[rfc][1/3] Remote core file generation: BFD support

["Ulrich Weigand" <uweigand@de.ibm.com>]

Hello,

when implementing support for core file generation with remote targets
in GDB I ran into the problem that the elfcore_write_prpsinfo and
elfcore_write_prstatus are only defined for native targets.  This is
even though they could be implemented for remote targets if the
back-end provides the backend_write_core_note callback.

The following patch provides those functions unconditionally, so that
they can use the back-end callback if present, and return NULL to
signal failure if the callback is not available.

The patch in addition implements the callback for ARM Linux.

Bye,
Ulrich


ChangeLog:

	* elf.c (elfcore_write_prpsinfo): Provide unconditionally.
	Return NULL if core file generation is unsupported.
	(elfcore_write_prstatus): Likewise.
	* elf32-arm.c (elf32_arm_nabi_write_core_note): New function.
	(elf_backend_write_core_note): Define.


Index: bfd/elf.c
===================================================================
RCS file: /cvs/src/src/bfd/elf.c,v
retrieving revision 1.544
diff -u -p -r1.544 elf.c
--- bfd/elf.c	30 Sep 2011 10:39:44 -0000	1.544
+++ bfd/elf.c	21 Oct 2011 16:49:52 -0000
@@ -8863,7 +8863,6 @@ elfcore_write_note (bfd *abfd,
   return buf;
 }
 
-#if defined (HAVE_PRPSINFO_T) || defined (HAVE_PSINFO_T)
 char *
 elfcore_write_prpsinfo (bfd  *abfd,
 			char *buf,
@@ -8871,7 +8870,6 @@ elfcore_write_prpsinfo (bfd  *abfd,
 			const char *fname,
 			const char *psargs)
 {
-  const char *note_name = "CORE";
   const struct elf_backend_data *bed = get_elf_backend_data (abfd);
 
   if (bed->elf_backend_write_core_note != NULL)
@@ -8883,6 +8881,7 @@ elfcore_write_prpsinfo (bfd  *abfd,
 	return ret;
     }
 
+#if defined (HAVE_PRPSINFO_T) || defined (HAVE_PSINFO_T)
 #if defined (HAVE_PRPSINFO32_T) || defined (HAVE_PSINFO32_T)
   if (bed->s->elfclass == ELFCLASS32)
     {
@@ -8898,7 +8897,7 @@ elfcore_write_prpsinfo (bfd  *abfd,
       strncpy (data.pr_fname, fname, sizeof (data.pr_fname));
       strncpy (data.pr_psargs, psargs, sizeof (data.pr_psargs));
       return elfcore_write_note (abfd, buf, bufsiz,
-				 note_name, note_type, &data, sizeof (data));
+				 "CORE", note_type, &data, sizeof (data));
     }
   else
 #endif
@@ -8915,12 +8914,14 @@ elfcore_write_prpsinfo (bfd  *abfd,
       strncpy (data.pr_fname, fname, sizeof (data.pr_fname));
       strncpy (data.pr_psargs, psargs, sizeof (data.pr_psargs));
       return elfcore_write_note (abfd, buf, bufsiz,
-				 note_name, note_type, &data, sizeof (data));
+				 "CORE", note_type, &data, sizeof (data));
     }
-}
 #endif	/* PSINFO_T or PRPSINFO_T */
 
-#if defined (HAVE_PRSTATUS_T)
+  free (buf);
+  return NULL;
+}
+
 char *
 elfcore_write_prstatus (bfd *abfd,
 			char *buf,
@@ -8929,7 +8930,6 @@ elfcore_write_prstatus (bfd *abfd,
 			int cursig,
 			const void *gregs)
 {
-  const char *note_name = "CORE";
   const struct elf_backend_data *bed = get_elf_backend_data (abfd);
 
   if (bed->elf_backend_write_core_note != NULL)
@@ -8942,6 +8942,7 @@ elfcore_write_prstatus (bfd *abfd,
 	return ret;
     }
 
