Thread (6 messages) 6 messages, 3 authors, 2022-03-30

Re: [PATCH] recordmcount: Support empty section from recent binutils

From: LEROY Christophe <hidden>
Date: 2021-11-26 08:45:32
Also in: lkml


Le 24/11/2021 à 15:43, Christophe Leroy a écrit :
Looks like recent binutils (2.36 and over ?) may empty some section,
leading to failure like:

	Cannot find symbol for section 11: .text.unlikely.
	kernel/kexec_file.o: failed
	make[1]: *** [scripts/Makefile.build:287: kernel/kexec_file.o] Error 1

In order to avoid that, ensure that the section has a content before
returning it's name in has_rel_mcount().
This patch doesn't work, on PPC32 I get the following message with this 
patch applied:

[    0.000000] ftrace: No functions to be traced?

Without the patch I get:

[    0.000000] ftrace: allocating 22381 entries in 66 pages
[    0.000000] ftrace: allocated 66 pages with 2 groups

Christophe
quoted hunk ↗ jump to hunk
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Link: https://github.com/linuxppc/issues/issues/388
Link: https://lore.kernel.org/all/20210215162209.5e2a475b@gandalf.local.home/ (local)
Signed-off-by: Christophe Leroy <redacted>
---
  scripts/recordmcount.h | 2 ++
  1 file changed, 2 insertions(+)
diff --git a/scripts/recordmcount.h b/scripts/recordmcount.h
index 1e9baa5c4fc6..cc6600b729ae 100644
--- a/scripts/recordmcount.h
+++ b/scripts/recordmcount.h
@@ -575,6 +575,8 @@ static char const *has_rel_mcount(Elf_Shdr const *const relhdr,
  				  char const *const shstrtab,
  				  char const *const fname)
  {
+	if (!shdr0->sh_size)
+		return NULL;
  	if (w(relhdr->sh_type) != SHT_REL && w(relhdr->sh_type) != SHT_RELA)
  		return NULL;
  	return __has_rel_mcount(relhdr, shdr0, shstrtab, fname);
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