perf symbol: Update symbols__fixup_end()

Now arch-specific functions all do the same thing.  When it fixes the
symbol address it needs to check the boundary between the kernel image
and modules.  For the last symbol in the previous region, it cannot
know the exact size as it's discarded already.  Thus it just uses a
small page size (4096) and rounds it up like the last symbol.

Fixes: 3cf6a32 ("perf symbols: Fix symbol size calculation condition")
Signed-off-by: Namhyung Kim <[email protected]>
Acked-by: Ian Rogers <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: John Garry <[email protected]>
Cc: Leo Yan <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Mathieu Poirier <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Michael Petlan <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Song Liu <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: [email protected]
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: namhyung

tools/perf/util/symbol.c

@@ -217,8 +217,8 @@ void symbols__fixup_duplicate(struct rb_root_cached *symbols)
 	}
 }
 
-void symbols__fixup_end(struct rb_root_cached *symbols,
-			bool is_kallsyms __maybe_unused)
+/* Update zero-sized symbols using the address of the next symbol */
+void symbols__fixup_end(struct rb_root_cached *symbols, bool is_kallsyms)
 {
 	struct rb_node *nd, *prevnd = rb_first_cached(symbols);
 	struct symbol *curr, *prev;
@@ -232,8 +232,29 @@ void symbols__fixup_end(struct rb_root_cached *symbols,
 		prev = curr;
 		curr = rb_entry(nd, struct symbol, rb_node);
 
-		if (prev->end == prev->start || prev->end != curr->start)
-			arch__symbols__fixup_end(prev, curr);
+		/*
+		 * On some architecture kernel text segment start is located at
+		 * some low memory address, while modules are located at high
+		 * memory addresses (or vice versa).  The gap between end of
+		 * kernel text segment and beginning of first module's text
+		 * segment is very big.  Therefore do not fill this gap and do
+		 * not assign it to the kernel dso map (kallsyms).
+		 *
+		 * In kallsyms, it determines module symbols using '[' character
+		 * like in:
+		 *   ffffffffc1937000 T hdmi_driver_init  [snd_hda_codec_hdmi]
+		 */
+		if (prev->end == prev->start) {
+			/* Last kernel/module symbol mapped to end of page */
+			if (is_kallsyms && (!strchr(prev->name, '[') !=
+					    !strchr(curr->name, '[')))
+				prev->end = roundup(prev->end + 4096, 4096);
+			else
+				prev->end = curr->start;
+
+			pr_debug4("%s sym:%s end:%#" PRIx64 "\n",
+				  __func__, prev->name, prev->end);
+		}
 	}
 
 	/* Last entry */