Add support uClibc++ excpetions. This involves additional handling for relative relation types, additional support for unwinding, as well as additional changes. The culmination of a big effort fromo Leo Aloe3132

arch/arm/src/armv7-m/Kconfig

@@ -106,6 +106,13 @@ config ARMV7M_OABI_TOOLCHAIN
 		Most of the older buildroot toolchains are OABI and are named
 		arm-nuttx-elf- vs. arm-nuttx-eabi-
 
+config ARMV7M_TARGET2_PREL
+	bool "R_ARM_TARGET2 is PC relative"
+	default n
+	depends on ELF
+	---help---
+		Perform a PC relative relocation for relocation type R_ARM_TARGET2
+
 config ARMV7M_HAVE_STACKCHECK
 	bool
 	default n

arch/arm/src/armv7-m/up_elf.c

@@ -48,6 +48,8 @@
 #include <nuttx/arch.h>
 #include <nuttx/binfmt/elf.h>
 
+#ifdef CONFIG_ELF
+
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
@@ -60,6 +62,14 @@
  * Private Functions
  ****************************************************************************/
 
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#ifdef CONFIG_UCLIBCXX_EXCEPTION
+extern void init_unwind_exidx(Elf32_Addr start, Elf32_Addr end);
+#endif
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -204,6 +214,18 @@ int up_relocate(FAR const Elf32_Rel *rel, FAR const Elf32_Sym *sym,
       }
       break;
 
+#ifdef CONFIG_ARMV7M_TARGET2_PREL
+    case R_ARM_TARGET2:  /* TARGET2 is a platform-specific relocation: gcc-arm-none-eabi
+                          * performs a self relocation */
+      {
+        bvdbg("Performing TARGET2 link at addr=%08lx [%08lx] to sym=%p st_value=%08lx\n",
+              (long)addr, (long)(*(uint32_t*)addr), sym, (long)sym->st_value);
+
+        *(uint32_t*)addr += sym->st_value - addr;
+      }
+      break;
+#endif
+
     case R_ARM_THM_CALL:
     case R_ARM_THM_JUMP24:
       {
@@ -464,3 +486,14 @@ int up_relocateadd(FAR const Elf32_Rela *rel, FAR const Elf32_Sym *sym,
   bdbg("RELA relocation not supported\n");
   return -ENOSYS;
 }
+
+#ifdef CONFIG_UCLIBCXX_EXCEPTION
+int up_init_exidx(Elf32_Addr address, Elf32_Word size)
+{
+  init_unwind_exidx(address, size);
+
+  return OK;
+}
+#endif
+
+#endif /* CONFIG_ELF */

binfmt/libelf/Kconfig

@@ -38,3 +38,13 @@ config ELF_DUMPBUFFER
 	depends on DEBUG && DEBUG_VERBOSE
 	---help---
 		Dump various ELF buffers for debug purposes
+
+config ELF_EXIDX_SECTNAME
+	string "ELF Section Name for Exception Index"
+	default ".ARM.exidx"
+	depends on UCLIBCXX_EXCEPTION
+	---help---
+		Set the name string for the exception index section on the ELF modules to
+		be loaded by the ELF binary loader.
+
+		This is needed to support exception handling on loadable ELF modules.

binfmt/libelf/libelf_load.c

@@ -245,6 +245,9 @@ static inline int elf_loadfile(FAR struct elf_loadinfo_s *loadinfo)
 int elf_load(FAR struct elf_loadinfo_s *loadinfo)
 {
   size_t heapsize;
+#ifdef CONFIG_UCLIBCXX_EXCEPTION
+  int exidx;
+#endif
   int ret;
 
   bvdbg("loadinfo: %p\n", loadinfo);
@@ -328,6 +331,18 @@ int elf_load(FAR struct elf_loadinfo_s *loadinfo)
     }
 #endif
 
