ld: aarch64: Adjust TLS relaxation condition

In aarch64_tls_transition_without_check and elfNN_aarch64_tls_relax we
choose whether to perform a relaxation to an IE access model or an LE
access model based on whether the symbol itself is marked as local (i.e.
`h == NULL`).

This is problematic in two ways.  The first is that sometimes a global
dynamic access can be relaxed to an initial exec access when creating a
shared library, and if that happens on a local symbol then we currently
relax it to a local exec access instead.  This usually does not happen
since we only relax an access if aarch64_can_relax_tls returns true and
aarch64_can_relax_tls does not have the same problem.  However, it can
happen when we have seen both an IE and GD access on the same symbol.
This case is exercised in the newly added testcase tls-relax-gd-ie-2.

The second problem is that deciding based on whether the symbol is local
misses the case when the symbol is global but is still non-interposable
and known to be located in the executable.  This happens on all global
symbols in executables.
This case is exercised in the newly added testcase tls-relax-ie-le-4.

Here we adjust the condition we base our relaxation on so that we relax
to local-exec if we are creating an executable and the relevant symbol
we're accessing is stored inside that executable.

-- Updating tests for new relaxation criteria

Many of the tests added to check our relaxation to IE were implemented
by taking advantage of the fact that we did not relax a global symbol
defined in an executable.

Since a global symbol defined in an executable is still not
interposable, we know that a TLS version of such a symbol will be in the
main TLS block.  This means that we can perform a stronger relaxation on
such symbols and relax their accesses to a local-exec access.

Hence we have to update all tests that relied on the older suboptimal
decision making.

The two cases when we still would want to relax a general dynamic access
to an initial exec one are:
1) When in a shared library and accessing a symbol which we have already
   seen accessed with an initial exec access sequence.
2) When in an executable and accessing a symbol defined in a shared
   library.

Both of these require shared library support, which means that these
tests are now only available on targets with that.

I have chosen to switch the existing testcases from a plain executable
to one dynamically linked to a shared object as that doesn't require
changing the testcases quite so much (just requires accessing a
different variable rather than requiring adding another code sequence).

The tls-relax-all testcase was an outlier to the above approach, since
it included a general dynamic access to both a local and global symbol
and inspected for the difference accordingly.

1 files changed, 37 insertions, 33 deletions

diff --git a/bfd/elfnn-aarch64.c b/bfd/elfnn-aarch64.c
index cf4db84..ac48a17 100644
--- a/bfd/elfnn-aarch64.c
+++ b/bfd/elfnn-aarch64.c
@@ -4898,60 +4898,62 @@ aarch64_calculate_got_entry_vma (struct elf_link_hash_entry *h,
 
 static bfd_reloc_code_real_type
 aarch64_tls_transition_without_check (bfd_reloc_code_real_type r_type,
-				      struct elf_link_hash_entry *h)
+				      struct elf_link_hash_entry *h,
+				      struct bfd_link_info *info)
 {
-  bool is_local = h == NULL;
+  bool local_exec = bfd_link_executable (info)
+    && SYMBOL_REFERENCES_LOCAL (info, h);
 
   switch (r_type)
     {
     case BFD_RELOC_AARCH64_TLSDESC_ADR_PAGE21:
     case BFD_RELOC_AARCH64_TLSGD_ADR_PAGE21:
-      return (is_local
+      return (local_exec
 	      ? BFD_RELOC_AARCH64_TLSLE_MOVW_TPREL_G1
 	      : BFD_RELOC_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21);
 
     case BFD_RELOC_AARCH64_TLSDESC_ADR_PREL21:
-      return (is_local
+      return (local_exec
 	      ? BFD_RELOC_AARCH64_TLSLE_MOVW_TPREL_G0_NC
 	      : r_type);
 
     case BFD_RELOC_AARCH64_TLSDESC_LD_PREL19:
-      return (is_local
+      return (local_exec
 	      ? BFD_RELOC_AARCH64_TLSLE_MOVW_TPREL_G1
 	      : BFD_RELOC_AARCH64_TLSIE_LD_GOTTPREL_PREL19);
 
