A little more ELF loader logic

git-svn-id: http://svn.code.sf.net/p/nuttx/code/trunk@5257 42af7a65-404d-4744-a932-0658087f49c3

10 files changed, 406 insertions, 102 deletions

diff --git a/nuttx/binfmt/libelf/Kconfig b/nuttx/binfmt/libelf/Kconfig
index ba931b57e..f16dd4e90 100644
--- a/nuttx/binfmt/libelf/Kconfig
+++ b/nuttx/binfmt/libelf/Kconfig
@@ -9,6 +9,12 @@ config ELF_ALIGN_LOG2
 	---help---
 		Align all sections to this Log2 value:  0->1, 1->2, 2->4, etc.
 
+config ELF_STACKSIZE
+	int "ELF Stack Size"
+	default 2048
+	---help---
+		This is the default stack size that will will be used when starting ELF binaries.
+
 config ELF_CONSTRUCTORS
 	bool "C++ Static Constructor Support"
 	default n
@@ -16,13 +22,6 @@ config ELF_CONSTRUCTORS
 	---help---
 		Build in support for C++ constructors in ELF modules.
 
-config ELF_SYMBOLS
-	bool "Export symbols from ELF modules"
-	default n
-	---help---
-		Allow symbols from one ELF module to be used by another. NOT
-		fully implemented!
-
 config ELF_DUMPBUFFER
 	bool "Dump ELF buffers"
 	default n
diff --git a/nuttx/binfmt/libelf/Make.defs b/nuttx/binfmt/libelf/Make.defs
index 629961863..82f5f3e64 100644
--- a/nuttx/binfmt/libelf/Make.defs
+++ b/nuttx/binfmt/libelf/Make.defs
@@ -43,11 +43,12 @@ BINFMT_CSRCS += elf.c
 
 BINFMT_CSRCS = libelf_init.c libelf_uninit.c libelf_load.c \
 			   libelf_unload.c libelf_verify.c libelf_read.c \
-			   libelf_bind.c
+			   libelf_bind.c libelf_symbols.c
 
 # Hook the libelf subdirectory into the build
 
 VPATH += libelf
 SUBDIRS += libelf
+DEPPATH += --dep-path libelf
 
 endif
diff --git a/nuttx/binfmt/libelf/arm.h b/nuttx/binfmt/libelf/arm.h
deleted file mode 100644
index e80457b6e..000000000
--- a/nuttx/binfmt/libelf/arm.h
+++ /dev/null
@@ -1,53 +0,0 @@
-/****************************************************************************
- * binfmt/libelf/arm.h
- *
- *   Copyright (C) 2012 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 __BINFMT_LIBELF_ARM_H
-#define __BINFMT_LIBELF_ARM_H
-
-/****************************************************************************
- * Included Files
- ****************************************************************************/
-
-#include <nuttx/config.h>
-
-/****************************************************************************
- * Pre-processor Definitions
- ****************************************************************************/
-
-/****************************************************************************
- * Public Types
- ****************************************************************************/
-
-#endif /* __BINFMT_LIBELF_ARM_H */
diff --git a/nuttx/binfmt/libelf/libelf.h b/nuttx/binfmt/libelf/libelf.h
index ed352865c..a7ffbc6a6 100644
--- a/nuttx/binfmt/libelf/libelf.h
+++ b/nuttx/binfmt/libelf/libelf.h
@@ -42,8 +42,11 @@
 
 #include <nuttx/config.h>
 
+#include <sys/types.h>
 #include <elf.h>
 
+#include <nuttx/binfmt/elf.h>
+
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
@@ -53,14 +56,58 @@
  ****************************************************************************/
 
