[PATCH 3/4] ELF/BFD: Handle both variants of the 64-bit Linux core PRPSINFO note

["Maciej W. Rozycki" <macro at imgtec dot com>]

Fix commit 70a38d42c5b3 ("New entry points for writing Linux NT_PRPSINFO 
notes."), <https://sourceware.org/ml/binutils/2013-02/msg00023.html>, 
and handle both variants of the 64-bit Linux core PRPSINFO note across 
all targets.

The 64-bit Linux core PRPSINFO note matches the 64-bit kernel structure, 
defined as follows:

(gdb) ptype struct elf_prpsinfo
type = struct elf_prpsinfo {
    char pr_state;
    char pr_sname;
    char pr_zomb;
    char pr_nice;
    unsigned long pr_flag;
    __kernel_uid_t pr_uid;
    __kernel_gid_t pr_gid;
    pid_t pr_pid;
    pid_t pr_ppid;
    pid_t pr_pgrp;
    pid_t pr_sid;
    char pr_fname[16];
    char pr_psargs[80];
}
(gdb)

where the individual data types of most members are the same across all 
64-bit Linux ports, with the exception of `__kernel_uid_t' and 
`__kernel_gid_t'.  These are defined in <asm-generic/posix_types.h> as 
32-bit `unsigned int' by default, however overridden as 16-bit `unsigned 
short' in port-specific <asm/posix_types.h> for the SuperH target.

The default is already handled, as from the commit referred.  Add the 
other variant then and provide a backend flag to switch between the two 
cases possible, with the 32-bit one being the default and the 16-bit one 
explicitly selected.  Set the flag in the SuperH target backend.  This 
arrangement is analogous to how the 32-bit Linux core PRPSINFO note is
handled.

	bfd/
	* elf-bfd.h (elf_backend_data): Add `linux_prpsinfo64_ugid16' 
	member.
	* elf-linux-core.h (elf_external_linux_prpsinfo64): Rename to...
	(elf_external_linux_prpsinfo64_ugid32): ... this.
	(swap_linux_prpsinfo32_out): Rename to...
	(swap_linux_prpsinfo32_ugid32_out): ... this.
	(elf_external_linux_prpsinfo64_ugid16): New structure.
	(swap_linux_prpsinfo64_ugid16_out): New function.
	* elfxx-target.h [!elf_backend_linux_prpsinfo64_ugid16]
	(elf_backend_linux_prpsinfo64_ugid16): Define.
	(elfNN_bed): Initialize `linux_prpsinfo64_ugid16' member.
	* elf.c (elfcore_write_linux_prpsinfo64): Handle both variants 
	of the 64-bit Linux core PRPSINFO note.
	* elf64-sh64.c (elf_backend_linux_prpsinfo64_ugid16): Define.
---
 bfd/elf-bfd.h        |    4 +++
 bfd/elf-linux-core.h |   68 +++++++++++++++++++++++++++++++++++++++++++++++----
 bfd/elf.c            |   21 ++++++++++++---
 bfd/elf64-sh64.c     |    2 +
 bfd/elfxx-target.h   |    6 +++-
 5 files changed, 90 insertions(+), 11 deletions(-)

gdb-elf-linux-core-prpsinfo64-ugid.diff
Index: binutils/bfd/elf-bfd.h
===================================================================
--- binutils.orig/bfd/elf-bfd.h	2017-09-20 13:03:18.000000000 +0100
+++ binutils/bfd/elf-bfd.h	2017-09-20 13:06:49.534308157 +0100
@@ -1556,6 +1556,10 @@ struct elf_backend_data
   /* True if the 32-bit Linux PRPSINFO structure's `pr_uid' and `pr_gid'
      members use a 16-bit data type.  */
   unsigned linux_prpsinfo32_ugid16 : 1;
+
+  /* True if the 64-bit Linux PRPSINFO structure's `pr_uid' and `pr_gid'
+     members use a 16-bit data type.  */
+  unsigned linux_prpsinfo64_ugid16 : 1;
 };
 
 /* Information about reloc sections associated with a bfd_elf_section_data
Index: binutils/bfd/elf-linux-core.h
===================================================================
--- binutils.orig/bfd/elf-linux-core.h	2017-09-20 13:03:18.000000000 +0100
+++ binutils/bfd/elf-linux-core.h	2017-09-20 13:15:40.694234169 +0100
@@ -129,10 +129,14 @@ swap_linux_prpsinfo32_ugid16_out
    ABI-defined, thus we choose to use char arrays here in order to
    avoid dealing with different types in different architectures.
 
