FreeBSD-specific porting work.

cgo/libmach remain unimplemented. However, compilers, runtime,
and packages are 100%. I still need to go through and implement
missing syscalls (at least make sure they're all listed), but
for all shipped functionality, this is done. Ship! ;)

R=rsc, VenkateshSrinivas
https://golang.org/cl/152142

misc/cgo/stdio/test.bash

@@ -4,7 +4,7 @@
 # license that can be found in the LICENSE file.
 
 set -e
-make hello fib chain
+gomake hello fib chain
 echo '*' hello >run.out
 ./hello >>run.out
 echo '*' fib >>run.out
@@ -12,4 +12,4 @@ echo '*' fib >>run.out
 echo '*' chain >>run.out
 ./chain >>run.out
 diff run.out golden.out
-make clean
+gomake clean

src/cmd/6l/asm.c

@@ -38,6 +38,7 @@
 #define PADDR(a)	((uint32)(a) & ~0x80000000)
 
 char linuxdynld[] = "/lib64/ld-linux-x86-64.so.2";
+char freebsddynld[] = "/libexec/ld-elf.so.1";
 
 char	zeroes[32];
 
@@ -284,7 +285,7 @@ doelf(void)
 	Sym *s, *shstrtab, *dynamic, *dynstr, *d;
 	int h, nsym, t;
 
-	if(HEADTYPE != 7)
+	if(HEADTYPE != 7 && HEADTYPE != 9)
 		return;
 
 	/* predefine strings we need for section headers */
@@ -317,7 +318,14 @@ doelf(void)
 		s = lookup(".interp", 0);
 		s->reachable = 1;
 		s->type = SDATA;	// TODO: rodata
-		addstring(lookup(".interp", 0), linuxdynld);
+		switch(HEADTYPE) {
+		case 7:
+			addstring(lookup(".interp", 0), linuxdynld);
+			break;
+		case 9:
+			addstring(lookup(".interp", 0), freebsddynld);
+			break;
+		}
 
 		/*
 		 * hash table.
@@ -512,6 +520,7 @@ asmb(void)
 		break;
 
 	case 7:
+	case 9:
 		debug['8'] = 1;	/* 64-bit addresses */
 		v = rnd(HEADR+textsize, INITRND);
 		seek(cout, v, 0);
@@ -565,6 +574,7 @@ asmb(void)
 			symo = rnd(HEADR+textsize, INITRND)+rnd(datsize, INITRND)+machlink;
 			break;
 		case 7:
+		case 9:
 			symo = rnd(HEADR+textsize, INITRND)+datsize;
 			symo = rnd(symo, INITRND);
 			break;
@@ -649,6 +659,7 @@ asmb(void)
 		asmbmacho(symdatva, symo);
 		break;
 	case 7:
+	case 9:
 		/* elf amd-64 */
 
 		eh = getElfEhdr();
@@ -871,6 +882,8 @@ asmb(void)
 		eh->ident[EI_MAG1] = 'E';
 		eh->ident[EI_MAG2] = 'L';
 		eh->ident[EI_MAG3] = 'F';
+		if(HEADTYPE == 9)
+			eh->ident[EI_OSABI] = 9;
 		eh->ident[EI_CLASS] = ELFCLASS64;
 		eh->ident[EI_DATA] = ELFDATA2LSB;
 		eh->ident[EI_VERSION] = EV_CURRENT;

src/cmd/6l/obj.c

@@ -46,6 +46,7 @@ char*	paramspace	= "FP";
  *	-H5 -T0x80110000 -R4096		is ELF32
  *	-H6 -Tx -Rx			is apple MH-exec
  *	-H7 -Tx -Rx			is linux elf-exec
+ *      -H9 -Tx -Rx			is FreeBSD elf-exec
  *
  *	options used: 189BLQSWabcjlnpsvz
  */
@@ -149,6 +150,10 @@ main(int argc, char *argv[])
 		if(strcmp(goos, "darwin") == 0)
 			HEADTYPE = 6;
 		else
+		if(strcmp(goos, "freebsd") == 0) {
+			debug['d'] = 1;	/* no dynamic syms for now */
+			HEADTYPE = 9;
+		} else
 			print("goos is not known: %s\n", goos);
 	}
 