 /****************************************************************************
- * Name: arch_checkarch
+ * Name: elf_verifyheader
+ *
+ * Description:
+ *   Given the header from a possible ELF executable, verify that it is
+ *   an ELF executable.
+ *
+ * Returned Value:
+ *   0 (OK) is returned on success and a negated errno is returned on
+ *   failure.
+ *
+ ****************************************************************************/
+
+int elf_verifyheader(FAR const Elf32_Ehdr *header);
+
+/****************************************************************************
+ * Name: elf_read
+ *
+ * Description:
+ *   Read 'readsize' bytes from the object file at 'offset'
+ *
+ * Returned Value:
+ *   0 (OK) is returned on success and a negated errno is returned on
+ *   failure.
+ *
+ ****************************************************************************/
+
+int elf_read(FAR struct elf_loadinfo_s *loadinfo, FAR uint8_t *buffer,
+             size_t readsize, off_t offset);
+
+/****************************************************************************
+ * Name: elf_findsymtab
+ *
+ * Description:
+ *   Find the symbol table section.
+ *
+ * Returned Value:
+ *   0 (OK) is returned on success and a negated errno is returned on
+ *   failure.
+ *
+ ****************************************************************************/
+
+int elf_findsymtab(FAR struct elf_loadinfo_s *loadinfo);
+
+/****************************************************************************
+ * Name: elf_readsym
  *
  * Description:
- *   Given the ELF header in hdr, verify that the ELF file is appropriate
- *   for the current, configured architecture.
+ *   Read the ELFT symbol structure at the specfied index into memory.
  *
  ****************************************************************************/
 
-bool arch_checkarch(const struct Elf32_Ehdr *hdr);
+int elf_readsym(FAR struct elf_loadinfo_s *loadinfo, int index,
+                FAR Elf32_Sym *sym);
 
 #endif /* __BINFMT_LIBELF_LIBELF_H */
diff --git a/nuttx/binfmt/libelf/libelf_bind.c b/nuttx/binfmt/libelf/libelf_bind.c
index 74b713b9e..dd75809ec 100644
--- a/nuttx/binfmt/libelf/libelf_bind.c
+++ b/nuttx/binfmt/libelf/libelf_bind.c
@@ -49,6 +49,8 @@
 #include <nuttx/binfmt/elf.h>
 #include <nuttx/binfmt/symtab.h>
 
+#include "libelf.h"
+
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
@@ -80,6 +82,120 @@
  ****************************************************************************/
 
 /****************************************************************************
+ * Name: elf_readsym
+ *
+ * Description:
+ *   Read the ELFT symbol structure at the specfied index into memory.
+ *
+ ****************************************************************************/
+
+static inline int elf_readrel(FAR struct elf_loadinfo_s *loadinfo,
+                              FAR const Elf32_Shdr *relsec,
+                              int index, FAR Elf32_Rel *rel)
+{
+  off_t offset;
+
+  /* Verify that the symbol table index lies within symbol table */
+
+  if (index < 0 || index > (relsec->sh_size / sizeof(Elf32_Rel)))
+    {
+      bdbg("Bad relocation symbol index: %d\n", index);
+      return -EINVAL;
+    }
+
+  /* Get the file offset to the symbol table entry */
+
+  offset = relsec->sh_offset + sizeof(Elf32_Rel) * index;
+
+  /* And, finally, read the symbol table entry into memory */
+
+  return elf_read(loadinfo, (FAR uint8_t*)rel, sizeof(Elf32_Rel), offset);
+}
+
+/****************************************************************************
+ * Name: elf_relocate and elf_relocateadd
+ *
+ * Description:
+ *   Perform all relocations associated with a section.
+ *
+ * Returned Value:
+ *   0 (OK) is returned on success and a negated errno is returned on
+ *   failure.
+ *
+ ****************************************************************************/
+
+static int elf_relocate(FAR struct elf_loadinfo_s *loadinfo, int relidx)
+{
+  FAR Elf32_Shdr *relsec = &loadinfo->shdr[relidx];
+  FAR Elf32_Shdr *dstsec = &loadinfo->shdr[relsec->sh_info];
+  Elf32_Rel       rel;
+  Elf32_Sym       sym;
+  uintptr_t       addr;
+  int             symidx;
+  int             ret;
+  int             i;
+
+  /* Examine each relocation in the section */
+
+  for (i = 0; i < relsec->sh_size / sizeof(Elf32_Rel); i++)
+    {
+      /* Read the relocation entry into memory */
+
+      ret = elf_readrel(loadinfo, relsec, i, &rel);
+      if (ret < 0)
+        {
+          bdbg("Section %d reloc %d: Failed to read relocation entry: %d\n",
+               relidx, i, ret);
+          return ret;
+        }
+
+      /* Get the symbol table index for the relocation.  This is contained
+       * in a bit-field within the r_info element.
+       */
+
+      symidx = ELF32_R_SYM(rel.r_info);
+
+      /* Read the symbol table entry into memory */
+
+      ret = elf_readsym(loadinfo, symidx, &sym);
+      if (ret < 0)
+        {
+          bdbg("Section %d reloc %d: Failed to read symbol[%d]: %d\n",
+               relidx, i, symidx, ret);
+          return ret;
+        }
+
+      /* Calculate the relocation address */
+
+      if (rel.r_offset < 0 || rel.r_offset > dstsec->sh_size - sizeof(uint32_t))
+        {
+          bdbg("Section %d reloc %d: Relocation address out of range, offset %d size %d\n",
+               relidx, i, rel.r_offset, dstsec->sh_size);
+          return -EINVAL;
+        }
+
+      addr = dstsec->sh_addr + rel.r_offset;
+
+      /* Now perform the architecture-specific relocation */
+
+      ret = arch_relocate(&rel, &sym, addr);
+      if (ret < 0)
+        {
+          bdbg("Section %d reloc %d: Relocation failed: %d\n", ret);
+          return ret;
+        }
+    }
+
+  return OK;
+}
+
+static int elf_relocateadd(FAR struct elf_loadinfo_s *loadinfo, int relidx)
+{
+  bdbg("Not implemented\n");
+  return -ENOSYS;
+}
+
+/****************************************************************************
  * Public Functions
  ****************************************************************************/
 
