Factor out shared definitions from bits/signum.h.

Many of the things defined by bits/signum.h are invariant across all
supported operating systems.  This patch factors out all of them to a
new header bits/signum-generic.h, which each bits/signum.h will include
and then override whichever things need adjustment.  Normally that will
mean, at most, adding or changing a few signal numbers.

A user-visible side effect is that the obsolete signal constant SIGUNUSED
(which is an alias for SIGSYS on all platforms that define it) is no
longer exposed by any version of bits/signum.h.

A side effect only relevant to glibc hackers is that _NSIG is now defined
in terms of __SIGRTMAX, instead of the other way around.  This is because
__SIGRTMAX varies from platform to platform, but _NSIG==__SIGRTMAX+1 is
true universally.  If your platform doesn't support realtime signals,
leave __SIGRTMAX equal to __SIGRTMIN.

I also added a Linux-specific test to make sure that our signal constants
match the ones in <asm/signal.h>, since we can't use that header (it's
not even vaguely namespace-clean).

	* bits/signum-generic.h: Renamed from bits/signum.h.
	Add proper multiple include guard and misuse check.
	Define __SIGRTMIN = __SIGRTMAX = 32, and define _NSIG = __SIGRTMAX+1.
	Move definition of SIGIO to "archaic names for compatibility" section.
	* bits/signum.h: New file which just includes bits/signum-generic.h.
	* sysdeps/unix/bsd/bits/signum.h
	* sysdeps/unix/sysv/linux/bits/signum.h
	* sysdeps/unix/sysv/linux/alpha/bits/signum.h
	* sysdeps/unix/sysv/linux/hppa/bits/signum.h
	* sysdeps/unix/sysv/linux/mips/bits/signum.h
	* sysdeps/unix/sysv/linux/sparc/bits/signum.h
	Just include <bits/signum-generic.h> and then add or adjust
	signal constants.  Do not define SIGUNUSED, SIGRTMIN, or SIGRTMAX.

	* signal/Makefile: Install bits/signum-generic.h.
	* signal/signal.h: Define SIGRTMIN and SIGRTMAX here.

	* sysdeps/generic/siglist.h: SIGSYS and SIGWINCH are
	universal.  Prefer SIGPOLL to SIGIO. Simplify #ifdeffage.

	* sysdeps/unix/sysv/linux/tst-signal-numbers.sh: New test.
	* sysdeps/unix/sysv/linux/Makefile: Run it.

9 files changed, 273 insertions, 343 deletions

diff --git a/sysdeps/generic/siglist.h b/sysdeps/generic/siglist.h
index dd72929ed5..022be56059 100644
--- a/sysdeps/generic/siglist.h
+++ b/sysdeps/generic/siglist.h
@@ -24,7 +24,8 @@
 
 /* This file is included multiple times.  */
 
-/* Standard signals  */
+/* Standard signals, in the numerical order defined in
+   bits/signum-generic.h.  */
   init_sig (SIGHUP, "HUP", N_("Hangup"))
   init_sig (SIGINT, "INT", N_("Interrupt"))
   init_sig (SIGQUIT, "QUIT", N_("Quit"))
@@ -34,6 +35,7 @@
   init_sig (SIGFPE, "FPE", N_("Floating point exception"))
   init_sig (SIGKILL, "KILL", N_("Killed"))
   init_sig (SIGBUS, "BUS", N_("Bus error"))
+  init_sig (SIGSYS, "SYS", N_("Bad system call"))
   init_sig (SIGSEGV, "SEGV", N_("Segmentation fault"))
   init_sig (SIGPIPE, "PIPE", N_("Broken pipe"))
   init_sig (SIGALRM, "ALRM", N_("Alarm clock"))
@@ -45,32 +47,28 @@
   init_sig (SIGCHLD, "CHLD", N_("Child exited"))
   init_sig (SIGTTIN, "TTIN", N_("Stopped (tty input)"))
   init_sig (SIGTTOU, "TTOU", N_("Stopped (tty output)"))
-  init_sig (SIGIO, "IO", N_("I/O possible"))
+  init_sig (SIGPOLL, "POLL", N_("I/O possible"))
   init_sig (SIGXCPU, "XCPU", N_("CPU time limit exceeded"))
   init_sig (SIGXFSZ, "XFSZ", N_("File size limit exceeded"))
   init_sig (SIGVTALRM, "VTALRM", N_("Virtual timer expired"))
   init_sig (SIGPROF, "PROF", N_("Profiling timer expired"))
   init_sig (SIGUSR1, "USR1", N_("User defined signal 1"))
   init_sig (SIGUSR2, "USR2", N_("User defined signal 2"))
+  init_sig (SIGWINCH, "WINCH", N_("Window changed"))
 
