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authorAlan Modra <amodra@gmail.com>2017-11-12 17:44:15 +1030
committerAlan Modra <amodra@gmail.com>2017-11-12 17:45:23 +1030
commit529fe20eeb0030ea5d653d0ebec433f9e3145874 (patch)
tree1915772ed022a482238d3fcd64d48e4db6d4af11 /bfd/elf32-hppa.c
parentd95639024585ce43e8fe0557ac85e706452e1515 (diff)
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non_got_ref after adjust_dynamic_relocs
This patch was aimed at a FIXME in elf32-hppa.c, the ludicrous and confusing fact that non_got_ref after adjust_dynamic_relocs in that backend means precisely the inverse of what it means before adjust_dynamic_relocs. Before, when non_got_ref is set it means there are dynamic relocs, after, if non_got_ref is clear it means "keep dynamic relocs" and later, "has dynamic relocs". There is a reason why it was done that way.. Some symbols that may have dynamic relocations pre-allocated in check_relocs turn out to not be dynamic, and then are not seen by the backend adjust_dynamic_symbols. We want those symbols to lose their dynamic relocs when non-pic, so it's handy that non_got_ref means the opposite after adjust_dynamic_relocs. But it's really confusing. Most other targets, like ppc32, don't always set non_got_ref on non-GOT references that have dynamic relocations. This is because the primary purpose of non_got_ref before adjust_dynamic_relocs is to flag symbols that might need to be copied to .dynbss, and there are relocation types that may require dyn_relocs but clearly cannot have symbols copied into .dynbss, for example, TLS relocations. Why do we need a flag after adjust_dynamic_relocs to say "keep dynamic relocations"? Well, you can discard most unwanted dyn_relocs in the backend adjust_dynamic_relocs, and for those symbols that aren't seen by the backend adjust_dynamic_relocs, in allocate_dynrelocs based on a flag set by adjust_dynamic relocs, dynamic_adjusted. That doesn't solve all our difficulties though. relocate_section needs to know whether a symbol has dyn_relocs, and many targets transfer dyn_relocs to a weakdef if the symbol has one. The transfer means relocate_section can't test dyn_relocs itself and the weakdef field has been overwritten by that time. So non_got_ref is used to flag "this symbol has dynamic relocations" for relocate_section. Confused still? Well, let's hope the comments I've added help clarify things.. The patch also fixes a case where we might wrongly emit dynamic relocations in an executable for common and undefined symbols. * elf32-hppa.c (elf32_hppa_adjust_dynamic_symbol): Set non_got_ref to keep dyn_relocs, clear to discard. Comment. (allocate_dynrelocs): Always clear non_got_ref when clearing dyn_relocs in non-pic case. Invert non_got_ref test. Also test dynamic_adjusted and ELF_COMMON_DEF_P. Move code deleting dyn_relocs on undefined syms to handle for non-pic too. (elf32_hppa_relocate_section): Simplify test for non-pic dyn relocs. * elf32-ppc.c (ppc_elf_adjust_dynamic_symbol): Set non_got_ref to keep dyn_relocs, clear to discard. Comment. (allocate_dynrelocs): Always clear non_got_ref when clearing dyn_relocs in non-pic case. Invert non_got_ref test. Also test dynamic_adjusted and ELF_COMMON_DEF_P. Move code deleting dyn_relocs on undefined syms to handle for non-pic too. (ppc_elf_relocate_section): Simplify test for non-pic dyn relocs. * elf64-ppc.c (ppc64_elf_adjust_dynamic_symbol): Discard dyn_relocs here. Don't bother setting non_got_ref. Comment. (allocate_dynrelocs): Delete special handling of non-pic ELFv2 ifuncs. Move code deleting dyn_relocs on undefined symbols to handle for non-pic too. Don't test non_got_ref. Do test dynamic_adjusted and ELF_COMMON_DEF_P.
Diffstat (limited to 'bfd/elf32-hppa.c')
-rw-r--r--bfd/elf32-hppa.c75
1 files changed, 36 insertions, 39 deletions
diff --git a/bfd/elf32-hppa.c b/bfd/elf32-hppa.c
index f9629e4..7fc447e 100644
--- a/bfd/elf32-hppa.c
+++ b/bfd/elf32-hppa.c
@@ -1692,7 +1692,9 @@ elf32_hppa_adjust_dynamic_symbol (struct bfd_link_info *info,
if (eh->type == STT_FUNC
|| eh->needs_plt)
{
- /* After adjust_dynamic_symbol, non_got_ref set in the non-pic
+ /* Prior to adjust_dynamic_symbol, non_got_ref set means that
+ check_relocs generated dyn_relocs for this symbol.
+ After adjust_dynamic_symbol, non_got_ref clear in the non-pic
case means that dyn_relocs for this symbol should be
discarded; We either want the symbol to remain undefined, or
we have a local definition of some sort. The "local
@@ -1700,22 +1702,13 @@ elf32_hppa_adjust_dynamic_symbol (struct bfd_link_info *info,
local definition in .dynbss.
Unlike other targets, elf32-hppa.c does not define a function
symbol in a non-pic executable on PLT stub code, so we don't
- have a local definition in that case. dyn_relocs therefore
- should not be discarded for function symbols, generally.