+#ifdef CONFIG_UCLIBCXX_EXCEPTION
+  exidx = elf_findsection(loadinfo, CONFIG_ELF_EXIDX_SECTNAME);
+  if (exidx < 0)
+    {
+      bvdbg("elf_findsection: Exception Index section not found: %d\n", exidx);
+    }
+  else
+    {
+      up_init_exidx(loadinfo->shdr[exidx].sh_addr, loadinfo->shdr[exidx].sh_size);
+    }
+#endif
+
 #ifdef CONFIG_ARCH_ADDRENV
   /* Restore the original address environment */
 

configs/stm32f4discovery/scripts/gnu-elf.ld

@@ -56,6 +56,16 @@ SECTIONS
       _etext = . ;
     }
 
+  .ARM.extab :
+    {
+      *(.ARM.extab*)
+    }
+
+  .ARM.exidx :
+    {
+      *(.ARM.exidx*)
+    }
+
   .rodata :
     {
       _srodata = . ;

include/nuttx/binfmt/elf.h

@@ -320,6 +320,25 @@ int up_relocate(FAR const Elf32_Rel *rel, FAR const Elf32_Sym *sym,
 int up_relocateadd(FAR const Elf32_Rela *rel,
                    FAR const Elf32_Sym *sym, uintptr_t addr);
 
+#ifdef CONFIG_UCLIBCXX_EXCEPTION
+/****************************************************************************
+ * Name: up_init_exidx
+ *
+ * Description:
+ *   Load the boundaries of the Exception Index ELF section in order to
+ *   support exception handling for loaded ELF modules.
+ *
+ * Input Parameters:
+ *   address - The ELF section address for the Exception Index
+ *   size    - The size of the ELF section.
+ *
+ * Returned Value:
+ *   Always returns Zero (OK).
+ *
+ ****************************************************************************/
+int up_init_exidx(Elf32_Addr address, Elf32_Word size);
+#endif
+
 /****************************************************************************
  * Name: up_coherent_dcache
  *

libxx/Makefile

@@ -41,6 +41,9 @@ ASRCS =
 CSRCS =
 
 CXXSRCS  = libxx_cxapurevirtual.cxx libxx_eabi_atexit.cxx  libxx_cxa_atexit.cxx
+ifeq ($(CONFIG_UCLIBCXX_EXCEPTION),y)
+CXXSRCS += libxx__gnu_unwind_find_exidx.cxx
+endif
 
