /* Get the ASIDBits supported by the current CPU */
 static u32 get_cpu_asid_bits(void)
 {
@@ -416,8 +420,10 @@ void check_and_switch_context(struct mm_struct *mm)
 		atomic64_set(&mm->context.id, asid);
 	}
 
-	if (cpumask_test_and_clear_cpu(cpu, &tlb_flush_pending))
+	if (cpumask_test_and_clear_cpu(cpu, &tlb_flush_pending)) {
 		local_flush_tlb_all();
+		trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL);
+	}
 
 	atomic64_set(this_cpu_ptr(&active_asids), asid);
 	raw_spin_unlock_irqrestore(&cpu_asid_lock, flags);
-- 
2.27.0