MIPS: IEEE 754-2008 NaN encoding support

It has been a long practice for software using IEEE 754 floating-point
arithmetic run on MIPS processors to use an encoding of Not-a-Number
(NaN) data different to one used by software run on other processors.
And as of IEEE 754-2008 revision [1] this encoding does not follow one
recommended in the standard, as specified in section 6.2.1, where it
is stated that quiet NaNs should have the first bit (d1) of their
significand set to 1 while signalling NaNs should have that bit set to
0, but MIPS software interprets the two bits in the opposite manner.

As from revision 3.50 [2][3] the MIPS Architecture provides for
processors that support the IEEE 754-2008 preferred NaN encoding format.
As the two formats (further referred to as "legacy NaN" and "2008 NaN")
are incompatible to each other, tools have to provide support for the
two formats to help people avoid using incompatible binary modules.

The change is comprised of two functional groups of features, both of
which are required for correct support.

1. Dynamic linker support.

   To enforce the NaN encoding requirement in dynamic linking a new ELF
   file header flag has been defined.  This flag is set for 2008-NaN
   shared modules and executables and clear for legacy-NaN ones.  The
   dynamic linker silently ignores any incompatible modules it
   encounters in dependency processing.

   To avoid unnecessary processing of incompatible modules in the
   presence of a shared module cache, a set of new cache flags has been
   defined to mark 2008-NaN modules for the three ABIs supported.
   Changes to sysdeps/unix/sysv/linux/mips/readelflib.c have been made
   following an earlier code quality suggestion made here:

   http://sourceware.org/ml/libc-ports/2009-03/msg00036.html

   and are therefore a little bit more extensive than the minimum
   required.

   Finally a new name has been defined for the dynamic linker so that
   2008-NaN and legacy-NaN binaries can coexist on a single system that
   supports dual-mode operation and that a legacy dynamic linker that
   does not support verifying the 2008-NaN ELF file header flag is not
   chosen to interpret a 2008-NaN binary by accident.

2. Floating environment support.

   IEEE 754-2008 features are controlled in the Floating-Point Control
   and Status (FCSR) register and updates are needed to floating
   environment support so that the 2008-NaN flag is set correctly and
   the kernel default, inferred from the 2008-NaN ELF file header flag
   at the time an executable is loaded, respected.

As the NaN encoding format is a property of GCC code generation that is
both a user-selected GCC configuration default and can be overridden
with GCC options, code that needs to know what NaN encoding standard it
has been configured for checks for the __mips_nan2008 macro that is
defined internally by GCC whenever the 2008-NaN mode has been selected.
This mode is determined at the glibc configuration time and therefore a
few consistency checks have been added to catch cases where compilation
flags have been overridden by the user.

The 2008 NaN set of features relies on kernel support as the in-kernel
floating-point emulator needs to be aware of the NaN encoding used even
on hard-float processors and configure the FPU context according to the
value of the 2008 NaN ELF file header flag of the executable being
started.  As at this time work on kernel support is still in progress
and the relevant changes have not made their way yet to linux.org master
repository.

Therefore the minimum version supported has been artificially set to
10.0.0 so that 2008-NaN code is not accidentally run on a Linux kernel
that does not suppport it.  It is anticipated that the version is
adjusted later on to the actual initial linux.org kernel version to
support this feature.  Legacy NaN encoding support is unaffected, older
kernel versions remain supported.

[1] "IEEE Standard for Floating-Point Arithmetic", IEEE Computer
    Society, IEEE Std 754-2008, 29 August 2008

[2] "MIPS Architecture For Programmers, Volume I-A: Introduction to the
    MIPS32 Architecture", MIPS Technologies, Inc., Document Number:
    MD00082, Revision 3.50, September 20, 2012

[3] "MIPS Architecture For Programmers, Volume I-A: Introduction to the
    MIPS64 Architecture", MIPS Technologies, Inc., Document Number:
    MD00083, Revision 3.50, September 20, 2012

5 files changed, 316 insertions, 29 deletions

diff --git a/ports/sysdeps/unix/sysv/linux/mips/Makefile b/ports/sysdeps/unix/sysv/linux/mips/Makefile
index 1e54036bfe..9070b775c4 100644
--- a/ports/sysdeps/unix/sysv/linux/mips/Makefile
+++ b/ports/sysdeps/unix/sysv/linux/mips/Makefile
@@ -8,7 +8,9 @@ sysdep_routines += cachectl cacheflush sysmips _test_and_set
 sysdep_headers += sys/cachectl.h sys/sysmips.h sys/tas.h
 endif
 
