perf cputopo: Fix CPU topology reading on s/390

Commit fdf1e29b6118c18f ("perf expr: Add metric literals for topology.")
fails on s390:

 # ./perf test -Fv 7
   ...
 # FAILED tests/expr.c:173 #num_dies >= #num_packages
   ---- end ----
   Simple expression parser: FAILED!
 #

Investigating this issue leads to these functions:
 build_cpu_topology()
   +--> has_die_topology(void)
        {
           struct utsname uts;

           if (uname(&uts) < 0)
                  return false;
           if (strncmp(uts.machine, "x86_64", 6))
                  return false;
           ....
        }

which always returns false on s390. The caller build_cpu_topology()
checks has_die_topology() return value. On false the
the struct cpu_topology::die_cpu_list is not contructed and has zero
entries. This leads to the failing comparison: #num_dies >= #num_packages.
s390 of course has a positive number of packages.

Fix this by adding s390 architecture to support CPU die list.

Output after:
 # ./perf test -Fv 7
  7: Simple expression parser                                        :
  --- start ---
  division by zero
  syntax error
  ---- end ----
  Simple expression parser: Ok
 #

Fixes: fdf1e29b6118c18f ("perf expr: Add metric literals for topology.")
Reviewed-by: Ian Rogers <[email protected]>
Signed-off-by: Thomas Richter <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Ian Rogers <[email protected]>
Cc: Sumanth Korikkar <[email protected]>
Cc: Sven Schnelle <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

1 files changed, 2 insertions, 1 deletions

diff --git a/tools/perf/util/cputopo.c b/tools/perf/util/cputopo.c
index 84ca106a3246..e20b835a1194 100644
--- a/tools/perf/util/cputopo.c
+++ b/tools/perf/util/cputopo.c
@@ -165,7 +165,8 @@ static bool has_die_topology(void)
 	if (uname(&uts) < 0)
 		return false;
 
-	if (strncmp(uts.machine, "x86_64", 6))
+	if (strncmp(uts.machine, "x86_64", 6) &&
+	    strncmp(uts.machine, "s390x", 5))
 		return false;
 
 	scnprintf(filename, MAXPATHLEN, DIE_CPUS_FMT,