# DP: Backport r241072 from trunk

syscall, internal/syscall/unix: Fix getrandom, clone on sparc64

Since sparc is a valid architecture, the name of
getrandom_linux_sparc.go means that it will be ignored on sparc64,
even though it's whitelisted with a +build line.

On SPARC, clone has a unique return value convention which requires
some inline assembly to convert it to the normal convention.

Reviewed-on: https://go-review.googlesource.com/30873

Index: b/src/libgo/mksysinfo.sh
===================================================================
--- a/src/libgo/mksysinfo.sh
+++ b/src/libgo/mksysinfo.sh
@@ -603,8 +603,10 @@ fi
 sizeof_long=`grep '^const ___SIZEOF_LONG__ = ' gen-sysinfo.go | sed -e 's/.*= //'`
 if test "$sizeof_long" = "4"; then
   echo "type _C_long int32" >> ${OUT}
+  echo "type _C_ulong uint32" >> ${OUT}
 elif test "$sizeof_long" = "8"; then
   echo "type _C_long int64" >> ${OUT}
+  echo "type _C_ulong uint64" >> ${OUT}
 else
   echo 1>&2 "mksysinfo.sh: could not determine size of long (got $sizeof_long)"
   exit 1
Index: b/src/libgo/go/internal/syscall/unix/getrandom_linux_sparc.go
===================================================================
--- a/src/libgo/go/internal/syscall/unix/getrandom_linux_sparc.go
+++ b/src/libgo/go/internal/syscall/unix/getrandom_linux_sparc.go
@@ -1,11 +0,0 @@
-// Copyright 2016 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build sparc sparc64
-
-package unix
-
-// Linux getrandom system call number.
-// See GetRandom in getrandom_linux.go.
-const randomTrap uintptr = 347
Index: b/src/libgo/go/internal/syscall/unix/getrandom_linux_sparcx.go
===================================================================
--- /dev/null
+++ b/src/libgo/go/internal/syscall/unix/getrandom_linux_sparcx.go
@@ -0,0 +1,11 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build sparc sparc64
+
+package unix
+
+// Linux getrandom system call number.
+// See GetRandom in getrandom_linux.go.
+const randomTrap uintptr = 347
Index: b/src/libgo/go/syscall/clone_linux.c
===================================================================
--- /dev/null
+++ b/src/libgo/go/syscall/clone_linux.c
@@ -0,0 +1,100 @@
+/* clone_linux.c -- consistent wrapper around Linux clone syscall
+
+   Copyright 2016 The Go Authors. All rights reserved.
+   Use of this source code is governed by a BSD-style
+   license that can be found in the LICENSE file.  */
+
+#include <errno.h>
+#include <asm/ptrace.h>
+#include <sys/syscall.h>
+
+#include "runtime.h"
+
+long rawClone (unsigned long flags, void *child_stack, void *ptid, void *ctid, struct pt_regs *regs) __asm__ (GOSYM_PREFIX "syscall.rawClone");
+
+long
+rawClone (unsigned long flags, void *child_stack, void *ptid, void *ctid, struct pt_regs *regs)
+{
+#if defined(__arc__) || defined(__aarch64__) || defined(__arm__) || defined(__mips__) || defined(__hppa__) || defined(__powerpc__) || defined(__score__) || defined(__i386__) || defined(__xtensa__)
+  // CLONE_BACKWARDS
+  return syscall(__NR_clone, flags, child_stack, ptid, regs, ctid);
+#elif defined(__s390__) || defined(__cris__)
+  // CLONE_BACKWARDS2
+  return syscall(__NR_clone, child_stack, flags, ptid, ctid, regs);
+#elif defined(__microblaze__)
+  // CLONE_BACKWARDS3
+  return syscall(__NR_clone, flags, child_stack, 0, ptid, ctid, regs);
+#elif defined(__sparc__)
+
+  /* SPARC has a unique return value convention:
+
+     Parent -->  %o0 == child's  pid, %o1 == 0
+     Child  -->  %o0 == parent's pid, %o1 == 1
+
+     Translate this to look like a normal clone.  */
+
+# if defined(__arch64__)
+
+#  define SYSCALL_STRING						\
+	"ta	0x6d;"							\
+	"bcc,pt	%%xcc, 1f;"						\
+	" mov	0, %%g1;"						\
+	"sub	%%g0, %%o0, %%o0;"					\
+	"mov	1, %%g1;"						\
+	"1:"
+
+#  define SYSCALL_CLOBBERS						\
+	"f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7",			\
+	"f8", "f9", "f10", "f11", "f12", "f13", "f14", "f15",		\
+	"f16", "f17", "f18", "f19", "f20", "f21", "f22", "f23",		\
+	"f24", "f25", "f26", "f27", "f28", "f29", "f30", "f31",		\
+	"f32", "f34", "f36", "f38", "f40", "f42", "f44", "f46",		\
+	"f48", "f50", "f52", "f54", "f56", "f58", "f60", "f62",		\
+	"cc", "memory"
+
+# else /* __arch64__ */
+
+#  define SYSCALL_STRING						\
+	"ta	0x10;"							\
+	"bcc	1f;"							\
+	" mov	0, %%g1;"						\
+	"sub	%%g0, %%o0, %%o0;"					\
+	"mov	1, %%g1;"						\
+	"1:"
+
+#  define SYSCALL_CLOBBERS						\
+	"f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7",			\
+	"f8", "f9", "f10", "f11", "f12", "f13", "f14", "f15",		\
+	"f16", "f17", "f18", "f19", "f20", "f21", "f22", "f23",		\
+	"f24", "f25", "f26", "f27", "f28", "f29", "f30", "f31",		\
+	"cc", "memory"
+
+# endif /* __arch64__ */
+
+  register long o0 __asm__ ("o0") = (long)flags;
+  register long o1 __asm__ ("o1") = (long)child_stack;
+  register long o2 __asm__ ("o2") = (long)ptid;
+  register long o3 __asm__ ("o3") = (long)ctid;
+  register long o4 __asm__ ("o4") = (long)regs;
+  register long g1 __asm__ ("g1") = __NR_clone;
+
+  __asm __volatile (SYSCALL_STRING :
+		    "=r" (g1), "=r" (o0), "=r" (o1) :
+		    "0" (g1), "1" (o0), "2" (o1),
+		    "r" (o2), "r" (o3), "r" (o4) :
+		    SYSCALL_CLOBBERS);
+
+  if (__builtin_expect(g1 != 0, 0))
+    {
+      errno = -o0;
+      o0 = -1L;
+    }
+  else
+    o0 &= (o1 - 1);
+
+  return o0;
+
+#else
+  return syscall(__NR_clone, flags, child_stack, ptid, ctid, regs);
+#endif
+}
Index: b/src/libgo/go/syscall/exec_linux.go
===================================================================
--- a/src/libgo/go/syscall/exec_linux.go
+++ b/src/libgo/go/syscall/exec_linux.go
@@ -7,7 +7,6 @@
 package syscall
 