-/* Variations  */
+/* Signals that are not present on all supported platforms.  */
 #ifdef SIGEMT
   init_sig (SIGEMT, "EMT", N_("EMT trap"))
 #endif
-#ifdef SIGSYS
-  init_sig (SIGSYS, "SYS", N_("Bad system call"))
-#endif
 #ifdef SIGSTKFLT
   init_sig (SIGSTKFLT, "STKFLT", N_("Stack fault"))
 #endif
-#ifdef SIGINFO
-  init_sig (SIGINFO, "INFO", N_("Information request"))
-#elif defined(SIGPWR) && (!defined(SIGLOST) || (SIGPWR != SIGLOST))
+#ifdef SIGPWR
   init_sig (SIGPWR, "PWR", N_("Power failure"))
 #endif
-#ifdef SIGLOST
-  init_sig (SIGLOST, "LOST", N_("Resource lost"))
+#if defined SIGINFO && (!defined SIGPWR || SIGPWR != SIGINFO)
+  init_sig (SIGINFO, "INFO", N_("Information request"))
 #endif
-#ifdef SIGWINCH
-  init_sig (SIGWINCH, "WINCH", N_("Window changed"))
+#if defined SIGLOST && (!defined SIGPWR || SIGPWR != SIGLOST)
+  init_sig (SIGLOST, "LOST", N_("Resource lost"))
 #endif
diff --git a/sysdeps/unix/bsd/bits/signum.h b/sysdeps/unix/bsd/bits/signum.h
index 268c24a702..f55edc93a3 100644
--- a/sysdeps/unix/bsd/bits/signum.h
+++ b/sysdeps/unix/bsd/bits/signum.h
@@ -16,58 +16,20 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#ifdef	_SIGNAL_H
+#ifndef _BITS_SIGNUM_H
+#define _BITS_SIGNUM_H 1
 
-/* This file defines the fake signal functions and signal
-   number constants for 4.2 or 4.3 BSD-derived Unix system.  */
-
-/* Fake signal functions.  */
-#define	SIG_ERR	((__sighandler_t) -1) /* Error return.  */
-#define	SIG_DFL	((__sighandler_t) 0) /* Default action.  */
-#define	SIG_IGN	((__sighandler_t) 1) /* Ignore signal.  */
-
-#ifdef __USE_XOPEN
-# define SIG_HOLD      ((__sighandler_t) 2)    /* Add signal to hold mask.  */
+#ifndef _SIGNAL_H
+#error "Never include <bits/signum.h> directly; use <signal.h> instead."
 #endif
 
+#include <bits/signum-generic.h>
 
-/* Signals.  */
-#define	SIGHUP		1	/* Hangup (POSIX).  */
-#define	SIGINT		2	/* Interrupt (ANSI).  */
-#define	SIGQUIT		3	/* Quit (POSIX).  */
-#define	SIGILL		4	/* Illegal instruction (ANSI).  */
-#define	SIGABRT		SIGIOT	/* Abort (ANSI).  */
-#define	SIGTRAP		5	/* Trace trap (POSIX).  */
-#define	SIGIOT		6	/* IOT trap (4.2 BSD).  */
-#define	SIGEMT		7	/* EMT trap (4.2 BSD).  */
-#define	SIGFPE		8	/* Floating-point exception (ANSI).  */
-#define	SIGKILL		9	/* Kill, unblockable (POSIX).  */
-#define	SIGBUS		10	/* Bus error (4.2 BSD).  */
-#define	SIGSEGV		11	/* Segmentation violation (ANSI).  */
-#define	SIGSYS		12	/* Bad argument to system call (4.2 BSD).  */
-#define	SIGPIPE		13	/* Broken pipe (POSIX).  */
-#define	SIGALRM		14	/* Alarm clock (POSIX).  */
-#define	SIGTERM		15	/* Termination (ANSI).  */
-#define	SIGURG		16	/* Urgent condition on socket (4.2 BSD).  */
-#define	SIGSTOP		17	/* Stop, unblockable (POSIX).  */
-#define	SIGTSTP		18	/* Keyboard stop (POSIX).  */
-#define	SIGCONT		19	/* Continue (POSIX).  */
-#define	SIGCHLD		20	/* Child status has changed (POSIX).  */
-#define	SIGCLD		SIGCHLD	/* Same as SIGCHLD (System V).  */
-#define	SIGTTIN		21	/* Background read from tty (POSIX).  */
-#define	SIGTTOU		22	/* Background write to tty (POSIX).  */
-#define	SIGIO		23	/* I/O now possible (4.2 BSD).  */
-#define	SIGPOLL		SIGIO	/* Same as SIGIO? (SVID).  */
-#define	SIGXCPU		24	/* CPU limit exceeded (4.2 BSD).  */
-#define	SIGXFSZ		25	/* File size limit exceeded (4.2 BSD).  */
-#define	SIGVTALRM	26	/* Virtual alarm clock (4.2 BSD).  */
-#define	SIGPROF		27	/* Profiling alarm clock (4.2 BSD).  */
-#define	SIGWINCH	28	/* Window size change (4.3 BSD, Sun).  */
+/* Adjustments and additions to the signal number constants for
+   4.2 or 4.3 BSD-derived Unix systems.  */
+
+#define SIGEMT		 7	/* Emulator trap (4.2 BSD).  */
 #define SIGINFO		29	/* Information request (4.4 BSD).  */
-#define	SIGUSR1		30	/* User-defined signal 1 (POSIX).  */
-#define	SIGUSR2		31	/* User-defined signal 2 (POSIX).  */
 #define SIGLOST		32	/* Resource lost (Sun); server died (GNU).  */
 