@@ -194,6 +199,7 @@ main(int argc, char *argv[])
 			INITDAT = 0;
 		break;
 	case 7:	/* elf64 executable */
+	case 9: /* freebsd */
 		elfinit();
 		HEADR = ELFRESERVE;
 		if(INITTEXT == -1)

src/cmd/cov/Makefile

@@ -24,6 +24,7 @@ clean:
 
 install: install-$(shell uname | tr A-Z a-z)
 install-linux: install-default
+install-freebsd: install-default
 
 # on Darwin, have to install and setgid; see $GOROOT/src/sudo.bash
 install-darwin: $(TARG)

src/cmd/prof/Makefile

@@ -24,6 +24,7 @@ clean:
 
 install: install-$(shell uname | tr A-Z a-z)
 install-linux: install-default
+install-freebsd: install-default
 
 # on Darwin, have to install and setgid; see $GOROOT/src/sudo.bash
 install-darwin: $(TARG)

src/libcgo/Makefile

@@ -16,6 +16,7 @@ CFLAGS_amd64=-m64
 
 LDFLAGS_linux=-shared -lpthread -lm
 LDFLAGS_darwin=-dynamiclib -Wl,-undefined,dynamic_lookup /usr/lib/libpthread.dylib
+LDFLAGS_freebsd=-pthread -shared -lm
 
 %.o: %.c
 	gcc $(CFLAGS_$(GOARCH)) -O2 -fPIC -o $@ -c $*.c

src/libcgo/freebsd_amd64.c

+// 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.
+
+#include <pthread.h>
+#include "libcgo.h"
+
+static void* threadentry(void*);
+
+void
+initcgo(void)
+{
+}
+
+void
+libcgo_sys_thread_start(ThreadStart *ts)
+{
+	pthread_attr_t attr;
+	pthread_t p;
+	size_t size;
+
+	pthread_attr_init(&attr);
+	pthread_attr_getstacksize(&attr, &size);
+	ts->g->stackguard = size;
+	pthread_create(&p, &attr, threadentry, ts);
+}
+
+static void*
+threadentry(void *v)
+{
+	ThreadStart ts;
+
+	ts = *(ThreadStart*)v;
+	free(v);
+
+	ts.g->stackbase = (uintptr)&ts;
+
+	/*
+	 * libcgo_sys_thread_start set stackguard to stack size;
+	 * change to actual guard pointer.
+	 */
+	ts.g->stackguard = (uintptr)&ts - ts.g->stackguard + 4096;
+
+	crosscall_amd64(ts.m, ts.g, ts.fn);
+	return nil;
+}

src/libmach/freebsd.c

+// This is stubbed out for the moment. Will revisit when the time comes.
+#include <u.h>
+#include <libc.h>
+#include <bio.h>
+#include <mach.h>
+
+int
+ctlproc(int pid, char *msg)
+{
+	sysfatal("ctlproc unimplemented in FreeBSD");
+}
+
+char*
+proctextfile(int pid)
+{
+	sysfatal("proctextfile unimplemented in FreeBSD");
+}
+
+char*
+procstatus(int pid)
+{
+	sysfatal("procstatus unimplemented in FreeBSD");
+}
+
+Map*
+attachproc(int pid, Fhdr *fp)
+{
+	sysfatal("attachproc unimplemented in FreeBSD");
+}
+
+void
+detachproc(Map *m)
+{
+	sysfatal("detachproc unimplemented in FreeBSD");
+}
+
+int
+procthreadpids(int pid, int *p, int np)
+{
+	sysfatal("procthreadpids unimplemented in FreeBSD");
+}

src/pkg/debug/proc/proc_freebsd.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.
+
+package proc
+
+import "os"
+
+// Process tracing is not supported on FreeBSD yet.
+
+func Attach(pid int) (Process, os.Error) {
+	return nil, os.NewError("debug/proc not implemented on FreeBSD")
+}
+
+func ForkExec(argv0 string, argv []string, envv []string, dir string, fd []*os.File) (Process, os.Error) {
+	return Attach(0)
+}

src/pkg/debug/proc/regs_freebsd_amd64.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.
+
+package proc

