libgo: handle linking to NetBSD's versioned symbols

On NetBSD, for backwards compatibility, various libc symbols are
renamed to a symbol with a version suffix. For example, this is the
(abbreviated) definition of sigaction:

    int sigaction(...) __asm__ ("__sigaction14")

This poses a challenge for libgo, which attempts to link sigaction by
way of an "//extern" comment:

    //extern sigaction
    func sigaction(...)

This results in a reference to the deprecated compatibility symbol
"sigaction", rather than the desired "__sigaction14" symbol.

This patch introduces a new "//extern-sysinfo" comment to handle this
situation. The new mklinknames.awk script scans a package for these
comments and outputs a "//go:linkname" directive that links the wrapper
to the correct versioned symbol, as determined by parsing the __asm__
annotation on the function's declaration in gen-sysinfo.go.

For now, only the following packages are scanned by mklinknames.awk:

    os
    os/user
    runtime
    syscall

gotools/:
	* Makefile.am (check-runtime): Add runtime_linknames.go to
	--extrafiles.
	* Makefile.in: Regenerate.

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/265125

5 files changed, 20 insertions, 20 deletions

diff --git a/libgo/go/runtime/netpoll_kqueue.go b/libgo/go/runtime/netpoll_kqueue.go
index c41a7d0..1724f37 100644
--- a/libgo/go/runtime/netpoll_kqueue.go
+++ b/libgo/go/runtime/netpoll_kqueue.go
@@ -13,11 +13,11 @@ import (
 	"unsafe"
 )
 
-//extern kqueue
+//extern-sysinfo kqueue
 func kqueue() int32
 
 //go:noescape
-//extern kevent
+//extern-sysinfo kevent
 func kevent(kq int32, ch *keventt, nch uintptr, ev *keventt, nev uintptr, ts *timespec) int32
 
 var (
diff --git a/libgo/go/runtime/os_gccgo.go b/libgo/go/runtime/os_gccgo.go
index a8859c0..79331c5 100644
--- a/libgo/go/runtime/os_gccgo.go
+++ b/libgo/go/runtime/os_gccgo.go
@@ -52,7 +52,7 @@ func getRandomData(r []byte) {
 }
 
 //go:noescape
-//extern pipe
+//extern-sysinfo pipe
 func libcPipe(*[2]int32) int32
 
 func pipe() (r, w int32, e int32) {
@@ -65,7 +65,7 @@ func pipe() (r, w int32, e int32) {
 }
 
 //go:noescape
-//extern pipe2
+//extern-sysinfo pipe2
 func libcPipe2(*[2]int32, int32) int32
 
 func pipe2(flags int32) (r, w int32, e int32) {
diff --git a/libgo/go/runtime/os_netbsd.go b/libgo/go/runtime/os_netbsd.go
index 9ebb652..00c3285 100644
--- a/libgo/go/runtime/os_netbsd.go
+++ b/libgo/go/runtime/os_netbsd.go
@@ -18,19 +18,19 @@ func getProcID() uint64 {
 	return uint64(lwp_self())
 }
 
-//extern _lwp_self
+//extern-sysinfo _lwp_self
 func lwp_self() int32
 
 //go:noescape
-//extern _lwp_park
+//extern-sysinfo _lwp_park
 func lwp_park(ts int32, rel int32, abstime *timespec, unpark int32, hint, unparkhint unsafe.Pointer) int32
 
 //go:noescape
-//extern _lwp_unpark
+//extern-sysinfo _lwp_unpark
 func lwp_unpark(lwp int32, hint unsafe.Pointer) int32
 
 //go:noescape
-//extern sysctl
+//extern-sysinfo sysctl
 func sysctl(*uint32, uint32, *byte, *uintptr, *byte, uintptr) int32
 
 func getncpu() int32 {
diff --git a/libgo/go/runtime/signal_gccgo.go b/libgo/go/runtime/signal_gccgo.go
index c555712..2eece68 100644
--- a/libgo/go/runtime/signal_gccgo.go
+++ b/libgo/go/runtime/signal_gccgo.go
@@ -14,44 +14,44 @@ import (
 // these are written in OS-specific files and in assembler.
 
 //go:noescape
-//extern sigaction
+//extern-sysinfo sigaction
 func sigaction(signum uint32, act *_sigaction, oact *_sigaction) int32
 
 //go:noescape
-//extern sigprocmask
+//extern-sysinfo sigprocmask
 func sigprocmask(how int32, set *sigset, oldset *sigset) int32
 
 //go:noescape
-//extern sigfillset
+//extern-sysinfo sigfillset
 func sigfillset(set *sigset) int32
 
 //go:noescape
-//extern sigemptyset
+//extern-sysinfo sigemptyset
 func sigemptyset(set *sigset) int32
 
 //go:noescape
-//extern sigaddset
+//extern-sysinfo sigaddset
 func c_sigaddset(set *sigset, signum uint32) int32
 
 //go:noescape
-//extern sigdelset
+//extern-sysinfo sigdelset
 func c_sigdelset(set *sigset, signum uint32) int32
 
 //go:noescape
-//extern sigaltstack
+//extern-sysinfo sigaltstack
 func sigaltstack(ss *_stack_t, oss *_stack_t) int32
 
-//extern raise
+//extern-sysinfo raise
 func raise(sig uint32) int32
 
-//extern getpid
+//extern-sysinfo getpid
 func getpid() _pid_t
 
-//extern kill
+//extern-sysinfo kill
 func kill(pid _pid_t, sig uint32) int32
 
 //go:noescape
-//extern setitimer
+//extern-sysinfo setitimer
 func setitimer(which int32, new *_itimerval, old *_itimerval) int32
 
 type sigctxt struct {
diff --git a/libgo/go/runtime/stubs2.go b/libgo/go/runtime/stubs2.go
index 454afee..0aaed29 100644
--- a/libgo/go/runtime/stubs2.go
+++ b/libgo/go/runtime/stubs2.go
@@ -17,7 +17,7 @@ func read(fd int32, p unsafe.Pointer, n int32) int32
 
 func closefd(fd int32) int32
 
-//extern exit
+//extern-sysinfo exit
 func exit(code int32)
 func usleep(usec uint32)