-#endif	/* <signal.h> included.  */
-
-#define	_NSIG		33	/* Biggest signal number + 1.  */
+#endif /* bits/signum.h.  */
diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index 1a170c29d6..8b340d4988 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -128,6 +128,20 @@ sysdep_headers += sys/timex.h bits/timex.h
 sysdep_routines += ntp_gettime ntp_gettimex
 endif
 
+ifeq ($(subdir),signal)
+tests-special += $(objpfx)tst-signal-numbers.out
+# Depending on signal.o* is a hack.  What we actually want is a dependency
+# on signal.h and everything it includes.  That's impractical to write
+# in this context, but signal.c includes signal.h and not much else so it'll
+# be conservatively correct.
+$(objpfx)tst-signal-numbers.out: \
+		../sysdeps/unix/sysv/linux/tst-signal-numbers.sh \
+		$(objpfx)signal.o*
+	AWK=$(AWK) $(SHELL) ../sysdeps/unix/sysv/linux/tst-signal-numbers.sh \
+	$(CC) $(patsubst -DMODULE_NAME=%,-DMODULE_NAME=testsuite,$(CPPFLAGS)) \
+	< /dev/null > $@; $(evaluate-test)
+endif
+
 ifeq ($(subdir),socket)
 sysdep_headers += net/if_ppp.h net/ppp-comp.h \
 		  net/ppp_defs.h net/if_arp.h net/route.h net/ethernet.h \
diff --git a/sysdeps/unix/sysv/linux/alpha/bits/signum.h b/sysdeps/unix/sysv/linux/alpha/bits/signum.h
index e5cc5218e3..8227be91b5 100644
--- a/sysdeps/unix/sysv/linux/alpha/bits/signum.h
+++ b/sysdeps/unix/sysv/linux/alpha/bits/signum.h
@@ -16,66 +16,25 @@
    License along with the GNU C Library.  If not, see
    <http://www.gnu.org/licenses/>.  */
 
-#ifdef	_SIGNAL_H
+#ifndef _BITS_SIGNUM_H
+#define _BITS_SIGNUM_H 1
 
-/* Fake signal functions.  */
-#define SIG_ERR ((__sighandler_t) -1) /* Error return.  */
-#define SIG_DFL ((__sighandler_t) 0) /* Default action.  */
-#define SIG_IGN ((__sighandler_t) 1) /* Ignore signal.  */
-
-#ifdef __USE_XOPEN
-# define SIG_HOLD	((__sighandler_t) 2)	/* Add signal to hold mask.  */
+#ifndef _SIGNAL_H
+#error "Never include <bits/signum.h> directly; use <signal.h> instead."
 #endif
 
-/*
- * Linux/AXP has different signal numbers that Linux/i386: I'm trying
- * to make it OSF/1 binary compatible, at least for normal binaries.
- */
-#define SIGHUP		 1
-#define SIGINT		 2
-#define SIGQUIT		 3
-#define SIGILL		 4
-#define SIGTRAP		 5
-#define SIGABRT		 6
-#define SIGEMT		 7
-#define SIGFPE		 8
-#define SIGKILL		 9
-#define SIGBUS		10
-#define SIGSEGV		11
-#define SIGSYS		12
-#define SIGPIPE		13
-#define SIGALRM		14
-#define SIGTERM		15
-#define SIGURG		16
-#define SIGSTOP		17
-#define SIGTSTP		18
-#define SIGCONT		19
-#define SIGCHLD		20
-#define SIGCLD          SIGCHLD
-#define SIGTTIN		21
-#define SIGTTOU		22
-#define SIGIO		23
-#define SIGXCPU		24
-#define SIGXFSZ		25
-#define SIGVTALRM	26
-#define SIGPROF		27
-#define SIGWINCH	28
-#define SIGINFO		29
-#define SIGUSR1		30
-#define SIGUSR2		31
-
-#define SIGPOLL	SIGIO
-#define SIGPWR	SIGINFO
-#define SIGIOT	SIGABRT
+#include <bits/signum-generic.h>
 
-#define	_NSIG		65	/* Biggest signal number + 1.  */
+/* Adjustments and additions to the signal number constants for
+   Linux/Alpha.  Signal values on this platform were chosen for OSF/1
+   binary compatibility, and are therefore almost identical to the
+   BSD-derived defaults.  */
 
-#define SIGRTMIN	(__libc_current_sigrtmin ())
-#define SIGRTMAX	(__libc_current_sigrtmax ())
+#define SIGEMT		 7	/* Emulator trap (4.2 BSD).  */
+#define SIGINFO		29	/* Information request (BSD).  */
+#define SIGPWR		SIGINFO	/* Power failure imminent (System V).  */
 
