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Subject[PATCH] arm64: smccc: Add trace events to SMC calls.
Date
This patch adds start and end trace events to an SMC call sent from
kernel to ATF. The start trace event prints the smc_id and the end
trace event prints the smc_id and the time taken to process the SMC
call.

Signed-off-by: Rakesh Babu Saladi <rsaladi2@marvell.com>
---
drivers/firmware/smccc/Makefile | 3 +-
drivers/firmware/smccc/smccc.c | 14 ++++++++++
drivers/firmware/smccc/smccc_trace.c | 7 +++++
drivers/firmware/smccc/smccc_trace.h | 41 ++++++++++++++++++++++++++++
include/linux/arm-smccc.h | 4 ++-
kernel/time/timekeeping.c | 7 +++++
6 files changed, 74 insertions(+), 2 deletions(-)
create mode 100644 drivers/firmware/smccc/smccc_trace.c
create mode 100644 drivers/firmware/smccc/smccc_trace.h

diff --git a/drivers/firmware/smccc/Makefile b/drivers/firmware/smccc/Makefile
index 40d19144a860..e74c35191b49 100644
--- a/drivers/firmware/smccc/Makefile
+++ b/drivers/firmware/smccc/Makefile
@@ -1,4 +1,5 @@
# SPDX-License-Identifier: GPL-2.0
#
-obj-$(CONFIG_HAVE_ARM_SMCCC_DISCOVERY) += smccc.o kvm_guest.o
+ccflags-y += -I$(src)
+obj-$(CONFIG_HAVE_ARM_SMCCC_DISCOVERY) += smccc_trace.o smccc.o kvm_guest.o
obj-$(CONFIG_ARM_SMCCC_SOC_ID) += soc_id.o
diff --git a/drivers/firmware/smccc/smccc.c b/drivers/firmware/smccc/smccc.c
index 60ccf3e90d7d..7631a16479e9 100644
--- a/drivers/firmware/smccc/smccc.c
+++ b/drivers/firmware/smccc/smccc.c
@@ -11,6 +11,7 @@
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <asm/archrandom.h>
+#include "smccc_trace.h"

static u32 smccc_version = ARM_SMCCC_VERSION_1_0;
static enum arm_smccc_conduit smccc_conduit = SMCCC_CONDUIT_NONE;
@@ -59,3 +60,16 @@ static int __init smccc_devices_init(void)
return 0;
}
device_initcall(smccc_devices_init);
+
+void arm_smccc_smc(unsigned long a0, unsigned long a1, unsigned long a2, unsigned long a3,
+ unsigned long a4, unsigned long a5, unsigned long a6, unsigned long a7,
+ struct arm_smccc_res *res)
+{
+ u64 start, elapsed;
+
+ trace_arm_smccc_smc_start(a0);
+ start = ktime_get_ns();
+ __arm_smccc_smc(a0, a1, a2, a3, a4, a5, a6, a7, res, NULL);
+ elapsed = ktime_get_ns() - start;
+ trace_arm_smccc_smc_end(a0, elapsed);
+}
diff --git a/drivers/firmware/smccc/smccc_trace.c b/drivers/firmware/smccc/smccc_trace.c
new file mode 100644
index 000000000000..6b94d5d9c0f4
--- /dev/null
+++ b/drivers/firmware/smccc/smccc_trace.c
@@ -0,0 +1,7 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#define CREATE_TRACE_POINTS
+#include "smccc_trace.h"
+
+EXPORT_TRACEPOINT_SYMBOL(arm_smccc_smc_start);
+EXPORT_TRACEPOINT_SYMBOL(arm_smccc_smc_end);
diff --git a/drivers/firmware/smccc/smccc_trace.h b/drivers/firmware/smccc/smccc_trace.h
new file mode 100644
index 000000000000..c0ef836bc093
--- /dev/null
+++ b/drivers/firmware/smccc/smccc_trace.h
@@ -0,0 +1,41 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM smccc
+
+#if !defined(__SMCCC_TRACE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define __SMCCC_TRACE_H
+
+#include <linux/types.h>
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(arm_smccc_smc_start,
+ TP_PROTO(unsigned long smc_id),
+ TP_ARGS(smc_id),
+ TP_STRUCT__entry(__field(unsigned long, smc_id)),
+ TP_fast_assign(__entry->smc_id = smc_id;),
+ TP_printk("SMC ID: 0x%lx", __entry->smc_id)
+);
+
+TRACE_EVENT(arm_smccc_smc_end,
+ TP_PROTO(unsigned long smc_id, u64 elapsed_time),
+ TP_ARGS(smc_id, elapsed_time),
+ TP_STRUCT__entry(__field(unsigned long, smc_id)
+ __field(u64, elapsed_time)
+ ),
+ TP_fast_assign(__entry->smc_id = smc_id;
+ __entry->elapsed_time = elapsed_time;
+ ),
+ TP_printk("SMC ID: 0x%lx time taken to process : %llu ns",
+ __entry->smc_id, __entry->elapsed_time)
+);
+
+#endif /* __SMCCC_TRACE_H */
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE smccc_trace
+
+#include <trace/define_trace.h>
diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index 220c8c60e021..39588c3db486 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -358,7 +358,9 @@ asmlinkage void __arm_smccc_hvc(unsigned long a0, unsigned long a1,
unsigned long a5, unsigned long a6, unsigned long a7,
struct arm_smccc_res *res, struct arm_smccc_quirk *quirk);

-#define arm_smccc_smc(...) __arm_smccc_smc(__VA_ARGS__, NULL)
+void arm_smccc_smc(unsigned long a0, unsigned long a1, unsigned long a2,
+ unsigned long a3, unsigned long a4, unsigned long a5,
+ unsigned long a6, unsigned long a7, struct arm_smccc_res *res);

#define arm_smccc_smc_quirk(...) __arm_smccc_smc(__VA_ARGS__)

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 5579ead449f2..3a3bf2d674a3 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -192,6 +192,13 @@ static inline u64 tk_clock_read(const struct tk_read_base *tkr)
{
struct clocksource *clock = READ_ONCE(tkr->clock);

+ /* At the time of kernel booting some SMC calls are called before the
+ * clock is initialized, in such cases it would lead to kernel crash.
+ * To prevent kernel crash in such cases this check is included.
+ */
+ if (unlikely(!clock))
+ return 0;
+
return clock->read(clock);
}

--
2.17.1
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