Patchwork [1/2] Split up endian.h to minimize exposure of BYTE_ORDER.

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Submitter Alistair Francis
Date Sept. 25, 2019, 12:29 a.m.
Message ID <20190925002903.15928-1-alistair.francis@wdc.com>
Download mbox | patch
Permalink /patch/34648/
State New
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Comments

Alistair Francis - Sept. 25, 2019, 12:29 a.m.
With only two exceptions (sys/types.h and sys/param.h, both of which
historically might have defined BYTE_ORDER) the public headers that
include <endian.h> only want to be able to test __BYTE_ORDER against
__*_ENDIAN.

This patch creates a new bits/endian.h that can be included by any
header that wants to be able to test __BYTE_ORDER and/or
__FLOAT_WORD_ORDER against the __*_ENDIAN constants, or needs
__LONG_LONG_PAIR.  It only defines macros in the implementation
namespace.

The existing bits/endian.h (which could not be included independently
of endian.h, and only defines __BYTE_ORDER and maybe __FLOAT_WORD_ORDER)
is renamed to bits/endianness.h.  I also took the opportunity to
canonicalize the form of this header, which we are stuck with having
one copy of per architecture.  Since they are so short, this means git
doesn’t understand that they were renamed from existing headers, sigh.

endian.h itself is a nonstandard header and its only remaining use
from a standard header is guarded by __USE_MISC, so I dropped the
__USE_MISC conditionals from around all of the public-namespace things
it defines.  (This means, an application that requests strict library
conformance but includes endian.h will still see the definition of
BYTE_ORDER.)

A few changes to specific bits/endian(ness).h variants deserve
mention:

 - sysdeps/unix/sysv/linux/ia64/bits/endian.h is moved to
   sysdeps/ia64/bits/endianness.h.  If I remember correctly, ia64 did
   have selectable endianness, but we have assembly code in
   sysdeps/ia64 that assumes it’s little-endian, so there is no reason
   to treat the ia64 endianness.h as linux-specific.

 - The C-SKY port does not fully support big-endian mode, but I do
   not think this is sufficient reason to make csky/bits/endian(ness).h
   error out if __CSKYBE__ is defined, so it now defines __BYTE_ORDER
   appropriately for whichever mode the compiler is in.

 - The PowerPC port had extra logic in its bits/endian.h to detect a
   broken compiler, which strikes me as unnecessary, so I removed it.

 - The only files that defined __FLOAT_WORD_ORDER always defined it to
   the same value as __BYTE_ORDER, so I removed those definitions.
   The SH bits/endian(ness).h had comments inconsistent with the
   actual setting of __FLOAT_WORD_ORDER, which I also removed.

 - I *removed* copyright boilerplate from the few bits/endian(ness).h
   headers that had it; these files record a single fact in a fashion
   dictated by an external spec, so I do not think they are copyrightable.

As long as I was changing every copy of ieee754.h in the tree, I
noticed that only the MIPS variant includes float.h, because it uses
LDBL_MANT_DIG to decide among three different versions of
ieee854_long_double.  This patch makes it not include float.h when
GCC’s intrinsic __LDBL_MANT_DIG__ is available.

	* string/endian.h: Unconditionally define LITTLE_ENDIAN,
	BIG_ENDIAN, PDP_ENDIAN, and BYTE_ORDER.	 Condition byteswapping
	macros only on !__ASSEMBLER__.	Move the definitions of
	__BIG_ENDIAN, __LITTLE_ENDIAN, __PDP_ENDIAN, __FLOAT_WORD_ORDER,
	and __LONG_LONG_PAIR to...
	* string/bits/endian.h: ...this new file, which includes
	the renamed header bits/endianness.h for the definition of
	__BYTE_ORDER and possibly __FLOAT_WORD_ORDER.

	* string/Makefile: Install bits/endianness.h.
	* include/bits/endian.h: New wrapper.

	* bits/endian.h: Rename to bits/endianness.h.
	Add multiple-include guard.  Rewrite the comment explaining what
	the machine-specific variants of this file should do.

	* sysdeps/unix/sysv/linux/ia64/bits/endian.h:
	Move to sysdeps/ia64.

	* sysdeps/aarch64/bits/endian.h
	* sysdeps/alpha/bits/endian.h
	* sysdeps/arm/bits/endian.h
	* sysdeps/csky/bits/endian.h
	* sysdeps/hppa/bits/endian.h
	* sysdeps/ia64/bits/endian.h
	* sysdeps/m68k/bits/endian.h
	* sysdeps/microblaze/bits/endian.h
	* sysdeps/mips/bits/endian.h
	* sysdeps/nios2/bits/endian.h
	* sysdeps/powerpc/bits/endian.h
	* sysdeps/riscv/bits/endian.h
	* sysdeps/s390/bits/endian.h
	* sysdeps/sh/bits/endian.h
	* sysdeps/sparc/bits/endian.h
	* sysdeps/x86/bits/endian.h:
	Rename to endianness.h; canonicalize form of file; remove
	redundant definitions of __FLOAT_WORD_ORDER.

	* sysdeps/csky/bits/endianness.h: Do not error out if __CSKYEB__
	is defined.
	* sysdeps/powerpc/bits/endianness.h: Remove logic to check for
	broken compilers.

	* ctype/ctype.h
	* inet/netinet/in.h
	* resolv/arpa/nameser_compat.h
	* sysdeps/aarch64/nptl/bits/pthreadtypes-arch.h
	* sysdeps/arm/nptl/bits/pthreadtypes-arch.h
	* sysdeps/csky/nptl/bits/pthreadtypes-arch.h
	* sysdeps/ia64/ieee754.h
	* sysdeps/ieee754/ieee754.h
	* sysdeps/ieee754/ldbl-128/ieee754.h
	* sysdeps/ieee754/ldbl-128ibm/ieee754.h
	* sysdeps/m68k/nptl/bits/pthreadtypes-arch.h
	* sysdeps/microblaze/nptl/bits/pthreadtypes-arch.h
	* sysdeps/mips/ieee754/ieee754.h
	* sysdeps/mips/nptl/bits/pthreadtypes-arch.h
	* sysdeps/nios2/nptl/bits/pthreadtypes-arch.h
	* sysdeps/nptl/pthread.h
	* sysdeps/riscv/nptl/bits/pthreadtypes-arch.h
	* sysdeps/sh/nptl/bits/pthreadtypes-arch.h
	* sysdeps/sparc/sparc32/ieee754.h
	* sysdeps/unix/sysv/linux/generic/bits/stat.h
	* sysdeps/unix/sysv/linux/generic/bits/statfs.h
	* sysdeps/unix/sysv/linux/sys/acct.h
	* wctype/bits/wctype-wchar.h:
	Include bits/endian.h, not endian.h.

	* sysdeps/unix/sysv/linux/hppa/pthread.h: Don’t include endian.h.

