5 files changed, 126 insertions, 5 deletions

diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index bb0fd6da2d5..1a31feb9999 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -189,6 +189,50 @@ void event__synthesize_threads(int (*process)(event_t *event,
 	closedir(proc);
 }
 
+struct process_symbol_args {
+	const char *name;
+	u64	   start;
+};
+
+static int find_symbol_cb(void *arg, const char *name, char type, u64 start)
+{
+	struct process_symbol_args *args = arg;
+
+	if (!symbol_type__is_a(type, MAP__FUNCTION) || strcmp(name, args->name))
+		return 0;
+
+	args->start = start;
+	return 1;
+}
+
+int event__synthesize_kernel_mmap(int (*process)(event_t *event,
+						 struct perf_session *session),
+				  struct perf_session *session,
+				  const char *symbol_name)
+{
+	size_t size;
+	event_t ev = {
+		.header = { .type = PERF_RECORD_MMAP },
+	};
+	/*
+	 * We should get this from /sys/kernel/sections/.text, but till that is
+	 * available use this, and after it is use this as a fallback for older
+	 * kernels.
+	 */
+	struct process_symbol_args args = { .name = symbol_name, };
+
+	if (kallsyms__parse(&args, find_symbol_cb) <= 0)
+		return -ENOENT;
+
+	size = snprintf(ev.mmap.filename, sizeof(ev.mmap.filename),
+			"[kernel.kallsyms.%s]", symbol_name) + 1;
+	size = ALIGN(size, sizeof(u64));
+	ev.mmap.header.size = (sizeof(ev.mmap) - (sizeof(ev.mmap.filename) - size));
+	ev.mmap.start = args.start;
+
+	return process(&ev, session);
+}
+
 static void thread__comm_adjust(struct thread *self)
 {
 	char *comm = self->comm;
@@ -240,9 +284,9 @@ int event__process_lost(event_t *self, struct perf_session *session)
 
 int event__process_mmap(event_t *self, struct perf_session *session)
 {
-	struct thread *thread = perf_session__findnew(session, self->mmap.pid);
-	struct map *map = map__new(&self->mmap, MAP__FUNCTION,
-				   session->cwd, session->cwdlen);
+	struct thread *thread;
+	struct map *map;
+	static const char kmmap_prefix[] = "[kernel.kallsyms.";
 
 	dump_printf(" %d/%d: [%p(%p) @ %p]: %s\n",
 		    self->mmap.pid, self->mmap.tid,
@@ -251,6 +295,20 @@ int event__process_mmap(event_t *self, struct perf_session *session)
 		    (void *)(long)self->mmap.pgoff,
 		    self->mmap.filename);
 
+	if (self->mmap.pid == 0 &&
+	    memcmp(self->mmap.filename, kmmap_prefix,
+		   sizeof(kmmap_prefix) - 1) == 0) {
+		const char *symbol_name = (self->mmap.filename +
+					   sizeof(kmmap_prefix) - 1);
+		perf_session__set_kallsyms_ref_reloc_sym(session, symbol_name,
+							 self->mmap.start);
+		return 0;
+	}
+
+	thread = perf_session__findnew(session, self->mmap.pid);
+	map = map__new(&self->mmap, MAP__FUNCTION,
+		       session->cwd, session->cwdlen);
+
 	if (thread == NULL || map == NULL)
 		dump_printf("problem processing PERF_RECORD_MMAP, skipping event.\n");
 	else
diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
index 80fb3653c80..61fc0dc658c 100644
--- a/tools/perf/util/event.h
+++ b/tools/perf/util/event.h
@@ -110,6 +110,10 @@ int event__synthesize_thread(pid_t pid,
 void event__synthesize_threads(int (*process)(event_t *event,
 					      struct perf_session *session),
 			       struct perf_session *session);
+int event__synthesize_kernel_mmap(int (*process)(event_t *event,
+						 struct perf_session *session),
+				  struct perf_session *session,
+				  const char *symbol_name);
 
