runtime: call timer functions via syscall

It turns out to be painful to require linking against -lrt on
GNU/Linux, as that makes it harder to link Go code into C programs.
Instead just call the timer syscalls directly.  That is what the
upstream library does anyhow.

gcc/go/
	* gospec.cc: Revert 2022-02-09 change:
	(RTLIB, RT_LIBRARY): Don't define.
	(lang_specific_driver): Don't add -lrt if linking statically
	on GNU/Linux.

gotools/
	* configure.ac: Revert 2022-02-09 change:
	(RT_LIBS): Don't define.
	* Makefile.am (check-runtime): Don't set GOLIBS to $(RT_LIBS).
	* configure, Makefile.in: Regenerate.

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/385475

6 files changed, 18 insertions, 35 deletions

diff --git a/libgo/Makefile.am b/libgo/Makefile.am
index be889f2a984..9318f38714a 100644
--- a/libgo/Makefile.am
+++ b/libgo/Makefile.am
@@ -832,8 +832,7 @@ libgo_ldflags = \
 
 libgo_libadd = \
 	$(libgo_go_objs) ../libbacktrace/libbacktrace.la \
-	$(LIBATOMIC) $(LIBFFI) $(PTHREAD_LIBS) $(MATH_LIBS) \
-	$(NET_LIBS) $(RT_LIBS)
+	$(LIBATOMIC) $(LIBFFI) $(PTHREAD_LIBS) $(MATH_LIBS) $(NET_LIBS)
 
 libgo_la_SOURCES = $(runtime_files)
 libgo_la_LDFLAGS = $(libgo_ldflags)
@@ -924,7 +923,7 @@ GOBENCH =
 CHECK = \
 	GC="$(GOC) $(GOCFLAGS) $($(subst /,_,$@)_GOCFLAGS) -L `${PWD_COMMAND}` -L `${PWD_COMMAND}`/.libs"; \
 	export GC; \
-	GOLIBS="$(extra_check_libs_$(subst .,_,$(subst /,_,$(@D)))) $(PTHREAD_LIBS) $(MATH_LIBS) $(NET_LIBS) $(RT_LIBS) $(LIBS)"; \
+	GOLIBS="$(extra_check_libs_$(subst .,_,$(subst /,_,$(@D)))) $(PTHREAD_LIBS) $(MATH_LIBS) $(NET_LIBS) $(LIBS)"; \
 	export GOLIBS; \
 	RUNTESTFLAGS="$(RUNTESTFLAGS)"; \
 	export RUNTESTFLAGS; \
diff --git a/libgo/Makefile.in b/libgo/Makefile.in
index 216be43f14a..642688e9dae 100644
--- a/libgo/Makefile.in
+++ b/libgo/Makefile.in
@@ -233,8 +233,7 @@ am__DEPENDENCIES_4 =
 am__DEPENDENCIES_5 = $(am__DEPENDENCIES_3) \
 	../libbacktrace/libbacktrace.la $(am__DEPENDENCIES_4) \
 	$(am__DEPENDENCIES_4) $(am__DEPENDENCIES_4) \
-	$(am__DEPENDENCIES_4) $(am__DEPENDENCIES_4) \
-	$(am__DEPENDENCIES_4)
+	$(am__DEPENDENCIES_4) $(am__DEPENDENCIES_4)
 libgo_llgo_la_DEPENDENCIES = $(am__DEPENDENCIES_5)
 @LIBGO_IS_LINUX_TRUE@@LIBGO_IS_X86_TRUE@am__objects_1 =  \
 @LIBGO_IS_LINUX_TRUE@@LIBGO_IS_X86_TRUE@	runtime/go-context.lo
@@ -466,7 +465,6 @@ PATH_SEPARATOR = @PATH_SEPARATOR@
 PTHREAD_CFLAGS = @PTHREAD_CFLAGS@
 PTHREAD_LIBS = @PTHREAD_LIBS@
 RANLIB = @RANLIB@
-RT_LIBS = @RT_LIBS@
 SED = @SED@
 SET_MAKE = @SET_MAKE@
 SHELL = @SHELL@
@@ -972,8 +970,7 @@ libgo_ldflags = \
 
 libgo_libadd = \
 	$(libgo_go_objs) ../libbacktrace/libbacktrace.la \
-	$(LIBATOMIC) $(LIBFFI) $(PTHREAD_LIBS) $(MATH_LIBS) \
-	$(NET_LIBS) $(RT_LIBS)
+	$(LIBATOMIC) $(LIBFFI) $(PTHREAD_LIBS) $(MATH_LIBS) $(NET_LIBS)
 
