Revert "PowerPC PLT speculative execution barriers"

This reverts most of commit 1be5d8d3bb.
Left in place are addition of --no-plt-align to some ppc32 ld tests
and the ld.texinfo --no-plt-thread-safe fix.

5 files changed, 26 insertions, 87 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 4a4167c..6dd9f47 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,11 @@
+2018-02-07  Alan Modra  <amodra@gmail.com>
+
+	Revert 2018-01-17  Alan Modra  <amodra@gmail.com>
+	* elf32-ppc.c: Remove speculation barrier support.
+	* elf32-ppc.h: Likewise.
+	* elf64-ppc.c: Likewise.
+	* elf64-ppc.h: Likewise.
+
 2018-02-06  Jim Wilson  <jimw@sifive.com>
 
 	* elfnn-riscv.c (riscv_elf_relocate_section): Return TRUE if used
diff --git a/bfd/elf32-ppc.c b/bfd/elf32-ppc.c
index 32104a1..092b1ce 100644
--- a/bfd/elf32-ppc.c
+++ b/bfd/elf32-ppc.c
@@ -69,7 +69,7 @@ static bfd_reloc_status_type ppc_elf_unhandled_reloc
 /* For new-style .glink and .plt.  */
 #define GLINK_PLTRESOLVE 16*4
 #define GLINK_ENTRY_SIZE(htab, h)					\
-  (((!htab->params->speculate_indirect_jumps ? 6*4 : 4*4)			\
+  ((4*4									\
     + (h != NULL							\
        && h == htab->tls_get_addr					\
        && !htab->params->no_tls_get_addr_opt ? 8*4 : 0)			\
@@ -155,8 +155,6 @@ static const bfd_vma ppc_elf_vxworks_pic_plt0_entry
 #define BA		0x48000002
 #define BCL_20_31	0x429f0005
 #define BCTR		0x4e800420
-#define CRSETEQ		0x4c421242
-#define BEQCTRM		0x4dc20420
 #define BEQLR		0x4d820020
 #define CMPWI_11_0	0x2c0b0000
 #define LIS_11		0x3d600000
@@ -2880,14 +2878,15 @@ ppc_elf_final_write_processing (bfd *abfd, bfd_boolean linker ATTRIBUTE_UNUSED)
 static bfd_boolean
 is_nonpic_glink_stub (bfd *abfd, asection *glink, bfd_vma off)
 {
-  bfd_byte buf[3 * 4];
+  bfd_byte buf[4 * 4];
 
   if (!bfd_get_section_contents (abfd, glink, buf, off, sizeof buf))
     return FALSE;
 
   return ((bfd_get_32 (abfd, buf + 0) & 0xffff0000) == LIS_11
 	  && (bfd_get_32 (abfd, buf + 4) & 0xffff0000) == LWZ_11_11
-	  && bfd_get_32 (abfd, buf + 8) == MTCTR_11);
+	  && bfd_get_32 (abfd, buf + 8) == MTCTR_11
+	  && bfd_get_32 (abfd, buf + 12) == BCTR);
 }
 
 static bfd_boolean
@@ -3366,7 +3365,7 @@ ppc_elf_link_hash_table_create (bfd *abfd)
 {
   struct ppc_elf_link_hash_table *ret;
   static struct ppc_elf_params default_params
-    = { PLT_OLD, 0, 1, 0, 1, 0, 0, 12, 0, 0, 0 };
+    = { PLT_OLD, 0, 0, 1, 0, 0, 12, 0, 0, 0 };
 
   ret = bfd_zmalloc (sizeof (struct ppc_elf_link_hash_table));
   if (ret == NULL)
@@ -7171,8 +7170,6 @@ ppc_elf_relax_section (bfd *abfd,
 		  size = 4 * ARRAY_SIZE (stub_entry);
 		  insn_offset = 0;
 		}
-	      if (!htab->params->speculate_indirect_jumps)
-		size += 8;
 	      stub_rtype = R_PPC_RELAX;
 	      if (tsec == htab->elf.splt
 		  || tsec == htab->glink)
@@ -7454,26 +7451,6 @@ elf_finish_pointer_linker_section (bfd *input_bfd,
 #define PPC_HI(v) (((v) >> 16) & 0xffff)
 #define PPC_HA(v) PPC_HI ((v) + 0x8000)
 