src/pkg/net/fd_freebsd.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.
+
+// Waiting for FDs via kqueue/kevent.
+
+package net
+
+import (
+	"os";
+	"syscall";
+)
+
+type pollster struct {
+	kq		int;
+	eventbuf	[10]syscall.Kevent_t;
+	events		[]syscall.Kevent_t;
+}
+
+func newpollster() (p *pollster, err os.Error) {
+	p = new(pollster);
+	var e int;
+	if p.kq, e = syscall.Kqueue(); e != 0 {
+		return nil, os.NewSyscallError("kqueue", e)
+	}
+	p.events = p.eventbuf[0:0];
+	return p, nil;
+}
+
+func (p *pollster) AddFD(fd int, mode int, repeat bool) os.Error {
+	var kmode int;
+	if mode == 'r' {
+		kmode = syscall.EVFILT_READ
+	} else {
+		kmode = syscall.EVFILT_WRITE
+	}
+	var events [1]syscall.Kevent_t;
+	ev := &events[0];
+	// EV_ADD - add event to kqueue list
+	// EV_ONESHOT - delete the event the first time it triggers
+	flags := syscall.EV_ADD;
+	if !repeat {
+		flags |= syscall.EV_ONESHOT
+	}
+	syscall.SetKevent(ev, fd, kmode, flags);
+
+	n, e := syscall.Kevent(p.kq, &events, nil, nil);
+	if e != 0 {
+		return os.NewSyscallError("kevent", e)
+	}
+	if n != 1 || (ev.Flags&syscall.EV_ERROR) == 0 || int(ev.Ident) != fd || int(ev.Filter) != kmode {
+		return os.NewSyscallError("kqueue phase error", e)
+	}
+	if ev.Data != 0 {
+		return os.Errno(int(ev.Data))
+	}
+	return nil;
+}
+
+func (p *pollster) DelFD(fd int, mode int) {
+	var kmode int;
+	if mode == 'r' {
+		kmode = syscall.EVFILT_READ
+	} else {
+		kmode = syscall.EVFILT_WRITE
+	}
+	var events [1]syscall.Kevent_t;
+	ev := &events[0];
+	// EV_DELETE - delete event from kqueue list
+	syscall.SetKevent(ev, fd, kmode, syscall.EV_DELETE);
+	syscall.Kevent(p.kq, &events, nil, nil);
+}
+
+func (p *pollster) WaitFD(nsec int64) (fd int, mode int, err os.Error) {
+	var t *syscall.Timespec;
+	for len(p.events) == 0 {
+		if nsec > 0 {
+			if t == nil {
+				t = new(syscall.Timespec)
+			}
+			*t = syscall.NsecToTimespec(nsec);
+		}
+		nn, e := syscall.Kevent(p.kq, nil, &p.eventbuf, t);
+		if e != 0 {
+			if e == syscall.EINTR {
+				continue
+			}
+			return -1, 0, os.NewSyscallError("kevent", e);
+		}
+		if nn == 0 {
+			return -1, 0, nil
+		}
+		p.events = p.eventbuf[0:nn];
+	}
+	ev := &p.events[0];
+	p.events = p.events[1:len(p.events)];
+	fd = int(ev.Ident);
+	if ev.Filter == syscall.EVFILT_READ {
+		mode = 'r'
+	} else {
+		mode = 'w'
+	}
+	return fd, mode, nil;
+}
+
+func (p *pollster) Close() os.Error	{ return os.NewSyscallError("close", syscall.Close(p.kq)) }

src/pkg/net/ipsock.go

@@ -18,6 +18,10 @@ import (
 // Unfortunately, we need to run on kernels built without IPv6 support too.
 // So probe the kernel to figure it out.
 func kernelSupportsIPv6() bool {
+	// FreeBSD does not support this sort of interface.
+	if syscall.OS == "freebsd" {
+		return false
+	}
 	fd, e := syscall.Socket(syscall.AF_INET6, syscall.SOCK_STREAM, syscall.IPPROTO_TCP);
 	if fd >= 0 {
 		syscall.Close(fd)

