[PATCH] riscv: Add tracepoints for SBI calls and returns

[Samuel Holland]

These are useful for measuring the latency of SBI calls. The SBI HSM
extension is excluded because those functions are called from contexts
such as cpuidle where instrumentation is not allowed.

Signed-off-by: Samuel Holland <samuel.holland at sifive.com>
---

 arch/riscv/include/asm/trace.h | 60 ++++++++++++++++++++++++++++++++++
 arch/riscv/kernel/sbi.c        |  7 ++++
 2 files changed, 67 insertions(+)
 create mode 100644 arch/riscv/include/asm/trace.h

diff --git a/arch/riscv/include/asm/trace.h b/arch/riscv/include/asm/trace.h
new file mode 100644
index 000000000000..f96091f83c25
--- /dev/null
+++ b/arch/riscv/include/asm/trace.h
@@ -0,0 +1,60 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM riscv
+
+#if !defined(_TRACE_RISCV_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_RISCV_H
+
+#include <linux/tracepoint.h>
+
+TRACE_EVENT_CONDITION(sbi_call,
+
+	TP_PROTO(int ext, int fid),
+
+	TP_ARGS(ext, fid),
+
+	TP_CONDITION(ext != SBI_EXT_HSM),
+
+	TP_STRUCT__entry(
+		__field(int, ext)
+		__field(int, fid)
+	),
+
+	TP_fast_assign(
+		__entry->ext = ext;
+		__entry->fid = fid;
+	),
+
+	TP_printk("ext=0x%x fid=%d", __entry->ext, __entry->fid)
+);
+
+TRACE_EVENT_CONDITION(sbi_return,
+
+	TP_PROTO(int ext, long error, long value),
+
+	TP_ARGS(ext, error, value),
+
+	TP_CONDITION(ext != SBI_EXT_HSM),
+
+	TP_STRUCT__entry(
+		__field(long, error)
+		__field(long, value)
+	),
+
+	TP_fast_assign(
+		__entry->error = error;
+		__entry->value = value;
+	),
+
+	TP_printk("error=%ld value=0x%lx", __entry->error, __entry->value)
+);
+
+#endif /* _TRACE_RISCV_H */
+
+#undef TRACE_INCLUDE_PATH
+#undef TRACE_INCLUDE_FILE
+
+#define TRACE_INCLUDE_PATH asm
+#define TRACE_INCLUDE_FILE trace
+
+#include <trace/define_trace.h>
diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c
index e66e0999a800..a1d21d8f5293 100644
--- a/arch/riscv/kernel/sbi.c
+++ b/arch/riscv/kernel/sbi.c
@@ -14,6 +14,9 @@
 #include <asm/smp.h>
 #include <asm/tlbflush.h>
 
+#define CREATE_TRACE_POINTS
+#include <asm/trace.h>
+
 /* default SBI version is 0.1 */
 unsigned long sbi_spec_version __ro_after_init = SBI_SPEC_VERSION_DEFAULT;
 EXPORT_SYMBOL(sbi_spec_version);
@@ -31,6 +34,8 @@ struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0,
 {
 	struct sbiret ret;
 
+	trace_sbi_call(ext, fid);
+
 	register uintptr_t a0 asm ("a0") = (uintptr_t)(arg0);
 	register uintptr_t a1 asm ("a1") = (uintptr_t)(arg1);
 	register uintptr_t a2 asm ("a2") = (uintptr_t)(arg2);
@@ -46,6 +51,8 @@ struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0,
 	ret.error = a0;
 	ret.value = a1;
 
+	trace_sbi_return(ext, ret.error, ret.value);
+
 	return ret;
 }
 EXPORT_SYMBOL(sbi_ecall);
-- 
2.43.1