[PATCH/RFC] perf report: Add option to change offset format when address is specified as a sort_key

[Aaron Tomlin]

With --call-graph option, a user can choose to display call chains with a
specific sort_key. The sort_key can be either: function, address or srcline.
By default, when the address is specified as the sort_key, the offset (i.e.
symbol + offset) is provided in decimal (base 10) form.
This is because in __get_srcline() we use PRIu64 to display the offset.
This may or may not be desirable.

This patch adds a new option --hex, to change the offset format to
hexidecimal. Note, this can only be used with the -g, --call-graph option
when address is specified as a sort_key.  When this option is not
specified, the default behavior is used, which is to display the offset
in decimal form.

Before:

$ ./perf report -n --fields=overhead,sample,period,pid,symbol --stdio \
> -g graph,callee,address --percent-limit 10 --no-children
[ ... ]
    10.87%             1     506940477     15:migration/3   [k] _spin_trylock
            |
            ---_spin_trylock +13
               double_lock_balance +48
               schedule +2007
               migration_thread +613
               kthread +158
               child_rip +10

After:

$ ./perf report -n --fields=overhead,sample,period,pid,symbol --stdio \
> -g graph,callee,address --percent-limit 10 --hex --no-children
[ ... ]
    10.87%             1     506940477     15:migration/3   [k] _spin_trylock
            |
            ---_spin_trylock +0xd
               double_lock_balance +0x30
               schedule +0x7d7
               migration_thread +0x265
               kthread +0x9e
               child_rip +0xa

Signed-off-by: Aaron Tomlin <atomlin@xxxxxxxxxx>
---
 tools/perf/Documentation/perf-report.txt | 4 ++++
 tools/perf/builtin-report.c              | 2 ++
 tools/perf/util/srcline.c                | 6 ++++--
 tools/perf/util/srcline.h                | 1 +
 4 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/tools/perf/Documentation/perf-report.txt b/tools/perf/Documentation/perf-report.txt
index ddde2b5..589435a 100644
--- a/tools/perf/Documentation/perf-report.txt
+++ b/tools/perf/Documentation/perf-report.txt
@@ -386,6 +386,10 @@ OPTIONS
 	sum of shown entries will be always 100%.  "absolute" means it retains
 	the original value before and after the filter is applied.
 
+--hex::
+	When address is specified as a sort_key, show the offset in
+	hexidecimal form. (Default: decimal)
+
 --header::
 	Show header information in the perf.data file.  This includes
 	various information like hostname, OS and perf version, cpu/mem
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index af5dd03..7820e55 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -866,6 +866,8 @@ int cmd_report(int argc, const char **argv)
 			    itrace_parse_synth_opts),
 	OPT_BOOLEAN(0, "full-source-path", &srcline_full_filename,
 			"Show full source file name path for source lines"),
+	OPT_BOOLEAN(0, "hex", &show_hex_offset,
+			"When address is specified as a sort_key, show the offset in hexidecimal form"),
 	OPT_BOOLEAN(0, "show-ref-call-graph", &symbol_conf.show_ref_callgraph,
 		    "Show callgraph from reference event"),
 	OPT_INTEGER(0, "socket-filter", &report.socket_filter,
diff --git a/tools/perf/util/srcline.c b/tools/perf/util/srcline.c
index d19f05c..98fc911 100644
--- a/tools/perf/util/srcline.c
+++ b/tools/perf/util/srcline.c
@@ -15,6 +15,7 @@
 #include "symbol.h"
 
 bool srcline_full_filename;
+bool show_hex_offset;
 
 static const char *dso__name(struct dso *dso)
 {
@@ -535,8 +536,9 @@ char *__get_srcline(struct dso *dso, u64 addr, struct symbol *sym,
 			    strndup(sym->name, sym->namelen) : NULL;
 
 	if (sym) {
-		if (asprintf(&srcline, "%s+%" PRIu64, show_sym ? sym->name : "",
-					addr - sym->start) < 0)
+		if (asprintf(&srcline,
+			show_hex_offset ? "%s+%#" PRIx64 : "%s+%" PRIu64,
+			show_sym ? sym->name : "", addr - sym->start) < 0)
 			return SRCLINE_UNKNOWN;
 	} else if (asprintf(&srcline, "%s[%" PRIx64 "]", dso->short_name, addr) < 0)
 		return SRCLINE_UNKNOWN;
diff --git a/tools/perf/util/srcline.h b/tools/perf/util/srcline.h
index 847b708..1bca068 100644
--- a/tools/perf/util/srcline.h
+++ b/tools/perf/util/srcline.h
@@ -10,6 +10,7 @@ struct dso;
 struct symbol;
 
 extern bool srcline_full_filename;
+extern bool show_hex_offset;
 char *get_srcline(struct dso *dso, u64 addr, struct symbol *sym,
 		  bool show_sym, bool show_addr);
 char *__get_srcline(struct dso *dso, u64 addr, struct symbol *sym,
-- 
2.9.5