perf tools: Fixup end address of modules

In machine__create_module(), it reads /proc/modules to get a list of
modules in the system.  The file shows the start address (of text) and
the size of the module so it uses the info to reconstruct system memory
maps for symbol resolution.

But module memory consists of multiple segments and they can be
scaterred.  Currently perf tools assume they are contiguous and see some
overlaps.  This can confuse the tool when it finds a map containing a
given address.

As we mostly care about the function symbols in the text segment, it can
fixup the size or end address of modules when there's an overlap.  We
can use maps__fixup_end() which updates the end address using the start
address of the next map.

Ideally it should be able to track other segments (like data/rodata),
but that would require some changes in /proc/modules IMHO.

Reported-by: Blake Jones <[email protected]>
Signed-off-by: Namhyung Kim <[email protected]>
Acked-by: Ian Rogers <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Daniel Gomez <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Kan Liang <[email protected]>
Cc: Luis Chamberlain <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Petr Pavlu <[email protected]>
Cc: Sami Tolvanen <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

tools/perf/util/machine.c

@@ -1468,6 +1468,8 @@ static int machine__create_modules(struct machine *machine)
 	if (modules__parse(modules, machine, machine__create_module))
 		return -1;
 
+	maps__fixup_end(machine__kernel_maps(machine));
+
 	if (!machine__set_modules_path(machine))
 		return 0;