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PowerPC PLT stub alignment fixes

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Asking for ppc32 plt call stubs to be aligned at 32 byte boundaries
didn't quite work.  For ld.bfd they were spaced 32 bytes apart, but
only started on a 16 byte boundary.  ld.gold also didn't get it right.

Finding that bug made me check over the ppc64 plt stub alignment,
where I found that negative values for alignment (meaning align to
minimize boundary crossing) were not accepted.  Since no one has
complained about that, I guess I could have removed the feature from
ld.bfd documentation, but I've opted instead to correct the code.

I've also added an optional alignment paramenter for ppc32
--plt-align, for some consistency with gold and ppc64 ld.bfd.

bfd/
	* elf32-ppc.c (ppc_elf_create_glink): Correct alignment of .glink.
	* elf64-ppc.c (ppc64_elf_size_stubs): Handle negative plt_stub_align.
	(ppc64_elf_build_stubs): Likewise.
gold/
	* powerpc.cc (param_plt_align): New function supplying default
	--plt-align values.  Use it..
	(Stub_table::plt_call_align): ..here, and..
	(Output_data_glink::global_entry_align): ..here.
	(Stub_table::stub_align): Correct 32-bit minimum alignment.
ld/
	* emultempl/ppc32elf.em: Support optional --plt-align arg.
	* emultempl/ppc64elf.em: Support negative --plt-align arg.
This commit is contained in:
Alan Modra 2018-01-18 22:06:40 +10:30
parent 7ab8203798
commit 691d2e9af2
8 changed files with 58 additions and 19 deletions
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6
bfd/ChangeLog
View File

@ -1,3 +1,9 @@
2018-01-18 Alan Modra <amodra@gmail.com>
* elf32-ppc.c (ppc_elf_create_glink): Correct alignment of .glink.
* elf64-ppc.c (ppc64_elf_size_stubs): Handle negative plt_stub_align.
(ppc64_elf_build_stubs): Likewise.
2018-01-17 Nick Clifton <nickc@redhat.com>
* po/ru.po: Updated Russian translation.

7
bfd/elf32-ppc.c
View File

@ -3475,14 +3475,17 @@ ppc_elf_create_glink (bfd *abfd, struct bfd_link_info *info)
struct ppc_elf_link_hash_table *htab = ppc_elf_hash_table (info);
asection *s;
flagword flags;
int p2align;
flags = (SEC_ALLOC | SEC_LOAD | SEC_CODE | SEC_READONLY | SEC_HAS_CONTENTS
| SEC_IN_MEMORY | SEC_LINKER_CREATED);
s = bfd_make_section_anyway_with_flags (abfd, ".glink", flags);
htab->glink = s;
p2align = htab->params->ppc476_workaround ? 6 : 4;
if (p2align < htab->params->plt_stub_align)
p2align = htab->params->plt_stub_align;
if (s == NULL
|| !bfd_set_section_alignment (abfd, s,
htab->params->ppc476_workaround ? 6 : 4))
|| !bfd_set_section_alignment (abfd, s, p2align))
return FALSE;
if (!info->no_ld_generated_unwind_info)

15
bfd/elf64-ppc.c
View File

@ -12743,9 +12743,11 @@ ppc64_elf_size_stubs (struct bfd_link_info *info)
if (htab->params->plt_stub_align != 0)
for (group = htab->group; group != NULL; group = group->next)
if (group->stub_sec != NULL)
group->stub_sec->size = ((group->stub_sec->size
+ (1 << htab->params->plt_stub_align) - 1)
& -(1 << htab->params->plt_stub_align));
{
int align = abs (htab->params->plt_stub_align);
group->stub_sec->size
= (group->stub_sec->size + (1 << align) - 1) & -(1 << align);
}
for (group = htab->group; group != NULL; group = group->next)
if (group->stub_sec != NULL
@ -13285,9 +13287,10 @@ ppc64_elf_build_stubs (struct bfd_link_info *info,
if (htab->params->plt_stub_align != 0)
for (group = htab->group; group != NULL; group = group->next)
if ((stub_sec = group->stub_sec) != NULL)
stub_sec->size = ((stub_sec->size
+ (1 << htab->params->plt_stub_align) - 1)
& -(1 << htab->params->plt_stub_align));
{
int align = abs (htab->params->plt_stub_align);
stub_sec->size = (stub_sec->size + (1 << align) - 1) & -(1 << align);
}
for (group = htab->group; group != NULL; group = group->next)
if ((stub_sec = group->stub_sec) != NULL)

8
gold/ChangeLog
View File

@ -1,3 +1,11 @@
2018-01-18 Alan Modra <amodra@gmail.com>
* powerpc.cc (param_plt_align): New function supplying default
--plt-align values. Use it..
(Stub_table::plt_call_align): ..here, and..
(Output_data_glink::global_entry_align): ..here.
(Stub_table::stub_align): Correct 32-bit minimum alignment.
2018-01-17 Alan Modra <amodra@gmail.com>
* options.h (speculate_indirect_jumps): New option.

