perf map: Consider PTI entry trampolines in rip_2objdump()

perf tools uses map__rip_2objdump() to calculate objdump virtual addresses.
map__rip_2objdump() needs to be amended to deal with PTI entry trampolines.

Signed-off-by: Adrian Hunter <[e-mail]>
Reported-by: Arnaldo Carvalho de Melo <[e-mail]>
Tested-by: Arnaldo Carvalho de Melo <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
[ split from a larger patch ]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/map.c

···
  */
 u64 map__rip_2objdump(struct map *map, u64 rip)
 {
+	struct kmap *kmap = __map__kmap(map);
+
+	/*
+	 * vmlinux does not have program headers for PTI entry trampolines and
+	 * kcore may not either. However the trampoline object code is on the
+	 * main kernel map, so just use that instead.
+	 */
+	if (kmap && is_entry_trampoline(kmap->name) && kmap->kmaps && kmap->kmaps->machine) {
+		struct map *kernel_map = machine__kernel_map(kmap->kmaps->machine);
+
+		if (kernel_map)
+			map = kernel_map;
+	}
+
 	if (!map->dso->adjust_symbols)
 		return rip;