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Re: [PATCH 0/2] Support for FreeBSD/mips N32


On Wednesday, September 20, 2017 11:31:05 AM Alan Modra wrote:
> On Tue, Sep 19, 2017 at 01:48:12PM -0700, John Baldwin wrote:
> > The first patch to bfd/elf.c might be too hackish.
> 
> Yeah, I dislike the inclusion of mips.h in elf.c.
> 
> >  Not sure if adding a
> > new 'bed' method for 'grok_freebsd_prstatus' is a better approach?
> 
> Yes please.

Ok, how about this:

>From 5a2f8adf9d03f0cb80d9bcc849150936bfd64687 Mon Sep 17 00:00:00 2001
From: John Baldwin <jhb@FreeBSD.org>
Date: Mon, 18 Sep 2017 11:42:47 -0700
Subject: [PATCH v2 1/2] Account for padding in FreeBSD/mipsn32 NT_PRSTATUS
 notes.
To: gdb-patches@sourceware.org,
    binutils@sourceware.org

Add a new ELF backend method to grok FreeBSD NT_PRSTATUS core dump
notes.  Define a method for MIPS N32 to override the default
elfcore_grok_freebsd_prstatus that accounts for additional padding
between pr_pid and pr_reg that is not present in other 32-bit FreeBSD
platforms.

	* elf-bfd.h (struct elf_backend_data): Add
	`elf_backend_grok_freebsd_prstatus'.
	* elf.c (elfcore_grok_freebsd_note): Call
	`elf_backend_grok_freebsd_prstatus' to handle NT_PRSTATUS if
	present.
	* elfn32-mips.c (elf_n32_mips_grok_freebsd_prstatus): New
	function.
	(elf_backend_grok_freebsd_prstatus): Define.
	* elfxx-target.h (elf_backend_grok_freebsd_prstatus): Define.
	(elfNN_bed): Initialize `elf_backend_grok_freebsd_prstatus'.
---
 bfd/ChangeLog      | 13 +++++++++++++
 bfd/elf-bfd.h      |  5 +++++
 bfd/elf.c          |  5 +++++
 bfd/elfn32-mips.c  | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 bfd/elfxx-target.h |  4 ++++
 5 files changed, 81 insertions(+)

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 4c8c12cd46..033a634f28 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,16 @@
+2017-09-19  John Baldwin  <jhb@FreeBSD.org>
+
+	* elf-bfd.h (struct elf_backend_data): Add
+	`elf_backend_grok_freebsd_prstatus'.
+	* elf.c (elfcore_grok_freebsd_note): Call
+	`elf_backend_grok_freebsd_prstatus' to handle NT_PRSTATUS if
+	present.
+	* elfn32-mips.c (elf_n32_mips_grok_freebsd_prstatus): New
+	function.
+	(elf_backend_grok_freebsd_prstatus): Define.
+	* elfxx-target.h (elf_backend_grok_freebsd_prstatus): Define.
+	(elfNN_bed): Initialize `elf_backend_grok_freebsd_prstatus'.
+
 2017-09-19  Alan Modra  <amodra@gmail.com>
 
 	PR 21441
diff --git a/bfd/elf-bfd.h b/bfd/elf-bfd.h
index fd08748ae2..399e298a8d 100644
--- a/bfd/elf-bfd.h
+++ b/bfd/elf-bfd.h
@@ -1270,6 +1270,11 @@ struct elf_backend_data
   bfd_boolean (*elf_backend_grok_psinfo)
     (bfd *, Elf_Internal_Note *);
 
+  /* This function, if defined, is called when a "FreeBSD" NT_PRSTATUS
+     note is found in a core file.  */
+  bfd_boolean (*elf_backend_grok_freebsd_prstatus)
+    (bfd *, Elf_Internal_Note *);
+
   /* This function, if defined, is called to write a note to a corefile.  */
   char *(*elf_backend_write_core_note)
     (bfd *abfd, char *buf, int *bufsiz, int note_type, ...);
diff --git a/bfd/elf.c b/bfd/elf.c
index 2aa2337724..428506f862 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -9970,9 +9970,14 @@ elfcore_grok_freebsd_prstatus (bfd *abfd, Elf_Internal_Note *note)
 static bfd_boolean
 elfcore_grok_freebsd_note (bfd *abfd, Elf_Internal_Note *note)
 {
+  const struct elf_backend_data *bed = get_elf_backend_data (abfd);
+
   switch (note->type)
     {
     case NT_PRSTATUS:
+      if (bed->elf_backend_grok_freebsd_prstatus)
+	if ((*bed->elf_backend_grok_freebsd_prstatus) (abfd, note))
+	  return TRUE;
       return elfcore_grok_freebsd_prstatus (abfd, note);
 