     case BFD_RELOC_AARCH64_TLSDESC_LDR:
-      return (is_local
+      return (local_exec
 	      ? BFD_RELOC_AARCH64_TLSLE_MOVW_TPREL_G0_NC
 	      : BFD_RELOC_AARCH64_NONE);
 
     case BFD_RELOC_AARCH64_TLSDESC_OFF_G0_NC:
-      return (is_local
+      return (local_exec
 	      ? BFD_RELOC_AARCH64_TLSLE_MOVW_TPREL_G1_NC
 	      : BFD_RELOC_AARCH64_TLSIE_MOVW_GOTTPREL_G0_NC);
 
     case BFD_RELOC_AARCH64_TLSDESC_OFF_G1:
-      return (is_local
+      return (local_exec
 	      ? BFD_RELOC_AARCH64_TLSLE_MOVW_TPREL_G2
 	      : BFD_RELOC_AARCH64_TLSIE_MOVW_GOTTPREL_G1);
 
     case BFD_RELOC_AARCH64_TLSDESC_LDNN_LO12_NC:
     case BFD_RELOC_AARCH64_TLSGD_ADD_LO12_NC:
-      return (is_local
+      return (local_exec
 	      ? BFD_RELOC_AARCH64_TLSLE_MOVW_TPREL_G0_NC
 	      : BFD_RELOC_AARCH64_TLSIE_LDNN_GOTTPREL_LO12_NC);
 
     case BFD_RELOC_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21:
-      return is_local ? BFD_RELOC_AARCH64_TLSLE_MOVW_TPREL_G1 : r_type;
+      return local_exec ? BFD_RELOC_AARCH64_TLSLE_MOVW_TPREL_G1 : r_type;
 
     case BFD_RELOC_AARCH64_TLSIE_LDNN_GOTTPREL_LO12_NC:
-      return is_local ? BFD_RELOC_AARCH64_TLSLE_MOVW_TPREL_G0_NC : r_type;
+      return local_exec ? BFD_RELOC_AARCH64_TLSLE_MOVW_TPREL_G0_NC : r_type;
 
     case BFD_RELOC_AARCH64_TLSIE_LD_GOTTPREL_PREL19:
       return r_type;
 
     case BFD_RELOC_AARCH64_TLSGD_ADR_PREL21:
-      return (is_local
+      return (local_exec
 	      ? BFD_RELOC_AARCH64_TLSLE_ADD_TPREL_HI12
 	      : BFD_RELOC_AARCH64_TLSIE_LD_GOTTPREL_PREL19);
 
@@ -4964,16 +4966,16 @@ aarch64_tls_transition_without_check (bfd_reloc_code_real_type r_type,
     case BFD_RELOC_AARCH64_TLSLD_ADD_LO12_NC:
     case BFD_RELOC_AARCH64_TLSLD_ADR_PAGE21:
     case BFD_RELOC_AARCH64_TLSLD_ADR_PREL21:
-      return is_local ? BFD_RELOC_AARCH64_NONE : r_type;
+      return local_exec ? BFD_RELOC_AARCH64_NONE : r_type;
 
 #if ARCH_SIZE == 64
     case BFD_RELOC_AARCH64_TLSGD_MOVW_G0_NC:
-      return is_local
+      return local_exec
 	? BFD_RELOC_AARCH64_TLSLE_MOVW_TPREL_G1_NC
 	: BFD_RELOC_AARCH64_TLSIE_MOVW_GOTTPREL_G0_NC;
 
     case BFD_RELOC_AARCH64_TLSGD_MOVW_G1:
-      return is_local
+      return local_exec
 	? BFD_RELOC_AARCH64_TLSLE_MOVW_TPREL_G2
 	: BFD_RELOC_AARCH64_TLSIE_MOVW_GOTTPREL_G1;
 #endif
@@ -5082,7 +5084,7 @@ aarch64_tls_transition (bfd *input_bfd,
   if (! aarch64_can_relax_tls (input_bfd, info, bfd_r_type, h, r_symndx))
     return bfd_r_type;
 