19
gold/powerpc.cc
View File

@ -4186,6 +4186,15 @@ output_bctr(unsigned char* p)
return p;
}
template<int size>
static inline unsigned int
param_plt_align()
{
if (!parameters->options().user_set_plt_align())
return size == 64 ? 32 : 8;
return 1 << parameters->options().plt_align();
}
// Stub_table holds information about plt and long branch stubs.
// Stubs are built in an area following some input section determined
// by group_sections(). This input section is converted to a relaxed
@ -4412,9 +4421,7 @@ class Stub_table : public Output_relaxed_input_section
unsigned int
stub_align() const
{
unsigned int min_align = 4;
if (!parameters->options().user_set_plt_align())
return size == 64 ? 32 : min_align;
unsigned int min_align = size == 64 ? 32 : 16;
unsigned int user_align = 1 << parameters->options().plt_align();
return std::max(user_align, min_align);
}
@ -4483,7 +4490,7 @@ class Stub_table : public Output_relaxed_input_section
unsigned int
plt_call_align(unsigned int bytes) const
{
unsigned int align = this->stub_align();
unsigned int align = param_plt_align<size>();
return (bytes + align - 1) & -align;
}
@ -4926,9 +4933,7 @@ class Output_data_glink : public Output_section_data
unsigned int
global_entry_align(unsigned int off) const
{
unsigned int align = 1 << parameters->options().plt_align();
if (!parameters->options().user_set_plt_align())
align = size == 64 ? 32 : 4;
unsigned int align = param_plt_align<size>();
return (off + align - 1) & -align;
}

5
ld/ChangeLog
View File

@ -1,3 +1,8 @@
2018-01-18 Alan Modra <amodra@gmail.com>
* emultempl/ppc32elf.em: Support optional --plt-align arg.
* emultempl/ppc64elf.em: Support negative --plt-align arg.
2018-01-17 Alan Modra <amodra@gmail.com>
* emultempl/ppc32elf.em (params): Init new field.

13
ld/emultempl/ppc32elf.em
View File

@ -271,7 +271,7 @@ if test -z "$VXWORKS_BASE_EM_FILE" ; then
{ "bss-plt", no_argument, NULL, OPTION_OLD_PLT },
{ "speculate-indirect-jumps", no_argument, NULL, OPTION_SPECULATE_INDIRECT_JUMPS },
{ "no-speculate-indirect-jumps", no_argument, NULL, OPTION_NO_SPECULATE_INDIRECT_JUMPS },
{ "plt-align", no_argument, NULL, OPTION_PLT_ALIGN },
{ "plt-align", optional_argument, NULL, OPTION_PLT_ALIGN },
{ "no-plt-align", no_argument, NULL, OPTION_NO_PLT_ALIGN },
{ "sdata-got", no_argument, NULL, OPTION_OLD_GOT },'
fi
@ -369,7 +369,16 @@ PARSE_AND_LIST_ARGS_CASES=${PARSE_AND_LIST_ARGS_CASES}'
break;
case OPTION_PLT_ALIGN:
params.plt_stub_align = 5;
if (optarg != NULL)
{
char *end;
unsigned long val = strtoul (optarg, &end, 0);
if (*end || val > 5)
einfo (_("%P%F: invalid --plt-align `%s'\''\n"), optarg);
params.plt_stub_align = val;
}
else
params.plt_stub_align = 5;
break;
case OPTION_NO_PLT_ALIGN:

4
ld/emultempl/ppc64elf.em
View File

@ -872,8 +872,8 @@ PARSE_AND_LIST_ARGS_CASES=${PARSE_AND_LIST_ARGS_CASES}'
if (optarg != NULL)
{
char *end;
unsigned long val = strtoul (optarg, &end, 0);
if (*end || val > 8)
long val = strtol (optarg, &end, 0);
if (*end || (unsigned long) val + 8 > 16)
einfo (_("%P%F: invalid --plt-align `%s'\''\n"), optarg);
params.plt_stub_align = val;
}