	* sysdeps/mips/ieee754/ieee754.h: Use __LDBL_MANT_DIG__
	in ifdefs, instead of LDBL_MANT_DIG.  Only include float.h
	when __LDBL_MANT_DIG__ is not predefined, in which case
	define __LDBL_MANT_DIG__ to equal LDBL_MANT_DIG.
---
 ctype/ctype.h                                 |  2 +-
 include/bits/endian.h                         |  1 +
 inet/netinet/in.h                             |  2 +-
 resolv/arpa/nameser_compat.h                  |  2 +-
 string/Makefile                               |  3 +-
 string/bits/endian.h                          | 48 +++++++++++++++++++
 string/endian.h                               | 39 +++------------
 sysdeps/aarch64/bits/endian.h                 | 30 ------------
 sysdeps/aarch64/bits/endianness.h             | 15 ++++++
 sysdeps/aarch64/nptl/bits/pthreadtypes-arch.h |  2 +-
 sysdeps/alpha/bits/endian.h                   |  7 ---
 sysdeps/alpha/bits/endianness.h               | 11 +++++
 sysdeps/arm/bits/endian.h                     | 10 ----
 sysdeps/arm/bits/endianness.h                 | 15 ++++++
 sysdeps/arm/nptl/bits/pthreadtypes-arch.h     |  2 +-
 sysdeps/csky/bits/endian.h                    |  9 ----
 sysdeps/csky/bits/endianness.h                | 15 ++++++
 sysdeps/csky/nptl/bits/pthreadtypes-arch.h    |  2 +-
 sysdeps/hppa/bits/endian.h                    |  7 ---
 sysdeps/hppa/bits/endianness.h                | 11 +++++
 sysdeps/ia64/bits/endianness.h                | 11 +++++
 sysdeps/ia64/ieee754.h                        |  4 +-
 sysdeps/ieee754/ieee754.h                     |  4 +-
 sysdeps/ieee754/ldbl-128/ieee754.h            |  4 +-
 sysdeps/ieee754/ldbl-128ibm/ieee754.h         |  4 +-
 sysdeps/m68k/bits/endian.h                    |  7 ---
 sysdeps/m68k/bits/endianness.h                | 11 +++++
 sysdeps/m68k/nptl/bits/pthreadtypes-arch.h    |  2 +-
 sysdeps/microblaze/bits/endian.h              | 30 ------------
 sysdeps/microblaze/bits/endianness.h          | 15 ++++++
 .../microblaze/nptl/bits/pthreadtypes-arch.h  |  2 +-
 sysdeps/mips/bits/endian.h                    | 15 ------
 sysdeps/mips/bits/endianness.h                | 16 +++++++
 sysdeps/mips/ieee754/ieee754.h                | 17 ++++---
 sysdeps/mips/nptl/bits/pthreadtypes-arch.h    |  2 +-
 sysdeps/nios2/bits/endian.h                   | 12 -----
 sysdeps/nios2/bits/endianness.h               | 16 +++++++
 sysdeps/nios2/nptl/bits/pthreadtypes-arch.h   |  2 +-
 sysdeps/nptl/pthread.h                        |  2 +-
 sysdeps/powerpc/bits/endian.h                 | 36 --------------
 sysdeps/powerpc/bits/endianness.h             | 16 +++++++
 sysdeps/riscv/bits/endian.h                   |  5 --
 sysdeps/riscv/bits/endianness.h               | 11 +++++
 sysdeps/riscv/nptl/bits/pthreadtypes-arch.h   |  2 +-
 sysdeps/s390/bits/endian.h                    |  7 ---
 sysdeps/s390/bits/endianness.h                | 11 +++++
 sysdeps/sh/bits/endian.h                      | 13 -----
 sysdeps/sh/bits/endianness.h                  | 15 ++++++
 sysdeps/sh/nptl/bits/pthreadtypes-arch.h      |  2 +-
 sysdeps/sparc/bits/{endian.h => endianness.h} | 12 +++--
 sysdeps/sparc/sparc32/ieee754.h               |  4 +-
 sysdeps/unix/sysv/linux/generic/bits/stat.h   |  2 +-
 sysdeps/unix/sysv/linux/generic/bits/statfs.h |  2 +-
 sysdeps/unix/sysv/linux/hppa/pthread.h        |  1 -
 sysdeps/unix/sysv/linux/ia64/bits/endian.h    |  7 ---
 sysdeps/unix/sysv/linux/powerpc/htm.h         |  2 +-
 sysdeps/unix/sysv/linux/sys/acct.h            |  2 +-
 sysdeps/x86/bits/endian.h                     |  7 ---
 sysdeps/x86/bits/endianness.h                 | 11 +++++
 wctype/bits/wctype-wchar.h                    |  2 +-
 60 files changed, 303 insertions(+), 276 deletions(-)
 create mode 100644 include/bits/endian.h
 create mode 100644 string/bits/endian.h
 delete mode 100644 sysdeps/aarch64/bits/endian.h
 create mode 100644 sysdeps/aarch64/bits/endianness.h
 delete mode 100644 sysdeps/alpha/bits/endian.h
 create mode 100644 sysdeps/alpha/bits/endianness.h
 delete mode 100644 sysdeps/arm/bits/endian.h
 create mode 100644 sysdeps/arm/bits/endianness.h
 delete mode 100644 sysdeps/csky/bits/endian.h
 create mode 100644 sysdeps/csky/bits/endianness.h
 delete mode 100644 sysdeps/hppa/bits/endian.h
 create mode 100644 sysdeps/hppa/bits/endianness.h
 create mode 100644 sysdeps/ia64/bits/endianness.h
 delete mode 100644 sysdeps/m68k/bits/endian.h
 create mode 100644 sysdeps/m68k/bits/endianness.h
 delete mode 100644 sysdeps/microblaze/bits/endian.h
 create mode 100644 sysdeps/microblaze/bits/endianness.h
 delete mode 100644 sysdeps/mips/bits/endian.h
 create mode 100644 sysdeps/mips/bits/endianness.h
 delete mode 100644 sysdeps/nios2/bits/endian.h
 create mode 100644 sysdeps/nios2/bits/endianness.h
 delete mode 100644 sysdeps/powerpc/bits/endian.h
 create mode 100644 sysdeps/powerpc/bits/endianness.h
 delete mode 100644 sysdeps/riscv/bits/endian.h
 create mode 100644 sysdeps/riscv/bits/endianness.h
 delete mode 100644 sysdeps/s390/bits/endian.h
 create mode 100644 sysdeps/s390/bits/endianness.h
 delete mode 100644 sysdeps/sh/bits/endian.h
 create mode 100644 sysdeps/sh/bits/endianness.h
 rename sysdeps/sparc/bits/{endian.h => endianness.h} (56%)
 delete mode 100644 sysdeps/unix/sysv/linux/ia64/bits/endian.h
 delete mode 100644 sysdeps/x86/bits/endian.h
 create mode 100644 sysdeps/x86/bits/endianness.h
Andreas Schwab - Sept. 25, 2019, 7:33 a.m.
On Sep 24 2019, Alistair Francis <alistair.francis@wdc.com> wrote:

> diff --git a/inet/netinet/in.h b/inet/netinet/in.h
> index 148bc663fc7..609ad66bcb8 100644
> --- a/inet/netinet/in.h
> +++ b/inet/netinet/in.h
> @@ -380,9 +380,9 @@ extern uint32_t htonl (uint32_t __hostlong)
>  extern uint16_t htons (uint16_t __hostshort)
>       __THROW __attribute__ ((__const__));
>  
> -#include <endian.h>
>  
>  /* Get machine dependent optimized versions of byte swapping functions.  */
> +#include <bits/endian.h>
>  #include <bits/byteswap.h>
>  #include <bits/uintn-identity.h>
>  
> diff --git a/resolv/arpa/nameser_compat.h b/resolv/arpa/nameser_compat.h
> index f1c390f3b91..37c178b5243 100644
> --- a/resolv/arpa/nameser_compat.h
> +++ b/resolv/arpa/nameser_compat.h
> @@ -29,7 +29,7 @@
>  #ifndef _ARPA_NAMESER_COMPAT_
>  #define	_ARPA_NAMESER_COMPAT_
>  
> -#include <endian.h>
> +#include <bits/endian.h>
>  
>  /*%
>   * Structure for query header.  The order of the fields is machine- and

Not sure whether we should change the network headers.  There are
probably uses that depend on BYTE_ORDER to be defined through them.

