From 206c98a6503de9c78550b7e503526f59b5b2f491 Mon Sep 17 00:00:00 2001
From: Kamil Rytarowski <n54@gmx.com>
Date: Wed, 8 Apr 2020 04:01:10 +0200
Subject: Add SVR4 psABI specific parser for AUXV entries

NetBSD and OpenBSD always use an int to store the type as
defined in the SVR4 psABI specifications rather than long
as assumed by the default parser.

Define svr4_auxv_parse() that shares code with default_auxv_parse().

Remove obsd_auxv_parse() and switch OpenBSD to svr4_auxv_parse().
Remove not fully accurate comment from obsd-tdep.c.

Use svr4_auxv_parse() on NetBSD.

gdb/ChangeLog:

	* auxv.h (svr4_auxv_parse): New.
	* auxv.c (default_auxv_parse): Split into default_auxv_parse
	and generic_auxv_parse.
	(svr4_auxv_parse): Add.
	* obsd-tdep.c: Include "auxv.h".
	(obsd_auxv_parse): Remove.
	(obsd_init_abi): Remove comment.
	(obsd_init_abi): Change set_gdbarch_auxv_parse passed argument
	from `obsd_auxv_parse' to `svr4_auxv_parse'.
	* nbsd-tdep.c: Include "auxv.h".
	(nbsd_init_abi): Call set_gdbarch_auxv_parse.
---
 gdb/auxv.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 46 insertions(+), 15 deletions(-)

(limited to 'gdb/auxv.c')

diff --git a/gdb/auxv.c b/gdb/auxv.c
index c13d7a2..2ffcd73 100644
--- a/gdb/auxv.c
+++ b/gdb/auxv.c
@@ -248,34 +248,65 @@ memory_xfer_auxv (struct target_ops *ops,
   return procfs_xfer_auxv (readbuf, writebuf, offset, len, xfered_len);
 }
 
-/* Read one auxv entry from *READPTR, not reading locations >= ENDPTR.
-   Return 0 if *READPTR is already at the end of the buffer.
-   Return -1 if there is insufficient buffer for a whole entry.
-   Return 1 if an entry was read into *TYPEP and *VALP.  */
-int
-default_auxv_parse (struct target_ops *ops, gdb_byte **readptr,
-		   gdb_byte *endptr, CORE_ADDR *typep, CORE_ADDR *valp)
+/* This function compared to other auxv_parse functions: it takes the size of
+   the auxv type field as a parameter.  */
+
+static int
+generic_auxv_parse (struct gdbarch *gdbarch, gdb_byte **readptr,
+		    gdb_byte *endptr, CORE_ADDR *typep, CORE_ADDR *valp,
+		    int sizeof_auxv_type)
 {
-  const int sizeof_auxv_field = gdbarch_ptr_bit (target_gdbarch ())
-				/ TARGET_CHAR_BIT;
-  const enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
+  struct type *ptr_type = builtin_type (gdbarch)->builtin_data_ptr;
+  const int sizeof_auxv_val = TYPE_LENGTH (ptr_type);
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
   gdb_byte *ptr = *readptr;
 
   if (endptr == ptr)
     return 0;
 
-  if (endptr - ptr < sizeof_auxv_field * 2)
+  if (endptr - ptr < 2 * sizeof_auxv_val)
     return -1;
 
-  *typep = extract_unsigned_integer (ptr, sizeof_auxv_field, byte_order);
-  ptr += sizeof_auxv_field;
-  *valp = extract_unsigned_integer (ptr, sizeof_auxv_field, byte_order);
-  ptr += sizeof_auxv_field;
+  *typep = extract_unsigned_integer (ptr, sizeof_auxv_type, byte_order);
+  /* Even if the auxv type takes less space than an auxv value, there is
+     padding after the type such that the value is aligned on a multiple of
+     its size (and this is why we advance by `sizeof_auxv_val` and not
+     `sizeof_auxv_type`).  */
+  ptr += sizeof_auxv_val;
+  *valp = extract_unsigned_integer (ptr, sizeof_auxv_val, byte_order);
+  ptr += sizeof_auxv_val;
 
   *readptr = ptr;
   return 1;
 }
 
+/* See auxv.h.  */
+
+int
+default_auxv_parse (struct target_ops *ops, gdb_byte **readptr,
+		    gdb_byte *endptr, CORE_ADDR *typep, CORE_ADDR *valp)
+{
+  struct gdbarch *gdbarch = target_gdbarch ();
+  struct type *ptr_type = builtin_type (gdbarch)->builtin_data_ptr;
+  const int sizeof_auxv_type = TYPE_LENGTH (ptr_type);
+
+  return generic_auxv_parse (gdbarch, readptr, endptr, typep, valp,
+			     sizeof_auxv_type);
+}
+
+/* See auxv.h.  */
+
+int
+svr4_auxv_parse (struct gdbarch *gdbarch, gdb_byte **readptr,
+		 gdb_byte *endptr, CORE_ADDR *typep, CORE_ADDR *valp)
+{
+  struct type *int_type = builtin_type (gdbarch)->builtin_int;
+  const int sizeof_auxv_type = TYPE_LENGTH (int_type);
+
+  return generic_auxv_parse (gdbarch, readptr, endptr, typep, valp,
+			     sizeof_auxv_type);
+}
+
 /* Read one auxv entry from *READPTR, not reading locations >= ENDPTR.
    Return 0 if *READPTR is already at the end of the buffer.
    Return -1 if there is insufficient buffer for a whole entry.
-- 
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