+   This is the variant for targets which use a 32-bit data type for
+   UID and GID, as most Linux ports do.  The SH64 port uses a 16-bit
+   data type instead; see below for the alternative variant.
+
    This structure will ultimately be written in the corefile's note
    section, as the PRPSINFO.  */
 
-struct elf_external_linux_prpsinfo64
+struct elf_external_linux_prpsinfo64_ugid32
   {
     char pr_state;			/* Numeric process state.  */
     char pr_sname;			/* Char for pr_state.  */
@@ -151,12 +155,13 @@ struct elf_external_linux_prpsinfo64
   };
 
 /* Helper function to copy an elf_internal_linux_prpsinfo in host
-   endian to an elf_external_linux_prpsinfo64 in target endian.  */
+   endian to an elf_external_linux_prpsinfo64_ugid32 in target endian.  */
 
 static inline void
-swap_linux_prpsinfo64_out (bfd *obfd,
-			   const struct elf_internal_linux_prpsinfo *from,
-			   struct elf_external_linux_prpsinfo64 *to)
+swap_linux_prpsinfo64_ugid32_out
+  (bfd *obfd,
+   const struct elf_internal_linux_prpsinfo *from,
+   struct elf_external_linux_prpsinfo64_ugid32 *to)
 {
   bfd_put_8 (obfd, from->pr_state, &to->pr_state);
   bfd_put_8 (obfd, from->pr_sname, &to->pr_sname);
@@ -173,4 +178,57 @@ swap_linux_prpsinfo64_out (bfd *obfd,
   strncpy (to->pr_psargs, from->pr_psargs, sizeof (to->pr_psargs));
 }
 
