PowerPC PLT stub alignment fixes

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.

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index f1c5c413f605c9b6ccca48bcc02bb320e135f185..3c8fcf3ab747a896ce147d9c8de9378ccb774443 100644 (file)
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -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.

diff --git a/bfd/elf32-ppc.c b/bfd/elf32-ppc.c
index 73701d48c6f68359eee1943c6e73c84c31156211..32104a12fdf03bb727f73c4aaedc72eee9fa9d75 100644 (file)
--- a/bfd/elf32-ppc.c
+++ b/bfd/elf32-ppc.c
@@ -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)

diff --git a/bfd/elf64-ppc.c b/bfd/elf64-ppc.c
index 65cf7feb3914a02d65abefe8dbc3b4640222c418..b2d288bd4e77e7e576523643efa410585babc695 100644 (file)
--- a/bfd/elf64-ppc.c
+++ b/bfd/elf64-ppc.c
@@ -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)

diff --git a/gold/ChangeLog b/gold/ChangeLog
index ec56a89467422472a58821ce27277ca2fb3e7a02..b833a7b36306bc63df40f17661b22da39fdd20ed 100644 (file)
--- a/gold/ChangeLog
+++ b/gold/ChangeLog
@@ -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.

diff --git a/gold/powerpc.cc b/gold/powerpc.cc
index 6b65792a66ff11150f348fd0997883532b6c8961..3c38a06e83afa29c210dd5d4900036c058875a4d 100644 (file)
--- a/gold/powerpc.cc
+++ b/gold/powerpc.cc
@@ -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;
   }
 

diff --git a/ld/ChangeLog b/ld/ChangeLog
index 9ee555baa7ad20f4f95fa86ee22106c9ce40bf33..380170530266ccf1f4390f90f4820b69c3eb13cc 100644 (file)
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -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.

diff --git a/ld/emultempl/ppc32elf.em b/ld/emultempl/ppc32elf.em
index 4e71a7802cc32dcbcdc5ffbae8bd8f05beeba590..3007fb2f801da834a24ce7ac84247da336f0bc87 100644 (file)
--- a/ld/emultempl/ppc32elf.em
+++ b/ld/emultempl/ppc32elf.em
@@ -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:

diff --git a/ld/emultempl/ppc64elf.em b/ld/emultempl/ppc64elf.em
index c7c27b04152958fabe23d3af6fddda739175088e..0baa424339a61ae03d5fa4fae2c6ad7657825511 100644 (file)
--- a/ld/emultempl/ppc64elf.em
+++ b/ld/emultempl/ppc64elf.em
@@ -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;
        }