-  return aarch64_tls_transition_without_check (bfd_r_type, h);
+  return aarch64_tls_transition_without_check (bfd_r_type, h, info);
 }
 
 /* Return the base VMA address which should be subtracted from real addresses
@@ -6321,9 +6323,11 @@ static bfd_reloc_status_type
 elfNN_aarch64_tls_relax (struct elf_aarch64_link_hash_table *globals,
 			 bfd *input_bfd, asection *input_section,
 			 bfd_byte *contents, Elf_Internal_Rela *rel,
-			 struct elf_link_hash_entry *h)
+			 struct elf_link_hash_entry *h,
+			 struct bfd_link_info *info)
 {
-  bool is_local = h == NULL;
+  bool local_exec = bfd_link_executable (info)
+    && SYMBOL_REFERENCES_LOCAL (info, h);
   unsigned int r_type = ELFNN_R_TYPE (rel->r_info);
   unsigned long insn;
 
@@ -6333,7 +6337,7 @@ elfNN_aarch64_tls_relax (struct elf_aarch64_link_hash_table *globals,
     {
     case BFD_RELOC_AARCH64_TLSDESC_ADR_PAGE21:
     case BFD_RELOC_AARCH64_TLSGD_ADR_PAGE21:
-      if (is_local)
+      if (local_exec)
 	{
 	  /* GD->LE relaxation:
 	     adrp x0, :tlsgd:var     =>   movz R0, :tprel_g1:var
@@ -6362,7 +6366,7 @@ elfNN_aarch64_tls_relax (struct elf_aarch64_link_hash_table *globals,
       break;
 
     case BFD_RELOC_AARCH64_TLSDESC_LD_PREL19:
-      if (is_local)
+      if (local_exec)
 	{
 	  /* Tiny TLSDESC->LE relaxation:
 	     ldr   x1, :tlsdesc:var	 =>  movz  R0, #:tprel_g1:var
@@ -6404,7 +6408,7 @@ elfNN_aarch64_tls_relax (struct elf_aarch64_link_hash_table *globals,
 	}
 
     case BFD_RELOC_AARCH64_TLSGD_ADR_PREL21:
-      if (is_local)
+      if (local_exec)
 	{
 	  /* Tiny GD->LE relaxation:
 	     adr x0, :tlsgd:var	     =>	  mrs  x1, tpidr_el0
@@ -6456,7 +6460,7 @@ elfNN_aarch64_tls_relax (struct elf_aarch64_link_hash_table *globals,
       BFD_ASSERT (rel->r_offset + 12 == rel[2].r_offset);
       BFD_ASSERT (ELFNN_R_TYPE (rel[2].r_info) == AARCH64_R (CALL26));
 
-      if (is_local)
+      if (local_exec)
 	{
 	  /* Large GD->LE relaxation:
 	     movz x0, #:tlsgd_g1:var	=> movz x0, #:tprel_g2:var, lsl #32
@@ -6500,7 +6504,7 @@ elfNN_aarch64_tls_relax (struct elf_aarch64_link_hash_table *globals,
       return bfd_reloc_continue;
 
     case BFD_RELOC_AARCH64_TLSDESC_LDNN_LO12_NC:
-      if (is_local)
+      if (local_exec)
 	{
 	  /* GD->LE relaxation:
 	     ldr xd, [x0, #:tlsdesc_lo12:var]   =>   movk x0, :tprel_g0_nc:var
@@ -6521,7 +6525,7 @@ elfNN_aarch64_tls_relax (struct elf_aarch64_link_hash_table *globals,
 	}
 
     case BFD_RELOC_AARCH64_TLSGD_ADD_LO12_NC:
-      if (is_local)
+      if (local_exec)
 	{
 	  /* GD->LE relaxation
 	     add  x0, #:tlsgd_lo12:var	=> movk R0, :tprel_g0_nc:var
@@ -6574,7 +6578,7 @@ elfNN_aarch64_tls_relax (struct elf_aarch64_link_hash_table *globals,
       return bfd_reloc_ok;
 
     case BFD_RELOC_AARCH64_TLSDESC_LDR:
-      if (is_local)
+      if (local_exec)
 	{
 	  /* GD->LE relaxation:
 	     ldr xd, [gp, xn]   =>   movk R0, #:tprel_g0_nc:var
@@ -6601,12 +6605,12 @@ elfNN_aarch64_tls_relax (struct elf_aarch64_link_hash_table *globals,
 	 movk xd, #:tlsdesc_off_g0_nc:var => movk Rd, #:gottprel_g0_nc:var
 