 import (
-	"runtime"
 	"unsafe"
 )
 
@@ -48,6 +47,9 @@ type SysProcAttr struct {
 func runtime_BeforeFork()
 func runtime_AfterFork()
 
+// Implemented in clone_linux.c
+func rawClone(flags _C_ulong, child_stack *byte, ptid *Pid_t, ctid *Pid_t, regs unsafe.Pointer) _C_long
+
 // Fork, dup fd onto 0..len(fd), and exec(argv0, argvv, envv) in child.
 // If a dup or exec fails, write the errno error to pipe.
 // (Pipe is close-on-exec so if exec succeeds, it will be closed.)
@@ -63,6 +65,7 @@ func forkAndExecInChild(argv0 *byte, arg
 	// declarations require heap allocation (e.g., err1).
 	var (
 		r1     uintptr
+		r2     _C_long
 		err1   Errno
 		err2   Errno
 		nextfd int
@@ -97,20 +100,16 @@ func forkAndExecInChild(argv0 *byte, arg
 	// About to call fork.
 	// No more allocation or calls of non-assembly functions.
 	runtime_BeforeFork()
-	if runtime.GOARCH == "s390x" || runtime.GOARCH == "s390" {
-		r1, _, err1 = RawSyscall6(SYS_CLONE, 0, uintptr(SIGCHLD)|sys.Cloneflags, 0, 0, 0, 0)
-	} else {
-		r1, _, err1 = RawSyscall6(SYS_CLONE, uintptr(SIGCHLD)|sys.Cloneflags, 0, 0, 0, 0, 0)
-	}
-	if err1 != 0 {
+	r2 = rawClone(_C_ulong(uintptr(SIGCHLD)|sys.Cloneflags), nil, nil, nil, unsafe.Pointer(nil))
+	if r2 < 0 {
 		runtime_AfterFork()
-		return 0, err1
+		return 0, GetErrno()
 	}
 