Andreas.
Alistair Francis - Sept. 25, 2019, 10:49 p.m.
On Wed, Sep 25, 2019 at 12:33 AM Andreas Schwab <schwab@suse.de> wrote:
>
> On Sep 24 2019, Alistair Francis <alistair.francis@wdc.com> wrote:
>
> > diff --git a/inet/netinet/in.h b/inet/netinet/in.h
> > index 148bc663fc7..609ad66bcb8 100644
> > --- a/inet/netinet/in.h
> > +++ b/inet/netinet/in.h
> > @@ -380,9 +380,9 @@ extern uint32_t htonl (uint32_t __hostlong)
> >  extern uint16_t htons (uint16_t __hostshort)
> >       __THROW __attribute__ ((__const__));
> >
> > -#include <endian.h>
> >
> >  /* Get machine dependent optimized versions of byte swapping functions.  */
> > +#include <bits/endian.h>
> >  #include <bits/byteswap.h>
> >  #include <bits/uintn-identity.h>
> >
> > diff --git a/resolv/arpa/nameser_compat.h b/resolv/arpa/nameser_compat.h
> > index f1c390f3b91..37c178b5243 100644
> > --- a/resolv/arpa/nameser_compat.h
> > +++ b/resolv/arpa/nameser_compat.h
> > @@ -29,7 +29,7 @@
> >  #ifndef _ARPA_NAMESER_COMPAT_
> >  #define      _ARPA_NAMESER_COMPAT_
> >
> > -#include <endian.h>
> > +#include <bits/endian.h>
> >
> >  /*%
> >   * Structure for query header.  The order of the fields is machine- and
>
> Not sure whether we should change the network headers.  There are
> probably uses that depend on BYTE_ORDER to be defined through them.

Isn't BYTE_ORDER still defined after this patch in the network headers?

Alistair

>
> Andreas.
>
> --
> Andreas Schwab, SUSE Labs, schwab@suse.de
> GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
> "And now for something completely different."
Andreas Schwab - Sept. 26, 2019, 7:02 a.m.
On Sep 25 2019, Alistair Francis <alistair23@gmail.com> wrote:

> On Wed, Sep 25, 2019 at 12:33 AM Andreas Schwab <schwab@suse.de> wrote:
>>
>> On Sep 24 2019, Alistair Francis <alistair.francis@wdc.com> wrote:
>>
>> > diff --git a/inet/netinet/in.h b/inet/netinet/in.h
>> > index 148bc663fc7..609ad66bcb8 100644
>> > --- a/inet/netinet/in.h
>> > +++ b/inet/netinet/in.h
>> > @@ -380,9 +380,9 @@ extern uint32_t htonl (uint32_t __hostlong)
>> >  extern uint16_t htons (uint16_t __hostshort)
>> >       __THROW __attribute__ ((__const__));
>> >
>> > -#include <endian.h>
>> >
>> >  /* Get machine dependent optimized versions of byte swapping functions.  */
>> > +#include <bits/endian.h>
>> >  #include <bits/byteswap.h>
>> >  #include <bits/uintn-identity.h>
>> >
>> > diff --git a/resolv/arpa/nameser_compat.h b/resolv/arpa/nameser_compat.h
>> > index f1c390f3b91..37c178b5243 100644
>> > --- a/resolv/arpa/nameser_compat.h
>> > +++ b/resolv/arpa/nameser_compat.h
>> > @@ -29,7 +29,7 @@
>> >  #ifndef _ARPA_NAMESER_COMPAT_
>> >  #define      _ARPA_NAMESER_COMPAT_
>> >
>> > -#include <endian.h>
>> > +#include <bits/endian.h>
>> >
>> >  /*%
>> >   * Structure for query header.  The order of the fields is machine- and
>>
>> Not sure whether we should change the network headers.  There are
>> probably uses that depend on BYTE_ORDER to be defined through them.
>
> Isn't BYTE_ORDER still defined after this patch in the network headers?

Not through <bits/endian.h>, AFAICS.

Andreas.
Alistair Francis - Sept. 27, 2019, 12:51 a.m.
On Thu, Sep 26, 2019 at 12:02 AM Andreas Schwab <schwab@suse.de> wrote:
>
> On Sep 25 2019, Alistair Francis <alistair23@gmail.com> wrote:
>
> > On Wed, Sep 25, 2019 at 12:33 AM Andreas Schwab <schwab@suse.de> wrote:
> >>
> >> On Sep 24 2019, Alistair Francis <alistair.francis@wdc.com> wrote:
> >>
> >> > diff --git a/inet/netinet/in.h b/inet/netinet/in.h
> >> > index 148bc663fc7..609ad66bcb8 100644
> >> > --- a/inet/netinet/in.h
> >> > +++ b/inet/netinet/in.h
> >> > @@ -380,9 +380,9 @@ extern uint32_t htonl (uint32_t __hostlong)
> >> >  extern uint16_t htons (uint16_t __hostshort)
> >> >       __THROW __attribute__ ((__const__));
> >> >
> >> > -#include <endian.h>
> >> >
> >> >  /* Get machine dependent optimized versions of byte swapping functions.  */
> >> > +#include <bits/endian.h>
> >> >  #include <bits/byteswap.h>
> >> >  #include <bits/uintn-identity.h>
> >> >
> >> > diff --git a/resolv/arpa/nameser_compat.h b/resolv/arpa/nameser_compat.h
> >> > index f1c390f3b91..37c178b5243 100644
> >> > --- a/resolv/arpa/nameser_compat.h
> >> > +++ b/resolv/arpa/nameser_compat.h
> >> > @@ -29,7 +29,7 @@
> >> >  #ifndef _ARPA_NAMESER_COMPAT_
> >> >  #define      _ARPA_NAMESER_COMPAT_
> >> >
> >> > -#include <endian.h>
> >> > +#include <bits/endian.h>
> >> >
> >> >  /*%
> >> >   * Structure for query header.  The order of the fields is machine- and
> >>
> >> Not sure whether we should change the network headers.  There are
> >> probably uses that depend on BYTE_ORDER to be defined through them.
> >
> > Isn't BYTE_ORDER still defined after this patch in the network headers?
>
> Not through <bits/endian.h>, AFAICS.

Ah, I see what you mean. I got confused.

__BYTE_ORDER is exposed in the network headers, while BYTE_ORDER is not.

Do you want me to add #include <endian.h> back to?
 - inet/netinet/in.h
 - resolv/arpa/nameser_compat.h

Alistair

>
> Andreas.
>
> --
> Andreas Schwab, SUSE Labs, schwab@suse.de
> GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
> "And now for something completely different."
Joseph Myers - Sept. 27, 2019, 3:37 p.m.
On Thu, 26 Sep 2019, Alistair Francis wrote:

> __BYTE_ORDER is exposed in the network headers, while BYTE_ORDER is not.
> 
> Do you want me to add #include <endian.h> back to?
>  - inet/netinet/in.h
>  - resolv/arpa/nameser_compat.h

Given the concern expressed, I think it makes sense to keep the <endian.h> 
include there.  Zack's cleanup series can always keep a reduced version of 
the patch that just changes those includes to <bits/endian.h> if we wish 
to consider the change in those headers as a future cleanup.

As the goal of getting this patch in right now is to avoid adding a new 
include of <endian.h> from all headers that end up defining struct 
timespec, it should be fine to omit (defer to later) the removal from any 
headers where there are concerns about the removal.

Note also: the text in the commit message and the ChangeLog entry about 
C-SKY needs updating to reflect the big-endian still results in an error.
Alistair Francis - Sept. 27, 2019, 9:35 p.m.
On Fri, Sep 27, 2019 at 8:37 AM Joseph Myers <joseph@codesourcery.com> wrote:
>
> On Thu, 26 Sep 2019, Alistair Francis wrote:
>
> > __BYTE_ORDER is exposed in the network headers, while BYTE_ORDER is not.
> >
> > Do you want me to add #include <endian.h> back to?
> >  - inet/netinet/in.h
> >  - resolv/arpa/nameser_compat.h
>
> Given the concern expressed, I think it makes sense to keep the <endian.h>
> include there.  Zack's cleanup series can always keep a reduced version of
> the patch that just changes those includes to <bits/endian.h> if we wish
> to consider the change in those headers as a future cleanup.
>
> As the goal of getting this patch in right now is to avoid adding a new
> include of <endian.h> from all headers that end up defining struct
> timespec, it should be fine to omit (defer to later) the removal from any
> headers where there are concerns about the removal.

Works for me, I have not made changes to the two networking files.

>
> Note also: the text in the commit message and the ChangeLog entry about
> C-SKY needs updating to reflect the big-endian still results in an error.

