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authorAnders Kaseorg <andersk@mit.edu>2009-04-23 16:49:33 -0400
committerSam Ravnborg <sam@ravnborg.org>2009-05-01 04:54:05 -0400
commitb614a697dc17dff82f140d72d21a095f810fa7fb (patch)
treeb16edfeaddf7e808d6fa4b71ee11e497968476b2 /scripts/mod/modpost.c
parentc993971f4a7dc7ae43963aecb958395353c109ae (diff)
kbuild, modpost: Check the section flags, to catch missing "ax"/"aw"
When you put .section ".foo" in an assembly file instead of .section "foo", "ax" , one of the possible symptoms is that modpost will see an ld-generated section name ".foo.1" in section_rel() or section_rela(). But this heuristic has two problems: it will miss a bad section that has no relocations, and it will incorrectly flag many gcc-generated sections as bad when compiling with -ffunction-sections -fdata-sections. On mips it fixes a lot of bogus warnings with gcc 4.4.0 lije this one: WARNING: crypto/cryptd.o (.text.T.349): unexpected section name. So instead of checking whether the section name matches a particular pattern, we directly check for a missing SHF_ALLOC in the section flags. Signed-off-by: Anders Kaseorg <andersk@mit.edu> Tested-by: Ralf Baechle <ralf@linux-mips.org> Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Diffstat (limited to 'scripts/mod/modpost.c')
-rw-r--r--scripts/mod/modpost.c51
1 files changed, 19 insertions, 32 deletions
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index e5ae695458eb..936b6f8e46ff 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -716,41 +716,27 @@ int match(const char *sym, const char * const pat[])
716 716
717/* sections that we do not want to do full section mismatch check on */ 717/* sections that we do not want to do full section mismatch check on */
718static const char *section_white_list[] = 718static const char *section_white_list[] =
719 { ".debug*", ".stab*", ".note*", ".got*", ".toc*", NULL }; 719 { ".comment", ".debug*", ".stab*", ".note*", ".got*", ".toc*", NULL };
720 720
721/* 721/*
722 * Is this section one we do not want to check? 722 * This is used to find sections missing the SHF_ALLOC flag.
723 * This is often debug sections.
724 * If we are going to check this section then
725 * test if section name ends with a dot and a number.
726 * This is used to find sections where the linker have
727 * appended a dot-number to make the name unique.
728 * The cause of this is often a section specified in assembler 723 * The cause of this is often a section specified in assembler
729 * without "ax" / "aw" and the same section used in .c 724 * without "ax" / "aw".
730 * code where gcc add these.
731 */ 725 */
732static int check_section(const char *modname, const char *sec) 726static void check_section(const char *modname, struct elf_info *elf,
733{ 727 Elf_Shdr *sechdr)
734 const char *e = sec + strlen(sec) - 1; 728{
735 if (match(sec, section_white_list)) 729 const char *sec = sech_name(elf, sechdr);
736 return 1; 730
737 731 if (sechdr->sh_type == SHT_PROGBITS &&
738 if (*e && isdigit(*e)) { 732 !(sechdr->sh_flags & SHF_ALLOC) &&
739 /* consume all digits */ 733 !match(sec, section_white_list)) {
740 while (*e && e != sec && isdigit(*e)) 734 warn("%s (%s): unexpected non-allocatable section.\n"
741 e--; 735 "Did you forget to use \"ax\"/\"aw\" in a .S file?\n"
742 if (*e == '.' && !strstr(sec, ".linkonce")) { 736 "Note that for example <linux/init.h> contains\n"
743 warn("%s (%s): unexpected section name.\n" 737 "section definitions for use in .S files.\n\n",
744 "The (.[number]+) following section name are " 738 modname, sec);
745 "ld generated and not expected.\n"
746 "Did you forget to use \"ax\"/\"aw\" "
747 "in a .S file?\n"
748 "Note that for example <linux/init.h> contains\n"
749 "section definitions for use in .S files.\n\n",
750 modname, sec);
751 }
752 } 739 }
753 return 0;
754} 740}
755 741
756 742
@@ -1358,7 +1344,7 @@ static void section_rela(const char *modname, struct elf_info *elf,
1358 fromsec = sech_name(elf, sechdr); 1344 fromsec = sech_name(elf, sechdr);
1359 fromsec += strlen(".rela"); 1345 fromsec += strlen(".rela");
1360 /* if from section (name) is know good then skip it */ 1346 /* if from section (name) is know good then skip it */
1361 if (check_section(modname, fromsec)) 1347 if (match(fromsec, section_white_list))
1362 return; 1348 return;
1363 1349
1364 for (rela = start; rela < stop; rela++) { 1350 for (rela = start; rela < stop; rela++) {
@@ -1402,7 +1388,7 @@ static void section_rel(const char *modname, struct elf_info *elf,
1402 fromsec = sech_name(elf, sechdr); 1388 fromsec = sech_name(elf, sechdr);
1403 fromsec += strlen(".rel"); 1389 fromsec += strlen(".rel");
1404 /* if from section (name) is know good then skip it */ 1390 /* if from section (name) is know good then skip it */
1405 if (check_section(modname, fromsec)) 1391 if (match(fromsec, section_white_list))
1406 return; 1392 return;
1407 1393
1408 for (rel = start; rel < stop; rel++) { 1394 for (rel = start; rel < stop; rel++) {
@@ -1465,6 +1451,7 @@ static void check_sec_ref(struct module *mod, const char *modname,
1465 1451
1466 /* Walk through all sections */ 1452 /* Walk through all sections */
1467 for (i = 0; i < elf->hdr->e_shnum; i++) { 1453 for (i = 0; i < elf->hdr->e_shnum; i++) {
1454 check_section(modname, elf, &elf->sechdrs[i]);
1468 /* We want to process only relocation sections and not .init */ 1455 /* We want to process only relocation sections and not .init */
1469 if (sechdrs[i].sh_type == SHT_RELA) 1456 if (sechdrs[i].sh_type == SHT_RELA)
1470 section_rela(modname, elf, &elf->sechdrs[i]); 1457 section_rela(modname, elf, &elf->sechdrs[i]);