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nixpkgs/pkgs/development/tools/misc/binutils/elf-check-orphan-placement.patch
2017-08-04 08:36:44 +02:00

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From 36088682f447540fd8666a2c437fa232064044a7 Mon Sep 17 00:00:00 2001
From: Alan Modra <amodra@gmail.com>
Date: Thu, 3 Aug 2017 14:01:34 +0930
Subject: [PATCH] ELF checks for orphan placement
The loop checking for previous orphan placement should run even when
the output is non-ELF.
PR ld/21884
* emultempl/elf32.em (gld${EMULATION_NAME}_place_orphan): Revert
last change. Rename iself to elfinput. Expand comments. Condition
ELF checks on having both input and output ELF files. Extract..
(elf_orphan_compatible): ..this new function.
---
ld/ChangeLog | 8 ++++++
ld/emultempl/elf32.em | 76 +++++++++++++++++++++++++++++++--------------------
2 files changed, 55 insertions(+), 29 deletions(-)
diff --git a/ld/emultempl/elf32.em b/ld/emultempl/elf32.em
index 75ded12..9ac1840 100644
--- a/ld/emultempl/elf32.em
+++ b/ld/emultempl/elf32.em
@@ -2008,6 +2008,29 @@ output_rel_find (asection *sec, int isdyn)
return last;
}
+/* Return whether IN is suitable to be part of OUT. */
+
+static bfd_boolean
+elf_orphan_compatible (asection *in, asection *out)
+{
+ /* Non-zero sh_info implies a section with SHF_INFO_LINK with
+ unknown semantics for the generic linker, or a SHT_REL/SHT_RELA
+ section where sh_info specifies a symbol table. (We won't see
+ SHT_GROUP, SHT_SYMTAB or SHT_DYNSYM sections here.) We clearly
+ can't merge SHT_REL/SHT_RELA using differing symbol tables, and
+ shouldn't merge sections with differing unknown semantics. */
+ if (elf_section_data (out)->this_hdr.sh_info
+ != elf_section_data (in)->this_hdr.sh_info)
+ return FALSE;
+ /* We can't merge two sections with differing SHF_EXCLUDE when doing
+ a relocatable link. */
+ if (bfd_link_relocatable (&link_info)
+ && ((elf_section_flags (out) ^ elf_section_flags (in)) & SHF_EXCLUDE) != 0)
+ return FALSE;
+ return _bfd_elf_match_sections_by_type (link_info.output_bfd, out,
+ in->owner, in);
+}
+
/* Place an orphan section. We use this to put random SHF_ALLOC
sections in the right segment. */
@@ -2064,8 +2087,9 @@ gld${EMULATION_NAME}_place_orphan (asection *s,
lang_output_section_statement_type *os;
lang_output_section_statement_type *match_by_name = NULL;
int isdyn = 0;
- int iself = s->owner->xvec->flavour == bfd_target_elf_flavour;
- unsigned int sh_type = iself ? elf_section_type (s) : SHT_NULL;
+ int elfinput = s->owner->xvec->flavour == bfd_target_elf_flavour;
+ int elfoutput = link_info.output_bfd->xvec->flavour == bfd_target_elf_flavour;
+ unsigned int sh_type = elfinput ? elf_section_type (s) : SHT_NULL;
flagword flags;
asection *nexts;
@@ -2073,7 +2097,7 @@ gld${EMULATION_NAME}_place_orphan (asection *s,
&& link_info.combreloc
&& (s->flags & SEC_ALLOC))
{
- if (iself)
+ if (elfinput)
switch (sh_type)
{
case SHT_RELA:
@@ -2095,6 +2119,8 @@ gld${EMULATION_NAME}_place_orphan (asection *s,
}
if (!bfd_link_relocatable (&link_info)
+ && elfinput
+ && elfoutput
&& (s->flags & SEC_ALLOC) != 0
&& (elf_section_flags (s) & SHF_GNU_MBIND) != 0)
{
