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

From-SVN: r241051

3 files changed, 109 insertions, 10 deletions

diff --git a/libgo/go/internal/syscall/unix/getrandom_linux_sparc.go b/libgo/go/internal/syscall/unix/getrandom_linux_sparcx.go
index 4874ec1..4874ec1 100644
--- a/libgo/go/internal/syscall/unix/getrandom_linux_sparc.go
+++ b/libgo/go/internal/syscall/unix/getrandom_linux_sparcx.go
diff --git a/libgo/go/syscall/clone_linux.c b/libgo/go/syscall/clone_linux.c
new file mode 100644
index 0000000..a1a15ea
--- /dev/null
+++ b/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
+}
diff --git a/libgo/go/syscall/exec_linux.go b/libgo/go/syscall/exec_linux.go
index 581a988..83d9c1ca 100644
--- a/libgo/go/syscall/exec_linux.go
+++ b/libgo/go/syscall/exec_linux.go
@@ -7,7 +7,6 @@
 package syscall
 
 import (
-	"runtime"
 	"unsafe"
 )
 
@@ -49,6 +48,9 @@ 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.)
@@ -64,6 +66,7 @@ func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr
 	// declarations require heap allocation (e.g., err1).
 	var (
 		r1     uintptr
+		r2     _C_long
 		err1   Errno
 		err2   Errno
 		nextfd int
@@ -98,20 +101,16 @@ func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr
 	// 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])