From af11708e83ab826202593ab1b9c22601c46a5056 Mon Sep 17 00:00:00 2001 From: Alan Modra Date: Sun, 8 Nov 2015 09:29:00 -0800 Subject: ELF unexec: _OBJC_ symbols in bss sections Emacs should build on ppc64el. A problem with the bss has been fixed. This upstream patch has been added [5/10]: ELF unexec: _OBJC_ symbols in bss sections This code assumed that there was only one bss section. Rather than checking for a particular index, check the section type. Also, handle the possibility that the section was SHT_NOBITS originally and is unchanged, in which case no clearing is needed (and sh_offset isn't necessarily valid, which can lead to a wild memset). * unexelf.c (unexec): Properly handle _OBJC_ symbols in bss sections. Origin: upstream, commit: 3ff9fc0e8d738be5004c65c3be314af9aca68148 Bug: http://debbugs.gnu.org/20614 Bug-Debian: http://bugs.debian.org/808347 Added-by: Rob Browning --- src/unexelf.c | 31 ++++++++++++++++++------------- 1 file changed, 18 insertions(+), 13 deletions(-) Index: emacs-24.5/src/unexelf.c =================================================================== --- emacs-24.5.orig/src/unexelf.c +++ emacs-24.5/src/unexelf.c @@ -1177,20 +1177,25 @@ temacs: "_OBJC_", sizeof ("_OBJC_") - 1) == 0) { ElfW (Shdr) *new_shdr = &NEW_SECTION_H (symp->st_shndx); - ptrdiff_t reladdr = symp->st_value - new_shdr->sh_addr; - ptrdiff_t newoff = reladdr + new_shdr->sh_offset; - - /* "Unpatch" index. */ - nn = symp->st_shndx; - if (nn > old_bss_index) - nn--; - if (nn == old_bss_index) - memset (new_base + newoff, 0, symp->st_size); - else + if (new_shdr->sh_type != SHT_NOBITS) { - ElfW (Shdr) *old_shdr = &OLD_SECTION_H (nn); - ptrdiff_t oldoff = reladdr + old_shdr->sh_offset; - memcpy (new_base + newoff, old_base + oldoff, symp->st_size); + ElfW (Shdr) *old_shdr; + ptrdiff_t reladdr = symp->st_value - new_shdr->sh_addr; + ptrdiff_t newoff = reladdr + new_shdr->sh_offset; + + /* "Unpatch" index. */ + nn = symp->st_shndx; + if (nn > old_bss_index) + nn--; + old_shdr = &OLD_SECTION_H (nn); + if (old_shdr->sh_type == SHT_NOBITS) + memset (new_base + newoff, 0, symp->st_size); + else + { + ptrdiff_t oldoff = reladdr + old_shdr->sh_offset; + memcpy (new_base + newoff, old_base + oldoff, + symp->st_size); + } } } #endif