Add a more helpful warning message to explain why some AArch64 relocations can overflow.

[deliverable/binutils-gdb.git] / bfd / elfnn-aarch64.c

diff --git a/bfd/elfnn-aarch64.c b/bfd/elfnn-aarch64.c
index 292470df73ed97768880b172cf7e995cbb31dc4f..99acab4e7d0b60223e8a2984be1355c64f76e225 100644 (file)
--- a/bfd/elfnn-aarch64.c
+++ b/bfd/elfnn-aarch64.c
@@ -6405,10 +6405,6 @@ elfNN_aarch64_relocate_section (bfd *output_bfd,
          break;
        }
 
-      if (!save_addend)
-       addend = 0;
-
-
       /* Dynamic relocs are not propagated for SEC_DEBUGGING sections
          because such sections are not SEC_ALLOC and thus ld.so will
          not process them.  */
@@ -6448,6 +6444,34 @@ elfNN_aarch64_relocate_section (bfd *output_bfd,
                     name, input_bfd, input_section, rel->r_offset);
                  return FALSE;
                }
+             /* Overflow can occur when a variable is referenced with a type
+                that has a larger alignment than the type with which it was
+                declared. eg:
+                  file1.c: extern int foo; int a (void) { return foo; }
+                  file2.c: char bar, foo, baz;
+                If the variable is placed into a data section at an offset
+                that is incompatible with the larger alignment requirement
+                overflow will occur.  (Strictly speaking this is not overflow
+                but rather an alignment problem, but the bfd_reloc_ error
+                enum does not have a value to cover that situation).
+
+                Try to catch this situation here and provide a more helpful
+                error message to the user.  */
+             if (addend & ((1 << howto->rightshift) - 1)
+                 /* FIXME: Are we testing all of the appropriate reloc
+                    types here ?  */
+                 && (real_r_type == BFD_RELOC_AARCH64_LD_LO19_PCREL
+                     || real_r_type == BFD_RELOC_AARCH64_LDST16_LO12
+                     || real_r_type == BFD_RELOC_AARCH64_LDST32_LO12
+                     || real_r_type == BFD_RELOC_AARCH64_LDST64_LO12
+                     || real_r_type == BFD_RELOC_AARCH64_LDST128_LO12))
+               {
+                 info->callbacks->warning
+                   (info, _("One possible cause of this error is that the \
+symbol is being referenced in the indicated code as if it had a larger \
+alignment than was declared where it was defined."),
+                    name, input_bfd, input_section, rel->r_offset);
+               }
              break;
 
            case bfd_reloc_undefined:
@@ -6482,6 +6506,9 @@ elfNN_aarch64_relocate_section (bfd *output_bfd,
              break;
            }
        }
+
+      if (!save_addend)
+       addend = 0;
     }
 
   return TRUE;