Good point, fixed.

Alistair

>
> --
> Joseph S. Myers
> joseph@codesourcery.com

Patch

diff --git a/ctype/ctype.h b/ctype/ctype.h
index 35efe0d2cf5..d17f727cf0d 100644
--- a/ctype/ctype.h
+++ b/ctype/ctype.h
@@ -36,7 +36,7 @@  __BEGIN_DECLS
    endian).  We define the bit value interpretations here dependent on the
    machine's byte order.  */
 
-# include <endian.h>
+# include <bits/endian.h>
 # if __BYTE_ORDER == __BIG_ENDIAN
 #  define _ISbit(bit)	(1 << (bit))
 # else /* __BYTE_ORDER == __LITTLE_ENDIAN */
diff --git a/include/bits/endian.h b/include/bits/endian.h
new file mode 100644
index 00000000000..ad614f1c1ac
--- /dev/null
+++ b/include/bits/endian.h
@@ -0,0 +1 @@ 
+#include <string/bits/endian.h>
diff --git a/inet/netinet/in.h b/inet/netinet/in.h
index 148bc663fc7..609ad66bcb8 100644
--- a/inet/netinet/in.h
+++ b/inet/netinet/in.h
@@ -380,9 +380,9 @@  extern uint32_t htonl (uint32_t __hostlong)
 extern uint16_t htons (uint16_t __hostshort)
      __THROW __attribute__ ((__const__));
 
-#include <endian.h>
 
 /* Get machine dependent optimized versions of byte swapping functions.  */
+#include <bits/endian.h>
 #include <bits/byteswap.h>
 #include <bits/uintn-identity.h>
 
diff --git a/resolv/arpa/nameser_compat.h b/resolv/arpa/nameser_compat.h
index f1c390f3b91..37c178b5243 100644
--- a/resolv/arpa/nameser_compat.h
+++ b/resolv/arpa/nameser_compat.h
@@ -29,7 +29,7 @@ 
 #ifndef _ARPA_NAMESER_COMPAT_
 #define	_ARPA_NAMESER_COMPAT_
 
-#include <endian.h>
+#include <bits/endian.h>
 
 /*%
  * Structure for query header.  The order of the fields is machine- and
diff --git a/string/Makefile b/string/Makefile
index 52fe28207c1..f01b34509aa 100644
--- a/string/Makefile
+++ b/string/Makefile
@@ -25,7 +25,8 @@  include ../Makeconfig
 headers		:= string.h bits/string_fortified.h			\
 		   strings.h bits/strings_fortified.h			\
 		   byteswap.h bits/byteswap.h				\
-		   endian.h bits/endian.h bits/uintn-identity.h		\
+		   endian.h bits/endian.h bits/endianness.h		\
+		   bits/uintn-identity.h				\
 		   memory.h argz.h envz.h
 
 routines	:= strcat strchr strcmp strcoll strcpy strcspn		\
diff --git a/string/bits/endian.h b/string/bits/endian.h
new file mode 100644
index 00000000000..ed2ee578c3b
--- /dev/null
+++ b/string/bits/endian.h
@@ -0,0 +1,48 @@ 
+/* Copyright (C) 1992-2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef _BITS_ENDIAN_H
+#define _BITS_ENDIAN_H 1
+
+/* Definitions for byte order, according to significance of bytes,
+   from low addresses to high addresses.  The value is what you get by
+   putting '4' in the most significant byte, '3' in the second most
+   significant byte, '2' in the second least significant byte, and '1'
+   in the least significant byte, and then writing down one digit for
+   each byte, starting with the byte at the lowest address at the left,
+   and proceeding to the byte with the highest address at the right.  */
+
+#define	__LITTLE_ENDIAN	1234
+#define	__BIG_ENDIAN	4321
+#define	__PDP_ENDIAN	3412
+
+/* This file defines `__BYTE_ORDER' for the particular machine.  */
+#include <bits/endianness.h>
+
+/* Some machines may need to use a different endianness for floating point
+   values.  */
+#ifndef __FLOAT_WORD_ORDER
+# define __FLOAT_WORD_ORDER __BYTE_ORDER
+#endif
+
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+# define __LONG_LONG_PAIR(HI, LO) LO, HI
+#elif __BYTE_ORDER == __BIG_ENDIAN
+# define __LONG_LONG_PAIR(HI, LO) HI, LO
+#endif
+
+#endif /* bits/endian.h */
diff --git a/string/endian.h b/string/endian.h
index 17e4e893fb5..0eb534e434b 100644
--- a/string/endian.h
+++ b/string/endian.h
@@ -20,42 +20,15 @@ 
 
 #include <features.h>
 
-/* Definitions for byte order, according to significance of bytes,
-   from low addresses to high addresses.  The value is what you get by
-   putting '4' in the most significant byte, '3' in the second most
-   significant byte, '2' in the second least significant byte, and '1'
-   in the least significant byte, and then writing down one digit for
-   each byte, starting with the byte at the lowest address at the left,
-   and proceeding to the byte with the highest address at the right.  */
-
-#define	__LITTLE_ENDIAN	1234
-#define	__BIG_ENDIAN	4321
-#define	__PDP_ENDIAN	3412
-
-/* This file defines `__BYTE_ORDER' for the particular machine.  */
+/* Get the definitions of __*_ENDIAN, __BYTE_ORDER, and __FLOAT_WORD_ORDER.  */
 #include <bits/endian.h>
 
-/* Some machines may need to use a different endianness for floating point
-   values.  */
-#ifndef __FLOAT_WORD_ORDER
-# define __FLOAT_WORD_ORDER __BYTE_ORDER
-#endif
-
-#ifdef	__USE_MISC
-# define LITTLE_ENDIAN	__LITTLE_ENDIAN
-# define BIG_ENDIAN	__BIG_ENDIAN
-# define PDP_ENDIAN	__PDP_ENDIAN
-# define BYTE_ORDER	__BYTE_ORDER
-#endif
-
-#if __BYTE_ORDER == __LITTLE_ENDIAN
-# define __LONG_LONG_PAIR(HI, LO) LO, HI
-#elif __BYTE_ORDER == __BIG_ENDIAN
-# define __LONG_LONG_PAIR(HI, LO) HI, LO
-#endif
-
+#define LITTLE_ENDIAN	__LITTLE_ENDIAN
+#define BIG_ENDIAN	__BIG_ENDIAN
+#define PDP_ENDIAN	__PDP_ENDIAN
+#define BYTE_ORDER	__BYTE_ORDER
 
-#if defined __USE_MISC && !defined __ASSEMBLER__
+#ifndef __ASSEMBLER__
 /* Conversion interfaces.  */
 # include <bits/byteswap.h>
 # include <bits/uintn-identity.h>
diff --git a/sysdeps/aarch64/bits/endian.h b/sysdeps/aarch64/bits/endian.h
deleted file mode 100644
index 03801d312a7..00000000000
--- a/sysdeps/aarch64/bits/endian.h
+++ /dev/null
@@ -1,30 +0,0 @@ 
-/* Copyright (C) 1997-2019 Free Software Foundation, Inc.
-
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public License as
-   published by the Free Software Foundation; either version 2.1 of the
-   License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library.  If not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-/* AArch64 can be either big or little endian.  */
-#ifdef __AARCH64EB__
-# define __BYTE_ORDER __BIG_ENDIAN
-#else
-# define __BYTE_ORDER __LITTLE_ENDIAN
-#endif
-
-#define __FLOAT_WORD_ORDER __BYTE_ORDER
diff --git a/sysdeps/aarch64/bits/endianness.h b/sysdeps/aarch64/bits/endianness.h
new file mode 100644
index 00000000000..300ebc8f9ca
--- /dev/null
+++ b/sysdeps/aarch64/bits/endianness.h
@@ -0,0 +1,15 @@ 
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* AArch64 has selectable endianness.  */
+#ifdef __AARCH64EB__
+# define __BYTE_ORDER __BIG_ENDIAN
+#else
+# define __BYTE_ORDER __LITTLE_ENDIAN
+#endif
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/aarch64/nptl/bits/pthreadtypes-arch.h b/sysdeps/aarch64/nptl/bits/pthreadtypes-arch.h
index 4cf3a689274..758b127a1a0 100644
--- a/sysdeps/aarch64/nptl/bits/pthreadtypes-arch.h
+++ b/sysdeps/aarch64/nptl/bits/pthreadtypes-arch.h
@@ -19,7 +19,7 @@ 
 #ifndef _BITS_PTHREADTYPES_ARCH_H
 #define _BITS_PTHREADTYPES_ARCH_H	1
 