-abi-variants := o32_soft o32_hard n32_soft n32_hard n64_soft n64_hard
+abi-variants := o32_soft o32_hard o32_soft_2008 o32_hard_2008
+abi-variants += n32_soft n32_hard n32_soft_2008 n32_hard_2008
+abi-variants += n64_soft n64_hard n64_soft_2008 n64_hard_2008
 
 ifeq (,$(filter $(default-abi),$(abi-variants)))
 Unknown ABI, must be one of $(abi-variants)
@@ -18,29 +20,89 @@ abi-includes := sgidefs.h
 
 # _MIPS_SIM_ABI32 == 1, _MIPS_SIM_NABI32 == 2, _MIPS_SIM_ABI64 == 3
 abi-o32_soft-options := -U_MIPS_SIM -D_MIPS_SIM=1 \
-			-D__mips_soft_float -U__mips_hard_float
-abi-o32_soft-condition := defined(__mips_soft_float) \
-			   && (_MIPS_SIM == _MIPS_SIM_ABI32)
+			-D__mips_soft_float -U__mips_hard_float \
+			-U__mips_nan2008
+abi-o32_soft-condition := !defined(__mips_nan2008) \
+			  && defined(__mips_soft_float) \
+			  && (_MIPS_SIM == _MIPS_SIM_ABI32)
+abi-o32_soft-ld-soname := ld.so.1
 abi-o32_hard-options := -U_MIPS_SIM -D_MIPS_SIM=1 \
-			-D__mips_hard_float -U__mips_soft_float
-abi-o32_hard-condition := defined(__mips_hard_float) \
+			-D__mips_hard_float -U__mips_soft_float \
+			-U__mips_nan2008
+abi-o32_hard-condition := !defined(__mips_nan2008) \
+			  && defined(__mips_hard_float) \
 			  && (_MIPS_SIM == _MIPS_SIM_ABI32)
+abi-o32_hard-ld-soname := ld.so.1
+abi-o32_soft_2008-options := -U_MIPS_SIM -D_MIPS_SIM=1 \
+			     -D__mips_soft_float -U__mips_hard_float \
+			     -D__mips_nan2008
+abi-o32_soft_2008-condition := defined(__mips_nan2008) \
+			       && defined(__mips_soft_float) \
+			       && (_MIPS_SIM == _MIPS_SIM_ABI32)
+abi-o32_soft_2008-ld-soname := ld-linux-mipsn8.so.1
+abi-o32_hard_2008-options := -U_MIPS_SIM -D_MIPS_SIM=1 \
+			     -D__mips_hard_float -U__mips_soft_float \
+			     -D__mips_nan2008
+abi-o32_hard_2008-condition := defined(__mips_nan2008) \
+			       && defined(__mips_hard_float) \
+			       && (_MIPS_SIM == _MIPS_SIM_ABI32)
+abi-o32_hard_2008-ld-soname := ld-linux-mipsn8.so.1
 abi-n32_soft-options := -U_MIPS_SIM -D_MIPS_SIM=2 \
-			-D__mips_soft_float -U__mips_hard_float
-abi-n32_soft-condition := defined(__mips_soft_float) \
+			-D__mips_soft_float -U__mips_hard_float \
+			-U__mips_nan2008
+abi-n32_soft-condition := !defined(__mips_nan2008) \
+			  && defined(__mips_soft_float) \
 			  && (_MIPS_SIM == _MIPS_SIM_NABI32)
+abi-n32_soft-ld-soname := ld.so.1
 abi-n32_hard-options := -U_MIPS_SIM -D_MIPS_SIM=2 \
-			-D__mips_hard_float -U__mips_soft_float
