Fix PR 20221 - adjust syms and relocs only if relax shrunk section.

This patch fixes an edge case in linker relaxation that causes symbol
values to be computed incorrectly in the presence of align directives
in input source code.

bfd/
	* elf32-avr.c (elf32_avr_relax_delete_bytes): Adjust syms
	and relocs only if shrinking occurred.

ld/
	* testsuite/ld-avr/avr-prop-5.d: New.
	* testsuite/ld-avr/avr-prop-5.s: New.

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 6d70417eb7cfdb1f8bcfd52eea917273745dea0e..c601d0057c990cec02821f0d22e27437e330abb7 100644 (file)
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,12 @@
+2016-06-13  Senthil Kumar Selvaraj  <senthil_kumar.selvaraj@atmel.com>
+
+       Backport from master
+       2016-06-08  Senthil Kumar Selvaraj  <senthil_kumar.selvaraj@atmel.com>
+
+       PR ld/20221
+       * elf32-avr.c (elf32_avr_relax_delete_bytes): Adjust syms
+       and relocs only if shrinking occurred.
+
 2016-06-09  Alan Modra  <amodra@gmail.com>
 
        PR ld/20159

diff --git a/bfd/elf32-avr.c b/bfd/elf32-avr.c
index 9aa5a68888af9e34085ed360be5674cf17a546e3..422c4aca679089241461ebfe5763ccabf45f6fa6 100644 (file)
--- a/bfd/elf32-avr.c
+++ b/bfd/elf32-avr.c
@@ -1832,6 +1832,7 @@ elf32_avr_relax_delete_bytes (bfd *abfd,
   unsigned int symcount;
   struct avr_relax_info *relax_info;
   struct avr_property_record *prop_record = NULL;
+  bfd_boolean did_shrink = FALSE;
 
   symtab_hdr = &elf_tdata (abfd)->symtab_hdr;
   sec_shndx = _bfd_elf_section_from_bfd_section (abfd, sec);
@@ -1867,10 +1868,16 @@ elf32_avr_relax_delete_bytes (bfd *abfd,
 
   /* Actually delete the bytes.  */
   if (toaddr - addr - count > 0)
-    memmove (contents + addr, contents + addr + count,
-             (size_t) (toaddr - addr - count));
+    {
+      memmove (contents + addr, contents + addr + count,
+               (size_t) (toaddr - addr - count));
+      did_shrink = TRUE;
+    }
   if (prop_record == NULL)
-    sec->size -= count;
+    {
+      sec->size -= count;
+      did_shrink = TRUE;
+    }
   else
     {
       /* Use the property record to fill in the bytes we've opened up.  */
@@ -1889,6 +1896,11 @@ elf32_avr_relax_delete_bytes (bfd *abfd,
           prop_record->data.align.preceding_deleted += count;
           break;
         };
+      /* If toaddr == (addr + count), then we didn't delete anything, yet
+         we fill count bytes backwards from toaddr. This is still ok - we
+         end up overwriting the bytes we would have deleted. We just need
+         to remember we didn't delete anything i.e. don't set did_shrink,
+         so that we don't corrupt reloc offsets or symbol values.*/
       memset (contents + toaddr - count, fill, count);
 
       /* Adjust the TOADDR to avoid moving symbols located at the address
@@ -1896,6 +1908,9 @@ elf32_avr_relax_delete_bytes (bfd *abfd,
       toaddr -= count;
     }
 
+  if (!did_shrink)
+    return TRUE;
+
   /* Adjust all the reloc addresses.  */
   for (irel = elf_section_data (sec)->relocs; irel < irelend; irel++)
     {

diff --git a/ld/ChangeLog b/ld/ChangeLog
index 7594faca06726aa4af23684c4c6b12942e143148..e78421634d6eb3dabce267920a44f2b66175d5b7 100644 (file)
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,12 @@
+2016-06-13  Senthil Kumar Selvaraj  <senthil_kumar.selvaraj@atmel.com>
+
+       Backport from master
+       2016-06-08  Senthil Kumar Selvaraj  <senthil_kumar.selvaraj@atmel.com>
+
+       PR ld/20221
+       * testsuite/ld-avr/avr-prop-5.d: New.
+       * testsuite/ld-avr/avr-prop-5.s: New.
+
 2016-06-11  H.J. Lu  <hongjiu.lu@intel.com>
 
        Backport from master

diff --git a/ld/testsuite/ld-avr/avr-prop-5.d b/ld/testsuite/ld-avr/avr-prop-5.d
new file mode 100644 (file)
index 0000000..5f62ba3
--- /dev/null
+++ b/ld/testsuite/ld-avr/avr-prop-5.d
@@ -0,0 +1,10 @@
+#name: AVR .avr.prop, single .align proper sym val test.
+#as: -mmcu=avrxmega2 -mlink-relax
+#ld: -mavrxmega2 --relax
+#source: avr-prop-5.s
+#objdump: -S
+#target: avr-*-*
+
+#...
+   0:  00 d0\s+rcall\s+\.\+0\s+; 0x2 <dest>
+#...
\ No newline at end of file

diff --git a/ld/testsuite/ld-avr/avr-prop-5.s b/ld/testsuite/ld-avr/avr-prop-5.s
new file mode 100644 (file)
index 0000000..6a3359a
--- /dev/null
+++ b/ld/testsuite/ld-avr/avr-prop-5.s
@@ -0,0 +1,7 @@
+        .text
+        .global _start, dest
+_start:
+        CALL    dest
+        .align  1
+dest:
+        NOP