-static inline bfd_byte *
-output_bctr (struct ppc_elf_link_hash_table *htab, bfd *obfd, bfd_byte *p)
-{
-  if (!htab->params->speculate_indirect_jumps)
-    {
-      bfd_put_32 (obfd, CRSETEQ, p);
-      p += 4;
-      bfd_put_32 (obfd, BEQCTRM, p);
-      p += 4;
-      bfd_put_32 (obfd, B, p);
-      p += 4;
-    }
-  else
-    {
-      bfd_put_32 (obfd, BCTR, p);
-      p += 4;
-    }
-  return p;
-}
-
 static void
 write_glink_stub (struct elf_link_hash_entry *h, struct plt_entry *ent,
 		  asection *plt_sec, unsigned char *p,
@@ -7541,7 +7518,8 @@ write_glink_stub (struct elf_link_hash_entry *h, struct plt_entry *ent,
   p += 4;
   bfd_put_32 (output_bfd, MTCTR_11, p);
   p += 4;
-  p = output_bctr (htab, output_bfd, p);
+  bfd_put_32 (output_bfd, BCTR, p);
+  p += 4;
   while (p < end)
     {
       bfd_put_32 (output_bfd, htab->params->ppc476_workaround ? BA : NOP, p);
@@ -8979,7 +8957,6 @@ ppc_elf_relocate_section (bfd *output_bfd,
 		stub = stub_entry;
 		size = ARRAY_SIZE (stub_entry);
 	      }
-	    --size;
 
 	    relocation += addend;
 	    if (bfd_link_relocatable (info))
@@ -9004,7 +8981,6 @@ ppc_elf_relocate_section (bfd *output_bfd,
 		bfd_put_32 (input_bfd, insn, contents + insn_offset);
 		insn_offset += 4;
 	      }
-	    output_bctr (htab, input_bfd, contents + insn_offset);
 
 	    /* Rewrite the reloc and convert one of the trailing nop
 	       relocs to describe this relocation.  */
@@ -10713,7 +10689,8 @@ ppc_elf_finish_dynamic_sections (bfd *output_bfd,
       p += 4;
       bfd_put_32 (output_bfd, ADD_11_0_11, p);
       p += 4;
-      p = output_bctr (htab, output_bfd, p);
+      bfd_put_32 (output_bfd, BCTR, p);
+      p += 4;
       while (p < endp)
 	{
 	  bfd_put_32 (output_bfd,
diff --git a/bfd/elf32-ppc.h b/bfd/elf32-ppc.h
index 8977efa..f56d027 100644
--- a/bfd/elf32-ppc.h
+++ b/bfd/elf32-ppc.h
@@ -35,9 +35,6 @@ struct ppc_elf_params
   /* Set if individual PLT call stubs should be aligned.  */
   int plt_stub_align;
 
-  /* Clear if PLT call stubs should use a speculative execution barrier.  */
-  int speculate_indirect_jumps;
-
   /* Whether to emit symbols for stubs.  */
   int emit_stub_syms;
 
diff --git a/bfd/elf64-ppc.c b/bfd/elf64-ppc.c
index d6ec12f..2d43df89 100644
--- a/bfd/elf64-ppc.c
+++ b/bfd/elf64-ppc.c
@@ -161,10 +161,6 @@ static bfd_vma opd_entry_value
 #define LD_R11_0R11	0xe96b0000	/* ld	 %r11,xxx+16@l(%r11) */
 #define BCTR		0x4e800420	/* bctr			     */
 
-#define CRSETEQ		0x4c421242	/* crset 4*%cr0+%eq	 */
-#define BEQCTRM		0x4dc20420	/* beqctr-		 */
-#define BEQCTRLM	0x4dc20421	/* beqctrl-		 */
-
 #define ADDI_R11_R11	0x396b0000	/* addi %r11,%r11,off@l	 */
 #define ADDIS_R2_R2	0x3c420000	/* addis %r2,%r2,off@ha	 */
 #define ADDI_R2_R2	0x38420000	/* addi	 %r2,%r2,off@l	 */
@@ -193,8 +189,7 @@ static bfd_vma opd_entry_value
 
 /* __glink_PLTresolve stub instructions.  We enter with the index in R0.  */
 #define GLINK_PLTRESOLVE_SIZE(htab)			\
-  (8u + (htab->opd_abi ? 11 * 4 : 14 * 4)		\
-   + (!htab->params->speculate_indirect_jumps ? 2 * 4 : 0))
+  (8u + (htab->opd_abi ? 11 * 4 : 14 * 4))
 					/* 0:				*/
 					/*  .quad plt0-1f		*/
 					/* __glink:			*/
@@ -9886,8 +9881,6 @@ size_global_entry_stubs (struct elf_link_hash_entry *h, void *inf)
 	unsigned int align_power;
 
 	stub_size = 16;
-	if (!htab->params->speculate_indirect_jumps)
-	  stub_size += 8;
 	stub_off = s->size;
 	if (htab->params->plt_stub_align >= 0)
 	  align_power = htab->params->plt_stub_align;
@@ -10453,8 +10446,6 @@ plt_stub_size (struct ppc_link_hash_table *htab,
     size += 4;
   if (PPC_HA (off) != 0)
     size += 4;
-  if (!htab->params->speculate_indirect_jumps)
-    size += 8;
   if (htab->opd_abi)
     {
       size += 4;
@@ -10476,11 +10467,7 @@ plt_stub_size (struct ppc_link_hash_table *htab,
       size += 7 * 4;
       if (ALWAYS_EMIT_R2SAVE
 	  || stub_entry->stub_type == ppc_stub_plt_call_r2save)
-	{
-	  size += 6 * 4;
-	  if (!htab->params->speculate_indirect_jumps)
-	    size -= 4;
-	}
+	size += 6 * 4;
     }
   return size;
 }
@@ -10515,26 +10502,6 @@ plt_stub_pad (struct ppc_link_hash_table *htab,
   return 0;
 }
 