-abi-n32_hard-condition := defined(__mips_hard_float) \
+			-D__mips_hard_float -U__mips_soft_float \
+			-U__mips_nan2008
+abi-n32_hard-condition := !defined(__mips_nan2008) \
+			  && defined(__mips_hard_float) \
 			  && (_MIPS_SIM == _MIPS_SIM_NABI32)
+abi-n32_hard-ld-soname := ld.so.1
+abi-n32_soft_2008-options := -U_MIPS_SIM -D_MIPS_SIM=2 \
+			     -D__mips_soft_float -U__mips_hard_float \
+			     -D__mips_nan2008
+abi-n32_soft_2008-condition := defined(__mips_nan2008) \
+			       && defined(__mips_soft_float) \
+			       && (_MIPS_SIM == _MIPS_SIM_NABI32)
+abi-n32_soft_2008-ld-soname := ld-linux-mipsn8.so.1
+abi-n32_hard_2008-options := -U_MIPS_SIM -D_MIPS_SIM=2 \
+			     -D__mips_hard_float -U__mips_soft_float \
+			     -D__mips_nan2008
+abi-n32_hard_2008-condition := defined(__mips_nan2008) \
+			       && defined(__mips_hard_float) \
+			       && (_MIPS_SIM == _MIPS_SIM_NABI32)
+abi-n32_hard_2008-ld-soname := ld-linux-mipsn8.so.1
 abi-n64_soft-options := -U_MIPS_SIM -D_MIPS_SIM=3 \
-			-D__mips_soft_float -U__mips_hard_float
-abi-n64_soft-condition := defined(__mips_soft_float) \
+			-D__mips_soft_float -U__mips_hard_float \
+			-U__mips_nan2008
+abi-n64_soft-condition := !defined(__mips_nan2008) \
+			  && defined(__mips_soft_float) \
 			  && (_MIPS_SIM == _MIPS_SIM_ABI64)
+abi-n64_soft-ld-soname := ld.so.1
 abi-n64_hard-options := -U_MIPS_SIM -D_MIPS_SIM=3 \
-			-D__mips_hard_float -U__mips_soft_float
-abi-n64_hard-condition := defined(__mips_hard_float) \
+			-D__mips_hard_float -U__mips_soft_float \
+			-U__mips_nan2008
+abi-n64_hard-condition := !defined(__mips_nan2008) \
+			  && defined(__mips_hard_float) \
 			  && (_MIPS_SIM == _MIPS_SIM_ABI64)
+abi-n64_hard-ld-soname := ld.so.1
+abi-n64_soft_2008-options := -U_MIPS_SIM -D_MIPS_SIM=3 \
+			     -D__mips_soft_float -U__mips_hard_float \
+			     -D__mips_nan2008
+abi-n64_soft_2008-condition := defined(__mips_nan2008) \
+			       && defined(__mips_soft_float) \
+			       && (_MIPS_SIM == _MIPS_SIM_ABI64)
+abi-n64_soft_2008-ld-soname := ld-linux-mipsn8.so.1
+abi-n64_hard_2008-options := -U_MIPS_SIM -D_MIPS_SIM=3 \
+			     -D__mips_hard_float -U__mips_soft_float \
+			     -D__mips_nan2008
+abi-n64_hard_2008-condition := defined(__mips_nan2008) \
+			       && defined(__mips_hard_float) \
+			       && (_MIPS_SIM == _MIPS_SIM_ABI64)
+abi-n64_hard_2008-ld-soname := ld-linux-mipsn8.so.1
 
