[binutils-gdb/or1k-large-fixes] or1k: Avoid R_OR1K_GOT16 overflow failures in presence of R_OR1K_GOT_AHI16

[Stafford Horne]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=3c3de29b048bca6b4aa4235c647b9328e71801b6

commit 3c3de29b048bca6b4aa4235c647b9328e71801b6
Author: Stafford Horne <shorne@gmail.com>
Date:   Thu May 6 20:51:25 2021 +0900

    or1k: Avoid R_OR1K_GOT16 overflow failures in presence of R_OR1K_GOT_AHI16
    
    Now that we support R_OR1K_GOT_AHI16 we can relax the R_OR1K_GOT16
    overflow validation check if the section has R_OR1K_GOT_AHI16.
    
    We cannot simple disable R_OR1K_GOT16 overflow validation as there will
    still be binaries that will have only R_OR1K_GOT16.  The
    R_OR1K_GOT_AHI16 relocation will only be added by GCC when building with
    the option -mcmodel=large.
    
    This assumes that R_OR1K_GOT_AHI16 will come before R_OR1K_GOT16, which
    is the code pattern that will be emitted by GCC.
    
    bfd/ChangeLog:
    
            PR 21464
            * elf32-or1k.c (or1k_elf_relocate_section): Relax R_OR1K_GOT16
            overflow check if we have R_OR1K_GOT_AHI16 followed by
            R_OR1K_GOT16.

Diff:
---
 bfd/ChangeLog    |  7 +++++++
 bfd/elf32-or1k.c | 11 +++++++++++
 2 files changed, 18 insertions(+)

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index c4a83dfe4f7..8293e9d7952 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,10 @@
+2021-05-06  Stafford Horne  <shorne@gmail.com>
+
+	PR 21464
+	* elf32-or1k.c (or1k_elf_relocate_section): Relax R_OR1K_GOT16
+	overflow check if we have R_OR1K_GOT_AHI16 followed by
+	R_OR1K_GOT16.
+
 2021-05-06  Stafford Horne  <shorne@gmail.com>
 
 	PR 21464
diff --git a/bfd/elf32-or1k.c b/bfd/elf32-or1k.c
index 1b8938df37f..5eca4300c45 100644
--- a/bfd/elf32-or1k.c
+++ b/bfd/elf32-or1k.c
@@ -1278,6 +1278,7 @@ or1k_elf_relocate_section (bfd *output_bfd,
   asection *sgot, *splt;
   bfd_vma plt_base, got_base, got_sym_value;
   bool ret_val = true;
+  bool saw_gotha = false;
 
   if (htab == NULL)
     return false;
@@ -1485,6 +1486,16 @@ or1k_elf_relocate_section (bfd *output_bfd,
 		|| r_type == R_OR1K_GOT_AHI16)
 	      relocation -= got_sym_value;
 
+	    if (r_type == R_OR1K_GOT_AHI16)
+	      saw_gotha = true;
+
+	    /* If we have a R_OR1K_GOT16 followed by a R_OR1K_GOT_AHI16
+	       relocation we assume the code is doing the right thing to avoid
+	       overflows.  Here we mask the lower 16-bit of the relocation to
+	       avoid overflow validation failures.  */
+	    if (r_type == R_OR1K_GOT16 && saw_gotha)
+	      relocation &= 0xffff;
+
 	  /* Addend should be zero.  */
 	  if (rel->r_addend != 0)
 	    {