-static inline bfd_byte *
-output_bctr (struct ppc_link_hash_table *htab, bfd *obfd, bfd_byte *p)
-{
-  if (!htab->params->speculate_indirect_jumps)
-    {
-      bfd_put_32 (obfd, CRSETEQ, p);
-      p += 4;
-      bfd_put_32 (obfd, BEQCTRM, p);
-      p += 4;
-      bfd_put_32 (obfd, B_DOT, p);
-      p += 4;
-    }
-  else
-    {
-      bfd_put_32 (obfd, BCTR, p);
-      p += 4;
-    }
-  return p;
-}
-
 /* Build a .plt call stub.  */
 
 static inline bfd_byte *
@@ -10555,7 +10522,6 @@ build_plt_stub (struct ppc_link_hash_table *htab,
   if (!ALWAYS_USE_FAKE_DEP
       && plt_load_toc
       && plt_thread_safe
-      && htab->params->speculate_indirect_jumps
       && !((stub_entry->h == htab->tls_get_addr_fd
 	    || stub_entry->h == htab->tls_get_addr)
 	   && htab->params->tls_get_addr_opt))
@@ -10710,7 +10676,7 @@ build_plt_stub (struct ppc_link_hash_table *htab,
       bfd_put_32 (obfd, B_DOT | (cmp_branch_off & 0x3fffffc), p), p += 4;
     }
   else
-    p = output_bctr (htab, obfd, p);
+    bfd_put_32 (obfd, BCTR, p),					p += 4;
   return p;
 }
 
@@ -10754,13 +10720,7 @@ build_tls_get_addr_stub (struct ppc_link_hash_table *htab,
   if (r != NULL)
     r[0].r_offset += 2 * 4;
   p = build_plt_stub (htab, stub_entry, p, offset, r);
-  if (!htab->params->speculate_indirect_jumps)
-    {
-      p -= 4;
-      bfd_put_32 (obfd, BEQCTRLM, p - 4);
-    }
-  else
-    bfd_put_32 (obfd, BCTRL, p - 4);
+  bfd_put_32 (obfd, BCTRL, p - 4);
 
   bfd_put_32 (obfd, LD_R2_0R1 + STK_TOC (htab), p),	p += 4;
   bfd_put_32 (obfd, LD_R11_0R1 + STK_LINKER (htab), p),	p += 4;
@@ -11113,7 +11073,8 @@ ppc_build_one_stub (struct bfd_hash_entry *gen_entry, void *in_arg)
       p += 4;
       bfd_put_32 (htab->params->stub_bfd, MTCTR_R12, p);
       p += 4;
-      p = output_bctr (htab, htab->params->stub_bfd, p);
+      bfd_put_32 (htab->params->stub_bfd, BCTR, p);
+      p += 4;
       break;
 
     case ppc_stub_plt_call:
@@ -11446,8 +11407,6 @@ ppc_size_one_stub (struct bfd_hash_entry *gen_entry, void *in_arg)
 	      if (PPC_LO (r2off) != 0)
 		size += 4;
 	    }
-	  if (!htab->params->speculate_indirect_jumps)
-	    size += 8;
 	}
       else if (info->emitrelocations)
 	{
@@ -13089,7 +13048,7 @@ build_global_entry_stubs (struct elf_link_hash_entry *h, void *inf)
 	p += 4;
 	bfd_put_32 (s->owner, MTCTR_R12, p);
 	p += 4;
-	output_bctr (htab, s->owner, p);
+	bfd_put_32 (s->owner, BCTR, p);
 	break;
       }
   return TRUE;
@@ -13218,7 +13177,8 @@ ppc64_elf_build_stubs (struct bfd_link_info *info,
 	  bfd_put_32 (htab->glink->owner, LD_R11_0R11 | 8, p);
 	  p += 4;
 	}
-      p = output_bctr (htab, htab->glink->owner, p);
+      bfd_put_32 (htab->glink->owner, BCTR, p);
+      p += 4;
       BFD_ASSERT (p == htab->glink->contents + GLINK_PLTRESOLVE_SIZE (htab));
 
       /* Build the .glink lazy link call stubs.  */
diff --git a/bfd/elf64-ppc.h b/bfd/elf64-ppc.h
index b3d4d59..8fa0140 100644
--- a/bfd/elf64-ppc.h
+++ b/bfd/elf64-ppc.h
@@ -51,9 +51,6 @@ struct ppc64_elf_params
   /* Set if PLT call stubs for localentry:0 functions should omit r2 save.  */
   int plt_localentry0;
 
-  /* Clear if PLT call stubs should use a speculative execution barrier.  */
-  int speculate_indirect_jumps;
-
   /* Whether to canonicalize .opd so that there are no overlapping
      .opd entries.  */
   int non_overlapping_opd;