@@ -99,7 +215,58 @@
 int elf_bind(FAR struct elf_loadinfo_s *loadinfo,
              FAR const struct symtab_s *exports, int nexports)
 {
-#warning "Missing logic"
-  return -ENOSYS;
+  int ret;
+  int i;
+
+  /* Find the symbol and string tables */
+
+  ret = elf_findsymtab(loadinfo);
+  if (ret < 0)
+    {
+      return ret;
+    }
+
+  /* Process relocations in every allocated section */
+
+  for (i = 1; i < loadinfo->ehdr.e_shnum; i++)
+    {
+      /* Get the index to the relocation section */
+      
+      int infosec = loadinfo->shdr[i].sh_info;
+      if (infosec >= loadinfo->ehdr.e_shnum)
+        {
+          continue;
+        }
+
+      /* Make sure that the section is allocated.  We can't relocated
+       * sections that were not loaded into memory.
+       */
+
+      if ((loadinfo->shdr[infosec].sh_flags & SHF_ALLOC) == 0)
+        {
+          continue;
+        }
+
+      /* Process the relocations by type */
+
+      if (loadinfo->shdr[i].sh_type == SHT_REL)
+        {
+          ret = elf_relocate(loadinfo, i);
+        }
+      else if (loadinfo->shdr[i].sh_type == SHT_RELA)
+        {
+          ret = elf_relocateadd(loadinfo, i);
+        }
+
+      if (ret < 0)
+        {
+          break;
+        }
+    }
+
+  /* Flush the instruction cache before starting the newly loaded module */
+
+  arch_flushicache((FAR void*)loadinfo->alloc, loadinfo->allocsize);
+  return ret;
 }
 
diff --git a/nuttx/binfmt/libelf/libelf_init.c b/nuttx/binfmt/libelf/libelf_init.c
index cf62666b9..a3a320b16 100644
--- a/nuttx/binfmt/libelf/libelf_init.c
+++ b/nuttx/binfmt/libelf/libelf_init.c
@@ -49,6 +49,8 @@
 
 #include <nuttx/binfmt/elf.h>
 
+#include "libelf.h"
+
 /****************************************************************************
  * Pre-Processor Definitions
  ****************************************************************************/
@@ -114,7 +116,7 @@ int elf_init(FAR const char *filename, FAR struct elf_loadinfo_s *loadinfo)
 
   /* Read the ELF ehdr from offset 0 */
 
-  ret = elf_read(loadinfo, (char*)&loadinfo->ehdr, sizeof(Elf32_Ehdr), 0);
+  ret = elf_read(loadinfo, (FAR uint8_t*)&loadinfo->ehdr, sizeof(Elf32_Ehdr), 0);
   if (ret < 0)
     {
       bdbg("Failed to read ELF header: %d\n", ret);
diff --git a/nuttx/binfmt/libelf/libelf_load.c b/nuttx/binfmt/libelf/libelf_load.c
index c30c109ce..127ebb314 100644
--- a/nuttx/binfmt/libelf/libelf_load.c
+++ b/nuttx/binfmt/libelf/libelf_load.c
@@ -46,11 +46,15 @@
 #include <stdlib.h>
 #include <unistd.h>
 #include <elf.h>
-#include <debug.h>
+#include <assert.h>
 #include <errno.h>
+#include <debug.h>
 