-#include <endian.h>
+#include <bits/endian.h>
 
 #ifdef __ILP32__
 # define __SIZEOF_PTHREAD_ATTR_T        32
diff --git a/sysdeps/alpha/bits/endian.h b/sysdeps/alpha/bits/endian.h
deleted file mode 100644
index 8a16e14e24e..00000000000
--- a/sysdeps/alpha/bits/endian.h
+++ /dev/null
@@ -1,7 +0,0 @@ 
-/* Alpha is little-endian.  */
-
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-#define __BYTE_ORDER __LITTLE_ENDIAN
diff --git a/sysdeps/alpha/bits/endianness.h b/sysdeps/alpha/bits/endianness.h
new file mode 100644
index 00000000000..69f9a147f68
--- /dev/null
+++ b/sysdeps/alpha/bits/endianness.h
@@ -0,0 +1,11 @@ 
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* Alpha is little-endian.  */
+#define __BYTE_ORDER __LITTLE_ENDIAN
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/arm/bits/endian.h b/sysdeps/arm/bits/endian.h
deleted file mode 100644
index f49f6ab1c9b..00000000000
--- a/sysdeps/arm/bits/endian.h
+++ /dev/null
@@ -1,10 +0,0 @@ 
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-/* ARM can be either big or little endian.  */
-#ifdef __ARMEB__
-#define __BYTE_ORDER __BIG_ENDIAN
-#else
-#define __BYTE_ORDER __LITTLE_ENDIAN
-#endif
diff --git a/sysdeps/arm/bits/endianness.h b/sysdeps/arm/bits/endianness.h
new file mode 100644
index 00000000000..2d671fff661
--- /dev/null
+++ b/sysdeps/arm/bits/endianness.h
@@ -0,0 +1,15 @@ 
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* ARM has selectable endianness.  */
+#ifdef __ARMEB__
+#define __BYTE_ORDER __BIG_ENDIAN
+#else
+#define __BYTE_ORDER __LITTLE_ENDIAN
+#endif
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/arm/nptl/bits/pthreadtypes-arch.h b/sysdeps/arm/nptl/bits/pthreadtypes-arch.h
index 70419c99f64..78b37eb5b89 100644
--- a/sysdeps/arm/nptl/bits/pthreadtypes-arch.h
+++ b/sysdeps/arm/nptl/bits/pthreadtypes-arch.h
@@ -18,7 +18,7 @@ 
 #ifndef _BITS_PTHREADTYPES_ARCH_H
 #define _BITS_PTHREADTYPES_ARCH_H	1
 
-#include <endian.h>
+#include <bits/endian.h>
 
 #define __SIZEOF_PTHREAD_ATTR_T 36
 #define __SIZEOF_PTHREAD_MUTEX_T 24
diff --git a/sysdeps/csky/bits/endian.h b/sysdeps/csky/bits/endian.h
deleted file mode 100644
index 51df38d8f91..00000000000
--- a/sysdeps/csky/bits/endian.h
+++ /dev/null
@@ -1,9 +0,0 @@ 
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-#ifdef __CSKYBE__
-# error "Big endian not supported for C-SKY."
-#else
-# define __BYTE_ORDER __LITTLE_ENDIAN
-#endif
diff --git a/sysdeps/csky/bits/endianness.h b/sysdeps/csky/bits/endianness.h
new file mode 100644
index 00000000000..b2b92bab440
--- /dev/null
+++ b/sysdeps/csky/bits/endianness.h
@@ -0,0 +1,15 @@ 
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* C-SKY has selectable endianness.  */
+#ifdef __CSKYBE__
+# error "C-SKY Big Endian is not fully supported."
+#else
+# define __BYTE_ORDER __LITTLE_ENDIAN
+#endif
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/csky/nptl/bits/pthreadtypes-arch.h b/sysdeps/csky/nptl/bits/pthreadtypes-arch.h
index 5260c58d37c..58be51dcfd0 100644
--- a/sysdeps/csky/nptl/bits/pthreadtypes-arch.h
+++ b/sysdeps/csky/nptl/bits/pthreadtypes-arch.h
@@ -19,7 +19,7 @@ 
 #ifndef _BITS_PTHREADTYPES_ARCH_H
 #define _BITS_PTHREADTYPES_ARCH_H	1
 
-#include <endian.h>
+#include <bits/endian.h>
 
 #define __SIZEOF_PTHREAD_ATTR_T			36
 #define __SIZEOF_PTHREAD_MUTEX_T		24
diff --git a/sysdeps/hppa/bits/endian.h b/sysdeps/hppa/bits/endian.h
deleted file mode 100644
index 585db0c0faa..00000000000
--- a/sysdeps/hppa/bits/endian.h
+++ /dev/null
@@ -1,7 +0,0 @@ 
-/* hppa1.1 big-endian.  */
-
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-#define __BYTE_ORDER __BIG_ENDIAN
diff --git a/sysdeps/hppa/bits/endianness.h b/sysdeps/hppa/bits/endianness.h
new file mode 100644
index 00000000000..96fd5ae5efb
--- /dev/null
+++ b/sysdeps/hppa/bits/endianness.h
@@ -0,0 +1,11 @@ 
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* HP-PA is big-endian.  */
+#define __BYTE_ORDER __BIG_ENDIAN
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/ia64/bits/endianness.h b/sysdeps/ia64/bits/endianness.h
new file mode 100644
index 00000000000..70c211e5696
--- /dev/null
+++ b/sysdeps/ia64/bits/endianness.h
@@ -0,0 +1,11 @@ 
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* IA64 is little-endian.  */
+#define __BYTE_ORDER __LITTLE_ENDIAN
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/ia64/ieee754.h b/sysdeps/ia64/ieee754.h
index 21c4149ba22..610631a71df 100644
--- a/sysdeps/ia64/ieee754.h
+++ b/sysdeps/ia64/ieee754.h
@@ -16,11 +16,11 @@ 
    <https://www.gnu.org/licenses/>.  */
 
 #ifndef _IEEE754_H
-
 #define _IEEE754_H 1
+
 #include <features.h>
 
-#include <endian.h>
+#include <bits/endian.h>
 
 __BEGIN_DECLS
 
diff --git a/sysdeps/ieee754/ieee754.h b/sysdeps/ieee754/ieee754.h
index 581fe5c9ded..7605d0d3217 100644
--- a/sysdeps/ieee754/ieee754.h
+++ b/sysdeps/ieee754/ieee754.h
@@ -16,11 +16,11 @@ 
    <https://www.gnu.org/licenses/>.  */
 
 #ifndef _IEEE754_H
-
 #define _IEEE754_H 1
+
 #include <features.h>
 
-#include <endian.h>
+#include <bits/endian.h>
 
 __BEGIN_DECLS
 
diff --git a/sysdeps/ieee754/ldbl-128/ieee754.h b/sysdeps/ieee754/ldbl-128/ieee754.h
index 87dc1d781dc..47f11d8a6b7 100644
--- a/sysdeps/ieee754/ldbl-128/ieee754.h
+++ b/sysdeps/ieee754/ldbl-128/ieee754.h
@@ -16,11 +16,11 @@ 
    <https://www.gnu.org/licenses/>.  */
 
