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 d544d0296d017fd6a78470776d852f8689eee696..460e68b8f0ea2914cca35d6a0776671344cd35e7 100644 (file)
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,9 @@
+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.
+
 2016-06-08  H.J. Lu  <hongjiu.lu@intel.com>
 
        * elf64-i386.c (elf_i386_link_hash_entry): Add tls_get_addr.

diff --git a/bfd/elf32-avr.c b/bfd/elf32-avr.c
index d463d78c86109f6c4f92da0dfa9b2d72e4881ca7..b95e251e1e05f06cb5d23eabfa95cdf4cfb5ab4b 100644 (file)
--- a/bfd/elf32-avr.c
+++ b/bfd/elf32-avr.c
@@ -1828,6 +1828,7 @@ 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);
@@ -1863,10 +1864,16 @@ 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.  */
@@ -1885,6 +1892,11 @@ 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
@@ -1892,6 +1904,9 @@ 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 cbb98e3dee487e2f1fe2ca1d982d8e60daa695da..11470c56d1631caffab1e9584098221adb5fdbb8 100644 (file)
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,4 +1,11 @@
+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.
+
 2016-06-09  Pitchumani Sivanupandi  <pitchumani.s@atmel.com>
+
        * testsuite/ld-avr/lds-mega.d: New test.
        * testsuite/ld-avr/lds-mega.s: New test source.
        * testsuite/ld-avr/lds-tiny.d: New test.

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