More fixes for ldnxflat. There are still problems with the GCC 4.6.3

git-svn-id: http://svn.code.sf.net/p/nuttx/code/trunk@5227 42af7a65-404d-4744-a932-0658087f49c3

misc/buildroot/ChangeLog

@@ -123,4 +123,7 @@ buildroot-1.11 2011-xx-xx <gnutt@nuttx.org>
 	  type was not generated by GCC/LD prior to gcc-4.6.3
 	* R_ARM_REL32 logic is conditionally disabled because it has not been
 	  tested.
+	* ldnxflat: Correct a memory allocation error that could cause written
+	  past the end of allocated memory.  Partial restoration of R_ARM_REL32
+	  logic.  There are lots of issues that I still do not understand here.
 

misc/buildroot/toolchain/nxflat/ldnxflat.c

@@ -800,11 +800,83 @@ static void alloc_got_entry(asymbol *sym)
 }
 
 /***********************************************************************
- * relocate_arm32
+ * relocate_rel32
  ***********************************************************************/
 
 static void
-relocate_arm32(arelent *relp, int32_t *target, symvalue sym_value)
+relocate_rel32(arelent *relp, int32_t *target, symvalue sym_value)
+{
+  reloc_howto_type      *how_to      = relp->howto;
+  asymbol               *rel_sym     = *relp->sym_ptr_ptr;
+  asection              *rel_section = rel_sym->section;
+  int32_t                value;
+  int32_t                temp;
+  int32_t                saved;
+  int                    reloc_type;
+
+  if (verbose > 1)
+    {
+      vdbg("  Original location %p is %08lx ",
+#ifdef ARCH_BIG_ENDIAN
+           target, (long)nxflat_swap32(*target));
+#else
+          target, (long)*target);
+#endif
+      if (verbose > 2)
+        {
+          printf("rsh %d ", how_to->rightshift);
+          printf(" sz %d ", how_to->size);
+          printf("bit %d ", how_to->bitsize);
+          printf("rel %d ", how_to->pc_relative);
+          printf("smask %08lx ", (long)how_to->src_mask);
+          printf("dmask %08lx ", (long)how_to->dst_mask);
+          printf("off %d ", how_to->pcrel_offset);
+        }
+
+      printf("\n");
+    }
+
+#ifdef ARCH_BIG_ENDIAN
+  saved = temp = (int32_t) nxflat_swap32(*target);
+#else
+  saved = temp = *target;
+#endif
+  /* Mask  and sign extend */
+
+  temp &= how_to->src_mask;
+  temp <<= (32 - how_to->bitsize);
+  temp >>= (32 - how_to->bitsize);
+
+  /* Calculate the new value:  Current value + VMA - current PC */
+
+  value = temp + sym_value + rel_section->vma - relp->address;
+
+  /* Offset */
+
+  temp += (value >> how_to->rightshift);
+
+  /* Mask upper bits from rollover */
+
+  temp &= how_to->dst_mask;
+
+  /* Replace data that was masked */
+
+  temp |= saved & (~how_to->dst_mask);
+
+  vdbg("  Modified location: %08lx\n", (long)temp);
+#ifdef ARCH_BIG_ENDIAN
+  *target = (long)nxflat_swap32(temp);
+#else
+  *target = (long)temp;
+#endif
+ }
+
+/***********************************************************************
+ * relocate_abs32
+ ***********************************************************************/
+
+static void
+relocate_abs32(arelent *relp, int32_t *target, symvalue sym_value)
 {
   reloc_howto_type      *how_to      = relp->howto;
   asymbol               *rel_sym     = *relp->sym_ptr_ptr;
@@ -901,7 +973,7 @@ relocate_arm32(arelent *relp, int32_t *target, symvalue sym_value)
   /* Re-allocate memory to include this relocation */
 
   relocs = (struct nxflat_reloc_s*)
-  realloc(nxflat_relocs, sizeof(struct nxflat_reloc_s) * nxflat_nrelocs + 1);
+  realloc(nxflat_relocs, sizeof(struct nxflat_reloc_s) * (nxflat_nrelocs + 1));
   if (!relocs)
     {
       err("Failed to re-allocate memory ABS32 relocations (%d relocations)\n",
@@ -1105,7 +1177,7 @@ resolve_segment_relocs(bfd *input_bfd, segment_info *inf, asymbol **syms)
                 dbg("Performing ABS32 link at addr %08lx [%08lx] to sym '%s' [%08lx]\n",
                      (long)relpp[j]->address, (long)*target, rel_sym->name, (long)sym_value);
 
-                relocate_arm32(relpp[j], target, sym_value);
+                relocate_abs32(relpp[j], target, sym_value);
               }
               break;
 
@@ -1114,18 +1186,12 @@ resolve_segment_relocs(bfd *input_bfd, segment_info *inf, asymbol **syms)
                 dbg("Performing REL32 link at addr %08lx [%08lx] to sym '%s' [%08lx]\n",
                      (long)relpp[j]->address, (long)*target, rel_sym->name, (long)sym_value);
 