+/* External 64-bit structure for PRPSINFO.  This structure is
+   ABI-defined, thus we choose to use char arrays here in order to
+   avoid dealing with different types in different architectures.
+
+   This is the variant for the SH64 port which uses a 16-bit data
+   type for UID and GID.  Most Linux ports use a 32-bit data type
+   instead; see above for the alternative variant.
+
+   This structure will ultimately be written in the corefile's note
+   section, as the PRPSINFO.  */
+
+struct elf_external_linux_prpsinfo64_ugid16
+  {
+    char pr_state;			/* Numeric process state.  */
+    char pr_sname;			/* Char for pr_state.  */
+    char pr_zomb;			/* Zombie.  */
+    char pr_nice;			/* Nice val.  */
+    char gap[4];
+    char pr_flag[8];			/* Flags.  */
+    char pr_uid[2];
+    char pr_gid[2];
+    char pr_pid[4];
+    char pr_ppid[4];
+    char pr_pgrp[4];
+    char pr_sid[4];
+    char pr_fname[16];			/* Filename of executable.  */
+    char pr_psargs[80];			/* Initial part of arg list.  */
+  };
+
+/* Helper function to copy an elf_internal_linux_prpsinfo in host
+   endian to an elf_external_linux_prpsinfo64_ugid16 in target endian.  */
+
+static inline void
+swap_linux_prpsinfo64_ugid16_out
+  (bfd *obfd,
+   const struct elf_internal_linux_prpsinfo *from,
+   struct elf_external_linux_prpsinfo64_ugid16 *to)
+{
+  bfd_put_8 (obfd, from->pr_state, &to->pr_state);
+  bfd_put_8 (obfd, from->pr_sname, &to->pr_sname);
+  bfd_put_8 (obfd, from->pr_zomb, &to->pr_zomb);
+  bfd_put_8 (obfd, from->pr_nice, &to->pr_nice);
+  bfd_put_64 (obfd, from->pr_flag, to->pr_flag);
+  bfd_put_16 (obfd, from->pr_uid, to->pr_uid);
+  bfd_put_16 (obfd, from->pr_gid, to->pr_gid);
+  bfd_put_32 (obfd, from->pr_pid, to->pr_pid);
+  bfd_put_32 (obfd, from->pr_ppid, to->pr_ppid);
+  bfd_put_32 (obfd, from->pr_pgrp, to->pr_pgrp);
+  bfd_put_32 (obfd, from->pr_sid, to->pr_sid);
+  strncpy (to->pr_fname, from->pr_fname, sizeof (to->pr_fname));
+  strncpy (to->pr_psargs, from->pr_psargs, sizeof (to->pr_psargs));
+}
+
 #endif
Index: binutils/bfd/elf.c
===================================================================
--- binutils.orig/bfd/elf.c	2017-09-20 13:03:18.000000000 +0100
+++ binutils/bfd/elf.c	2017-09-20 13:18:25.396554524 +0100
@@ -10470,11 +10470,22 @@ elfcore_write_linux_prpsinfo64
   (bfd *abfd, char *buf, int *bufsiz,
    const struct elf_internal_linux_prpsinfo *prpsinfo)
 {
-  struct elf_external_linux_prpsinfo64 data;
-
-  swap_linux_prpsinfo64_out (abfd, prpsinfo, &data);
-  return elfcore_write_note (abfd, buf, bufsiz,
-			     "CORE", NT_PRPSINFO, &data, sizeof (data));
+  if (get_elf_backend_data (abfd)->linux_prpsinfo64_ugid16)
+    {
+      struct elf_external_linux_prpsinfo64_ugid16 data;
+
+      swap_linux_prpsinfo64_ugid16_out (abfd, prpsinfo, &data);
+      return elfcore_write_note (abfd, buf, bufsiz,
+				 "CORE", NT_PRPSINFO, &data, sizeof (data));
+    }
+  else
+    {
+      struct elf_external_linux_prpsinfo64_ugid32 data;
+
+      swap_linux_prpsinfo64_ugid32_out (abfd, prpsinfo, &data);
+      return elfcore_write_note (abfd, buf, bufsiz,
+				 "CORE", NT_PRPSINFO, &data, sizeof (data));
+    }
 }
 
 char *
Index: binutils/bfd/elf64-sh64.c
===================================================================
--- binutils.orig/bfd/elf64-sh64.c	2017-08-02 13:13:26.000000000 +0100
+++ binutils/bfd/elf64-sh64.c	2017-09-20 13:19:29.748292419 +0100
@@ -3944,6 +3944,8 @@ static const struct bfd_elf_special_sect
 #define elf_backend_got_header_size	24
 #define elf_backend_dtrel_excludes_plt	1
 
+#define elf_backend_linux_prpsinfo64_ugid16	TRUE
+
 #include "elf64-target.h"
 
 /* NetBSD support.  */
Index: binutils/bfd/elfxx-target.h
===================================================================
--- binutils.orig/bfd/elfxx-target.h	2017-09-20 13:03:18.000000000 +0100
+++ binutils/bfd/elfxx-target.h	2017-09-20 13:20:49.220803426 +0100
@@ -135,6 +135,9 @@
 #ifndef elf_backend_linux_prpsinfo32_ugid16
 #define elf_backend_linux_prpsinfo32_ugid16 FALSE
 #endif
+#ifndef elf_backend_linux_prpsinfo64_ugid16
+#define elf_backend_linux_prpsinfo64_ugid16 FALSE
+#endif
 #ifndef elf_backend_stack_align
 #define elf_backend_stack_align 16
 #endif
@@ -895,7 +898,8 @@ static struct elf_backend_data elfNN_bed
   elf_backend_caches_rawsize,
   elf_backend_extern_protected_data,
   elf_backend_always_renumber_dynsyms,
-  elf_backend_linux_prpsinfo32_ugid16
+  elf_backend_linux_prpsinfo32_ugid16,
+  elf_backend_linux_prpsinfo64_ugid16
 };
 
 /* Forward declaration for use when initialising alternative_target field.  */