 #ifndef _IEEE754_H
-
 #define _IEEE754_H 1
+
 #include <features.h>
 
-#include <endian.h>
+#include <bits/endian.h>
 
 __BEGIN_DECLS
 
diff --git a/sysdeps/ieee754/ldbl-128ibm/ieee754.h b/sysdeps/ieee754/ldbl-128ibm/ieee754.h
index 35f22895e6b..606b4c7d8a6 100644
--- a/sysdeps/ieee754/ldbl-128ibm/ieee754.h
+++ b/sysdeps/ieee754/ldbl-128ibm/ieee754.h
@@ -16,11 +16,11 @@ 
    <https://www.gnu.org/licenses/>.  */
 
 #ifndef _IEEE754_H
-
 #define _IEEE754_H 1
+
 #include <features.h>
 
-#include <endian.h>
+#include <bits/endian.h>
 
 __BEGIN_DECLS
 
diff --git a/sysdeps/m68k/bits/endian.h b/sysdeps/m68k/bits/endian.h
deleted file mode 100644
index bf4ecb60a4c..00000000000
--- a/sysdeps/m68k/bits/endian.h
+++ /dev/null
@@ -1,7 +0,0 @@ 
-/* m68k is big-endian.  */
-
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-#define __BYTE_ORDER __BIG_ENDIAN
diff --git a/sysdeps/m68k/bits/endianness.h b/sysdeps/m68k/bits/endianness.h
new file mode 100644
index 00000000000..7e5f0d29696
--- /dev/null
+++ b/sysdeps/m68k/bits/endianness.h
@@ -0,0 +1,11 @@ 
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* m68k is big-endian.  */
+#define __BYTE_ORDER __BIG_ENDIAN
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/m68k/nptl/bits/pthreadtypes-arch.h b/sysdeps/m68k/nptl/bits/pthreadtypes-arch.h
index 81990763999..792cb322896 100644
--- a/sysdeps/m68k/nptl/bits/pthreadtypes-arch.h
+++ b/sysdeps/m68k/nptl/bits/pthreadtypes-arch.h
@@ -19,7 +19,7 @@ 
 #ifndef _BITS_PTHREADTYPES_ARCH_H
 #define _BITS_PTHREADTYPES_ARCH_H	1
 
-#include <endian.h>
+#include <bits/endian.h>
 
 #define __SIZEOF_PTHREAD_ATTR_T 36
 #define __SIZEOF_PTHREAD_MUTEX_T 24
diff --git a/sysdeps/microblaze/bits/endian.h b/sysdeps/microblaze/bits/endian.h
deleted file mode 100644
index 6e961a55474..00000000000
--- a/sysdeps/microblaze/bits/endian.h
+++ /dev/null
@@ -1,30 +0,0 @@ 
-/* Copyright (C) 1997-2019 Free Software Foundation, Inc.
-
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public License as
-   published by the Free Software Foundation; either version 2.1 of the
-   License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library.  If not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-/* MicroBlaze can be either big or little endian.  */
-#ifdef _BIG_ENDIAN
-# define __BYTE_ORDER __BIG_ENDIAN
-# define __FLOAT_WORD_ORDER __BIG_ENDIAN
-#else
-# define __BYTE_ORDER __LITTLE_ENDIAN
-# define __FLOAT_WORD_ORDER __LITTLE_ENDIAN
-#endif
diff --git a/sysdeps/microblaze/bits/endianness.h b/sysdeps/microblaze/bits/endianness.h
new file mode 100644
index 00000000000..c4bb7e5f2e9
--- /dev/null
+++ b/sysdeps/microblaze/bits/endianness.h
@@ -0,0 +1,15 @@ 
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* MicroBlaze has selectable endianness.  */
+#ifdef _BIG_ENDIAN
+# define __BYTE_ORDER __BIG_ENDIAN
+#else
+# define __BYTE_ORDER __LITTLE_ENDIAN
+#endif
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/microblaze/nptl/bits/pthreadtypes-arch.h b/sysdeps/microblaze/nptl/bits/pthreadtypes-arch.h
index b1ae4aacdb1..7cf1ff6a725 100644
--- a/sysdeps/microblaze/nptl/bits/pthreadtypes-arch.h
+++ b/sysdeps/microblaze/nptl/bits/pthreadtypes-arch.h
@@ -19,7 +19,7 @@ 
 #ifndef _BITS_PTHREADTYPES_ARCH_H
 # define _BITS_PTHREADTYPES_ARCH_H	1
 
-# include <endian.h>
+# include <bits/endian.h>
 
 # define __SIZEOF_PTHREAD_ATTR_T         36
 # define __SIZEOF_PTHREAD_MUTEX_T        24
diff --git a/sysdeps/mips/bits/endian.h b/sysdeps/mips/bits/endian.h
deleted file mode 100644
index 126059799d7..00000000000
--- a/sysdeps/mips/bits/endian.h
+++ /dev/null
@@ -1,15 +0,0 @@ 
-/* The MIPS architecture has selectable endianness.
-   It exists in both little and big endian flavours and we
-   want to be able to share the installed header files between
-   both, so we define __BYTE_ORDER based on GCC's predefines.  */
-
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-#ifdef __MIPSEB
-# define __BYTE_ORDER __BIG_ENDIAN
-#endif
-#ifdef __MIPSEL
-# define __BYTE_ORDER __LITTLE_ENDIAN
-#endif
diff --git a/sysdeps/mips/bits/endianness.h b/sysdeps/mips/bits/endianness.h
new file mode 100644
index 00000000000..09e138b89be
--- /dev/null
+++ b/sysdeps/mips/bits/endianness.h
@@ -0,0 +1,16 @@ 
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* MIPS has selectable endianness.  */
+#ifdef __MIPSEB
+# define __BYTE_ORDER __BIG_ENDIAN
+#endif
+#ifdef __MIPSEL
+# define __BYTE_ORDER __LITTLE_ENDIAN
+#endif
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/mips/ieee754/ieee754.h b/sysdeps/mips/ieee754/ieee754.h
index ebaf8d84c39..250fa5e8c08 100644
--- a/sysdeps/mips/ieee754/ieee754.h
+++ b/sysdeps/mips/ieee754/ieee754.h
@@ -16,13 +16,16 @@ 
    <https://www.gnu.org/licenses/>.  */
 
 #ifndef _IEEE754_H
-
 #define _IEEE754_H 1
+
 #include <features.h>
 
-#include <endian.h>
+#include <bits/endian.h>
 
-#include <float.h>
+#ifndef __LDBL_MANT_DIG__
+# include <float.h>
+# define __LDBL_MANT_DIG__ __LDBL_MANT_DIG__
+#endif
 
 __BEGIN_DECLS
 
@@ -127,7 +130,7 @@  union ieee754_double
 
 #define IEEE754_DOUBLE_BIAS	0x3ff /* Added to exponent.  */
 
-#if LDBL_MANT_DIG == 113
+#if __LDBL_MANT_DIG__ == 113
 
 union ieee854_long_double
   {
@@ -184,7 +187,7 @@  union ieee854_long_double
 
 #define IEEE854_LONG_DOUBLE_BIAS 0x3fff /* Added to exponent.  */
 
-#elif LDBL_MANT_DIG == 64
+#elif __LDBL_MANT_DIG__ == 64
 
 union ieee854_long_double
   {
@@ -253,7 +256,7 @@  union ieee854_long_double
 
 #define IEEE854_LONG_DOUBLE_BIAS 0x3fff
 
-#elif LDBL_MANT_DIG == 53
+#elif __LDBL_MANT_DIG__ == 53
 
 union ieee854_long_double
   {
@@ -316,7 +319,7 @@  union ieee854_long_double
 
 #define IEEE854_LONG_DOUBLE_BIAS	0x3ff /* Added to exponent.  */
 
-#endif /* LDBL_MANT_DIG == 53 */
+#endif /* __LDBL_MANT_DIG__ == 53 */
 
 __END_DECLS
 
diff --git a/sysdeps/mips/nptl/bits/pthreadtypes-arch.h b/sysdeps/mips/nptl/bits/pthreadtypes-arch.h
index b32e888ea53..0bb703511c6 100644
--- a/sysdeps/mips/nptl/bits/pthreadtypes-arch.h
+++ b/sysdeps/mips/nptl/bits/pthreadtypes-arch.h
@@ -19,7 +19,7 @@ 
 #ifndef _BITS_PTHREADTYPES_ARCH_H
 #define _BITS_PTHREADTYPES_ARCH_H	1
 