src/pkg/os/dir_freebsd.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.
+
+package os
+
+import (
+	"syscall";
+	"unsafe";
+)
+
+const (
+	blockSize = 4096;	// TODO(r): use statfs
+)
+
+func (file *File) Readdirnames(count int) (names []string, err Error) {
+	// If this file has no dirinfo, create one.
+	if file.dirinfo == nil {
+		file.dirinfo = new(dirInfo);
+		// The buffer must be at least a block long.
+		// TODO(r): use fstatfs to find fs block size.
+		file.dirinfo.buf = make([]byte, blockSize);
+	}
+	d := file.dirinfo;
+	size := count;
+	if size < 0 {
+		size = 100
+	}
+	names = make([]string, 0, size);	// Empty with room to grow.
+	for count != 0 {
+		// Refill the buffer if necessary
+		if d.bufp >= d.nbuf {
+			var errno int;
+			d.bufp = 0;
+			// Final argument is (basep *uintptr) and the syscall doesn't take nil.
+			d.nbuf, errno = syscall.Getdirentries(file.fd, d.buf, new(uintptr));
+			if errno != 0 {
+				d.nbuf = 0;
+				return names, NewSyscallError("getdirentries", errno);
+			}
+			if d.nbuf <= 0 {
+				break	// EOF
+			}
+		}
+		// Drain the buffer
+		for count != 0 && d.bufp < d.nbuf {
+			dirent := (*syscall.Dirent)(unsafe.Pointer(&d.buf[d.bufp]));
+			if dirent.Reclen == 0 {
+				d.bufp = d.nbuf;
+				break;
+			}
+			d.bufp += int(dirent.Reclen);
+			if dirent.Fileno == 0 {	// File absent in directory.
+				continue
+			}
+			bytes := (*[len(dirent.Name)]byte)(unsafe.Pointer(&dirent.Name[0]));
+			var name = string(bytes[0:dirent.Namlen]);
+			if name == "." || name == ".." {	// Useless names
+				continue
+			}
+			count--;
+			if len(names) == cap(names) {
+				nnames := make([]string, len(names), 2*len(names));
+				for i := 0; i < len(names); i++ {
+					nnames[i] = names[i]
+				}
+				names = nnames;
+			}
+			names = names[0 : len(names)+1];
+			names[len(names)-1] = name;
+		}
+	}
+	return names, nil;
+}

src/pkg/os/stat_freebsd.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.
+
+package os
+
+import "syscall"
+
+func isSymlink(stat *syscall.Stat_t) bool {
+	return stat.Mode&syscall.S_IFMT == syscall.S_IFLNK
+}
+
+func dirFromStat(name string, dir *Dir, lstat, stat *syscall.Stat_t) *Dir {
+	dir.Dev = uint64(stat.Dev);
+	dir.Ino = uint64(stat.Ino);
+	dir.Nlink = uint64(stat.Nlink);
+	dir.Mode = uint32(stat.Mode);
+	dir.Uid = stat.Uid;
+	dir.Gid = stat.Gid;
+	dir.Rdev = uint64(stat.Rdev);
+	dir.Size = uint64(stat.Size);
+	dir.Blksize = uint64(stat.Blksize);
+	dir.Blocks = uint64(stat.Blocks);
+	dir.Atime_ns = uint64(syscall.TimespecToNsec(stat.Atimespec));
+	dir.Mtime_ns = uint64(syscall.TimespecToNsec(stat.Mtimespec));
+	dir.Ctime_ns = uint64(syscall.TimespecToNsec(stat.Ctimespec));
+	for i := len(name) - 1; i >= 0; i-- {
+		if name[i] == '/' {
+			name = name[i+1 : len(name)];
+			break;
+		}
+	}
+	dir.Name = name;
+	if isSymlink(lstat) && !isSymlink(stat) {
+		dir.FollowedSymlink = true
+	}
+	return dir;
+}

src/pkg/os/sys_freebsd.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.
+
+package os
+
+import "syscall"
+
+func Hostname() (name string, err Error) {
+	var errno int;
+	name, errno = syscall.Sysctl("kern.hostname");
+	if errno != 0 {
+		return "", NewSyscallError("sysctl kern.hostname", errno)
+	}
+	return name, nil;
+}

src/pkg/runtime/amd64/asm.s

@@ -5,10 +5,9 @@
 #include "amd64/asm.h"
 
 TEXT	_rt0_amd64(SB),7,$-8
-
 	// copy arguments forward on an even stack
-	MOVQ	0(SP), AX		// argc
-	LEAQ	8(SP), BX		// argv
+	MOVQ	0(DI), AX		// argc
+	LEAQ	8(DI), BX		// argv
 	SUBQ	$(4*8+7), SP		// 2args 2auto
 	ANDQ	$~7, SP
 	MOVQ	AX, 16(SP)

src/pkg/runtime/darwin/amd64/rt0.s

@@ -6,4 +6,5 @@
 
 TEXT	_rt0_amd64_darwin(SB),7,$-8
 	MOVQ	$_rt0_amd64(SB), AX
+	MOVQ	SP, DI
 	JMP	AX

