perf evlist: Handle default value for 'pages' on mmap method

Every tool that calls this and allows the user to override the value
needs this logic.

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-lwscxpg57xfzahz5dmdfp9uz@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-record.c

@@ -456,10 +456,6 @@ static int __cmd_record(int argc, const char **argv)
 	perf_header__set_feat(&session->header, HEADER_NUMA_TOPOLOGY);
 	perf_header__set_feat(&session->header, HEADER_CPUID);
 
-	/* 512 kiB: default amount of unprivileged mlocked memory */
-	if (mmap_pages == UINT_MAX)
-		mmap_pages = (512 * 1024) / page_size;
-
 	if (forks) {
 		err = perf_evlist__prepare_workload(evsel_list, &record_opts, argv);
 		if (err < 0) {

tools/perf/util/evlist.c

@@ -507,14 +507,20 @@ static int perf_evlist__mmap_per_thread(struct perf_evlist *evlist, int prot, in
  *
  * Using perf_evlist__read_on_cpu does this automatically.
  */
-int perf_evlist__mmap(struct perf_evlist *evlist, int pages, bool overwrite)
+int perf_evlist__mmap(struct perf_evlist *evlist, unsigned int pages,
+		      bool overwrite)
 {
 	unsigned int page_size = sysconf(_SC_PAGE_SIZE);
-	int mask = pages * page_size - 1;
 	struct perf_evsel *evsel;
 	const struct cpu_map *cpus = evlist->cpus;
 	const struct thread_map *threads = evlist->threads;
-	int prot = PROT_READ | (overwrite ? 0 : PROT_WRITE);
+	int prot = PROT_READ | (overwrite ? 0 : PROT_WRITE), mask;
+
+        /* 512 kiB: default amount of unprivileged mlocked memory */
+        if (pages == UINT_MAX)
+                pages = (512 * 1024) / page_size;
+
+	mask = pages * page_size - 1;
 
 	if (evlist->mmap == NULL && perf_evlist__alloc_mmap(evlist) < 0)
 		return -ENOMEM;

tools/perf/util/evlist.h

@@ -79,7 +79,8 @@ int perf_evlist__prepare_workload(struct perf_evlist *evlist,
 int perf_evlist__start_workload(struct perf_evlist *evlist);
 
 int perf_evlist__alloc_mmap(struct perf_evlist *evlist);
-int perf_evlist__mmap(struct perf_evlist *evlist, int pages, bool overwrite);
+int perf_evlist__mmap(struct perf_evlist *evlist, unsigned int pages,
+		      bool overwrite);
 void perf_evlist__munmap(struct perf_evlist *evlist);
 
 void perf_evlist__disable(struct perf_evlist *evlist);