 ifeq ($(subdir),elf)
 ifeq ($(build-shared),yes)
diff --git a/ports/sysdeps/unix/sysv/linux/mips/configure b/ports/sysdeps/unix/sysv/linux/mips/configure
index b4ee83e3ae..088210ff97 100644
--- a/ports/sysdeps/unix/sysv/linux/mips/configure
+++ b/ports/sysdeps/unix/sysv/linux/mips/configure
@@ -105,8 +105,168 @@ if test -z "$libc_mips_float"; then
   as_fn_error $? "could not determine if compiler is using hard or soft floating point ABI" "$LINENO" 5
 fi
 
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for grep that handles long lines and -e" >&5
+$as_echo_n "checking for grep that handles long lines and -e... " >&6; }
+if ${ac_cv_path_GREP+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  if test -z "$GREP"; then
+  ac_path_GREP_found=false
+  # Loop through the user's path and test for each of PROGNAME-LIST
+  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH$PATH_SEPARATOR/usr/xpg4/bin
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_prog in grep ggrep; do
+    for ac_exec_ext in '' $ac_executable_extensions; do
+      ac_path_GREP="$as_dir/$ac_prog$ac_exec_ext"
+      { test -f "$ac_path_GREP" && $as_test_x "$ac_path_GREP"; } || continue
+# Check for GNU ac_path_GREP and select it if it is found.
+  # Check for GNU $ac_path_GREP
+case `"$ac_path_GREP" --version 2>&1` in
+*GNU*)
+  ac_cv_path_GREP="$ac_path_GREP" ac_path_GREP_found=:;;
+*)
+  ac_count=0
+  $as_echo_n 0123456789 >"conftest.in"
+  while :
+  do
+    cat "conftest.in" "conftest.in" >"conftest.tmp"
+    mv "conftest.tmp" "conftest.in"
+    cp "conftest.in" "conftest.nl"
+    $as_echo 'GREP' >> "conftest.nl"
+    "$ac_path_GREP" -e 'GREP$' -e '-(cannot match)-' < "conftest.nl" >"conftest.out" 2>/dev/null || break
+    diff "conftest.out" "conftest.nl" >/dev/null 2>&1 || break
+    as_fn_arith $ac_count + 1 && ac_count=$as_val
+    if test $ac_count -gt ${ac_path_GREP_max-0}; then
+      # Best one so far, save it but keep looking for a better one
+      ac_cv_path_GREP="$ac_path_GREP"
+      ac_path_GREP_max=$ac_count
+    fi
+    # 10*(2^10) chars as input seems more than enough
+    test $ac_count -gt 10 && break
+  done
+  rm -f conftest.in conftest.tmp conftest.nl conftest.out;;
+esac
+
+      $ac_path_GREP_found && break 3
+    done
+  done
+  done
+IFS=$as_save_IFS
+  if test -z "$ac_cv_path_GREP"; then
+    as_fn_error $? "no acceptable grep could be found in $PATH$PATH_SEPARATOR/usr/xpg4/bin" "$LINENO" 5
+  fi
+else
+  ac_cv_path_GREP=$GREP
+fi
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_path_GREP" >&5
+$as_echo "$ac_cv_path_GREP" >&6; }
+ GREP="$ac_cv_path_GREP"
+
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for egrep" >&5
+$as_echo_n "checking for egrep... " >&6; }
+if ${ac_cv_path_EGREP+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  if echo a | $GREP -E '(a|b)' >/dev/null 2>&1
+   then ac_cv_path_EGREP="$GREP -E"
+   else
+     if test -z "$EGREP"; then
+  ac_path_EGREP_found=false
+  # Loop through the user's path and test for each of PROGNAME-LIST
+  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH$PATH_SEPARATOR/usr/xpg4/bin
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_prog in egrep; do
+    for ac_exec_ext in '' $ac_executable_extensions; do
+      ac_path_EGREP="$as_dir/$ac_prog$ac_exec_ext"
+      { test -f "$ac_path_EGREP" && $as_test_x "$ac_path_EGREP"; } || continue
+# Check for GNU ac_path_EGREP and select it if it is found.
+  # Check for GNU $ac_path_EGREP
+case `"$ac_path_EGREP" --version 2>&1` in
+*GNU*)
+  ac_cv_path_EGREP="$ac_path_EGREP" ac_path_EGREP_found=:;;
+*)
+  ac_count=0
+  $as_echo_n 0123456789 >"conftest.in"
+  while :
+  do
+    cat "conftest.in" "conftest.in" >"conftest.tmp"
+    mv "conftest.tmp" "conftest.in"
+    cp "conftest.in" "conftest.nl"
+    $as_echo 'EGREP' >> "conftest.nl"
+    "$ac_path_EGREP" 'EGREP$' < "conftest.nl" >"conftest.out" 2>/dev/null || break
+    diff "conftest.out" "conftest.nl" >/dev/null 2>&1 || break
+    as_fn_arith $ac_count + 1 && ac_count=$as_val
+    if test $ac_count -gt ${ac_path_EGREP_max-0}; then
+      # Best one so far, save it but keep looking for a better one
+      ac_cv_path_EGREP="$ac_path_EGREP"
+      ac_path_EGREP_max=$ac_count
+    fi
+    # 10*(2^10) chars as input seems more than enough
+    test $ac_count -gt 10 && break
+  done
+  rm -f conftest.in conftest.tmp conftest.nl conftest.out;;
+esac
+
+      $ac_path_EGREP_found && break 3
+    done
+  done
+  done
+IFS=$as_save_IFS
+  if test -z "$ac_cv_path_EGREP"; then
+    as_fn_error $? "no acceptable egrep could be found in $PATH$PATH_SEPARATOR/usr/xpg4/bin" "$LINENO" 5
+  fi
+else
+  ac_cv_path_EGREP=$EGREP
+fi
+
+   fi
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_path_EGREP" >&5
+$as_echo "$ac_cv_path_EGREP" >&6; }
+ EGREP="$ac_cv_path_EGREP"
+
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether the compiler is using the 2008 NaN encoding" >&5
+$as_echo_n "checking whether the compiler is using the 2008 NaN encoding... " >&6; }
+if ${libc_cv_mips_nan2008+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+dnl
+#ifdef __mips_nan2008
+yes
+#endif
+_ACEOF
+if (eval "$ac_cpp conftest.$ac_ext") 2>&5 |
+  $EGREP "yes" >/dev/null 2>&1; then :
+  libc_cv_mips_nan2008=yes
+else
+  libc_cv_mips_nan2008=no
+fi
+rm -f conftest*
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_mips_nan2008" >&5
+$as_echo "$libc_cv_mips_nan2008" >&6; }
+
+libc_mips_nan=
+if test x"$libc_cv_mips_nan2008" = xyes; then
+  libc_mips_nan=_2008
+fi
+
 config_vars="$config_vars
-default-abi = ${libc_mips_abi}_${libc_mips_float}"
+default-abi = ${libc_mips_abi}_${libc_mips_float}${libc_mips_nan}"
 
