From b614a697dc17dff82f140d72d21a095f810fa7fb Mon Sep 17 00:00:00 2001 From: Anders Kaseorg Date: Thu, 23 Apr 2009 16:49:33 -0400 Subject: [PATCH] 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 Tested-by: Ralf Baechle Signed-off-by: Sam Ravnborg --- scripts/mod/modpost.c | 47 ++++++++++++++++--------------------------- 1 file changed, 17 insertions(+), 30 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[]) /* sections that we do not want to do full section mismatch check on */ static const char *section_white_list[] = - { ".debug*", ".stab*", ".note*", ".got*", ".toc*", NULL }; + { ".comment", ".debug*", ".stab*", ".note*", ".got*", ".toc*", NULL }; /* - * Is this section one we do not want to check? - * This is often debug sections. - * If we are going to check this section then - * test if section name ends with a dot and a number. - * This is used to find sections where the linker have - * appended a dot-number to make the name unique. + * This is used to find sections missing the SHF_ALLOC flag. * The cause of this is often a section specified in assembler - * without "ax" / "aw" and the same section used in .c - * code where gcc add these. + * without "ax" / "aw". */ -static int check_section(const char *modname, const char *sec) +static void check_section(const char *modname, struct elf_info *elf, + Elf_Shdr *sechdr) { - const char *e = sec + strlen(sec) - 1; - if (match(sec, section_white_list)) - return 1; + const char *sec = sech_name(elf, sechdr); - if (*e && isdigit(*e)) { - /* consume all digits */ - while (*e && e != sec && isdigit(*e)) - e--; - if (*e == '.' && !strstr(sec, ".linkonce")) { - warn("%s (%s): unexpected section name.\n" - "The (.[number]+) following section name are " - "ld generated and not expected.\n" - "Did you forget to use \"ax\"/\"aw\" " - "in a .S file?\n" - "Note that for example contains\n" - "section definitions for use in .S files.\n\n", - modname, sec); - } + if (sechdr->sh_type == SHT_PROGBITS && + !(sechdr->sh_flags & SHF_ALLOC) && + !match(sec, section_white_list)) { + warn("%s (%s): unexpected non-allocatable section.\n" + "Did you forget to use \"ax\"/\"aw\" in a .S file?\n" + "Note that for example contains\n" + "section definitions for use in .S files.\n\n", + modname, sec); } - return 0; } @@ -1358,7 +1344,7 @@ static void section_rela(const char *modname, struct elf_info *elf, fromsec = sech_name(elf, sechdr); fromsec += strlen(".rela"); /* if from section (name) is know good then skip it */ - if (check_section(modname, fromsec)) + if (match(fromsec, section_white_list)) return; for (rela = start; rela < stop; rela++) { @@ -1402,7 +1388,7 @@ static void section_rel(const char *modname, struct elf_info *elf, fromsec = sech_name(elf, sechdr); fromsec += strlen(".rel"); /* if from section (name) is know good then skip it */ - if (check_section(modname, fromsec)) + if (match(fromsec, section_white_list)) return; for (rel = start; rel < stop; rel++) { @@ -1465,6 +1451,7 @@ static void check_sec_ref(struct module *mod, const char *modname, /* Walk through all sections */ for (i = 0; i < elf->hdr->e_shnum; i++) { + check_section(modname, elf, &elf->sechdrs[i]); /* We want to process only relocation sections and not .init */ if (sechdrs[i].sh_type == SHT_RELA) section_rela(modname, elf, &elf->sechdrs[i]);