-#include <endian.h>
+#include <bits/endian.h>
 
 #if _MIPS_SIM == _ABI64
 # define __SIZEOF_PTHREAD_ATTR_T 56
diff --git a/sysdeps/nios2/bits/endian.h b/sysdeps/nios2/bits/endian.h
deleted file mode 100644
index 164f9e4d785..00000000000
--- a/sysdeps/nios2/bits/endian.h
+++ /dev/null
@@ -1,12 +0,0 @@ 
-/* The Nios II architecture has selectable endianness.  */
-
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-#ifdef __nios2_big_endian__
-# define __BYTE_ORDER __BIG_ENDIAN
-#endif
-#ifdef __nios2_little_endian__
-# define __BYTE_ORDER __LITTLE_ENDIAN
-#endif
diff --git a/sysdeps/nios2/bits/endianness.h b/sysdeps/nios2/bits/endianness.h
new file mode 100644
index 00000000000..87e66ebd716
--- /dev/null
+++ b/sysdeps/nios2/bits/endianness.h
@@ -0,0 +1,16 @@ 
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* Nios II has selectable endianness.  */
+#ifdef __nios2_big_endian__
+# define __BYTE_ORDER __BIG_ENDIAN
+#endif
+#ifdef __nios2_little_endian__
+# define __BYTE_ORDER __LITTLE_ENDIAN
+#endif
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/nios2/nptl/bits/pthreadtypes-arch.h b/sysdeps/nios2/nptl/bits/pthreadtypes-arch.h
index 8cd8bbedafd..dcd3499a861 100644
--- a/sysdeps/nios2/nptl/bits/pthreadtypes-arch.h
+++ b/sysdeps/nios2/nptl/bits/pthreadtypes-arch.h
@@ -19,7 +19,7 @@ 
 #ifndef _BITS_PTHREADTYPES_ARCH_H
 #define _BITS_PTHREADTYPES_ARCH_H	1
 
-#include <endian.h>
+#include <bits/endian.h>
 
 #define __SIZEOF_PTHREAD_ATTR_T 36
 #define __SIZEOF_PTHREAD_MUTEX_T 24
diff --git a/sysdeps/nptl/pthread.h b/sysdeps/nptl/pthread.h
index ceb724d3a24..467b446aca5 100644
--- a/sysdeps/nptl/pthread.h
+++ b/sysdeps/nptl/pthread.h
@@ -19,10 +19,10 @@ 
 #define _PTHREAD_H	1
 
 #include <features.h>
-#include <endian.h>
 #include <sched.h>
 #include <time.h>
 
+#include <bits/endian.h>
 #include <bits/pthreadtypes.h>
 #include <bits/setjmp.h>
 #include <bits/wordsize.h>
diff --git a/sysdeps/powerpc/bits/endian.h b/sysdeps/powerpc/bits/endian.h
deleted file mode 100644
index c82f7ad4de6..00000000000
--- a/sysdeps/powerpc/bits/endian.h
+++ /dev/null
@@ -1,36 +0,0 @@ 
-/* Copyright (C) 1997-2019 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-/* PowerPC can be little or big endian.  Hopefully gcc will know...  */
-
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-#if defined __BIG_ENDIAN__ || defined _BIG_ENDIAN
-# if defined __LITTLE_ENDIAN__ || defined _LITTLE_ENDIAN
-#  error Both BIG_ENDIAN and LITTLE_ENDIAN defined!
-# endif
-# define __BYTE_ORDER __BIG_ENDIAN
-#else
-# if defined __LITTLE_ENDIAN__ || defined _LITTLE_ENDIAN
-#  define __BYTE_ORDER __LITTLE_ENDIAN
-# else
-#  warning Cannot determine current byte order, assuming big-endian.
-#  define __BYTE_ORDER __BIG_ENDIAN
-# endif
-#endif
diff --git a/sysdeps/powerpc/bits/endianness.h b/sysdeps/powerpc/bits/endianness.h
new file mode 100644
index 00000000000..3e7735237e4
--- /dev/null
+++ b/sysdeps/powerpc/bits/endianness.h
@@ -0,0 +1,16 @@ 
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* PowerPC has selectable endianness.  */
+#if defined __BIG_ENDIAN__ || defined _BIG_ENDIAN
+# define __BYTE_ORDER __BIG_ENDIAN
+#endif
+#if defined __LITTLE_ENDIAN__ || defined _LITTLE_ENDIAN
+# define __BYTE_ORDER __LITTLE_ENDIAN
+#endif
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/riscv/bits/endian.h b/sysdeps/riscv/bits/endian.h
deleted file mode 100644
index 4aaf559d4f4..00000000000
--- a/sysdeps/riscv/bits/endian.h
+++ /dev/null
@@ -1,5 +0,0 @@ 
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-#define __BYTE_ORDER __LITTLE_ENDIAN
diff --git a/sysdeps/riscv/bits/endianness.h b/sysdeps/riscv/bits/endianness.h
new file mode 100644
index 00000000000..952d08595a8
--- /dev/null
+++ b/sysdeps/riscv/bits/endianness.h
@@ -0,0 +1,11 @@ 
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* RISC-V is little-endian.  */
+#define __BYTE_ORDER __LITTLE_ENDIAN
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/riscv/nptl/bits/pthreadtypes-arch.h b/sysdeps/riscv/nptl/bits/pthreadtypes-arch.h
index 583443954e4..33f0ee43fe9 100644
--- a/sysdeps/riscv/nptl/bits/pthreadtypes-arch.h
+++ b/sysdeps/riscv/nptl/bits/pthreadtypes-arch.h
@@ -19,7 +19,7 @@ 
 #ifndef _BITS_PTHREADTYPES_ARCH_H
 #define _BITS_PTHREADTYPES_ARCH_H	1
 
-#include <endian.h>
+#include <bits/endian.h>
 
 #if __riscv_xlen == 64
 # define __SIZEOF_PTHREAD_ATTR_T 		56
diff --git a/sysdeps/s390/bits/endian.h b/sysdeps/s390/bits/endian.h
deleted file mode 100644
index ac27f0119a8..00000000000
--- a/sysdeps/s390/bits/endian.h
+++ /dev/null
@@ -1,7 +0,0 @@ 
-/* s390 is big-endian */
-
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-#define __BYTE_ORDER __BIG_ENDIAN
diff --git a/sysdeps/s390/bits/endianness.h b/sysdeps/s390/bits/endianness.h
new file mode 100644
index 00000000000..c2d34e1c3ee
--- /dev/null
+++ b/sysdeps/s390/bits/endianness.h
@@ -0,0 +1,11 @@ 
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* S/390 is big-endian.  */
+#define __BYTE_ORDER __BIG_ENDIAN
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/sh/bits/endian.h b/sysdeps/sh/bits/endian.h
deleted file mode 100644
index 1fef1ff938f..00000000000
--- a/sysdeps/sh/bits/endian.h
+++ /dev/null
@@ -1,13 +0,0 @@ 
-/* SH is bi-endian but with a big-endian FPU.  */
-
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-#ifdef __LITTLE_ENDIAN__
-#define __BYTE_ORDER __LITTLE_ENDIAN
-#define __FLOAT_WORD_ORDER __LITTLE_ENDIAN
-#else
-#define __BYTE_ORDER __BIG_ENDIAN
-#define __FLOAT_WORD_ORDER __BIG_ENDIAN
-#endif
diff --git a/sysdeps/sh/bits/endianness.h b/sysdeps/sh/bits/endianness.h
new file mode 100644
index 00000000000..45c7c83a63f
--- /dev/null
+++ b/sysdeps/sh/bits/endianness.h
@@ -0,0 +1,15 @@ 
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* SH has selectable endianness.  */
+#ifdef __LITTLE_ENDIAN__
+#define __BYTE_ORDER __LITTLE_ENDIAN
+#else
+#define __BYTE_ORDER __BIG_ENDIAN
+#endif
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/sh/nptl/bits/pthreadtypes-arch.h b/sysdeps/sh/nptl/bits/pthreadtypes-arch.h
index 6c9485d989d..219a8613987 100644
--- a/sysdeps/sh/nptl/bits/pthreadtypes-arch.h
+++ b/sysdeps/sh/nptl/bits/pthreadtypes-arch.h
@@ -18,7 +18,7 @@ 
 #ifndef _BITS_PTHREADTYPES_ARCH_H
 #define _BITS_PTHREADTYPES_ARCH_H	1
 
