runtime, net: fix arm build

Bring net/fd_linux.go back (it was deleted this morning)
because it is still needed for ARM.

Fix a few typos in the runtime reorg.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/7759046

src/pkg/net/fd_linux.go

+// Copyright 2009 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 arm
+
+// Waiting for FDs via epoll(7).
+
+package net
+
+import (
+	"os"
+	"syscall"
+)
+
+const (
+	readFlags  = syscall.EPOLLIN | syscall.EPOLLRDHUP
+	writeFlags = syscall.EPOLLOUT
+)
+
+type pollster struct {
+	epfd int
+
+	// Events we're already waiting for
+	// Must hold pollServer lock
+	events map[int]uint32
+
+	// An event buffer for EpollWait.
+	// Used without a lock, may only be used by WaitFD.
+	waitEventBuf [10]syscall.EpollEvent
+	waitEvents   []syscall.EpollEvent
+
+	// An event buffer for EpollCtl, to avoid a malloc.
+	// Must hold pollServer lock.
+	ctlEvent syscall.EpollEvent
+}
+
+func newpollster() (p *pollster, err error) {
+	p = new(pollster)
+	if p.epfd, err = syscall.EpollCreate1(syscall.EPOLL_CLOEXEC); err != nil {
+		if err != syscall.ENOSYS {
+			return nil, os.NewSyscallError("epoll_create1", err)
+		}
+		// The arg to epoll_create is a hint to the kernel
+		// about the number of FDs we will care about.
+		// We don't know, and since 2.6.8 the kernel ignores it anyhow.
+		if p.epfd, err = syscall.EpollCreate(16); err != nil {
+			return nil, os.NewSyscallError("epoll_create", err)
+		}
+		syscall.CloseOnExec(p.epfd)
+	}
+	p.events = make(map[int]uint32)
+	return p, nil
+}
+
+// First return value is whether the pollServer should be woken up.
+// This version always returns false.
+func (p *pollster) AddFD(fd int, mode int, repeat bool) (bool, error) {
+	// pollServer is locked.
+
+	var already bool
+	p.ctlEvent.Fd = int32(fd)
+	p.ctlEvent.Events, already = p.events[fd]
+	if !repeat {
+		p.ctlEvent.Events |= syscall.EPOLLONESHOT
+	}
+	if mode == 'r' {
+		p.ctlEvent.Events |= readFlags
+	} else {
+		p.ctlEvent.Events |= writeFlags
+	}
+
+	var op int
+	if already {
+		op = syscall.EPOLL_CTL_MOD
+	} else {
+		op = syscall.EPOLL_CTL_ADD
+	}
+	if err := syscall.EpollCtl(p.epfd, op, fd, &p.ctlEvent); err != nil {
+		return false, os.NewSyscallError("epoll_ctl", err)
+	}
+	p.events[fd] = p.ctlEvent.Events
+	return false, nil
+}
+
+func (p *pollster) StopWaiting(fd int, bits uint) {
+	// pollServer is locked.
+
+	events, already := p.events[fd]
+	if !already {
+		// The fd returned by the kernel may have been
+		// cancelled already; return silently.
+		return
+	}
+
+	// If syscall.EPOLLONESHOT is not set, the wait
+	// is a repeating wait, so don't change it.
+	if events&syscall.EPOLLONESHOT == 0 {
+		return
+	}
+
+	// Disable the given bits.
+	// If we're still waiting for other events, modify the fd
+	// event in the kernel.  Otherwise, delete it.
+	events &= ^uint32(bits)
+	if int32(events)&^syscall.EPOLLONESHOT != 0 {
+		p.ctlEvent.Fd = int32(fd)
+		p.ctlEvent.Events = events
+		if err := syscall.EpollCtl(p.epfd, syscall.EPOLL_CTL_MOD, fd, &p.ctlEvent); err != nil {
+			print("Epoll modify fd=", fd, ": ", err.Error(), "\n")
+		}
+		p.events[fd] = events
+	} else {
+		if err := syscall.EpollCtl(p.epfd, syscall.EPOLL_CTL_DEL, fd, nil); err != nil {
+			print("Epoll delete fd=", fd, ": ", err.Error(), "\n")
+		}
+		delete(p.events, fd)
+	}
+}
+
+// Return value is whether the pollServer should be woken up.
+// This version always returns false.
+func (p *pollster) DelFD(fd int, mode int) bool {
+	// pollServer is locked.
+
+	if mode == 'r' {
+		p.StopWaiting(fd, readFlags)
+	} else {
+		p.StopWaiting(fd, writeFlags)
+	}
+
+	// Discard any queued up events.
+	i := 0
+	for i < len(p.waitEvents) {
+		if fd == int(p.waitEvents[i].Fd) {
+			copy(p.waitEvents[i:], p.waitEvents[i+1:])
+			p.waitEvents = p.waitEvents[:len(p.waitEvents)-1]
+		} else {
+			i++
+		}
+	}
+	return false
+}
+
+func (p *pollster) WaitFD(s *pollServer, nsec int64) (fd int, mode int, err error) {
+	for len(p.waitEvents) == 0 {
+		var msec int = -1
+		if nsec > 0 {
+			msec = int((nsec + 1e6 - 1) / 1e6)
+		}
+
+		s.Unlock()
+		n, err := syscall.EpollWait(p.epfd, p.waitEventBuf[0:], msec)
+		s.Lock()
+
+		if err != nil {
+			if err == syscall.EAGAIN || err == syscall.EINTR {
+				continue
+			}
+			return -1, 0, os.NewSyscallError("epoll_wait", err)
+		}
+		if n == 0 {
+			return -1, 0, nil
+		}
+		p.waitEvents = p.waitEventBuf[0:n]
+	}
+
+	ev := &p.waitEvents[0]
+	p.waitEvents = p.waitEvents[1:]
+
+	fd = int(ev.Fd)
+
+	if ev.Events&writeFlags != 0 {
+		p.StopWaiting(fd, writeFlags)
+		return fd, 'w', nil
+	}
+	if ev.Events&readFlags != 0 {
+		p.StopWaiting(fd, readFlags)
+		return fd, 'r', nil
+	}
+
+	// Other events are error conditions - wake whoever is waiting.
+	events, _ := p.events[fd]
+	if events&writeFlags != 0 {
+		p.StopWaiting(fd, writeFlags)
+		return fd, 'w', nil
+	}
+	p.StopWaiting(fd, readFlags)
+	return fd, 'r', nil
+}
+
+func (p *pollster) Close() error {
+	return os.NewSyscallError("close", syscall.Close(p.epfd))
+}