 case "$prefix" in
 /usr | /usr/)
@@ -138,3 +298,12 @@ case "$prefix" in
 esac
 
 libc_cv_gcc_unwind_find_fde=yes
+
+if test -z "$arch_minimum_kernel"; then
+  if test x$libc_cv_mips_nan2008 = xyes; then
+    # FIXME: Adjust this setting to the actual first upstream kernel
+    # version to support the 2008 NaN encoding and then remove this
+    # comment.
+    arch_minimum_kernel=10.0.0
+  fi
+fi
diff --git a/ports/sysdeps/unix/sysv/linux/mips/configure.in b/ports/sysdeps/unix/sysv/linux/mips/configure.in
index b8dde6ef7a..7087a14a5e 100644
--- a/ports/sysdeps/unix/sysv/linux/mips/configure.in
+++ b/ports/sysdeps/unix/sysv/linux/mips/configure.in
@@ -44,7 +44,19 @@ if test -z "$libc_mips_float"; then
   AC_MSG_ERROR([could not determine if compiler is using hard or soft floating point ABI])
 fi
 
-LIBC_CONFIG_VAR([default-abi], [${libc_mips_abi}_${libc_mips_float}])
+AC_CACHE_CHECK([whether the compiler is using the 2008 NaN encoding],
+  libc_cv_mips_nan2008, [AC_EGREP_CPP(yes, [dnl
+#ifdef __mips_nan2008
+yes
+#endif], libc_cv_mips_nan2008=yes, libc_cv_mips_nan2008=no)])
+
+libc_mips_nan=
+if test x"$libc_cv_mips_nan2008" = xyes; then
+  libc_mips_nan=_2008
+fi
+
+LIBC_CONFIG_VAR([default-abi],
+  [${libc_mips_abi}_${libc_mips_float}${libc_mips_nan}])
 
 case "$prefix" in
 /usr | /usr/)
@@ -76,3 +88,12 @@ case "$prefix" in
 esac
 
 libc_cv_gcc_unwind_find_fde=yes
+
+if test -z "$arch_minimum_kernel"; then
+  if test x$libc_cv_mips_nan2008 = xyes; then
+    # FIXME: Adjust this setting to the actual first upstream kernel
+    # version to support the 2008 NaN encoding and then remove this
+    # comment.
+    arch_minimum_kernel=10.0.0
+  fi
+fi
diff --git a/ports/sysdeps/unix/sysv/linux/mips/dl-cache.h b/ports/sysdeps/unix/sysv/linux/mips/dl-cache.h
index 4a7f3f1f2a..49ad99ab92 100644
--- a/ports/sysdeps/unix/sysv/linux/mips/dl-cache.h
+++ b/ports/sysdeps/unix/sysv/linux/mips/dl-cache.h
@@ -18,11 +18,27 @@
 