-#include <endian.h>
+#include <bits/endian.h>
 
 #define __SIZEOF_PTHREAD_ATTR_T 36
 #define __SIZEOF_PTHREAD_MUTEX_T 24
diff --git a/sysdeps/sparc/bits/endian.h b/sysdeps/sparc/bits/endianness.h
similarity index 56%
rename from sysdeps/sparc/bits/endian.h
rename to sysdeps/sparc/bits/endianness.h
index 8acfdf5df6f..0b6f5bf8b23 100644
--- a/sysdeps/sparc/bits/endian.h
+++ b/sysdeps/sparc/bits/endianness.h
@@ -1,12 +1,16 @@ 
-/* Sparc is big-endian, but v9 supports endian conversion on loads/stores
-   and GCC supports such a mode.  Be prepared.  */
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
 
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
 #endif
 
+/* Sparc is big-endian, but v9 supports endian conversion on loads/stores
+   and GCC supports such a mode.  Be prepared.  */
 #ifdef __LITTLE_ENDIAN__
 # define __BYTE_ORDER __LITTLE_ENDIAN
 #else
 # define __BYTE_ORDER __BIG_ENDIAN
 #endif
+
+#endif /* bits/endianness.h */
diff --git a/sysdeps/sparc/sparc32/ieee754.h b/sysdeps/sparc/sparc32/ieee754.h
index 87dc1d781dc..47f11d8a6b7 100644
--- a/sysdeps/sparc/sparc32/ieee754.h
+++ b/sysdeps/sparc/sparc32/ieee754.h
@@ -16,11 +16,11 @@ 
    <https://www.gnu.org/licenses/>.  */
 
 #ifndef _IEEE754_H
-
 #define _IEEE754_H 1
+
 #include <features.h>
 
-#include <endian.h>
+#include <bits/endian.h>
 
 __BEGIN_DECLS
 
diff --git a/sysdeps/unix/sysv/linux/generic/bits/stat.h b/sysdeps/unix/sysv/linux/generic/bits/stat.h
index 62aeea5a88d..1565f3f8248 100644
--- a/sysdeps/unix/sysv/linux/generic/bits/stat.h
+++ b/sysdeps/unix/sysv/linux/generic/bits/stat.h
@@ -23,7 +23,7 @@ 
 #ifndef _BITS_STAT_H
 #define _BITS_STAT_H	1
 
-#include <endian.h>
+#include <bits/endian.h>
 #include <bits/wordsize.h>
 
 /* 64-bit libc uses the kernel's 'struct stat', accessed via the
diff --git a/sysdeps/unix/sysv/linux/generic/bits/statfs.h b/sysdeps/unix/sysv/linux/generic/bits/statfs.h
index 3472084ade0..c4069aba620 100644
--- a/sysdeps/unix/sysv/linux/generic/bits/statfs.h
+++ b/sysdeps/unix/sysv/linux/generic/bits/statfs.h
@@ -20,7 +20,7 @@ 
 # error "Never include <bits/statfs.h> directly; use <sys/statfs.h> instead."
 #endif
 
-#include <endian.h>
+#include <bits/endian.h>
 #include <bits/types.h>
 #include <bits/wordsize.h>
 
diff --git a/sysdeps/unix/sysv/linux/hppa/pthread.h b/sysdeps/unix/sysv/linux/hppa/pthread.h
index e168901ba05..424135c800d 100644
--- a/sysdeps/unix/sysv/linux/hppa/pthread.h
+++ b/sysdeps/unix/sysv/linux/hppa/pthread.h
@@ -19,7 +19,6 @@ 
 #define _PTHREAD_H	1
 
 #include <features.h>
-#include <endian.h>
 #include <sched.h>
 #include <time.h>
 
diff --git a/sysdeps/unix/sysv/linux/ia64/bits/endian.h b/sysdeps/unix/sysv/linux/ia64/bits/endian.h
deleted file mode 100644
index 98a5e239916..00000000000
--- a/sysdeps/unix/sysv/linux/ia64/bits/endian.h
+++ /dev/null
@@ -1,7 +0,0 @@ 
-/* Linux/ia64 is little-endian.  */
-
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-#define __BYTE_ORDER __LITTLE_ENDIAN
diff --git a/sysdeps/unix/sysv/linux/powerpc/htm.h b/sysdeps/unix/sysv/linux/powerpc/htm.h
index 75e3eb0397b..f17d7510130 100644
--- a/sysdeps/unix/sysv/linux/powerpc/htm.h
+++ b/sysdeps/unix/sysv/linux/powerpc/htm.h
@@ -50,7 +50,7 @@ 
 
 #else
 
-#include <endian.h>
+#include <bits/endian.h>
 
 /* Official HTM intrinsics interface matching GCC, but works
    on older GCC compatible compilers and binutils.
diff --git a/sysdeps/unix/sysv/linux/sys/acct.h b/sysdeps/unix/sysv/linux/sys/acct.h
index 5db43fd6759..1d2f22402af 100644
--- a/sysdeps/unix/sysv/linux/sys/acct.h
+++ b/sysdeps/unix/sysv/linux/sys/acct.h
@@ -20,7 +20,7 @@ 
 
 #include <sys/types.h>
 #include <stdint.h>
-#include <endian.h>
+#include <bits/endian.h>
 #include <bits/types/time_t.h>
 
 __BEGIN_DECLS
diff --git a/sysdeps/x86/bits/endian.h b/sysdeps/x86/bits/endian.h
deleted file mode 100644
index 5a56c726f71..00000000000
--- a/sysdeps/x86/bits/endian.h
+++ /dev/null
@@ -1,7 +0,0 @@ 
-/* i386/x86_64 are little-endian.  */
-
-#ifndef _ENDIAN_H
-# error "Never use <bits/endian.h> directly; include <endian.h> instead."
-#endif
-
-#define __BYTE_ORDER __LITTLE_ENDIAN
diff --git a/sysdeps/x86/bits/endianness.h b/sysdeps/x86/bits/endianness.h
new file mode 100644
index 00000000000..962a9ae4d6e
--- /dev/null
+++ b/sysdeps/x86/bits/endianness.h
@@ -0,0 +1,11 @@ 
+#ifndef _BITS_ENDIANNESS_H
+#define _BITS_ENDIANNESS_H 1
+
+#ifndef _BITS_ENDIAN_H
+# error "Never use <bits/endianness.h> directly; include <endian.h> instead."
+#endif
+
+/* i386/x86_64 are little-endian.  */
+#define __BYTE_ORDER __LITTLE_ENDIAN
+
+#endif /* bits/endianness.h */
diff --git a/wctype/bits/wctype-wchar.h b/wctype/bits/wctype-wchar.h
index 7481f33a8cd..f584669f358 100644
--- a/wctype/bits/wctype-wchar.h
+++ b/wctype/bits/wctype-wchar.h
@@ -42,7 +42,7 @@  typedef unsigned long int wctype_t;
    endian).  We define the bit value interpretations here dependent on the
    machine's byte order.  */
 
-#  include <endian.h>
+#  include <bits/endian.h>
 #  if __BYTE_ORDER == __BIG_ENDIAN
 #   define _ISwbit(bit)	(1 << (bit))
 #  else /* __BYTE_ORDER == __LITTLE_ENDIAN */