powerpc has two models of GOT+PLT placement: secure PLT (the new default)
and BSS PLT. ld handles the two possibilities in linker scripts by
including both locations in the script, but putting a constraint "SPECIAL"
on them, ala:
.plt : SPECIAL { *(.plt) }
As part of my RELRO hacking, I tried moving the padding logic *into* one
of those output sections and it worked Just Fine...until I used the -M
option to dump the link map, at which point the -M logic exploded because
it expected stuff to have been filled in by the Real Logic of ld, but it
was skipped because of the SPECIAL constraint.
So, diff below teachs ld -M to skip sections which the Real Logic of ld
skips because of constraints.
A solution to this isn't required immediately, but will be for RELRO to
work on powerpc.
ok?
Philip
Index: gnu/usr.bin/binutils-2.17/ld/ldlang.c
===================================================================
RCS file: /cvs/src/gnu/usr.bin/binutils-2.17/ld/ldlang.c,v
retrieving revision 1.4
diff -u -p -r1.4 ldlang.c
--- gnu/usr.bin/binutils-2.17/ld/ldlang.c 31 May 2016 17:05:04 -0000
1.4
+++ gnu/usr.bin/binutils-2.17/ld/ldlang.c 7 Aug 2016 03:18:37 -0000
@@ -3292,6 +3292,9 @@ print_output_section_statement
asection *section = output_section_statement->bfd_section;
int len;
+ if (output_section_statement->constraint == -1)
+ return;
+
if (output_section_statement != abs_output_section)
{
minfo ("\n%s", output_section_statement->name);