src/pkg/runtime/defs_linux_arm.h

-// godefs -f-I/usr/src/linux-headers-2.6.26-2-versatile/include defs_arm.c
-
-// MACHINE GENERATED - DO NOT EDIT.
+// TODO: Generate using cgo like defs_linux_{386,amd64}.h
 
 // Constants
 enum {
+	ENOMEM = 0xc,
+	EAGAIN = 0xb,
+
 	PROT_NONE = 0,
 	PROT_READ = 0x1,
 	PROT_WRITE = 0x2,

src/pkg/runtime/signal_arm.c

@@ -61,7 +61,7 @@ runtime·sighandler(int32 sig, Siginfo *info, void *ctxt, G *gp)
 		// the unwinding code.
 		gp->sig = sig;
 		gp->sigcode0 = SIG_CODE0(info, ctxt);
-		gp->sigcode1 = SIG_FAULT_ADDRESS(info, ctxt);
+		gp->sigcode1 = SIG_FAULT(info, ctxt);
 		gp->sigpc = SIG_PC(info, ctxt);
 
 		// We arrange lr, and pc to pretend the panicking
@@ -113,7 +113,7 @@ Throw:
 		runtime·traceback((void*)SIG_PC(info, ctxt), (void*)SIG_SP(info, ctxt), (void*)SIG_LR(info, ctxt), gp);
 		runtime·tracebackothers(gp);
 		runtime·printf("\n");
-		runtime·dumpregs(r);
+		runtime·dumpregs(info, ctxt);
 	}
 
 	runtime·exit(2);

src/pkg/runtime/signal_linux_arm.h

@@ -25,3 +25,4 @@
 #define SIG_TRAP(info, ctxt) (SIG_REGS(ctxt).trap_no)
 #define SIG_ERROR(info, ctxt) (SIG_REGS(ctxt).error_code)
 #define SIG_OLDMASK(info, ctxt) (SIG_REGS(ctxt).oldmask)
+#define SIG_CODE0(info, ctxt) ((uintptr)(info)->si_code)