Author: emaste Date: Fri Nov 8 14:59:41 2019 New Revision: 354544 URL: https://svnweb.freebsd.org/changeset/base/354544
Log: elfcopy/strip: Ensure sections have required alignment on output Object files may specify insufficient alignment on certain sections, for example due to a bug in NASM[1]. When we detect that case in elfcopy or strip, emit a warning and increase the alignment to the minimum required. The NASM bug was fixed in 2015[2], but we might as well have this fixup (and warning) in elfcopy in case we encounter such a file for any other reason. This might be reworked somewhat upstream - see ELF Tool Chain ticket 485[3]. [1] https://bugzilla.nasm.us/show_bug.cgi?id=3392307 [2] https://repo.or.cz/w/nasm.git/commit/1f0cb0f2c1ba632c0fab02424928cfb756a9160c [3] https://sourceforge.net/p/elftoolchain/tickets/485/ PR: 198611 Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D2292 Modified: head/contrib/elftoolchain/elfcopy/sections.c Modified: head/contrib/elftoolchain/elfcopy/sections.c ============================================================================== --- head/contrib/elftoolchain/elfcopy/sections.c Fri Nov 8 14:51:09 2019 (r354543) +++ head/contrib/elftoolchain/elfcopy/sections.c Fri Nov 8 14:59:41 2019 (r354544) @@ -879,6 +879,43 @@ pad_section(struct elfcopy *ecp, struct section *s) elf_errmsg(-1)); } +static int +section_type_alignment(int sht, int class) +{ + switch (sht) + { + case SHT_DYNAMIC: + case SHT_DYNSYM: + case SHT_FINI_ARRAY: + case SHT_GNU_HASH: + case SHT_INIT_ARRAY: + case SHT_PREINIT_ARRAY: + case SHT_REL: + case SHT_RELA: + case SHT_SYMTAB: + return (class == ELFCLASS64 ? 8 : 4); + case SHT_SUNW_move: + return (8); + case SHT_GNU_LIBLIST: + case SHT_GROUP: + case SHT_HASH: + case SHT_NOTE: + case SHT_SUNW_verdef: /* == SHT_GNU_verdef */ + case SHT_SUNW_verneed: /* == SHT_GNU_verneed */ + case SHT_SYMTAB_SHNDX: + return (4); + case SHT_SUNW_syminfo: + case SHT_SUNW_versym: /* == SHT_GNU_versym */ + return (2); + case SHT_NOBITS: + case SHT_PROGBITS: + case SHT_STRTAB: + case SHT_SUNW_dof: + return (1); + } + return (1); +} + void resync_sections(struct elfcopy *ecp) { @@ -886,6 +923,7 @@ resync_sections(struct elfcopy *ecp) GElf_Shdr osh; uint64_t off; int first; + int min_alignment; ps = NULL; first = 1; @@ -908,6 +946,12 @@ resync_sections(struct elfcopy *ecp) /* Align section offset. */ if (s->align == 0) s->align = 1; + min_alignment = section_type_alignment(s->type, ecp->oec); + if (s->align < INT_MAX && (int)s->align < min_alignment) { + warnx("section %s alignment %d increased to %d", + s->name, (int)s->align, min_alignment); + s->align = min_alignment; + } if (off <= s->off) { if (!s->loadable || (ecp->flags & RELOCATABLE)) s->off = roundup(off, s->align); @@ -937,6 +981,7 @@ resync_sections(struct elfcopy *ecp) errx(EXIT_FAILURE, "gelf_getshdr() failed: %s", elf_errmsg(-1)); osh.sh_addr = s->vma; + osh.sh_addralign = s->align; osh.sh_offset = s->off; osh.sh_size = s->sz; if (!gelf_update_shdr(s->os, &osh)) _______________________________________________ [email protected] mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "[email protected]"