src/pkg/runtime/freebsd/amd64/defs.h

+// godefs -f -m64 freebsd/defs.c
+
+// MACHINE GENERATED - DO NOT EDIT.
+
+// Constants
+enum {
+	PROT_NONE = 0,
+	PROT_READ = 0x1,
+	PROT_WRITE = 0x2,
+	PROT_EXEC = 0x4,
+	MAP_ANON = 0x1000,
+	MAP_PRIVATE = 0x2,
+	SA_SIGINFO = 0x40,
+	SA_RESTART = 0x2,
+	SA_ONSTACK = 0x1,
+	UMTX_OP_WAIT = 0x2,
+	UMTX_OP_WAKE = 0x3,
+	EINTR = 0x4,
+};
+
+// Types
+#pragma pack on
+
+typedef struct Sigaltstack Sigaltstack;
+struct Sigaltstack {
+	int8 *ss_sp;
+	uint64 ss_size;
+	int32 ss_flags;
+	byte pad0[4];
+};
+
+typedef struct Sigset Sigset;
+struct Sigset {
+	uint32 __bits[4];
+};
+
+typedef union Sigval Sigval;
+union Sigval {
+	int32 sival_int;
+	void *sival_ptr;
+	int32 sigval_int;
+	void *sigval_ptr;
+};
+
+typedef struct StackT StackT;
+struct StackT {
+	int8 *ss_sp;
+	uint64 ss_size;
+	int32 ss_flags;
+	byte pad0[4];
+};
+
+typedef struct Siginfo Siginfo;
+struct Siginfo {
+	int32 si_signo;
+	int32 si_errno;
+	int32 si_code;
+	int32 si_pid;
+	uint32 si_uid;
+	int32 si_status;
+	void *si_addr;
+	Sigval si_value;
+	byte _reason[40];
+};
+
+typedef struct Mcontext Mcontext;
+struct Mcontext {
+	int64 mc_onstack;
+	int64 mc_rdi;
+	int64 mc_rsi;
+	int64 mc_rdx;
+	int64 mc_rcx;
+	int64 mc_r8;
+	int64 mc_r9;
+	int64 mc_rax;
+	int64 mc_rbx;
+	int64 mc_rbp;
+	int64 mc_r10;
+	int64 mc_r11;
+	int64 mc_r12;
+	int64 mc_r13;
+	int64 mc_r14;
+	int64 mc_r15;
+	uint32 mc_trapno;
+	uint16 mc_fs;
+	uint16 mc_gs;
+	int64 mc_addr;
+	uint32 mc_flags;
+	uint16 mc_es;
+	uint16 mc_ds;
+	int64 mc_err;
+	int64 mc_rip;
+	int64 mc_cs;
+	int64 mc_rflags;
+	int64 mc_rsp;
+	int64 mc_ss;
+	int64 mc_len;
+	int64 mc_fpformat;
+	int64 mc_ownedfp;
+	int64 mc_fpstate[64];
+	int64 mc_fsbase;
+	int64 mc_gsbase;
+	int64 mc_spare[6];
+};
+
+typedef struct Ucontext Ucontext;
+struct Ucontext {
+	Sigset uc_sigmask;
+	Mcontext uc_mcontext;
+	Ucontext *uc_link;
+	StackT uc_stack;
+	int32 uc_flags;
+	int32 __spare__[4];
+	byte pad0[12];
+};
+
+typedef struct Sigcontext Sigcontext;
+struct Sigcontext {
+	Sigset sc_mask;
+	int64 sc_onstack;
+	int64 sc_rdi;
+	int64 sc_rsi;
+	int64 sc_rdx;
+	int64 sc_rcx;
+	int64 sc_r8;
+	int64 sc_r9;
+	int64 sc_rax;
+	int64 sc_rbx;
+	int64 sc_rbp;
+	int64 sc_r10;
+	int64 sc_r11;
+	int64 sc_r12;
+	int64 sc_r13;
+	int64 sc_r14;
+	int64 sc_r15;
+	int32 sc_trapno;
+	int16 sc_fs;
+	int16 sc_gs;
+	int64 sc_addr;
+	int32 sc_flags;
+	int16 sc_es;
+	int16 sc_ds;
+	int64 sc_err;
+	int64 sc_rip;
+	int64 sc_cs;
+	int64 sc_rflags;
+	int64 sc_rsp;
+	int64 sc_ss;
+	int64 sc_len;
+	int64 sc_fpformat;
+	int64 sc_ownedfp;
+	int64 sc_fpstate[64];
+	int64 sc_fsbase;
+	int64 sc_gsbase;
+	int64 sc_spare[6];
+};
+#pragma pack off