-/* These are the hard limits of the kernel.  These values should not be
-   used directly at user level.  */
-#define __SIGRTMIN	32
-#define __SIGRTMAX	(_NSIG - 1)
+#undef	__SIGRTMAX
+#define __SIGRTMAX	64
 
 #endif	/* <signal.h> included.  */
diff --git a/sysdeps/unix/sysv/linux/bits/signum.h b/sysdeps/unix/sysv/linux/bits/signum.h
index e30efead0d..1a68255d02 100644
--- a/sysdeps/unix/sysv/linux/bits/signum.h
+++ b/sysdeps/unix/sysv/linux/bits/signum.h
@@ -16,64 +16,43 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#ifdef	_SIGNAL_H
+#ifndef _BITS_SIGNUM_H
+#define _BITS_SIGNUM_H 1
 
-/* Fake signal functions.  */
-#define SIG_ERR	((__sighandler_t) -1)		/* Error return.  */
-#define SIG_DFL	((__sighandler_t) 0)		/* Default action.  */
-#define SIG_IGN	((__sighandler_t) 1)		/* Ignore signal.  */
-
-#ifdef __USE_XOPEN
-# define SIG_HOLD	((__sighandler_t) 2)	/* Add signal to hold mask.  */
+#ifndef _SIGNAL_H
+#error "Never include <bits/signum.h> directly; use <signal.h> instead."
 #endif
 
-
-/* Signals.  */
-#define	SIGHUP		1	/* Hangup (POSIX).  */
-#define	SIGINT		2	/* Interrupt (ANSI).  */
-#define	SIGQUIT		3	/* Quit (POSIX).  */
-#define	SIGILL		4	/* Illegal instruction (ANSI).  */
-#define	SIGTRAP		5	/* Trace trap (POSIX).  */
-#define	SIGABRT		6	/* Abort (ANSI).  */
-#define	SIGIOT		6	/* IOT trap (4.2 BSD).  */
-#define	SIGBUS		7	/* BUS error (4.2 BSD).  */
-#define	SIGFPE		8	/* Floating-point exception (ANSI).  */
-#define	SIGKILL		9	/* Kill, unblockable (POSIX).  */
-#define	SIGUSR1		10	/* User-defined signal 1 (POSIX).  */
-#define	SIGSEGV		11	/* Segmentation violation (ANSI).  */
-#define	SIGUSR2		12	/* User-defined signal 2 (POSIX).  */
-#define	SIGPIPE		13	/* Broken pipe (POSIX).  */
-#define	SIGALRM		14	/* Alarm clock (POSIX).  */
-#define	SIGTERM		15	/* Termination (ANSI).  */
-#define	SIGSTKFLT	16	/* Stack fault.  */
-#define	SIGCLD		SIGCHLD	/* Same as SIGCHLD (System V).  */
-#define	SIGCHLD		17	/* Child status has changed (POSIX).  */
-#define	SIGCONT		18	/* Continue (POSIX).  */
-#define	SIGSTOP		19	/* Stop, unblockable (POSIX).  */
-#define	SIGTSTP		20	/* Keyboard stop (POSIX).  */
-#define	SIGTTIN		21	/* Background read from tty (POSIX).  */
-#define	SIGTTOU		22	/* Background write to tty (POSIX).  */
-#define	SIGURG		23	/* Urgent condition on socket (4.2 BSD).  */
-#define	SIGXCPU		24	/* CPU limit exceeded (4.2 BSD).  */
-#define	SIGXFSZ		25	/* File size limit exceeded (4.2 BSD).  */
-#define	SIGVTALRM	26	/* Virtual alarm clock (4.2 BSD).  */
-#define	SIGPROF		27	/* Profiling alarm clock (4.2 BSD).  */
-#define	SIGWINCH	28	/* Window size change (4.3 BSD, Sun).  */
-#define	SIGPOLL		SIGIO	/* Pollable event occurred (System V).  */
-#define	SIGIO		29	/* I/O now possible (4.2 BSD).  */
-#define	SIGPWR		30	/* Power failure restart (System V).  */
-#define SIGSYS		31	/* Bad system call.  */
-#define SIGUNUSED	31
-
-#define	_NSIG		65	/* Biggest signal number + 1
-				   (including real-time signals).  */
-
-#define SIGRTMIN        (__libc_current_sigrtmin ())
-#define SIGRTMAX        (__libc_current_sigrtmax ())
-
-/* These are the hard limits of the kernel.  These values should not be
-   used directly at user level.  */
-#define __SIGRTMIN	32
-#define __SIGRTMAX	(_NSIG - 1)
+#include <bits/signum-generic.h>
+
+/* Adjustments and additions to the signal number constants for
+   most Linux systems.  */
+
+#define	SIGSTKFLT	16	/* Stack fault (obsolete).  */
+#define	SIGPWR		30	/* Power failure imminent.  */
+
+#undef	SIGBUS
+#define	SIGBUS		 7
+#undef	SIGUSR1
+#define	SIGUSR1		10
+#undef	SIGUSR2
+#define	SIGUSR2		12
+#undef	SIGCHLD
+#define	SIGCHLD		17
+#undef	SIGCONT
+#define	SIGCONT		18
+#undef	SIGSTOP
+#define	SIGSTOP		19
+#undef	SIGTSTP
+#define	SIGTSTP		20
+#undef	SIGURG
+#define	SIGURG		23
+#undef	SIGPOLL
+#define	SIGPOLL		29
+#undef	SIGSYS
+#define SIGSYS		31
+
+#undef	__SIGRTMAX
+#define __SIGRTMAX	64
 
