linux-kernel - [PATCH] iommu: Add device name to iommu map/unmap trace events

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Date:   Tue,  9 Feb 2021 18:06:20 +0530
From:   Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
To:     Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
        Joerg Roedel <joro@...tes.org>
Cc:     iommu@...ts.linux-foundation.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org,
        Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
Subject: [PATCH] iommu: Add device name to iommu map/unmap trace events

IOMMU map/unmap traces become hard to decode i.e., it becomes hard
to associate the map/unmap events with the particular device from
the iova/paddr/size parameters alone when there are multiple
devices attached. So it is useful to add the device name to iommu
trace events which can be used to filter out map/unmap traces for
a particular device when we are debugging iommu faults such as
context faults where we are interested with the map/unmap traces
for a specific device.

Before:
  map: IOMMU: iova=0x0000000ffff36000 paddr=0x00000001164d8000 size=4096
  unmap: IOMMU: iova=0x0000000ffff36000 size=4096 unmapped_size=4096

After:
  map: IOMMU: dev=1d84000.ufshc iova=0x0000000fffa88000 paddr=0x00000001063db000 size=4096
  unmap: IOMMU: dev=1d84000.ufshc iova=0x0000000fffa88000 size=4096 unmapped_size=4096

Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
---
 drivers/iommu/iommu.c        |  8 +++++---
 include/linux/iommu.h        |  1 +
 include/trace/events/iommu.h | 20 ++++++++++++--------
 3 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index d0b0a15dba84..37081b745f38 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1947,8 +1947,10 @@ static int __iommu_attach_device(struct iommu_domain *domain,
 		return -ENODEV;
 
 	ret = domain->ops->attach_dev(domain, dev);
-	if (!ret)
+	if (!ret) {
 		trace_attach_device_to_domain(dev);
+		strscpy(domain->dev_name, dev_name(dev), sizeof(domain->dev_name));
+	}
 	return ret;
 }
 
@@ -2440,7 +2442,7 @@ static int __iommu_map(struct iommu_domain *domain, unsigned long iova,
 	if (ret)
 		iommu_unmap(domain, orig_iova, orig_size - size);
 	else
-		trace_map(orig_iova, orig_paddr, orig_size);
+		trace_map(orig_iova, orig_paddr, orig_size, domain->dev_name);
 
 	return ret;
 }
@@ -2523,7 +2525,7 @@ static size_t __iommu_unmap(struct iommu_domain *domain,
 		unmapped += unmapped_page;
 	}
 
-	trace_unmap(orig_iova, size, unmapped);
+	trace_unmap(orig_iova, size, unmapped, domain->dev_name);
 	return unmapped;
 }
 
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 5e7fe519430a..6064187d9bb6 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -87,6 +87,7 @@ struct iommu_domain {
 	void *handler_token;
 	struct iommu_domain_geometry geometry;
 	void *iova_cookie;
+	char dev_name[32];
 };
 
 enum iommu_cap {
diff --git a/include/trace/events/iommu.h b/include/trace/events/iommu.h
index 72b4582322ff..44e48fb8b677 100644
--- a/include/trace/events/iommu.h
+++ b/include/trace/events/iommu.h
@@ -85,47 +85,51 @@ DEFINE_EVENT(iommu_device_event, detach_device_from_domain,
 
 TRACE_EVENT(map,
 
-	TP_PROTO(unsigned long iova, phys_addr_t paddr, size_t size),
+	TP_PROTO(unsigned long iova, phys_addr_t paddr, size_t size, const char *dev_name),
 
-	TP_ARGS(iova, paddr, size),
+	TP_ARGS(iova, paddr, size, dev_name),
 
 	TP_STRUCT__entry(
 		__field(u64, iova)
 		__field(u64, paddr)
 		__field(size_t, size)
+		__string(dev_name, dev_name)
 	),
 
 	TP_fast_assign(
 		__entry->iova = iova;
 		__entry->paddr = paddr;
 		__entry->size = size;
+		__assign_str(dev_name, dev_name);
 	),
 
-	TP_printk("IOMMU: iova=0x%016llx paddr=0x%016llx size=%zu",
-			__entry->iova, __entry->paddr, __entry->size
+	TP_printk("IOMMU: dev=%s iova=0x%016llx paddr=0x%016llx size=%zu",
+		  __get_str(dev_name), __entry->iova, __entry->paddr, __entry->size
 	)
 );
 
 TRACE_EVENT(unmap,
 
-	TP_PROTO(unsigned long iova, size_t size, size_t unmapped_size),
+	TP_PROTO(unsigned long iova, size_t size, size_t unmapped_size, const char *dev_name),
 
-	TP_ARGS(iova, size, unmapped_size),
+	TP_ARGS(iova, size, unmapped_size, dev_name),
 
 	TP_STRUCT__entry(
 		__field(u64, iova)
 		__field(size_t, size)
 		__field(size_t, unmapped_size)
+		__string(dev_name, dev_name)
 	),
 
 	TP_fast_assign(
 		__entry->iova = iova;
 		__entry->size = size;
 		__entry->unmapped_size = unmapped_size;
+		__assign_str(dev_name, dev_name);
 	),
 
-	TP_printk("IOMMU: iova=0x%016llx size=%zu unmapped_size=%zu",
-			__entry->iova, __entry->size, __entry->unmapped_size
+	TP_printk("IOMMU: dev=%s iova=0x%016llx size=%zu unmapped_size=%zu",
+		  __get_str(dev_name), __entry->iova, __entry->size, __entry->unmapped_size
 	)
 );
 
-- 
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