[PATCH v7 09/16] tracing: probeevent: Add symbol type

[Masami Hiramatsu]

Add "symbol" type to probeevent, which is an alias of u32 or u64
(depends on BITS_PER_LONG). This shows the result value in
symbol+offset style. This type is only available with kprobe
events.

Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
---
 Changes in v2:
  - Add symbol type to README file.
---
 Documentation/trace/kprobetrace.rst |    2 ++
 kernel/trace/trace.c                |    2 +-
 kernel/trace/trace_probe.c          |    8 ++++++++
 kernel/trace/trace_probe.h          |   12 +++++++++---
 4 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/Documentation/trace/kprobetrace.rst b/Documentation/trace/kprobetrace.rst
index 3e0f971b12de..c920c9be221a 100644
--- a/Documentation/trace/kprobetrace.rst
+++ b/Documentation/trace/kprobetrace.rst
@@ -72,6 +72,8 @@ offset, and container-size (usually 32). The syntax is::
 
  b<bit-width>@<bit-offset>/<container-size>
 
+Symbol type('symbol') is an alias of u32 or u64 type (depends on BITS_PER_LONG)
+which shows given pointer in "symbol+offset" style.
 For $comm, the default type is "string"; any other type is invalid.
 
 
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index dfbcf9ee1447..4812ae046f43 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4621,7 +4621,7 @@ static const char readme_msg[] =
 	"\t     args: <name>=fetcharg[:type]\n"
 	"\t fetcharg: %<register>, @<address>, @<symbol>[+|-<offset>],\n"
 	"\t           $stack<index>, $stack, $retval, $comm\n"
-	"\t     type: s8/16/32/64, u8/16/32/64, x8/16/32/64, string,\n"
+	"\t     type: s8/16/32/64, u8/16/32/64, x8/16/32/64, string, symbol,\n"
 	"\t           b<bit-width>@<bit-offset>/<container-size>\n"
 #endif
 	"  events/\t\t- Directory containing all trace event subsystems:\n"
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index fff3ccfcdbb6..e2a31087f1f8 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -58,6 +58,13 @@ DEFINE_BASIC_PRINT_TYPE_FUNC(x16, u16, "0x%x")
 DEFINE_BASIC_PRINT_TYPE_FUNC(x32, u32, "0x%x")
 DEFINE_BASIC_PRINT_TYPE_FUNC(x64, u64, "0x%Lx")
 
+int PRINT_TYPE_FUNC_NAME(symbol)(struct trace_seq *s, void *data, void *ent)
+{
+	trace_seq_printf(s, "%pS", (void *)*(unsigned long *)data);
+	return !trace_seq_has_overflowed(s);
+}
+const char PRINT_TYPE_FMT_NAME(symbol)[] = "%pS";
+
 /* Print type function for string type */
 int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s, void *data, void *ent)
 {
@@ -91,6 +98,7 @@ static const struct fetch_type probe_fetch_types[] = {
 	ASSIGN_FETCH_TYPE_ALIAS(x16, u16, u16, 0),
 	ASSIGN_FETCH_TYPE_ALIAS(x32, u32, u32, 0),
 	ASSIGN_FETCH_TYPE_ALIAS(x64, u64, u64, 0),
+	ASSIGN_FETCH_TYPE_ALIAS(symbol, ADDR_FETCH_TYPE, ADDR_FETCH_TYPE, 0),
 
 	ASSIGN_FETCH_TYPE_END
 };
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index 3bc43c1ce628..ef477bd8468a 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -157,6 +157,7 @@ DECLARE_BASIC_PRINT_TYPE_FUNC(x32);
 DECLARE_BASIC_PRINT_TYPE_FUNC(x64);
 
 DECLARE_BASIC_PRINT_TYPE_FUNC(string);
+DECLARE_BASIC_PRINT_TYPE_FUNC(symbol);
 
 /* Default (unsigned long) fetch type */
 #define __DEFAULT_FETCH_TYPE(t) x##t
@@ -164,6 +165,10 @@ DECLARE_BASIC_PRINT_TYPE_FUNC(string);
 #define DEFAULT_FETCH_TYPE _DEFAULT_FETCH_TYPE(BITS_PER_LONG)
 #define DEFAULT_FETCH_TYPE_STR __stringify(DEFAULT_FETCH_TYPE)
 
+#define __ADDR_FETCH_TYPE(t) u##t
+#define _ADDR_FETCH_TYPE(t) __ADDR_FETCH_TYPE(t)
+#define ADDR_FETCH_TYPE _ADDR_FETCH_TYPE(BITS_PER_LONG)
+
 #define __ASSIGN_FETCH_TYPE(_name, ptype, ftype, _size, sign, _fmttype)	\
 	{.name = _name,				\
 	 .size = _size,					\
@@ -172,13 +177,14 @@ DECLARE_BASIC_PRINT_TYPE_FUNC(string);
 	 .fmt = PRINT_TYPE_FMT_NAME(ptype),		\
 	 .fmttype = _fmttype,				\
 	}
-
+#define _ASSIGN_FETCH_TYPE(_name, ptype, ftype, _size, sign, _fmttype)	\
+	__ASSIGN_FETCH_TYPE(_name, ptype, ftype, _size, sign, #_fmttype)
 #define ASSIGN_FETCH_TYPE(ptype, ftype, sign)			\
-	__ASSIGN_FETCH_TYPE(#ptype, ptype, ftype, sizeof(ftype), sign, #ptype)
+	_ASSIGN_FETCH_TYPE(#ptype, ptype, ftype, sizeof(ftype), sign, ptype)
 
 /* If ptype is an alias of atype, use this macro (show atype in format) */
 #define ASSIGN_FETCH_TYPE_ALIAS(ptype, atype, ftype, sign)		\
-	__ASSIGN_FETCH_TYPE(#ptype, ptype, ftype, sizeof(ftype), sign, #atype)
+	_ASSIGN_FETCH_TYPE(#ptype, ptype, ftype, sizeof(ftype), sign, atype)
 
 #define ASSIGN_FETCH_TYPE_END {}