-	if r1 != 0 {
+	if r2 != 0 {
 		// parent; return PID
 		runtime_AfterFork()
-		pid = int(r1)
+		pid = int(r2)
 
 		if sys.UidMappings != nil || sys.GidMappings != nil {
 			Close(p[0])
Index: b/src/libgo/Makefile.am
===================================================================
--- a/src/libgo/Makefile.am
+++ b/src/libgo/Makefile.am
@@ -2145,6 +2145,12 @@ else
 os_lib_inotify_lo =
 endif
 
+if LIBGO_IS_LINUX
+syscall_lib_clone_lo = syscall/clone_linux.lo
+else
+syscall_lib_clone_lo =
+endif
+
 libgo_go_objs = \
 	bufio.lo \
 	bytes.lo \
@@ -2175,6 +2181,7 @@ libgo_go_objs = \
 	strings/index.lo \
 	sync.lo \
 	syscall.lo \
+	$(syscall_lib_clone_lo) \
 	syscall/errno.lo \
 	syscall/signame.lo \
 	syscall/wait.lo \
@@ -3820,6 +3827,9 @@ syscall.lo.dep: $(go_syscall_files)
 	$(BUILDDEPS)
 syscall.lo: $(go_syscall_files)
 	$(BUILDPACKAGE)
+syscall/clone_linux.lo: go/syscall/clone_linux.c
+	@$(MKDIR_P) syscall
+	$(LTCOMPILE) -c -o $@ $<
 syscall/errno.lo: go/syscall/errno.c
 	@$(MKDIR_P) syscall
 	$(LTCOMPILE) -c -o $@ $<
Index: b/src/libgo/Makefile.in
===================================================================
--- a/src/libgo/Makefile.in
+++ b/src/libgo/Makefile.in
@@ -173,15 +173,16 @@ am__objects_3 = $(am__objects_2)
 am_libnetgo_a_OBJECTS = $(am__objects_3)
 libnetgo_a_OBJECTS = $(am_libnetgo_a_OBJECTS)
 LTLIBRARIES = $(toolexeclib_LTLIBRARIES)
-am__DEPENDENCIES_1 =
-am__DEPENDENCIES_2 = bufio.lo bytes.lo bytes/index.lo crypto.lo \
+@LIBGO_IS_LINUX_TRUE@am__DEPENDENCIES_1 = syscall/clone_linux.lo
+am__DEPENDENCIES_2 =
+am__DEPENDENCIES_3 = bufio.lo bytes.lo bytes/index.lo crypto.lo \
 	encoding.lo errors.lo expvar.lo flag.lo fmt.lo hash.lo html.lo \
 	image.lo io.lo log.lo math.lo mime.lo net.lo os.lo path.lo \
 	reflect-go.lo reflect/makefunc_ffi_c.lo regexp.lo \
 	runtime-go.lo sort.lo strconv.lo strings.lo strings/index.lo \
-	sync.lo syscall.lo syscall/errno.lo syscall/signame.lo \
-	syscall/wait.lo testing.lo time-go.lo unicode.lo \
-	archive/tar.lo archive/zip.lo compress/bzip2.lo \
+	sync.lo syscall.lo $(am__DEPENDENCIES_1) syscall/errno.lo \
+	syscall/signame.lo syscall/wait.lo testing.lo time-go.lo \
+	unicode.lo archive/tar.lo archive/zip.lo compress/bzip2.lo \
 	compress/flate.lo compress/gzip.lo compress/lzw.lo \
 	compress/zlib.lo container/heap.lo container/list.lo \
 	container/ring.lo crypto/aes.lo crypto/cipher.lo crypto/des.lo \
@@ -213,18 +214,18 @@ am__DEPENDENCIES_2 = bufio.lo bytes.lo b
 	math/rand.lo mime/multipart.lo mime/quotedprintable.lo \