 # Some of the libxx/ files are not need if uClibc++ is installed because
 # uClibx++ replaces them

libxx/libxx__gnu_unwind_find_exidx.cxx

@@ -0,0 +1,106 @@
+//***************************************************************************
+// libxx/libxx__gnu_unwind_find_exidx.cxx
+//
+//   Copyright (C) 2015 Gregory Nutt. All rights reserved.
+//   Author: Gregory Nutt <gnutt@nuttx.org>
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions
+// are met:
+//
+// 1. Redistributions of source code must retain the above copyright
+//    notice, this list of conditions and the following disclaimer.
+// 2. Redistributions in binary form must reproduce the above copyright
+//    notice, this list of conditions and the following disclaimer in
+//    the documentation and/or other materials provided with the
+//    distribution.
+// 3. Neither the name NuttX nor the names of its contributors may be
+//    used to endorse or promote products derived from this software
+//    without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+// COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+// OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+// AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+// ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+// POSSIBILITY OF SUCH DAMAGE.
+//
+//***************************************************************************
+
+//***************************************************************************
+// Included Files
+//***************************************************************************
+
+#include "libxx__gnu_unwind_find_exidx.hxx"
+
+//***************************************************************************
+// Pre-processor Definitions
+//***************************************************************************
+
+//***************************************************************************
+// Private Data
+//***************************************************************************
+
+//***************************************************************************
+// Operators
+//***************************************************************************
+
+//***************************************************************************
+// Name:  __gnu_Unwind_Find_exidx
+//
+// Description:
+//    This function is called (if exists) by the gcc generated unwind
+//    run-time in order to retrieve an alternative .ARM.exidx Exception
+//    index section.
+//    This is the case for an ELF module loaded by the elf binary loader.
+//    It is needed to support exception handling for loadable ELF modules.
+//
+//    NOTES:
+//
+//     1. The section to be searched is chosen by the address of the calling
+//        site: if we are in a runtime loaded ELF, the code will be executed
+//        in ram ( > 0x20000000 ) otherwise we will  be executing code  from
+//        flash (0x08000000) (running nuttx from ram will break this logic)
+//
+//     2. __exidx_start  and  __exidx_end refers to main nuttx elf image and
+//        are defined in its linker script.
+//
+//     2. __exidx_start_elf  and  __exidx_end_elf refers  to the elf module
+//        loaded by the elf binary loader, and are initialized at run-time.
+//
+//     3. TODO: if nuttx itself is running from ram, this logic will not work
+//
+//     4. TODO: in order to support multiple elf modules running at the same
+//        time, this error logic needs to be extended to store multiple
+//        start/end ranges that refers to the loaded binaries.
+//
+//***************************************************************************
+
+extern "C"
+{
+  void init_unwind_exidx(Elf32_Addr start, Elf32_Word size)
+  {
+    __exidx_start_elf = (__EIT_entry *) start;
+    __exidx_end_elf   = __exidx_start_elf + size;
+  }
+
+  _Unwind_Ptr __gnu_Unwind_Find_exidx (_Unwind_Ptr return_address, int *nrecp)
+  {
+    if (return_address < 0x20000000)
+      {
+        *nrecp = &__exidx_end - &__exidx_start;
+        return (_Unwind_Ptr) &__exidx_start;
+      }
+    else
+      {
+        *nrecp = (__exidx_end_elf - __exidx_start_elf) / sizeof(__EIT_entry);
+        return (_Unwind_Ptr) __exidx_start_elf;
+      }
+  }
+}

libxx/libxx__gnu_unwind_find_exidx.hxx

@@ -0,0 +1,80 @@
+//***************************************************************************
+// lib/libxx__gnu_unwind_find_exidx.hxx
+//
+//   Copyright (C) 2015 Gregory Nutt. All rights reserved.
+//   Author: Gregory Nutt <gnutt@nuttx.org>
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions
+// are met:
+//
+// 1. Redistributions of source code must retain the above copyright
+//    notice, this list of conditions and the following disclaimer.
+// 2. Redistributions in binary form must reproduce the above copyright
+//    notice, this list of conditions and the following disclaimer in
+//    the documentation and/or other materials provided with the
+//    distribution.
+// 3. Neither the name NuttX nor the names of its contributors may be
+//    used to endorse or promote products derived from this software
+//    without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+// COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+// OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+// AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+// ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+// POSSIBILITY OF SUCH DAMAGE.
+//
+//***************************************************************************
+
+#ifndef __LIBXX_LIBXX__GNU_UNWIND_FIND_EXIDX_HXX
+#define __LIBXX_LIBXX__GNU_UNWIND_FIND_EXIDX_HXX
+
+extern "C"
+{
+//***************************************************************************
+// Included Files
+//***************************************************************************
+
+#include <elf32.h>
+#include <unwind.h>
+
+//***************************************************************************
+// Pre-processor Definitions
+//***************************************************************************
+
+//***************************************************************************
+// Public Types
+//***************************************************************************/
+
+typedef struct __EIT_entry
+{
+  _uw fnoffset;
+  _uw content;
+} __EIT_entry;
+
+//***************************************************************************
+// Public Variables
+//***************************************************************************
+
+extern __EIT_entry __exidx_start;
+extern __EIT_entry __exidx_end;
+
+__EIT_entry *__exidx_start_elf;
+__EIT_entry *__exidx_end_elf;
+
+//***************************************************************************
+// Public Function Prototypes
+//***************************************************************************
+
+ _Unwind_Ptr __gnu_Unwind_Find_exidx(_Unwind_Ptr return_address, int *nrecp);
+
+} // extern "C"
+
+#endif // __LIBXX__GNU_UNWIND_FIND_EXIDX_HXX