     case NT_FPREGSET:
diff --git a/bfd/elfn32-mips.c b/bfd/elfn32-mips.c
index dce7ba1c7a..a8ccedaefc 100644
--- a/bfd/elfn32-mips.c
+++ b/bfd/elfn32-mips.c
@@ -80,6 +80,8 @@ static bfd_boolean elf32_mips_grok_prstatus
   (bfd *, Elf_Internal_Note *);
 static bfd_boolean elf32_mips_grok_psinfo
   (bfd *, Elf_Internal_Note *);
+static bfd_boolean elf_n32_mips_grok_freebsd_prstatus
+  (bfd *, Elf_Internal_Note *);
 static irix_compat_t elf_n32_mips_irix_compat
   (bfd *);
 
@@ -3578,6 +3580,56 @@ elf32_mips_grok_psinfo (bfd *abfd, Elf_Internal_Note *note)
 
   return TRUE;
 }
+
+static bfd_boolean
+elf_n32_mips_grok_freebsd_prstatus (bfd *abfd, Elf_Internal_Note *note)
+{
+  size_t offset;
+  size_t size;
+  size_t min_size;
+
+  /* Compute offset of pr_getregsz, skipping over pr_statussz.
+     Also compute minimum size of this note.  */
+  offset = 4 + 4;
+  min_size = offset + (4 * 2) + 4 + 4 + 4;
+
+  if (note->descsz < min_size)
+    return FALSE;
+
+  /* Check for version 1 in pr_version.  */
+  if (bfd_h_get_32 (abfd, (bfd_byte *) note->descdata) != 1)
+    return FALSE;
+
+  /* Extract size of pr_reg from pr_gregsetsz.  */
+  /* Skip over pr_gregsetsz and pr_fpregsetsz.  */
+  size = bfd_h_get_32 (abfd, (bfd_byte *) note->descdata + offset);
+  offset += 4 * 2;
+
+  /* Skip over pr_osreldate.  */
+  offset += 4;
+
+  /* Read signal from pr_cursig.  */
+  if (elf_tdata (abfd)->core->signal == 0)
+    elf_tdata (abfd)->core->signal
+      = bfd_h_get_32 (abfd, (bfd_byte *) note->descdata + offset);
+  offset += 4;
+
+  /* Read TID from pr_pid.  */
+  elf_tdata (abfd)->core->lwpid
+      = bfd_h_get_32 (abfd, (bfd_byte *) note->descdata + offset);
+  offset += 4;
+
+  /* Padding before pr_reg.  */
+  offset += 4;
+
+  /* Make sure that there is enough data remaining in the note.  */
+  if ((note->descsz - offset) < size)
+    return FALSE;
+
+  /* Make a ".reg/999" section and a ".reg" section.  */
+  return _bfd_elfcore_make_pseudosection (abfd, ".reg",
+					  size, note->descpos + offset);
+}
 
 /* Depending on the target vector we generate some version of Irix
    executables or "normal" MIPS ELF ABI executables.  */
@@ -3684,6 +3736,8 @@ static const struct ecoff_debug_swap mips_elf32_ecoff_debug_swap = {
 					_bfd_mips_elf_copy_indirect_symbol
 #define elf_backend_grok_prstatus	elf32_mips_grok_prstatus
 #define elf_backend_grok_psinfo		elf32_mips_grok_psinfo
+#define elf_backend_grok_freebsd_prstatus \
+					elf_n32_mips_grok_freebsd_prstatus
 #define elf_backend_ecoff_debug_swap	&mips_elf32_ecoff_debug_swap
 
 #define elf_backend_got_header_size	(4 * MIPS_RESERVED_GOTNO)
diff --git a/bfd/elfxx-target.h b/bfd/elfxx-target.h
index 551883fa09..6efca84e4e 100644
--- a/bfd/elfxx-target.h
+++ b/bfd/elfxx-target.h
@@ -597,6 +597,9 @@
 #ifndef elf_backend_grok_psinfo
 #define elf_backend_grok_psinfo			NULL
 #endif
+#ifndef elf_backend_grok_freebsd_prstatus
+#define elf_backend_grok_freebsd_prstatus	NULL
+#endif
 #ifndef elf_backend_write_core_note
 #define elf_backend_write_core_note		NULL
 #endif
@@ -820,6 +823,7 @@ static struct elf_backend_data elfNN_bed =
   elf_backend_sort_relocs_p,
   elf_backend_grok_prstatus,
   elf_backend_grok_psinfo,
+  elf_backend_grok_freebsd_prstatus,
   elf_backend_write_core_note,
   elf_backend_lookup_section_flags_hook,
   elf_backend_reloc_type_class,
-- 
2.13.3



-- 
John Baldwin


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