+#include <nuttx/kmalloc.h>
 #include <nuttx/binfmt/elf.h>
 
+#include "libelf.h"
+
 /****************************************************************************
  * Pre-Processor Definitions
  ****************************************************************************/
@@ -104,7 +108,7 @@ static inline int elf_filelen(FAR struct elf_loadinfo_s *loadinfo)
   if (!S_ISREG(buf.st_mode))
     {
       bdbg("Not a regular file.  mode: %d\n", buf.st_mode);
-      return -errval;
+      return -ENOENT;
     }
 
   /* TODO:  Verify that the file is readable */
@@ -132,20 +136,20 @@ static inline int elf_loadshdrs(FAR struct elf_loadinfo_s *loadinfo)
   size_t shdrsize;
   int ret;
 
-  DEBUGASSERT(loadinfo->shdrs == NULL);
+  DEBUGASSERT(loadinfo->shdr == NULL);
 
   /* Verify that there are sections */
 
-  if (loadinfo->e_shum < 1)
+  if (loadinfo->ehdr.e_shnum < 1)
     {
-      bdbg("No section(?)\n");
+      bdbg("No sections(?)\n");
       return -EINVAL;
     }
 
   /* Get the total size of the section header table */
 
-  shdrsize = (size_t)loadinfo->ehdr.e_shentsize * (size_t)loadinfo->e_shum;
-  if(loadinfo->e_shoff + shdrsize > loadinfo->filelen)
+  shdrsize = (size_t)loadinfo->ehdr.e_shentsize * (size_t)loadinfo->ehdr.e_shnum;
+  if(loadinfo->ehdr.e_shoff + shdrsize > loadinfo->filelen)
     {
       bdbg("Insufficent space in file for section header table\n");
       return -ESPIPE;
@@ -153,8 +157,8 @@ static inline int elf_loadshdrs(FAR struct elf_loadinfo_s *loadinfo)
 
   /* Allocate memory to hold a working copy of the sector header table */
 
-  loadinfo->shdrs = (FAR Elf32_Shdr*)kmalloc(shdrsize);
-  if (!loadinfo->shdrs)
+  loadinfo->shdr = (FAR Elf32_Shdr*)kmalloc(shdrsize);
+  if (!loadinfo->shdr)
     {
       bdbg("Failed to allocate the section header table. Size: %ld\n", (long)shdrsize);
       return -ENOMEM;
@@ -162,7 +166,7 @@ static inline int elf_loadshdrs(FAR struct elf_loadinfo_s *loadinfo)
 
   /* Read the section header table into memory */
 
-  ret = elf_read(loadinfo, loadinfo->shdrs, shdrsize, loadinfo->e_shoff);
+  ret = elf_read(loadinfo, (FAR uint8_t*)loadinfo->shdr, shdrsize, loadinfo->ehdr.e_shoff);
   if (ret < 0)
     {
       bdbg("Failed to read section header table: %d\n", ret);
@@ -172,8 +176,8 @@ static inline int elf_loadshdrs(FAR struct elf_loadinfo_s *loadinfo)
   return OK;
 
 errout_with_alloc:
-  kfree(loadinfo->shdrs);
-  loadinfo->shdrs = 0;
+  kfree(loadinfo->shdr);
+  loadinfo->shdr = 0;
   return ret;
 }
 
@@ -189,7 +193,7 @@ errout_with_alloc:
  *
  ****************************************************************************/
 
-static void elf_allocsize(struct load_info *loadinfo)
+static void elf_allocsize(struct elf_loadinfo_s *loadinfo)
 {
   size_t allocsize;
   int i;
@@ -199,7 +203,7 @@ static void elf_allocsize(struct load_info *loadinfo)
   allocsize = 0;
   for (i = 0; i < loadinfo->ehdr.e_shnum; i++)
     {
-      FAR Elf32_Shdr *shdr = &loadinfo->shdrs[i];
+      FAR Elf32_Shdr *shdr = &loadinfo->shdr[i];
 
       /* SHF_ALLOC indicates that the section requires memory during
        * execution.
@@ -213,7 +217,7 @@ static void elf_allocsize(struct load_info *loadinfo)
 
