[binutils-gdb] Set dynamic_undefined_weak to zero for static PIEs

[Alan Modra <amodra at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=22b1ee183d19a92cc57859c04307d31c06792d13

commit 22b1ee183d19a92cc57859c04307d31c06792d13
Author: Alan Modra <amodra@gmail.com>
Date:   Thu Oct 12 13:19:10 2017 +1030

    Set dynamic_undefined_weak to zero for static PIEs
    
    I believe we should be warning if ld is given both --no-dynamic-linker
    and -z dynamic-undefined-weak.  The two options are contradictory, the
    first says an executable has no dynamic interpreter to resolve dynamic
    symbols, while the second is asking for dynamic symbols to be emitted.
    (And even if a static PIE's relocation code, which is needed to
    process R_*_RELATIVE relocs, could process symbols, there are no
    DT_NEEDED dynamic objects to define such symbols.)
    
    I also think that dynamic_undefined_weak is the right flag to control
    whether undefined weaks are made dynamic, whether in static PIEs or
    anywhere else.  So force it to 0 for static PIEs, fixing PR 22269 for
    powerpc and any other target where the backend usually defaults to
    undefined weaks being made dynamic.
    
    This patch introduces regressions.  I'd normally not do that, but
    these are all in very recently added test cases, or expose bugs in the
    x86 backend.  The test cases were added after I'd made it known that
    this patch or one like it was imminent.
    
    	PR 22269
    	* emultempl/elf32.em (after_parse): Warn on --no-dynamic-linker
    	-z dynamic-undefined-weak combination.  Set dynamic_undefined_weak
    	to zero when nointerp.

Diff:
---
 ld/ChangeLog          | 7 +++++++
 ld/emultempl/elf32.em | 7 +++++++
 2 files changed, 14 insertions(+)

diff --git a/ld/ChangeLog b/ld/ChangeLog
index 0ae8134..1331a7b 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,5 +1,12 @@
 2017-10-12  Alan Modra  <amodra@gmail.com>
 
+	PR 22269
+	* emultempl/elf32.em (after_parse): Warn on --no-dynamic-linker
+	-z dynamic-undefined-weak combination.  Set dynamic_undefined_weak
+	to zero when nointerp.
+
+2017-10-12  Alan Modra  <amodra@gmail.com>
+
 	* emultempl/elf32.em (before_allocation): Call
 	elf_backend_hide_symbol, not _bfd_elf_link_hash_hide_symbol.
 	Formatting.
diff --git a/ld/emultempl/elf32.em b/ld/emultempl/elf32.em
index e6cf968..8737376 100644
--- a/ld/emultempl/elf32.em
+++ b/ld/emultempl/elf32.em
@@ -120,6 +120,13 @@ gld${EMULATION_NAME}_after_parse (void)
   if (bfd_link_pie (&link_info))
     link_info.flags_1 |= (bfd_vma) DF_1_PIE;
 
+  if (bfd_link_executable (&link_info)
+      && link_info.nointerp)
+    {
+      if (link_info.dynamic_undefined_weak > 0)
+	einfo (_("%P: warning: -z dynamic-undefined-weak ignored\n"));
+      link_info.dynamic_undefined_weak = 0;
+    }
   after_parse_default ();
 }