 #include <ldconfig.h>
 
-/* Redefine the cache ID for new ABIs; o32 keeps using the generic check.  */
-#if _MIPS_SIM == _ABI64
-# define _DL_CACHE_DEFAULT_ID	(FLAG_MIPS64_LIBN64 | FLAG_ELF_LIBC6)
-#elif _MIPS_SIM == _ABIN32
-# define _DL_CACHE_DEFAULT_ID	(FLAG_MIPS64_LIBN32 | FLAG_ELF_LIBC6)
+#if ((defined __mips_nan2008 && !defined HAVE_MIPS_NAN2008) \
+     || (!defined __mips_nan2008 && defined HAVE_MIPS_NAN2008))
+# error "Configuration inconsistency: __mips_nan2008 != HAVE_MIPS_NAN2008, overridden CFLAGS?"
+#endif
+
+/* Redefine the cache ID for new ABIs and 2008 NaN support; legacy o32
+   keeps using the generic check.  */
+#ifdef __mips_nan2008
+# if _MIPS_SIM == _ABIO32
+#  define _DL_CACHE_DEFAULT_ID	(FLAG_MIPS_LIB32_NAN2008 | FLAG_ELF_LIBC6)
+# elif _MIPS_SIM == _ABI64
+#  define _DL_CACHE_DEFAULT_ID	(FLAG_MIPS64_LIBN64_NAN2008 | FLAG_ELF_LIBC6)
+# elif _MIPS_SIM == _ABIN32
+#  define _DL_CACHE_DEFAULT_ID	(FLAG_MIPS64_LIBN32_NAN2008 | FLAG_ELF_LIBC6)
+# endif
+#else
+# if _MIPS_SIM == _ABI64
+#  define _DL_CACHE_DEFAULT_ID	(FLAG_MIPS64_LIBN64 | FLAG_ELF_LIBC6)
+# elif _MIPS_SIM == _ABIN32
+#  define _DL_CACHE_DEFAULT_ID	(FLAG_MIPS64_LIBN32 | FLAG_ELF_LIBC6)
+# endif
 #endif
 
 #ifdef _DL_CACHE_DEFAULT_ID
diff --git a/ports/sysdeps/unix/sysv/linux/mips/readelflib.c b/ports/sysdeps/unix/sysv/linux/mips/readelflib.c
index 10f0ff7022..fd57a735c3 100644
--- a/ports/sysdeps/unix/sysv/linux/mips/readelflib.c
+++ b/ports/sysdeps/unix/sysv/linux/mips/readelflib.c
@@ -33,19 +33,32 @@ process_elf_file (const char *file_name, const char *lib, int *flag,
 		  unsigned int *osversion, char **soname, void *file_contents,
 		  size_t file_length)
 {
-  ElfW(Ehdr) *elf_header = (ElfW(Ehdr) *) file_contents;
+  union
+    {
+      Elf64_Ehdr *eh64;
+      Elf32_Ehdr *eh32;
+      ElfW(Ehdr) *eh;
+    }
+  elf_header;
   int ret;
 
-  if (elf_header->e_ident [EI_CLASS] == ELFCLASS32)
+  elf_header.eh = file_contents;
+  if (elf_header.eh->e_ident [EI_CLASS] == ELFCLASS32)
     {
-      Elf32_Ehdr *elf32_header = (Elf32_Ehdr *) elf_header;
-
       ret = process_elf32_file (file_name, lib, flag, osversion, soname,
 				file_contents, file_length);
+      if (!ret)
+	{
+	  Elf32_Word flags = elf_header.eh32->e_flags;
+	  int nan2008 = (flags & EF_MIPS_NAN2008) != 0;
 
-      /* n32 libraries are always libc.so.6+.  */
-      if (!ret && (elf32_header->e_flags & EF_MIPS_ABI2) != 0)
-	*flag = FLAG_MIPS64_LIBN32|FLAG_ELF_LIBC6;
+	  /* n32 libraries are always libc.so.6+, o32 only if 2008 NaN.  */
+	  if ((flags & EF_MIPS_ABI2) != 0)
+	    *flag = (nan2008 ? FLAG_MIPS64_LIBN32_NAN2008
+		     : FLAG_MIPS64_LIBN32) | FLAG_ELF_LIBC6;
+	  else if (nan2008)
+	    *flag = FLAG_MIPS_LIB32_NAN2008 | FLAG_ELF_LIBC6;
+	}
     }
   else
     {
@@ -53,7 +66,13 @@ process_elf_file (const char *file_name, const char *lib, int *flag,
 				file_contents, file_length);
       /* n64 libraries are always libc.so.6+.  */
       if (!ret)
-	*flag = FLAG_MIPS64_LIBN64|FLAG_ELF_LIBC6;
+	{
+	  Elf64_Word flags = elf_header.eh64->e_flags;
+	  int nan2008 = (flags & EF_MIPS_NAN2008) != 0;
+
+	  *flag = (nan2008 ? FLAG_MIPS64_LIBN64_NAN2008
+		   : FLAG_MIPS64_LIBN64) | FLAG_ELF_LIBC6;
+	}
     }
 
   return ret;