 	 Where R is x for lp64 mode, and w for ILP32 mode.  */
-      if (is_local)
+      if (local_exec)
 	bfd_putl32 (ldr_hw_R0, contents + rel->r_offset);
       return bfd_reloc_continue;
 
     case BFD_RELOC_AARCH64_TLSDESC_OFF_G1:
-      if (is_local)
+      if (local_exec)
 	{
 	  /* GD->LE relaxation:
 	     movz xd, #:tlsdesc_off_g1:var => movz R0, #:tprel_g2:var, lsl #32
@@ -6631,7 +6635,7 @@ elfNN_aarch64_tls_relax (struct elf_aarch64_link_hash_table *globals,
 	 adrp xd, :gottprel:var   =>   movz Rd, :tprel_g1:var
 
 	 Where R is x for lp64 mode, and w for ILP32 mode.  */
-      if (is_local)
+      if (local_exec)
 	{
 	  insn = bfd_getl32 (contents + rel->r_offset);
 	  bfd_putl32 (movz_R0 | (insn & 0x1f), contents + rel->r_offset);
@@ -6646,7 +6650,7 @@ elfNN_aarch64_tls_relax (struct elf_aarch64_link_hash_table *globals,
 	 ldr  xd, [xm, #:gottprel_lo12:var]   =>   movk Rd, :tprel_g0_nc:var
 
 	 Where R is x for lp64 mode, and w for ILP32 mode.  */
-      if (is_local)
+      if (local_exec)
 	{
 	  insn = bfd_getl32 (contents + rel->r_offset);
 	  bfd_putl32 (movk_R0 | (insn & 0x1f), contents + rel->r_offset);
@@ -6659,7 +6663,7 @@ elfNN_aarch64_tls_relax (struct elf_aarch64_link_hash_table *globals,
 	 bl   __tls_get_addr => add R0, R0, TCB_SIZE
 
 	 Where R is x for lp64 mode, and w for ilp32 mode.  */
-      if (is_local)
+      if (local_exec)
 	{
 	  BFD_ASSERT (rel->r_offset + 4 == rel[1].r_offset);
 	  BFD_ASSERT (ELFNN_R_TYPE (rel[1].r_info) == AARCH64_R (CALL26));
@@ -6676,7 +6680,7 @@ elfNN_aarch64_tls_relax (struct elf_aarch64_link_hash_table *globals,
       /* LD->LE relaxation (small):
 	 adrp  x0, :tlsldm:x       => mrs x0, tpidr_el0
        */
-      if (is_local)
+      if (local_exec)
 	{
 	  bfd_putl32 (0xd53bd040, contents + rel->r_offset);
 	  return bfd_reloc_ok;
@@ -6689,7 +6693,7 @@ elfNN_aarch64_tls_relax (struct elf_aarch64_link_hash_table *globals,
 	 bl   __tls_get_addr       => nop
 
 	 Where R is x for lp64 mode, and w for ilp32 mode.  */
-      if (is_local)
+      if (local_exec)
 	{
 	  BFD_ASSERT (rel->r_offset + 4 == rel[1].r_offset);
 	  BFD_ASSERT (ELFNN_R_TYPE (rel[1].r_info) == AARCH64_R (CALL26));
@@ -6863,7 +6867,7 @@ elfNN_aarch64_relocate_section (bfd *output_bfd,
 	  BFD_ASSERT (howto != NULL);
 	  r_type = howto->type;
 	  r = elfNN_aarch64_tls_relax (globals, input_bfd, input_section,
-				       contents, rel, h);
+				       contents, rel, h, info);
 	  unresolved_reloc = 0;
 	}
       else