[PATCH v3] arch/x86: port I/O tracing on x86
From: Dan Raymond
Date: Fri Sep 29 2023 - 15:15:51 EST
Add support for port I/O tracing on x86. Memory mapped I/O tracing is
available on x86 via CONFIG_MMIOTRACE but that relies on page faults
so it doesn't work with port I/O. This feature uses tracepoints in a
similar manner as CONFIG_TRACE_MMIO_ACCESS.
Signed-off-by: Dan Raymond <raymod2@xxxxxxxxx>
Suggested-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
V1 -> V2:
- create header file for prototypes to silence new compiler warning
- reduce CPU overhead to 2 instructions (no branching) when tracing disabled
- fix imprecise IP logging by retrieving the IP off the stack instead of using
compile time labels
V2 -> V3:
- restore missing semicolon
arch/x86/include/asm/shared/io.h | 25 ++++++++++++++++
arch/x86/lib/Makefile | 1 +
arch/x86/lib/trace_portio.c | 21 ++++++++++++++
include/linux/trace_portio.h | 6 ++++
include/trace/events/portio.h | 49 ++++++++++++++++++++++++++++++++
5 files changed, 102 insertions(+)
create mode 100644 arch/x86/lib/trace_portio.c
create mode 100644 include/linux/trace_portio.h
create mode 100644 include/trace/events/portio.h
diff --git a/arch/x86/include/asm/shared/io.h b/arch/x86/include/asm/shared/io.h
index c0ef921c0586..9e5dce1cb62d 100644
--- a/arch/x86/include/asm/shared/io.h
+++ b/arch/x86/include/asm/shared/io.h
@@ -2,13 +2,36 @@
#ifndef _ASM_X86_SHARED_IO_H
#define _ASM_X86_SHARED_IO_H
+#include <linux/trace_portio.h>
#include <linux/types.h>
+/*
+ * We don't want the tracing logic included in the early boot modules (under
+ * arch/x86/boot) so we check for their include guards here. If we don't do
+ * this we will get compiler errors. These checks are not present in
+ * arch/x86/include/asm/msr.h which contains similar tracing logic. That is
+ * possible only because none of the msr inline functions are instantiated in
+ * the early boot modules. If that changes this issue will need to be addressed
+ * there as well. Therefore it might be better to handle this centrally in
+ * tracepoint-defs.h.
+ */
+
+#if defined(CONFIG_TRACEPOINTS) && !defined(BOOT_COMPRESSED_MISC_H) && !defined(BOOT_BOOT_H)
+#include <linux/tracepoint-defs.h>
+DECLARE_TRACEPOINT(portio_write);
+DECLARE_TRACEPOINT(portio_read);
+#define _tracepoint_enabled(tracepoint) tracepoint_enabled(tracepoint)
+#else
+#define _tracepoint_enabled(tracepoint) false
+#endif
+
#define BUILDIO(bwl, bw, type) \
static inline void __out##bwl(type value, u16 port) \
{ \
asm volatile("out" #bwl " %" #bw "0, %w1" \
: : "a"(value), "Nd"(port)); \
+ if (_tracepoint_enabled(portio_write)) \
+ do_trace_portio_write(value, port, #bwl[0]); \
} \
\
static inline type __in##bwl(u16 port) \
@@ -16,6 +39,8 @@ static inline type __in##bwl(u16 port) \
type value; \
asm volatile("in" #bwl " %w1, %" #bw "0" \
: "=a"(value) : "Nd"(port)); \
+ if (_tracepoint_enabled(portio_read)) \
+ do_trace_portio_read(value, port, #bwl[0]); \
return value; \
}
diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index f76747862bd2..254f223c025d 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -40,6 +40,7 @@ $(obj)/inat.o: $(obj)/inat-tables.c
clean-files := inat-tables.c
obj-$(CONFIG_SMP) += msr-smp.o cache-smp.o
+obj-$(CONFIG_TRACEPOINTS) += trace_portio.o
lib-y := delay.o misc.o cmdline.o cpu.o
lib-y += usercopy_$(BITS).o usercopy.o getuser.o putuser.o
diff --git a/arch/x86/lib/trace_portio.c b/arch/x86/lib/trace_portio.c
new file mode 100644
index 000000000000..c048dffcfe05
--- /dev/null
+++ b/arch/x86/lib/trace_portio.c
@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#include <linux/instruction_pointer.h>
+#include <linux/trace_portio.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/portio.h>
+
+void do_trace_portio_read(u32 value, u16 port, char width)
+{
+ trace_portio_read(value, port, width, _RET_IP_);
+}
+EXPORT_SYMBOL_GPL(do_trace_portio_read);
+EXPORT_TRACEPOINT_SYMBOL_GPL(portio_read);
+
+void do_trace_portio_write(u32 value, u16 port, char width)
+{
+ trace_portio_write(value, port, width, _RET_IP_);
+}
+EXPORT_SYMBOL_GPL(do_trace_portio_write);
+EXPORT_TRACEPOINT_SYMBOL_GPL(portio_write);
diff --git a/include/linux/trace_portio.h b/include/linux/trace_portio.h
new file mode 100644
index 000000000000..013418d3d2ae
--- /dev/null
+++ b/include/linux/trace_portio.h
@@ -0,0 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+#include <linux/types.h>
+
+extern void do_trace_portio_read(u32 value, u16 port, char width);
+extern void do_trace_portio_write(u32 value, u16 port, char width);
diff --git a/include/trace/events/portio.h b/include/trace/events/portio.h
new file mode 100644
index 000000000000..3591a75a475e
--- /dev/null
+++ b/include/trace/events/portio.h
@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM portio
+
+#if !defined(_TRACE_PORTIO_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_PORTIO_H
+
+#include <linux/tracepoint.h>
+
+DECLARE_EVENT_CLASS(portio_class,
+ TP_PROTO(u32 value, u16 port, char width, long ip_addr),
+
+ TP_ARGS(value, port, width, ip_addr),
+
+ TP_STRUCT__entry(
+ __field(u32, value)
+ __field(u16, port)
+ __field(char, width)
+ __field(long, ip_addr)
+ ),
+
+ TP_fast_assign(
+ __entry->value = value;
+ __entry->port = port;
+ __entry->width = width;
+ __entry->ip_addr = ip_addr;
+ ),
+
+ TP_printk("port=0x%04x value=0x%0*x %pS",
+ __entry->port,
+ __entry->width == 'b' ? 2 :
+ __entry->width == 'w' ? 4 : 8,
+ __entry->value, (void *)__entry->ip_addr)
+);
+
+DEFINE_EVENT(portio_class, portio_read,
+ TP_PROTO(u32 value, u16 port, char width, long ip_addr),
+ TP_ARGS(value, port, width, ip_addr)
+);
+
+DEFINE_EVENT(portio_class, portio_write,
+ TP_PROTO(u32 value, u16 port, char width, long ip_addr),
+ TP_ARGS(value, port, width, ip_addr)
+);
+
+#endif /* _TRACE_PORTIO_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
base-commit: be8b93b5cc7d533eb8c9b0590cdac055ecafe13a
--
2.25.1