-                /* The REL32 relocation is just like the ABS32 relocation except that (1)
+                /* The only valid REL32 relocation would be to relocate a reference from
-                 * the symbol value is relative to the PC, and (2) we cannot permit
+                 * I-Space to another symbol in I-Space.  That should be handled by the
-                 * REL32 relocations to data in I-Space.  That just would not make sense.
+                 * partially linking logic so we don't expect to see any R_ARM_REL32
-                 */
+                 * relocations here.
-#if 1
-                /* The logic below may or may not be correct.  It has not been verified
-                 * so, for now, it is disabled.
                  */
 
-                err("REL32 relocation not yet supported\n");
-                nerrors++;
-#else
                 switch (get_reloc_type(rel_section, NULL))
                   {
                     case NXFLAT_RELOC_TARGET_UNKNOWN:
@@ -1148,11 +1214,10 @@ resolve_segment_relocs(bfd *input_bfd, segment_info *inf, asymbol **syms)
                     case NXFLAT_RELOC_TARGET_TEXT:
                       {
                         vdbg("Symbol '%s' lies in I-Space\n", rel_sym->name);
-                        relocate_arm32(relpp[j], target, sym_value - relpp[j]->address);
+                        relocate_rel32(relpp[j], target, sym_value - relpp[j]->address);
                       }
                       break;
                   }
-#endif
               }
               break;
 

nuttx/Documentation/NuttXNxFlat.html

@@ -522,7 +522,7 @@ cat ../syscall/syscall.csv ../lib/lib.csv | sort >tmp.csv
 </p>
 
 <p><b>NOTE:</b>
-  There are two linker scripts located at <code>binfmt/libnxflat/gnu-nxflat-gotoff.ld</code>.
+  There are two linker scripts located at <code>binfmt/libnxflat/</code>.
 </p>
 <ol>
   <li>

nuttx/TODO

@@ -12,7 +12,7 @@ nuttx/
   (2)  Signals (sched/, arch/)
   (2)  pthreads (sched/)
   (2)  C++ Support
-  (5)  Binary loaders (binfmt/)
+  (6)  Binary loaders (binfmt/)
  (17)  Network (net/, drivers/net)
   (3)  USB (drivers/usbdev, drivers/usbhost)
  (11)  Libraries (lib/)
@@ -395,6 +395,46 @@ o Binary loaders (binfmt/)
   Priority:    There are too many references like the above.  They will have
                to get fixed as needed for Windows native tool builds.
 
+  Title:       TOOLCHAIN COMPATIBILITY PROBLEM
+  Descripton:  The older 4.3.3 compiler generates GOTOFF relocations to the constant
+               strings, like:
+
+               .L3:
+                  .word   .LC0(GOTOFF)
+                  .word   .LC1(GOTOFF)
+                  .word   .LC2(GOTOFF)
+                  .word   .LC3(GOTOFF)
+                  .word   .LC4(GOTOFF)
+
+               Where .LC0, LC1, LC2, LC3, and .LC4 are the labels correponding to strings in
+               the .rodata.str1.1 section.  One consequence of this is that .rodata must reside
+               in D-Space since it will addressed relative to the GOT (see the section entitled
+               "Read-Only Data in RAM" at
+               http://nuttx.org/Documentation/NuttXNxFlat.html#limitations).
+
+               The newer 4.6.3compiler generated PC relative relocations to the strings:
+
+               .L2:
+                  .word   .LC0-(.LPIC0+4)
+                  .word   .LC1-(.LPIC1+4)
+                  .word   .LC2-(.LPIC2+4)
+                  .word   .LC3-(.LPIC4+4)
+                  .word   .LC4-(.LPIC5+4)
+
+               This is good and bad.  This is good because it means that .rodata.str1.1 can not
+               reside in FLASH with .text and can be accessed using PC-relative addressing. 
+               That can be accomplished by simply moving the .rodata from the .data section to
+               the .text section in the linker script.  (The NXFLAT linker script is located at
+               nuttx/binfmt/libnxflat/gnu-nxflat.ld).
+
+               This is bad because a lot of stuff may get broken an a lot of test will need to
+               be done.  One question that I have is does this apply to all kinds of .rodata? 
+               Or just to .rodata.str1.1?
+  
+  Status:      Open.  Many of the required changes are in place but, unfortunately, not enought
+               go be fully functional.
+  Priority:    Medium.  The workaround for now is to use the older, 4.3.3 OABI compiler.
+
 o Network (net/, drivers/net)
   ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 

nuttx/binfmt/libnxflat/gnu-nxflat-gotoff.ld

@@ -107,11 +107,16 @@ SECTIONS
 
   .data 0x00000000 :
     {
+      /* In this model, .rodata is access using PC-relative addressing
+       * and, hence, must also reside in the .text section.
+       */
+
       __data_start = . ;
       *(.rodata)
       *(.rodata1)
       *(.rodata.*)
       *(.gnu.linkonce.r*)
+
       *(.data)
       *(.data1)
       *(.data.*)