 #endif	/* <signal.h> included.  */
diff --git a/sysdeps/unix/sysv/linux/hppa/bits/signum.h b/sysdeps/unix/sysv/linux/hppa/bits/signum.h
index 20c0b60c9f..5f54d1c893 100644
--- a/sysdeps/unix/sysv/linux/hppa/bits/signum.h
+++ b/sysdeps/unix/sysv/linux/hppa/bits/signum.h
@@ -16,74 +16,60 @@
    License along with the GNU C Library.  If not, see
    <http://www.gnu.org/licenses/>.  */
 
-#ifdef	_SIGNAL_H
+#ifndef _BITS_SIGNUM_H
+#define _BITS_SIGNUM_H 1
 
-/* Fake signal functions.  */
-#define SIG_ERR	((__sighandler_t) -1)		/* Error return.  */
-#define SIG_DFL	((__sighandler_t) 0)		/* Default action.  */
-#define SIG_IGN	((__sighandler_t) 1)		/* Ignore signal.  */
-
-#ifdef __USE_XOPEN
-# define SIG_HOLD	((__sighandler_t) 2)	/* Add signal to hold mask.  */
+#ifndef _SIGNAL_H
+#error "Never include <bits/signum.h> directly; use <signal.h> instead."
 #endif
 
+#include <bits/signum-generic.h>
 
-/* Signals.  */
-#define	SIGHUP		1	/* Hangup (POSIX).  */
-#define	SIGINT		2	/* Interrupt (ANSI).  */
-#define	SIGQUIT		3	/* Quit (POSIX).  */
-#define	SIGILL		4	/* Illegal instruction (ANSI).  */
-#define	SIGTRAP		5	/* Trace trap (POSIX).  */
-#define	SIGABRT		6	/* Abort (ANSI).  */
-#define	SIGIOT		6	/* IOT trap (4.2 BSD).  */
-#define	SIGSTKFLT	7	/* Stack fault.  */
-#define	SIGFPE		8	/* Floating-point exception (ANSI).  */
-#define	SIGKILL		9	/* Kill, unblockable (POSIX).  */
-#define	SIGBUS		10	/* BUS error (4.2 BSD).  */
-#define	SIGSEGV		11	/* Segmentation violation (ANSI).  */
-#define	SIGXCPU		12	/* CPU limit exceeded (4.2 BSD).  */
-#define	SIGPIPE		13	/* Broken pipe (POSIX).  */
-#define	SIGALRM		14	/* Alarm clock (POSIX).  */
-#define	SIGTERM		15	/* Termination (ANSI).  */
-#define	SIGUSR1		16	/* User-defined signal 1 (POSIX).  */
-#define SIGUSR2		17	/* User-defined signal 2 (POSIX).  */
-#define	SIGCLD		SIGCHLD	/* Same as SIGCHLD (System V).  */
-#define	SIGCHLD		18	/* Child status has changed (POSIX).  */
-#define	SIGPWR		19	/* Power failure restart (System V).  */
-#define	SIGVTALRM	20	/* Virtual alarm clock (4.2 BSD).  */
-#define	SIGPROF		21	/* Profiling alarm clock (4.2 BSD).  */
-#define	SIGPOLL		SIGIO	/* Pollable event occurred (System V).  */
-#define	SIGIO		22	/* I/O now possible (4.2 BSD).  */
-#define	SIGWINCH	23	/* Window size change (4.3 BSD, Sun).  */
-#define	SIGSTOP		24	/* Stop, unblockable (POSIX).  */
-#define	SIGTSTP		25	/* Keyboard stop (POSIX).  */
-#define	SIGCONT		26	/* Continue (POSIX).  */
-#define	SIGTTIN		27	/* Background read from tty (POSIX).  */
-#define	SIGTTOU		28	/* Background write to tty (POSIX).  */
-#define	SIGURG		29	/* Urgent condition on socket (4.2 BSD).  */
-#define	SIGXFSZ		30	/* File size limit exceeded (4.2 BSD).  */
-#define SIGSYS		31	/* Bad system call.  */
-#define SIGUNUSED	31
+/* Adjustments and additions to the signal number constants for
+   Linux/HPPA.  These values were originally chosen for HP/UX
+   compatibility, but were renumbered as of kernel 3.17 and glibc 2.21
+   to accommodate software (notably systemd) that assumed at least 29
+   real-time signal numbers would be available.  SIGEMT and SIGLOST
+   were removed, and the values of SIGSTKFLT, SIGXCPU, XIGXFSZ, and
+   SIGSYS were changed, enabling __SIGRTMIN to be 32.  */
 