   /* Save the allocation size */
 
-  loadinfo->allocize = allocsize;
+  loadinfo->allocsize = allocsize;
 }
 
 /****************************************************************************
@@ -221,7 +225,8 @@ static void elf_allocsize(struct load_info *loadinfo)
  *
  * Description:
  *   Allocate memory for the file and read the section data into the
- *   allocated memory.
+ *   allocated memory.  Section addresses in the shdr[] are updated to point
+ *   to the corresponding position in the allocated memory.
  *
  * Returned Value:
  *   0 (OK) is returned on success and a negated errno is returned on
@@ -229,14 +234,15 @@ static void elf_allocsize(struct load_info *loadinfo)
  *
  ****************************************************************************/
 
-static inline int elf_loadfile(FAR struct load_info *loadinfo)
+static inline int elf_loadfile(FAR struct elf_loadinfo_s *loadinfo)
 {
   FAR uint8_t *dest;
+  int ret;
   int i;
 
   /* Allocate (and zero) memory for the ELF file. */
   
-  loadinfo->alloc = kzalloc(loadinfo->allocsize);
+  loadinfo->alloc = (uintptr_t)kzalloc(loadinfo->allocsize);
   if (!loadinfo->alloc)
     {
       return -ENOMEM;
@@ -249,7 +255,7 @@ static inline int elf_loadfile(FAR struct load_info *loadinfo)
 
   for (i = 0; i < loadinfo->ehdr.e_shnum; i++)
     {
-      FAR Elf32_Shdr *shdr = &loadinfo->shdrs[i];
+      FAR Elf32_Shdr *shdr = &loadinfo->shdr[i];
 
       /* SHF_ALLOC indicates that the section requires memory during
        * execution */
@@ -275,7 +281,7 @@ static inline int elf_loadfile(FAR struct load_info *loadinfo)
             }
         }
 
-      /* Update sh_addr to point to copy in image. */
+      /* Update sh_addr to point to copy in memory */
 
       shdr->sh_addr = (uintptr_t)dest;
       bvdbg("%d. 0x%lx %s\n", (long)shdr->sh_addr, loadinfo->secstrings + shdr->sh_name);
@@ -288,7 +294,7 @@ static inline int elf_loadfile(FAR struct load_info *loadinfo)
   return OK;
 
 errout_with_alloc:
-  kfree(loadinfo->alloc);
+  kfree((FAR void*)loadinfo->alloc);
   loadinfo->alloc = 0;
   return ret;
 }
@@ -344,15 +350,16 @@ int elf_load(FAR struct elf_loadinfo_s *loadinfo)
       goto errout_with_shdrs;
     }
 
+  /* Find static constructors. */
+#warning "Missing logic"
+
   return OK;
 
   /* Error exits */
 
-errout_with_alloc:
-  kfree(loadinfo->alloc);
 errout_with_shdrs:
-  kfree(loadinfo->shdrs);
-errout:
+  kfree(loadinfo->shdr);
+  loadinfo->shdr = NULL;
   return ret;
 }
 
