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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Ian Rogers <irogers@google.com>,
        Thomas Richter <tmricht@linux.ibm.com>,
        Heiko Carstens <hca@linux.ibm.com>,
        Sumanth Korikkar <sumanthk@linux.ibm.com>,
        Sven Schnelle <svens@linux.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Arnaldo Carvalho de Melo <acme@redhat.com>
Subject: [PATCH 5.16 1000/1039] perf cputopo: Fix CPU topology reading on s/390
Date:   Mon, 24 Jan 2022 19:46:29 +0100
Message-Id: <20220124184158.895209300@linuxfoundation.org>
In-Reply-To: <20220124184125.121143506@linuxfoundation.org>
References: <20220124184125.121143506@linuxfoundation.org>
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From: Thomas Richter <tmricht@linux.ibm.com>

commit a6e62743621ea29bea461774c0bcc68e5de59068 upstream.

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 <irogers@google.com>
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Link: https://lore.kernel.org/r/20211124090343.9436-1-tmricht@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 tools/perf/util/cputopo.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- 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,