 int event__process_comm(event_t *self, struct perf_session *session);
 int event__process_lost(event_t *self, struct perf_session *session);
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 7f0537d1add..e0e6a075489 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -401,3 +401,49 @@ bool perf_session__has_traces(struct perf_session *self, const char *msg)
 
 	return true;
 }
+
+int perf_session__set_kallsyms_ref_reloc_sym(struct perf_session *self,
+					     const char *symbol_name,
+					     u64 addr)
+{
+	char *bracket;
+
+	self->ref_reloc_sym.name = strdup(symbol_name);
+	if (self->ref_reloc_sym.name == NULL)
+		return -ENOMEM;
+
+	bracket = strchr(self->ref_reloc_sym.name, ']');
+	if (bracket)
+		*bracket = '\0';
+
+	self->ref_reloc_sym.addr = addr;
+	return 0;
+}
+
+static u64 map__reloc_map_ip(struct map *map, u64 ip)
+{
+	return ip + (s64)map->pgoff;
+}
+
+static u64 map__reloc_unmap_ip(struct map *map, u64 ip)
+{
+	return ip - (s64)map->pgoff;
+}
+
+void perf_session__reloc_vmlinux_maps(struct perf_session *self,
+				      u64 unrelocated_addr)
+{
+	enum map_type type;
+	s64 reloc = unrelocated_addr - self->ref_reloc_sym.addr;
+
+	if (!reloc)
+		return;
+
+	for (type = 0; type < MAP__NR_TYPES; ++type) {
+		struct map *map = self->vmlinux_maps[type];
+
+		map->map_ip = map__reloc_map_ip;
+		map->unmap_ip = map__reloc_unmap_ip;
+		map->pgoff = reloc;
+	}
+}
diff --git a/tools/perf/util/session.h b/tools/perf/util/session.h
index 8db37bbf0e6..d4a9d20f8d4 100644
--- a/tools/perf/util/session.h
+++ b/tools/perf/util/session.h
@@ -24,6 +24,10 @@ struct perf_session {
 	unsigned long		unknown_events;
 	struct rb_root		hists;
 	u64			sample_type;
+	struct {
+		const char	*name;
+		u64		addr;
+	}			ref_reloc_sym;
 	int			fd;
 	int			cwdlen;
 	char			*cwd;
@@ -59,4 +63,10 @@ bool perf_session__has_traces(struct perf_session *self, const char *msg);
 
 int perf_header__read_build_ids(int input, u64 offset, u64 file_size);
 
+int perf_session__set_kallsyms_ref_reloc_sym(struct perf_session *self,
+					     const char *symbol_name,
+					     u64 addr);
+void perf_session__reloc_vmlinux_maps(struct perf_session *self,
+				      u64 unrelocated_addr);
+
 #endif /* __PERF_SESSION_H */
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index e290429e9c0..da2f07f1af8 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -956,11 +956,15 @@ static int dso__load_sym(struct dso *self, struct map *map,
 
 	elf_symtab__for_each_symbol(syms, nr_syms, idx, sym) {
 		struct symbol *f;
-		const char *elf_name;
+		const char *elf_name = elf_sym__name(&sym, symstrs);
 		char *demangled = NULL;
 		int is_label = elf_sym__is_label(&sym);
 		const char *section_name;
 
+		if (kernel && session->ref_reloc_sym.name != NULL &&
+		    strcmp(elf_name, session->ref_reloc_sym.name) == 0)
+			perf_session__reloc_vmlinux_maps(session, sym.st_value);
+
 		if (!is_label && !elf_sym__is_a(&sym, map->type))
 			continue;
 
@@ -973,7 +977,6 @@ static int dso__load_sym(struct dso *self, struct map *map,
 		if (is_label && !elf_sec__is_a(&shdr, secstrs, map->type))
 			continue;
 
-		elf_name = elf_sym__name(&sym, symstrs);
 		section_name = elf_sec__name(&shdr, secstrs);
 
 		if (kernel || kmodule) {