 libgo_la_SOURCES = $(runtime_files)
 libgo_la_LDFLAGS = $(libgo_ldflags)
@@ -1047,7 +1044,7 @@ GOBENCH =
 CHECK = \
 	GC="$(GOC) $(GOCFLAGS) $($(subst /,_,$@)_GOCFLAGS) -L `${PWD_COMMAND}` -L `${PWD_COMMAND}`/.libs"; \
 	export GC; \
-	GOLIBS="$(extra_check_libs_$(subst .,_,$(subst /,_,$(@D)))) $(PTHREAD_LIBS) $(MATH_LIBS) $(NET_LIBS) $(RT_LIBS) $(LIBS)"; \
+	GOLIBS="$(extra_check_libs_$(subst .,_,$(subst /,_,$(@D)))) $(PTHREAD_LIBS) $(MATH_LIBS) $(NET_LIBS) $(LIBS)"; \
 	export GOLIBS; \
 	RUNTESTFLAGS="$(RUNTESTFLAGS)"; \
 	export RUNTESTFLAGS; \
diff --git a/libgo/configure b/libgo/configure
index e2403634281..ffe17c9be55 100755
--- a/libgo/configure
+++ b/libgo/configure
@@ -649,7 +649,6 @@ HAVE_SYS_MMAN_H_FALSE
 HAVE_SYS_MMAN_H_TRUE
 PTHREAD_LIBS
 PTHREAD_CFLAGS
-RT_LIBS
 NET_LIBS
 MATH_LIBS
 GOC_IS_LLGO_FALSE
@@ -11545,7 +11544,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11548 "configure"
+#line 11547 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11651,7 +11650,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11654 "configure"
+#line 11653 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -14748,12 +14747,6 @@ $as_echo "$libgo_cv_lib_sockets" >&6; }
 NET_LIBS="$libgo_cv_lib_sockets"
 
 
-RT_LIBS=
-case ${host} in
-  *-*-linux*) RT_LIBS=-lrt ;;
-esac
-
-
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether -pthread is supported" >&5
 $as_echo_n "checking whether -pthread is supported... " >&6; }
 if ${libgo_cv_lib_pthread+:} false; then :
diff --git a/libgo/configure.ac b/libgo/configure.ac
index 1b44b226f62..7e2b98ba67c 100644
--- a/libgo/configure.ac
+++ b/libgo/configure.ac
@@ -549,12 +549,6 @@ AC_CACHE_CHECK([for socket libraries], libgo_cv_lib_sockets,
 NET_LIBS="$libgo_cv_lib_sockets"
 AC_SUBST(NET_LIBS)
 
-RT_LIBS=
-case ${host} in
-  *-*-linux*) RT_LIBS=-lrt ;;
-esac
-AC_SUBST(RT_LIBS)
-
 dnl Test whether the compiler supports the -pthread option.
 AC_CACHE_CHECK([whether -pthread is supported],
 [libgo_cv_lib_pthread],
diff --git a/libgo/go/runtime/os_linux.go b/libgo/go/runtime/os_linux.go
index 6ffd8980c5f..96fb178870e 100644
--- a/libgo/go/runtime/os_linux.go
+++ b/libgo/go/runtime/os_linux.go
@@ -18,7 +18,7 @@ type mOS struct {
 	// creates and manages its own timer, and these fields are read and written
 	// only by this thread. But because some of the reads on profileTimerValid
 	// are in signal handling code, access to that field uses atomic operations.
-	profileTimer      uintptr
+	profileTimer      int32
 	profileTimerValid uint32
 }
 
@@ -243,16 +243,17 @@ func osinit() {
 	physHugePageSize = getHugePageSize()
 }
 
-//go:noescape
-//extern-sysinfo timer_create
-func timer_create(clockid int32, sevp *_sigevent, timerid *uintptr) int32
+func timer_create(clockid int32, sevp *_sigevent, timerid *int32) int32 {
+	return int32(syscall(_SYS_timer_create, uintptr(clockid), uintptr(unsafe.Pointer(sevp)), uintptr(unsafe.Pointer(timerid)), 0, 0, 0))
+}
 
-//go:noescape
-//extern-sysinfo timer_settime
-func timer_settime(timerid uintptr, flags int32, new, old *_itimerspec) int32
+func timer_settime(timerid int32, flags int32, new, old *_itimerspec) int32 {
+	return int32(syscall(_SYS_timer_settime, uintptr(timerid), uintptr(flags), uintptr(unsafe.Pointer(new)), uintptr(unsafe.Pointer(old)), 0, 0))
+}
 
-//extern-sysinfo timer_delete
-func timer_delete(timerid uintptr) int32
+func timer_delete(timerid int32) int32 {
+	return int32(syscall(_SYS_timer_delete, uintptr(timerid), 0, 0, 0, 0, 0))
+}
 
 // go118UseTimerCreateProfiler enables the per-thread CPU profiler.
 const go118UseTimerCreateProfiler = true
@@ -360,7 +361,7 @@ func setThreadCPUProfiler(hz int32) {
 	spec.it_value.setNsec(1 + int64(fastrandn(uint32(1e9/hz))))
 	spec.it_interval.setNsec(1e9 / int64(hz))
 
-	var timerid uintptr
+	var timerid int32
 	var sevp _sigevent
 	sevp.sigev_notify = _SIGEV_THREAD_ID
 	sevp.sigev_signo = _SIGPROF
diff --git a/libgo/testsuite/Makefile.in b/libgo/testsuite/Makefile.in
index 6e143fa3bab..7869265851c 100644
--- a/libgo/testsuite/Makefile.in
+++ b/libgo/testsuite/Makefile.in
@@ -215,7 +215,6 @@ PATH_SEPARATOR = @PATH_SEPARATOR@
 PTHREAD_CFLAGS = @PTHREAD_CFLAGS@
 PTHREAD_LIBS = @PTHREAD_LIBS@
 RANLIB = @RANLIB@
-RT_LIBS = @RT_LIBS@
 SED = @SED@
 SET_MAKE = @SET_MAKE@
 SHELL = @SHELL@