Subject: bug#20614: Segmentation fault when building on Power8 Little Endian

From: Eli Zaretskii <[email-masked]>
Date: Fri, 02 Oct 2015 11:49:05 +0300

> Cc: [email-masked]
> From: Petr Hracek <[email-masked]>
> Date: Fri, 2 Oct 2015 10:36:27 +0200
> 
> What does this GDB command display in frame #1:
> 
>   (gdb) p old_section_names + NEW_SECTION_H (nn).sh_name
> 
> ?
> 
> It is a really strange.
> in our unexelf.c is NEW_SECTION_H defined as
> 
> #define NEW_SECTION_H(n) \
> (*(ElfW (Shdr) *) ((byte *) new_section_h + new_file_h->e_shentsize * (n)))
> 
> Paul Eggert did a some patch 1 or 2 year ago and modify it to
> #define NEW_SECTION_H(n) \
>   (*(ElfW (Shdr) *) entry_address (new_section_h, n, new_file_h->e_shentsize))
> 
> (gdb) frame 1
> #1 0x00000000102e3724 in unexec (new_name=0x116387e8
> "/home/phracek/rpmbuild/BUILD/emacs-24.3/src/emacs", old_name=0x11638838
> "/home/phracek/rpmbuild/BUILD/emacs-24.3/src/temacs")
> at unexelf.c:1258
> 1258 if (!strcmp (old_section_names + NEW_SECTION_H (nn).sh_name, ".data")
> (gdb) p old_section_names
> $1 = 0x3fffab1dbfcc ""
> (gdb) p old_section_names + NEW_SECTION_H (nn).sh_name
> No symbol "NEW_SECTION_H" in current context.

Use the expansion of that macro instead to display the value.