Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf fixes from Ingo Molnar:

 - Make /sys/devices/cpu/rdpmc based RDPMC enforcement more
   instantaneous

 - decoder: Update the Intel opcode map

 - Various tooling fixes, including a few late optimizations and
   cleanups.

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits)
  perf script: Fix invalid LBR/binary mismatch error
  perf script: Fix brstackinsn for AUXTRACE
  perf affinity: Add infrastructure to save/restore affinity
  perf pmu: Use file system cache to optimize sysfs access
  perf regs: Make perf_reg_name() return "unknown" instead of NULL
  perf diff: Use llabs() with 64-bit values
  perf diff: Use llabs() with 64-bit values
  perf/x86: Implement immediate enforcement of /sys/devices/cpu/rdpmc value of 0
  perf tools: Allow to link with libbpf dynamicaly
  perf tests: Rename tests/map_groups.c to tests/maps.c
  perf tests: Rename thread-mg-share to thread-maps-share
  perf maps: Rename map_groups.h to maps.h
  perf maps: Rename 'mg' variables to 'maps'
  perf map_symbol: Rename ms->mg to ms->maps
  perf addr_location: Rename al->mg to al->maps
  perf thread: Rename thread->mg to thread->maps
  perf maps: Merge 'struct maps' with 'struct map_groups'
  x86/insn: perf tools: Add some more instructions to the new instructions test
  x86/insn: Add some more Intel instructions to the opcode map
  perf map: Remove unused functions
  ...

1 files changed, 63 insertions, 0 deletions

diff --git a/tools/perf/util/fncache.c b/tools/perf/util/fncache.c
new file mode 100644
index 000000000000..6225cbc52310
--- /dev/null
+++ b/tools/perf/util/fncache.c
@@ -0,0 +1,63 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Manage a cache of file names' existence */
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <linux/list.h>
+#include "fncache.h"
+
+struct fncache {
+	struct hlist_node nd;
+	bool res;
+	char name[];
+};
+
+#define FNHSIZE 61
+
+static struct hlist_head fncache_hash[FNHSIZE];
+
+unsigned shash(const unsigned char *s)
+{
+	unsigned h = 0;
+	while (*s)
+		h = 65599 * h + *s++;
+	return h ^ (h >> 16);
+}
+
+static bool lookup_fncache(const char *name, bool *res)
+{
+	int h = shash((const unsigned char *)name) % FNHSIZE;
+	struct fncache *n;
+
+	hlist_for_each_entry(n, &fncache_hash[h], nd) {
+		if (!strcmp(n->name, name)) {
+			*res = n->res;
+			return true;
+		}
+	}
+	return false;
+}
+
+static void update_fncache(const char *name, bool res)
+{
+	struct fncache *n = malloc(sizeof(struct fncache) + strlen(name) + 1);
+	int h = shash((const unsigned char *)name) % FNHSIZE;
+
+	if (!n)
+		return;
+	strcpy(n->name, name);
+	n->res = res;
+	hlist_add_head(&n->nd, &fncache_hash[h]);
+}
+
+/* No LRU, only use when bounded in some other way. */
+bool file_available(const char *name)
+{
+	bool res;
+
+	if (lookup_fncache(name, &res))
+		return res;
+	res = access(name, R_OK) == 0;
+	update_fncache(name, res);
+	return res;
+}