@@ -2135,9 +2161,11 @@ gld${EMULATION_NAME}_place_orphan (asection *s,
secname = ".mbind.text";
}
- /* Look through the script to see where to place this section. */
- if (constraint == 0
- && link_info.output_bfd->xvec->flavour == bfd_target_elf_flavour)
+ /* Look through the script to see where to place this section. The
+ script includes entries added by previous lang_insert_orphan
+ calls, so this loop puts multiple compatible orphans of the same
+ name into a single output section. */
+ if (constraint == 0)
for (os = lang_output_section_find (secname);
os != NULL;
os = next_matching_output_section_statement (os, 0))
@@ -2146,29 +2174,19 @@ gld${EMULATION_NAME}_place_orphan (asection *s,
lang_insert_orphan to create a new output section. */
constraint = SPECIAL;
- /* SEC_EXCLUDE is cleared when doing a relocatable link. But
- we can't merge 2 input sections with the same name when only
- one of them has SHF_EXCLUDE. Don't merge 2 sections with
- different sh_info. */
+ /* Check to see if we already have an output section statement
+ with this name, and its bfd section has compatible flags.
+ If the section already exists but does not have any flags
+ set, then it has been created by the linker, possibly as a
+ result of a --section-start command line switch. */
if (os->bfd_section != NULL
- && (elf_section_data (os->bfd_section)->this_hdr.sh_info
- == elf_section_data (s)->this_hdr.sh_info)
&& (os->bfd_section->flags == 0
- || ((!bfd_link_relocatable (&link_info)
- || (iself && (((elf_section_flags (s)
- ^ elf_section_flags (os->bfd_section))
- & SHF_EXCLUDE) == 0)))
- && ((s->flags ^ os->bfd_section->flags)
+ || (((s->flags ^ os->bfd_section->flags)
& (SEC_LOAD | SEC_ALLOC)) == 0
- && _bfd_elf_match_sections_by_type (link_info.output_bfd,
- os->bfd_section,
- s->owner, s))))
+ && (!elfinput
+ || !elfoutput
+ || elf_orphan_compatible (s, os->bfd_section)))))
{
- /* We already have an output section statement with this
- name, and its bfd section has compatible flags.
- If the section already exists but does not have any flags
- set, then it has been created by the linker, probably as a
- result of a --section-start command line switch. */
lang_add_section (&os->children, s, NULL, os);
return os;
}
@@ -2244,8 +2262,8 @@ gld${EMULATION_NAME}_place_orphan (asection *s,
else if ((flags & SEC_ALLOC) == 0)
;
else if ((flags & SEC_LOAD) != 0
- && ((iself && sh_type == SHT_NOTE)
- || (!iself && CONST_STRNEQ (secname, ".note"))))
+ && ((elfinput && sh_type == SHT_NOTE)
+ || (!elfinput && CONST_STRNEQ (secname, ".note"))))
place = &hold[orphan_interp];
else if ((flags & (SEC_LOAD | SEC_HAS_CONTENTS | SEC_THREAD_LOCAL)) == 0)
place = &hold[orphan_bss];
@@ -2255,8 +2273,8 @@ gld${EMULATION_NAME}_place_orphan (asection *s,
place = &hold[orphan_tdata];
else if ((flags & SEC_READONLY) == 0)
place = &hold[orphan_data];
- else if (((iself && (sh_type == SHT_RELA || sh_type == SHT_REL))
- || (!iself && CONST_STRNEQ (secname, ".rel")))
+ else if (((elfinput && (sh_type == SHT_RELA || sh_type == SHT_REL))
+ || (!elfinput && CONST_STRNEQ (secname, ".rel")))
&& (flags & SEC_LOAD) != 0)
place = &hold[orphan_rel];
else if ((flags & SEC_CODE) == 0)
--
2.9.3