-#define	_NSIG		65	/* Biggest signal number + 1
-				   (including real-time signals).  */
+#define	SIGSTKFLT	 7	/* Stack fault (obsolete).  */
+#define	SIGPWR		19	/* Power failure imminent.  */
 
-#define SIGRTMIN        (__libc_current_sigrtmin ())
-#define SIGRTMAX        (__libc_current_sigrtmax ())
+#undef	SIGXCPU
+#define	SIGXCPU		12
+#undef	SIGUSR1
+#define	SIGUSR1		16
+#undef	SIGUSR2
+#define SIGUSR2		17
+#undef	SIGCHLD
+#define	SIGCHLD		18
+#undef	SIGVTALRM
+#define	SIGVTALRM	20
+#undef	SIGPROF
+#define	SIGPROF		21
+#undef	SIGPOLL
+#define	SIGPOLL		22
+#undef	SIGWINCH
+#define	SIGWINCH	23
+#undef	SIGSTOP
+#define	SIGSTOP		24
+#undef	SIGTSTP
+#define	SIGTSTP		25
+#undef	SIGCONT
+#define	SIGCONT		26
+#undef	SIGTTIN
+#define	SIGTTIN		27
+#undef	SIGTTOU
+#define	SIGTTOU		28
+#undef	SIGURG
+#define	SIGURG		29
+#undef	SIGXFSZ
+#define	SIGXFSZ		30
+#undef	SIGSYS
+#define SIGSYS		31
 
-/* These are the hard limits of the kernel.  These values should not be
-   used directly at user level.  */
-/* In the Linux kernel version 3.17, and glibc 2.21, the signal numbers
-   were rearranged in order to make hppa like every other arch. Previously
-   we started __SIGRTMIN at 37, and that meant several pieces of important
-   software, including systemd, would fail to build. To support systemd we
-   removed SIGEMT and SIGLOST, and rearranged the others according to
-   expected values. This is technically an ABI incompatible change, but
-   because zero applications use SIGSTKFLT, SIGXCPU, SIGXFSZ and SIGSYS
-   nothing broke.  Nothing uses SIGEMT and SIGLOST, and they were present
-   for HPUX compatibility which is no longer supported.  Thus because
-   nothing breaks we don't do any compatibility work here.  */
-#define __SIGRTMIN	32	/* Kernel > 3.17.  */
-#define __SIGRTMAX	(_NSIG - 1)
+#undef	__SIGRTMAX
+#define __SIGRTMAX	64
 
 #endif	/* <signal.h> included.  */
diff --git a/sysdeps/unix/sysv/linux/mips/bits/signum.h b/sysdeps/unix/sysv/linux/mips/bits/signum.h
index 6c31e01cd7..1672847212 100644
--- a/sysdeps/unix/sysv/linux/mips/bits/signum.h
+++ b/sysdeps/unix/sysv/linux/mips/bits/signum.h
@@ -1,4 +1,4 @@
-/* Signal number definitions.  Linux version.
+/* Signal number definitions.  Linux/MIPS version.
    Copyright (C) 1995-2017 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
@@ -16,63 +16,53 @@
    License along with the GNU C Library.  If not, see
    <http://www.gnu.org/licenses/>.  */
 
-#ifdef	_SIGNAL_H
+#ifndef _BITS_SIGNUM_H
+#define _BITS_SIGNUM_H 1
 
-/* Fake signal functions.  */
-#define SIG_ERR ((__sighandler_t) -1)		/* Error return.  */
-#define SIG_DFL ((__sighandler_t) 0)		/* Default action.  */
-#define SIG_IGN ((__sighandler_t) 1)		/* Ignore signal.  */
-
-#ifdef __USE_XOPEN
-# define SIG_HOLD	((__sighandler_t) 2)	/* Add signal to hold mask.  */
+#ifndef _SIGNAL_H
+#error "Never include <bits/signum.h> directly; use <signal.h> instead."
 #endif
 
