The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 8799ebce84d672aae1dc3170510f6a3e66f96b11 Mon Sep 17 00:00:00 2001 From: Namhyung Kim namhyung@kernel.org Date: Fri, 15 Apr 2022 17:40:47 -0700 Subject: [PATCH] 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: 3cf6a32f3f2a4594 ("perf symbols: Fix symbol size calculation condition") Signed-off-by: Namhyung Kim namhyung@kernel.org Acked-by: Ian Rogers irogers@google.com Cc: Heiko Carstens hca@linux.ibm.com Cc: Ingo Molnar mingo@kernel.org Cc: Jiri Olsa jolsa@kernel.org Cc: John Garry john.garry@huawei.com Cc: Leo Yan leo.yan@linaro.org Cc: Mark Rutland mark.rutland@arm.com Cc: Masami Hiramatsu mhiramat@kernel.org Cc: Mathieu Poirier mathieu.poirier@linaro.org Cc: Michael Ellerman mpe@ellerman.id.au Cc: Michael Petlan mpetlan@redhat.com Cc: Peter Zijlstra peterz@infradead.org Cc: Song Liu songliubraving@fb.com Cc: Will Deacon will@kernel.org Cc: linux-s390@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Link: https://lore.kernel.org/r/20220416004048.1514900-3-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c index 1b85cc1422a9..623094e866fd 100644 --- a/tools/perf/util/symbol.c +++ b/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 */