 	net/http.lo net/internal/socktest.lo net/mail.lo net/rpc.lo \
 	net/smtp.lo net/textproto.lo net/url.lo old/regexp.lo \
-	old/template.lo os/exec.lo $(am__DEPENDENCIES_1) os/signal.lo \
+	old/template.lo os/exec.lo $(am__DEPENDENCIES_2) os/signal.lo \
 	os/user.lo path/filepath.lo regexp/syntax.lo \
 	net/rpc/jsonrpc.lo runtime/debug.lo runtime/pprof.lo \
 	sync/atomic.lo sync/atomic_c.lo text/scanner.lo \
 	text/tabwriter.lo text/template.lo text/template/parse.lo \
 	testing/iotest.lo testing/quick.lo unicode/utf16.lo \
 	unicode/utf8.lo
-am__DEPENDENCIES_3 = $(am__DEPENDENCIES_2) \
-	../libbacktrace/libbacktrace.la $(am__DEPENDENCIES_1) \
-	$(am__DEPENDENCIES_1) $(am__DEPENDENCIES_1) \
-	$(am__DEPENDENCIES_1) $(am__DEPENDENCIES_1)
-libgo_llgo_la_DEPENDENCIES = $(am__DEPENDENCIES_3)
+am__DEPENDENCIES_4 = $(am__DEPENDENCIES_3) \
+	../libbacktrace/libbacktrace.la $(am__DEPENDENCIES_2) \
+	$(am__DEPENDENCIES_2) $(am__DEPENDENCIES_2) \
+	$(am__DEPENDENCIES_2) $(am__DEPENDENCIES_2)
+libgo_llgo_la_DEPENDENCIES = $(am__DEPENDENCIES_4)
 @LIBGO_IS_LINUX_FALSE@am__objects_4 = lock_sema.lo thread-sema.lo
 @LIBGO_IS_LINUX_TRUE@am__objects_4 = lock_futex.lo thread-linux.lo
 @HAVE_SYS_MMAN_H_FALSE@am__objects_5 = mem_posix_memalign.lo
@@ -276,7 +277,7 @@ libgo_llgo_la_LINK = $(LIBTOOL) --tag=CC
 	$(LIBTOOLFLAGS) --mode=link $(CCLD) $(AM_CFLAGS) $(CFLAGS) \
 	$(libgo_llgo_la_LDFLAGS) $(LDFLAGS) -o $@
 @GOC_IS_LLGO_TRUE@am_libgo_llgo_la_rpath = -rpath $(toolexeclibdir)
-libgo_la_DEPENDENCIES = $(am__DEPENDENCIES_3)
+libgo_la_DEPENDENCIES = $(am__DEPENDENCIES_4)
 am_libgo_la_OBJECTS = $(am__objects_9)
 libgo_la_OBJECTS = $(am_libgo_la_OBJECTS)
 libgo_la_LINK = $(LIBTOOL) --tag=CC $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) \
@@ -2156,6 +2157,8 @@ go_syscall_test_files = \
 
 # os_lib_inotify_lo = os/inotify.lo
 @LIBGO_IS_LINUX_TRUE@os_lib_inotify_lo = 
+@LIBGO_IS_LINUX_FALSE@syscall_lib_clone_lo = 
+@LIBGO_IS_LINUX_TRUE@syscall_lib_clone_lo = syscall/clone_linux.lo
 libgo_go_objs = \
 	bufio.lo \
 	bytes.lo \
@@ -2186,6 +2189,7 @@ libgo_go_objs = \
 	strings/index.lo \
 	sync.lo \
 	syscall.lo \
+	$(syscall_lib_clone_lo) \
 	syscall/errno.lo \
 	syscall/signame.lo \
 	syscall/wait.lo \
@@ -6197,6 +6201,9 @@ syscall.lo.dep: $(go_syscall_files)
 	$(BUILDDEPS)
 syscall.lo: $(go_syscall_files)
 	$(BUILDPACKAGE)
+syscall/clone_linux.lo: go/syscall/clone_linux.c
+	@$(MKDIR_P) syscall
+	$(LTCOMPILE) -c -o $@ $<
 syscall/errno.lo: go/syscall/errno.c
 	@$(MKDIR_P) syscall
 	$(LTCOMPILE) -c -o $@ $<