+#include <bits/signum-generic.h>
 
-#define SIGHUP		 1	/* Hangup (POSIX).  */
-#define SIGINT		 2	/* Interrupt (ANSI).  */
-#define SIGQUIT		 3	/* Quit (POSIX).  */
-#define SIGILL		 4	/* Illegal instruction (ANSI).  */
-#define SIGTRAP		 5	/* Trace trap (POSIX).  */
-#define SIGIOT		 6	/* IOT trap (4.2 BSD).  */
-#define SIGABRT		 SIGIOT	/* Abort (ANSI).  */
-#define SIGEMT		 7
-#define SIGFPE		 8	/* Floating-point exception (ANSI).  */
-#define SIGKILL		 9	/* Kill, unblockable (POSIX).  */
-#define SIGBUS		10	/* BUS error (4.2 BSD).  */
-#define SIGSEGV		11	/* Segmentation violation (ANSI).  */
-#define SIGSYS		12
-#define SIGPIPE		13	/* Broken pipe (POSIX).  */
-#define SIGALRM		14	/* Alarm clock (POSIX).  */
-#define SIGTERM		15	/* Termination (ANSI).  */
-#define SIGUSR1		16	/* User-defined signal 1 (POSIX).  */
-#define SIGUSR2		17	/* User-defined signal 2 (POSIX).  */
-#define SIGCHLD		18	/* Child status has changed (POSIX).  */
-#define SIGCLD		SIGCHLD	/* Same as SIGCHLD (System V).  */
-#define SIGPWR		19	/* Power failure restart (System V).  */
-#define SIGWINCH	20	/* Window size change (4.3 BSD, Sun).  */
-#define SIGURG		21	/* Urgent condition on socket (4.2 BSD).  */
-#define SIGIO		22	/* I/O now possible (4.2 BSD).  */
-#define SIGPOLL		SIGIO	/* Pollable event occurred (System V).  */
-#define SIGSTOP		23	/* Stop, unblockable (POSIX).  */
-#define SIGTSTP		24	/* Keyboard stop (POSIX).  */
-#define SIGCONT		25	/* Continue (POSIX).  */
-#define SIGTTIN		26	/* Background read from tty (POSIX).  */
-#define SIGTTOU		27	/* Background write to tty (POSIX).  */
-#define SIGVTALRM	28	/* Virtual alarm clock (4.2 BSD).  */
-#define SIGPROF		29	/* Profiling alarm clock (4.2 BSD).  */
-#define SIGXCPU		30	/* CPU limit exceeded (4.2 BSD).  */
-#define SIGXFSZ		31	/* File size limit exceeded (4.2 BSD).  */
-
+/* Adjustments and additions to the signal number constants for
+   Linux/MIPS.  */
 
-#define _NSIG		128	/* Biggest signal number + 1
-				   (including real-time signals).  */
+#define SIGEMT		 7	/* Emulator trap.  */
+#define SIGPWR		19	/* Power failure imminent.  */
 
-#define SIGRTMIN	(__libc_current_sigrtmin ())
-#define SIGRTMAX	(__libc_current_sigrtmax ())
+#undef	SIGUSR1
+#define SIGUSR1		16
+#undef	SIGUSR2
+#define SIGUSR2		17
+#undef	SIGCHLD
+#define SIGCHLD		18
+#undef	SIGWINCH
+#define SIGWINCH	20
+#undef	SIGURG
+#define SIGURG		21
+#undef	SIGPOLL
+#define SIGPOLL		22
+#undef	SIGSTOP
+#define SIGSTOP		23
+#undef	SIGTSTP
+#define SIGTSTP		24
+#undef	SIGCONT
+#define SIGCONT		25
+#undef	SIGTTIN
+#define SIGTTIN		26
+#undef	SIGTTOU
+#define SIGTTOU		27
+#undef	SIGVTALRM
+#define SIGVTALRM	28
+#undef	SIGPROF
+#define SIGPROF		29
+#undef	SIGXCPU
+#define SIGXCPU		30
+#undef	SIGXFSZ
+#define SIGXFSZ		31
 
-/* These are the hard limits of the kernel.  These values should not be
-   used directly at user level.  */
-#define __SIGRTMIN	32
-#define __SIGRTMAX	(_NSIG - 1)
+#undef	__SIGRTMAX
+#define __SIGRTMAX	127
 
 #endif	/* <signal.h> included.  */
diff --git a/sysdeps/unix/sysv/linux/sparc/bits/signum.h b/sysdeps/unix/sysv/linux/sparc/bits/signum.h
index a0c5be5fa5..25341ee42b 100644
--- a/sysdeps/unix/sysv/linux/sparc/bits/signum.h
+++ b/sysdeps/unix/sysv/linux/sparc/bits/signum.h
@@ -16,68 +16,24 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#ifdef	_SIGNAL_H
+#ifndef _BITS_SIGNUM_H
+#define _BITS_SIGNUM_H 1
 
-/* Fake signal functions.  */
-#define SIG_ERR ((__sighandler_t) -1) /* Error return.  */
-#define SIG_DFL ((__sighandler_t) 0) /* Default action.  */
-#define SIG_IGN ((__sighandler_t) 1) /* Ignore signal.  */
-
-#ifdef __USE_XOPEN
-# define SIG_HOLD	((__sighandler_t) 2)	/* Add signal to hold mask.  */
+#ifndef _SIGNAL_H
+#error "Never include <bits/signum.h> directly; use <signal.h> instead."
 #endif
 
-/*
- * Linux/SPARC has different signal numbers that Linux/i386: I'm trying
- * to make it OSF/1 binary compatible, at least for normal binaries.
- */
-#define SIGHUP		 1
-#define SIGINT		 2
-#define SIGQUIT		 3
-#define SIGILL		 4
-#define SIGTRAP		 5
-#define SIGABRT		 6
-#define SIGIOT		 6
-#define SIGEMT           7
-#define SIGFPE		 8
-#define SIGKILL		 9
-#define SIGBUS          10
-#define SIGSEGV		11
-#define SIGSYS		12
-#define SIGPIPE		13
-#define SIGALRM		14
-#define SIGTERM		15
-#define SIGURG          16
-
-/* SunOS values which deviate from the Linux/i386 ones */
-#define SIGSTOP		17
-#define SIGTSTP		18
-#define SIGCONT		19
-#define SIGCHLD		20
-#define SIGCLD		SIGCHLD	/* Same as SIGCHLD (System V).  */
-#define SIGTTIN		21
-#define SIGTTOU		22
-#define SIGIO		23
-#define SIGPOLL		SIGIO   /* SysV name for SIGIO */
-#define SIGXCPU		24
-#define SIGXFSZ		25
-#define SIGVTALRM	26
-#define SIGPROF		27
-#define SIGWINCH	28
-#define SIGLOST		29
-#define SIGPWR          SIGLOST
-#define SIGUSR1		30
-#define SIGUSR2		31
+#include <bits/signum-generic.h>
 