- However we should discard dyn_relocs if we've decided that an
- undefined function symbol is local, for example due to
- non-default visibility, or UNDEFWEAK_NO_DYNAMIC_RELOC is
- true for an undefined weak symbol. */
+ have a local definition in that case. */
bfd_boolean local = (SYMBOL_CALLS_LOCAL (info, eh)
|| UNDEFWEAK_NO_DYNAMIC_RELOC (info, eh));
- /* Prior to adjust_dynamic_symbol, non_got_ref set means that
- check_relocs set up some dyn_relocs for this symbol.
- The !non_got_ref term here is saying that if we didn't have
- any dyn_relocs set up by check_relocs, then we don't want
- relocate_section looking for them.
- FIXME: Get rid of the inversion, so non_got_ref set after
- dyn_relocs means we do have dyn_relocs. */
- eh->non_got_ref = local || !eh->non_got_ref;
+ /* Arrange to discard dyn_relocs if we've decided that a
+ function symbol is local. */
+ if (local)
+ eh->non_got_ref = 0;
/* If the symbol is used by a plabel, we must allocate a PLT slot.
The refcounts are not reliable when it has been hidden since
@@ -1773,24 +1766,17 @@ elf32_hppa_adjust_dynamic_symbol (struct bfd_link_info *info,
/* If there are no references to this symbol that do not use the
GOT, we don't need to generate a copy reloc. */
if (!eh->non_got_ref)
- {
- eh->non_got_ref = 1;
- return TRUE;
- }
+ return TRUE;
/* If -z nocopyreloc was given, we won't generate them either. */
if (info->nocopyreloc)
- {
- eh->non_got_ref = 0;
- return TRUE;
- }
+ return TRUE;
if (ELIMINATE_COPY_RELOCS
&& !readonly_dynrelocs (eh))
{
/* If we didn't find any dynamic relocs in read-only sections, then
we'll be keeping the dynamic relocs and avoiding the copy reloc. */
- eh->non_got_ref = 0;
return TRUE;
}
@@ -1827,6 +1813,8 @@ elf32_hppa_adjust_dynamic_symbol (struct bfd_link_info *info,
eh->needs_copy = 1;
}
+ /* We no longer want dyn_relocs. */
+ eh->non_got_ref = 0;
return _bfd_elf_adjust_dynamic_copy (info, eh, sec);
}
@@ -2011,8 +1999,17 @@ allocate_dynrelocs (struct elf_link_hash_entry *eh, void *inf)
if (!htab->etab.dynamic_sections_created)
hh->dyn_relocs = NULL;
+ /* Discard relocs on undefined syms with non-default visibility. */
+ else if ((eh->root.type == bfd_link_hash_undefined
+ && ELF_ST_VISIBILITY (eh->other) != STV_DEFAULT)
+ || UNDEFWEAK_NO_DYNAMIC_RELOC (info, eh))
+ hh->dyn_relocs = NULL;
+
if (hh->dyn_relocs == NULL)
- return TRUE;
+ {
+ eh->non_got_ref = 0;
+ return TRUE;
+ }
/* If this is a -Bsymbolic shared link, then we need to discard all
space allocated for dynamic pc-relative relocs against symbols
@@ -2021,14 +2018,8 @@ allocate_dynrelocs (struct elf_link_hash_entry *eh, void *inf)
changes. */
if (bfd_link_pic (info))
{
- /* Discard relocs on undefined syms with non-default visibility. */
- if ((eh->root.type == bfd_link_hash_undefined
- && ELF_ST_VISIBILITY (eh->other) != STV_DEFAULT)
- || UNDEFWEAK_NO_DYNAMIC_RELOC (info, eh))
- hh->dyn_relocs = NULL;
-
#if RELATIVE_DYNRELOCS
- else if (SYMBOL_CALLS_LOCAL (info, eh))
+ if (SYMBOL_CALLS_LOCAL (info, eh))
{
struct elf32_hppa_dyn_reloc_entry **hdh_pp;
@@ -2056,17 +2047,25 @@ allocate_dynrelocs (struct elf_link_hash_entry *eh, void *inf)
symbols which turn out to need copy relocs or are not
dynamic. */
- if (!eh->non_got_ref
- && !eh->def_regular)
+ if (eh->dynamic_adjusted
+ && eh->non_got_ref
+ && !eh->def_regular
+ && !ELF_COMMON_DEF_P (eh))
{
if (!ensure_undef_dynamic (info, eh))
return FALSE;
if (eh->dynindx == -1)
- hh->dyn_relocs = NULL;
+ {
+ eh->non_got_ref = 0;
+ hh->dyn_relocs = NULL;
+ }
}
else
- hh->dyn_relocs = NULL;
+ {
+ eh->non_got_ref = 0;
+ hh->dyn_relocs = NULL;
+ }
}
/* Finally, allocate space. */
@@ -3913,9 +3912,7 @@ elf32_hppa_relocate_section (bfd *output_bfd,
|| (ELIMINATE_COPY_RELOCS
&& !bfd_link_pic (info)
&& hh != NULL
- && hh->eh.dynindx != -1
- && !hh->eh.non_got_ref
- && !hh->eh.def_regular))
+ && hh->eh.non_got_ref))
{
Elf_Internal_Rela outrel;
bfd_boolean skip;