[rtems commit] libdl: Add ARM C++ relocation record support.

[Chris Johns]

Module:    rtems
Branch:    master
Commit:    11323b7da92e59ef61791e6f85d879d1d0a3f1c5
Changeset: http://git.rtems.org/rtems/commit/?id=11323b7da92e59ef61791e6f85d879d1d0a3f1c5

Author:    Chris Johns <chrisj at rtems.org>
Date:      Tue Sep  6 16:20:14 2016 +1000

libdl: Add ARM C++ relocation record support.

Closes #2767

---

 cpukit/libdl/include/arch/arm/machine/elf_machdep.h |  3 ++-
 cpukit/libdl/rtl-mdreloc-arm.c                      | 17 ++++++++++++++++-
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/cpukit/libdl/include/arch/arm/machine/elf_machdep.h b/cpukit/libdl/include/arch/arm/machine/elf_machdep.h
index 78c88b5..8f01d05 100644
--- a/cpukit/libdl/include/arch/arm/machine/elf_machdep.h
+++ b/cpukit/libdl/include/arch/arm/machine/elf_machdep.h
@@ -80,7 +80,8 @@
 #define R_ARM_ALU_SBREL_19_12	36
 #define R_ARM_ALU_SBREL_27_20	37
 #define R_ARM_V4BX        40
-#define R_ARM_PREL31      41
+#define R_ARM_TARGET2     41
+#define R_ARM_PREL31      42
 
 #define R_ARM_MOVW_ABS_NC     43
 #define R_ARM_MOVT_ABS        44
diff --git a/cpukit/libdl/rtl-mdreloc-arm.c b/cpukit/libdl/rtl-mdreloc-arm.c
index 692c829..84d58e3 100644
--- a/cpukit/libdl/rtl-mdreloc-arm.c
+++ b/cpukit/libdl/rtl-mdreloc-arm.c
@@ -52,6 +52,15 @@ isThumb(Elf_Word symvalue)
   else return false;
 }
 
+static inline Elf_SOff
+sign_extend31(Elf_Addr val)
+{
+  if (0x40000000 & val)
+    return ~((Elf_Addr)0x7fffffff) | (0x7fffffff & val);
+  else
+    return 0x7fffffff & val;
+}
+
 bool
 rtems_rtl_elf_rel_resolve_sym (Elf_Word type)
 {
@@ -165,12 +174,16 @@ rtems_rtl_elf_relocate_rel (const rtems_rtl_obj_t*      obj,
     case R_TYPE(REL32):     /* word32 (S + A) | T - P */
     case R_TYPE(ABS32):     /* word32 (S + A) | T */
     case R_TYPE(GLOB_DAT):  /* word32 (S + A) | T */
+    case R_TYPE(PREL31):    /* word32 (S + A) | T - P */
+    case R_TYPE(TARGET2):   /* Equivalent to ABS32 */
       if (__predict_true(RELOC_ALIGNED_P(where))) {
         tmp = *where + symvalue;
         if (isThumb(symvalue))
           tmp |= 1;
         if (ELF_R_TYPE(rel->r_info) == R_TYPE(REL32))
           tmp -= (Elf_Addr)where;
+        else if (ELF_R_TYPE(rel->r_info) == R_TYPE(PREL31))
+          tmp -= sign_extend31((Elf_Addr)where);
         *where = tmp;
       } else {
         tmp = load_ptr(where) + symvalue;
@@ -178,11 +191,13 @@ rtems_rtl_elf_relocate_rel (const rtems_rtl_obj_t*      obj,
           tmp |= 1;
         if (ELF_R_TYPE(rel->r_info) == R_TYPE(REL32))
           tmp -= (Elf_Addr)where;
+        else if (ELF_R_TYPE(rel->r_info) == R_TYPE(PREL31))
+          tmp -= sign_extend31((Elf_Addr)where);
         store_ptr(where, tmp);
       }
 
       if (rtems_rtl_trace (RTEMS_RTL_TRACE_RELOC))
-        printf ("rtl: REL32/ABS32/GLOB_DAT %p @ %p in %s",
+        printf ("rtl: REL32/ABS32/GLOB_DAT/PREL31/TARGET2 %p @ %p in %s",
                 (void *)tmp, where, rtems_rtl_obj_oname (obj));
       break;