diff --git a/nuttx/binfmt/libelf/libelf_symbols.c b/nuttx/binfmt/libelf/libelf_symbols.c
new file mode 100644
index 000000000..4788c874c
--- /dev/null
+++ b/nuttx/binfmt/libelf/libelf_symbols.c
@@ -0,0 +1,134 @@
+/****************************************************************************
+ * binfmt/libelf/libelf_symbols.c
+ *
+ *   Copyright (C) 2012 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 <nuttx/config.h>
+
+#include <elf.h>
+#include <debug.h>
+#include <errno.h>
+
+#include <nuttx/binfmt/elf.h>
+
+#include "libelf.h"
+
+/****************************************************************************
+ * Pre-Processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Constant Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: elf_findsymtab
+ *
+ * Description:
+ *   Find the symbol table section.
+ *
+ * Returned Value:
+ *   0 (OK) is returned on success and a negated errno is returned on
+ *   failure.
+ *
+ ****************************************************************************/
+
+int elf_findsymtab(FAR struct elf_loadinfo_s *loadinfo)
+{
+  int i;
+
+  /* Find the symbol table section header and its associated string table */
+
+  for (i = 1; i < loadinfo->ehdr.e_shnum; i++)
+    {
+      if (loadinfo->shdr[i].sh_type == SHT_SYMTAB)
+        {
+          loadinfo->symtabidx = i;
+          loadinfo->strtabidx = loadinfo->shdr[i].sh_link;
+          break;
+        }
+    }
+
+  /* Verify that there is a symbol and string table */
+
+  if (loadinfo->symtabidx == 0)
+    {
+      bdbg("No symbols in ELF file\n");
+      return -EINVAL;
+    }
+
+  return OK;
+}
+
+/****************************************************************************
+ * Name: elf_readsym
+ *
+ * Description:
+ *   Read the ELFT symbol structure at the specfied index into memory.
+ *
+ ****************************************************************************/
+
+int elf_readsym(FAR struct elf_loadinfo_s *loadinfo, int index,
+                FAR Elf32_Sym *sym)
+{
+  FAR Elf32_Shdr *symtab = &loadinfo->shdr[loadinfo->symtabidx];
+  off_t offset;
+
+  /* Verify that the symbol table index lies within symbol table */
+
+  if (index < 0 || index > (symtab->sh_size / sizeof(Elf32_Sym)))
+    {
+      bdbg("Bad relocation symbol index: %d\n", index);
+      return -EINVAL;
+    }
+
+  /* Get the file offset to the symbol table entry */
+
+  offset = symtab->sh_offset + sizeof(Elf32_Sym) * index;
+
+  /* And, finally, read the symbol table entry into memory */
+
+  return elf_read(loadinfo, (FAR uint8_t*)sym, sizeof(Elf32_Sym), offset);
+}
diff --git a/nuttx/binfmt/libelf/libelf_unload.c b/nuttx/binfmt/libelf/libelf_unload.c
index 217a1981e..ca8d2b708 100644
--- a/nuttx/binfmt/libelf/libelf_unload.c
+++ b/nuttx/binfmt/libelf/libelf_unload.c
@@ -39,10 +39,10 @@
 
 #include <nuttx/config.h>
 
-#include <sys/mman.h>
 #include <stdlib.h>
 #include <debug.h>
 
+#include <nuttx/kmalloc.h>
 #include <nuttx/binfmt/elf.h>
 
 /****************************************************************************
@@ -81,14 +81,14 @@ int elf_unload(struct elf_loadinfo_s *loadinfo)
   if (loadinfo->alloc)
     {
       kfree((void*)loadinfo->alloc);
-      loadinfo->alloc     = NULL;
+      loadinfo->alloc     = 0;
       loadinfo->allocsize = 0;
     }
 
-  if (loadinfo->shdrs)
+  if (loadinfo->shdr)
     {
-      kfree((void*)loadinfo->shdrs);
-      loadinfo->shdrs = 0;
+      kfree((void*)loadinfo->shdr);
+      loadinfo->shdr      = NULL;
     }
 
   return OK;
diff --git a/nuttx/binfmt/libelf/libelf_verify.c b/nuttx/binfmt/libelf/libelf_verify.c
index 0e0dd8e1a..c5f185ec3 100644
--- a/nuttx/binfmt/libelf/libelf_verify.c
+++ b/nuttx/binfmt/libelf/libelf_verify.c
@@ -53,7 +53,7 @@
  * Private Constant Data
  ****************************************************************************/
 
-static const char g_elfmagic[EI_MAGIC_SIZE] = { 0x7f, 'E', 'L', 'F' }
+static const char g_elfmagic[EI_MAGIC_SIZE] = { 0x7f, 'E', 'L', 'F' };
 
 /****************************************************************************
  * Private Functions
@@ -75,12 +75,12 @@ static const char g_elfmagic[EI_MAGIC_SIZE] = { 0x7f, 'E', 'L', 'F' }
  *   failure.
  *
  *   -ENOEXEC  : Not an ELF file
- *   -EINVALID : Not a relocatable ELF file or not supported by the current,
+ *   -EINVAL : Not a relocatable ELF file or not supported by the current,
  *               configured architecture.
  *
  ****************************************************************************/
 
-int elf_verifyheader(const Elf32_Ehdr *ehdr)
+int elf_verifyheader(FAR const Elf32_Ehdr *ehdr)
 {
   if (!ehdr)
     {
@@ -102,7 +102,7 @@ int elf_verifyheader(const Elf32_Ehdr *ehdr)
   if (ehdr->e_type != ET_REL)
     {
       bdbg("Not a relocatable file: e_type=%d\n", ehdr->e_type);
-      return -EINVALID;
+      return -EINVAL;
     }
 
   /* Verify that this file works with the currently configured architecture */