-#define	_NSIG		65	/* Biggest signal number + 1
-				   (including real-time signals).  */
+/* Adjustments and additions to the signal number constants for
+   Linux/SPARC systems.  Signal values on this platform were chosen
+   for SunOS binary compatibility.  */
 
-#define SIGRTMIN        (__libc_current_sigrtmin ())
-#define SIGRTMAX        (__libc_current_sigrtmax ())
+#define SIGEMT		 7	/* Emulator trap.  */
+#define SIGLOST		29	/* Resource lost (Sun); server died (GNU).  */
+#define SIGPWR		SIGLOST	/* Power failure imminent (SysV).  */
 
-/* These are the hard limits of the kernel.  These values should not be
-   used directly at user level.  */
-#define __SIGRTMIN	32
-#define __SIGRTMAX	(_NSIG - 1)
+#undef	__SIGRTMAX
+#define __SIGRTMAX	64
 
 #endif	/* <signal.h> included.  */
diff --git a/sysdeps/unix/sysv/linux/tst-signal-numbers.sh b/sysdeps/unix/sysv/linux/tst-signal-numbers.sh
new file mode 100644
index 0000000000..bdd75fbc25
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-signal-numbers.sh
@@ -0,0 +1,86 @@
+#! /bin/sh
+# Test that glibc's signal numbers match the kernel's.
+# Copyright (C) 2017 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/>.
+
+set -e
+if [ -n "$BASH_VERSION" ]; then set -o pipefail; fi
+LC_ALL=C; export LC_ALL
+
+# We cannot use Linux's asm/signal.h to define signal numbers, because
+# it isn't sufficiently namespace-clean.  Instead, this test checks
+# that our signal numbers match the kernel's.  This script expects
+# "$@" to be $(CC) $(CPPFLAGS) as set by glibc's Makefiles, and $AWK
+# to be set in the environment.
+
+# Before doing anything else, fail if the compiler doesn't work.
+"$@" -E -xc -dM - < /dev/null > /dev/null
+
+tmpG=`mktemp -t signums_glibc.XXXXXXXXX`
+tmpK=`mktemp -t signums_kernel.XXXXXXXXX`
+trap "rm -f '$tmpG' '$tmpK'" 0
+
+# Filter out constants that aren't signal numbers.
+# If SIGPOLL is defined as SIGIO, swap it around so SIGIO is defined as
+# SIGPOLL. Similarly for SIGABRT and SIGIOT.
+# Discard obsolete signal numbers and unrelated constants:
+#    SIGCLD, SIGIOT, SIGSWI, SIGUNUSED.
+#    SIGSTKSZ, SIGRTMIN, SIGRTMAX.
+# Then sort the list.
+filter_defines ()
+{
+    $AWK '
+/^#define SIG[A-Z]+ ([0-9]+|SIG[A-Z0-9]+)$/ { signals[$2] = $3 }
+END {
+  if ("SIGPOLL" in signals && "SIGIO" in signals &&
+      signals["SIGPOLL"] == "SIGIO") {
+    signals["SIGPOLL"] = signals["SIGIO"]
+    signals["SIGIO"] = "SIGPOLL"
+  }
+  if ("SIGABRT" in signals && "SIGIOT" in signals &&
+      signals["SIGABRT"] == "SIGIOT") {
+    signals["SIGABRT"] = signals["SIGIOT"]
+    signals["SIGIOT"] = "SIGABRT"
+  }
+  for (sig in signals) {
+    if (sig !~ /^SIG(CLD|IOT|RT(MIN|MAX)|STKSZ|SWI|UNUSED)$/) {
+      printf("#define %s %s\n", sig, signals[sig])
+    }
+  }
+}' | sort
+}
+
+# $CC may contain command-line switches, so it should be word-split.
+printf '%s' '#define _GNU_SOURCE 1
+#include <signal.h>
+' |
+    "$@" -E -xc -dM - |
+    filter_defines > "$tmpG"
+
+printf '%s' '#define _GNU_SOURCE 1
+#define __ASSEMBLER__ 1
+#include <asm/signal.h>
+' |
+    "$@" -E -xc -dM - |
+    filter_defines > "$tmpK"
+
+if cmp -s "$tmpG" "$tmpK"; then
+    exit 0
+else
+    diff -u "$tmpG" "$tmpK"
+    exit 1
+fi