perf machine: Fix map_groups__split_kallsyms() for entry trampoline symbols

When kernel symbols are derived from /proc/kallsyms only (not using
vmlinux or /proc/kcore) map_groups__split_kallsyms() is used. However
that function makes assumptions that are not true with entry trampoline
symbols. For now, remove the entry trampoline symbols at that point, as
they are no longer needed at that point.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86@kernel.org
Link: http://lkml.kernel.org/r/1526986485-6562-7-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/map.h b/tools/perf/util/map.h
index f1afe1ab6ff7e97f40019e4ae16b43dda5e592e6..fafcc375ed379acf84a81c505ce3bb650676b474 100644 (file)
--- a/tools/perf/util/map.h
+++ b/tools/perf/util/map.h
@@ -8,6 +8,7 @@
 #include <linux/rbtree.h>
 #include <pthread.h>
 #include <stdio.h>
+#include <string.h>
 #include <stdbool.h>
 #include <linux/types.h>
 #include "rwsem.h"
@@ -239,4 +240,11 @@ static inline bool __map__is_kmodule(const struct map *map)
 
 bool map__has_symbols(const struct map *map);
 
+#define ENTRY_TRAMPOLINE_NAME "__entry_SYSCALL_64_trampoline"
+
+static inline bool is_entry_trampoline(const char *name)
+{
+       return !strcmp(name, ENTRY_TRAMPOLINE_NAME);
+}
+
 #endif /* __PERF_MAP_H */

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 7011440941831d73b26b527678d416306264ef2a..929058da6727569fe6ec727da787552270845501 100644 (file)
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -737,12 +737,15 @@ static int map_groups__split_kallsyms(struct map_groups *kmaps, struct dso *dso,
        struct rb_root *root = &dso->symbols;
        struct rb_node *next = rb_first(root);
        int kernel_range = 0;
+       bool x86_64;
 
        if (!kmaps)
                return -1;
 
        machine = kmaps->machine;
 
+       x86_64 = machine__is(machine, "x86_64");
+
        while (next) {
                char *module;
 
@@ -790,6 +793,16 @@ static int map_groups__split_kallsyms(struct map_groups *kmaps, struct dso *dso,
                         */
                        pos->start = curr_map->map_ip(curr_map, pos->start);
                        pos->end   = curr_map->map_ip(curr_map, pos->end);
+               } else if (x86_64 && is_entry_trampoline(pos->name)) {
+                       /*
+                        * These symbols are not needed anymore since the
+                        * trampoline maps refer to the text section and it's
+                        * symbols instead. Avoid having to deal with
+                        * relocations, and the assumption that the first symbol
+                        * is the start of kernel text, by simply removing the
+                        * symbols at this point.
+                        */
+                       goto discard_symbol;
                } else if (curr_map != initial_map) {
                        char dso_name[PATH_MAX];
                        struct dso *ndso;