+#if defined (HAVE_PRSTATUS_T)
 #if defined (HAVE_PRSTATUS32_T)
   if (bed->s->elfclass == ELFCLASS32)
     {
@@ -8951,7 +8952,7 @@ elfcore_write_prstatus (bfd *abfd,
       prstat.pr_pid = pid;
       prstat.pr_cursig = cursig;
       memcpy (&prstat.pr_reg, gregs, sizeof (prstat.pr_reg));
-      return elfcore_write_note (abfd, buf, bufsiz, note_name,
+      return elfcore_write_note (abfd, buf, bufsiz, "CORE",
 				 NT_PRSTATUS, &prstat, sizeof (prstat));
     }
   else
@@ -8963,12 +8964,15 @@ elfcore_write_prstatus (bfd *abfd,
       prstat.pr_pid = pid;
       prstat.pr_cursig = cursig;
       memcpy (&prstat.pr_reg, gregs, sizeof (prstat.pr_reg));
-      return elfcore_write_note (abfd, buf, bufsiz, note_name,
+      return elfcore_write_note (abfd, buf, bufsiz, "CORE",
 				 NT_PRSTATUS, &prstat, sizeof (prstat));
     }
-}
 #endif /* HAVE_PRSTATUS_T */
 
+  free (buf);
+  return NULL;
+}
+
 #if defined (HAVE_LWPSTATUS_T)
 char *
 elfcore_write_lwpstatus (bfd *abfd,
Index: bfd/elf32-arm.c
===================================================================
RCS file: /cvs/src/src/bfd/elf32-arm.c,v
retrieving revision 1.278
diff -u -p -r1.278 elf32-arm.c
--- bfd/elf32-arm.c	19 Oct 2011 07:17:13 -0000	1.278
+++ bfd/elf32-arm.c	21 Oct 2011 16:49:54 -0000
@@ -1986,6 +1986,55 @@ elf32_arm_nabi_grok_psinfo (bfd *abfd, E
   return TRUE;
 }
 
+static char *
+elf32_arm_nabi_write_core_note (bfd *abfd, char *buf, int *bufsiz,
+				int note_type, ...)
+{
+  switch (note_type)
+    {
+    default:
+      return NULL;
+
+    case NT_PRPSINFO:
+      {
+	char data[124];
+	va_list ap;
+
+	va_start (ap, note_type);
+	memset (data, 0, 28);
+	strncpy (data + 28, va_arg (ap, const char *), 16);
+	strncpy (data + 44, va_arg (ap, const char *), 80);
+	va_end (ap);
+
+	return elfcore_write_note (abfd, buf, bufsiz,
+				   "CORE", note_type, data, sizeof (data));
+      }
+
+    case NT_PRSTATUS:
+      {
+	char data[148];
+	va_list ap;
+	long pid;
+	int cursig;
+	const void *greg;
+
+	va_start (ap, note_type);
+	memset (data, 0, 72);
+	pid = va_arg (ap, long);
+	bfd_put_32 (abfd, pid, data + 24);
+	cursig = va_arg (ap, int);
+	bfd_put_16 (abfd, cursig, data + 12);
+	greg = va_arg (ap, const void *);
+	memcpy (data + 72, greg, 72);
+	memset (data + 144, 0, 4);
+	va_end (ap);
+
+	return elfcore_write_note (abfd, buf, bufsiz,
+				   "CORE", note_type, data, sizeof (data));
+      }
+    }
+}
+
 #define TARGET_LITTLE_SYM               bfd_elf32_littlearm_vec
 #define TARGET_LITTLE_NAME              "elf32-littlearm"
 #define TARGET_BIG_SYM                  bfd_elf32_bigarm_vec
@@ -1993,6 +2042,7 @@ elf32_arm_nabi_grok_psinfo (bfd *abfd, E
 
 #define elf_backend_grok_prstatus	elf32_arm_nabi_grok_prstatus
 #define elf_backend_grok_psinfo		elf32_arm_nabi_grok_psinfo
+#define elf_backend_write_core_note	elf32_arm_nabi_write_core_note
 
 typedef unsigned long int insn32;
 typedef unsigned short int insn16;
-- 
  Dr. Ulrich Weigand
  GNU Toolchain for Linux on System z and Cell BE
  Ulrich.Weigand@de.ibm.com