src/pkg/runtime/freebsd/amd64/rt0.s

+// 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.
+
+// Darwin and Linux use the same linkage to main
+
+TEXT	_rt0_amd64_freebsd(SB),7,$-8
+	MOVQ	$_rt0_amd64(SB), DX
+	JMP	DX

src/pkg/runtime/freebsd/amd64/signal.c

+#include "runtime.h"
+#include "defs.h"
+#include "signals.h"
+#include "os.h"
+
+extern void sigtramp(void);
+
+typedef struct sigaction {
+	union {
+		void    (*__sa_handler)(int32);
+		void    (*__sa_sigaction)(int32, Siginfo*, void *);
+	} __sigaction_u;		/* signal handler */
+	int32	sa_flags;		/* see signal options below */
+	int64	sa_mask;		/* signal mask to apply */
+} Sigaction;
+
+void
+dumpregs(Sigcontext *r)
+{
+	printf("rax     %X\n", r->sc_rax);
+	printf("rbx     %X\n", r->sc_rbx);
+	printf("rcx     %X\n", r->sc_rcx);
+	printf("rdx     %X\n", r->sc_rdx);
+	printf("rdi     %X\n", r->sc_rdi);
+	printf("rsi     %X\n", r->sc_rsi);
+	printf("rbp     %X\n", r->sc_rbp);
+	printf("rsp     %X\n", r->sc_rsp);
+	printf("r8      %X\n", r->sc_r8 );
+	printf("r9      %X\n", r->sc_r9 );
+	printf("r10     %X\n", r->sc_r10);
+	printf("r11     %X\n", r->sc_r11);
+	printf("r12     %X\n", r->sc_r12);
+	printf("r13     %X\n", r->sc_r13);
+	printf("r14     %X\n", r->sc_r14);
+	printf("r15     %X\n", r->sc_r15);
+	printf("rip     %X\n", r->sc_rip);
+	printf("rflags  %X\n", r->sc_flags);
+	printf("cs      %X\n", (uint64)r->sc_cs);
+	printf("fs      %X\n", (uint64)r->sc_fsbase);
+	printf("gs      %X\n", (uint64)r->sc_gsbase);
+}
+
+void
+sighandler(int32 sig, Siginfo* info, void* context)
+{
+	Ucontext *uc;
+	Mcontext *mc;
+	Sigcontext *sc;
+
+	if(panicking)	// traceback already printed
+		exit(2);
+	panicking = 1;
+
+	uc = context;
+	mc = &uc->uc_mcontext;
+	sc = (Sigcontext*)mc;	// same layout, more conveient names
+
+	if(sig < 0 || sig >= NSIG)
+		printf("Signal %d\n", sig);
+	else
+		printf("%s\n", sigtab[sig].name);
+
+	printf("Faulting address: %p\n", info->si_addr);
+	printf("PC=%X\n", sc->sc_rip);
+	printf("\n");
+
+	if(gotraceback()){
+		traceback((void*)sc->sc_rip, (void*)sc->sc_rsp, (void*)sc->sc_r15);
+		tracebackothers((void*)sc->sc_r15);
+		dumpregs(sc);
+	}
+
+	breakpoint();
+	exit(2);
+}
+
+void
+sigignore(void)
+{
+}
+
+void
+signalstack(byte *p, int32 n)
+{
+	Sigaltstack st;
+
+	st.ss_sp = (int8*)p;
+	st.ss_size = n;
+	st.ss_flags = 0;
+	sigaltstack(&st, nil);
+}
+
+void
+initsig(void)
+{
+	static Sigaction sa;
+
+	int32 i;
+	sa.sa_flags |= SA_ONSTACK | SA_SIGINFO;
+	sa.sa_mask = ~0x0ull;
+	
+	for(i = 0; i < NSIG; i++) {
+		if(sigtab[i].flags) {
+			if(sigtab[i].flags & SigCatch)
+				sa.__sigaction_u.__sa_handler = (void*) sigtramp;
+			else
+				sa.__sigaction_u.__sa_handler = (void*) sigignore;
+
+			if(sigtab[i].flags & SigRestart)
+				sa.sa_flags |= SA_RESTART;
+			else
+				sa.sa_flags &= ~SA_RESTART;
+
+			sigaction(i, &sa, nil);
+		}
+	}
+}