Add support for executing the FreeBSD 1/i386 a.out binaries on amd64.

In particular:
- implement compat shims for old stat(2) variants and ogetdirentries(2);
- implement delivery of signals with ancient stack frame layout and
  corresponding sigreturn(2);
- implement old getpagesize(2);
- provide a user-mode trampoline and LDT call gate for lcall $7,$0;
- port a.out image activator and connect it to the build as a module
  on amd64.

The changes are hidden under COMPAT_43.

MFC after:   1 month

1 files changed, 12 insertions, 6 deletions

diff --git a/sys/compat/freebsd32/syscalls.master b/sys/compat/freebsd32/syscalls.master
index 8a4cadf..da42133 100644
--- a/sys/compat/freebsd32/syscalls.master
+++ b/sys/compat/freebsd32/syscalls.master
@@ -117,9 +117,11 @@
 35	AUE_FCHFLAGS	NOPROTO	{ int fchflags(int fd, int flags); }
 36	AUE_SYNC	NOPROTO	{ int sync(void); }
 37	AUE_KILL	NOPROTO	{ int kill(int pid, int signum); }
-38	AUE_STAT	UNIMPL	ostat
+38	AUE_STAT	COMPAT	{ int freebsd32_stat(char *path, \
+				    struct ostat32 *ub); }
 39	AUE_GETPPID	NOPROTO	{ pid_t getppid(void); }
-40	AUE_LSTAT	UNIMPL	olstat
+40	AUE_LSTAT	COMPAT	{ int freebsd32_lstat(char *path, \
+				    struct ostat *ub); }
 41	AUE_DUP		NOPROTO	{ int dup(u_int fd); }
 42	AUE_PIPE	NOPROTO	{ int pipe(void); }
 43	AUE_GETEGID	NOPROTO	{ gid_t getegid(void); }
@@ -153,9 +155,11 @@
 60	AUE_UMASK	NOPROTO	{ int umask(int newmask); } umask \
 				    umask_args int
 61	AUE_CHROOT	NOPROTO	{ int chroot(char *path); }
-62	AUE_FSTAT	OBSOL	ofstat
+62	AUE_FSTAT	COMPAT	{ int freebsd32_fstat(int fd, \
+				    struct ostat32 *ub); }
 63	AUE_NULL	OBSOL	ogetkerninfo
-64	AUE_NULL	OBSOL	ogetpagesize
+64	AUE_NULL	COMPAT	{ int freebsd32_getpagesize( \
+				    int32_t dummy); }
 65	AUE_MSYNC	NOPROTO	{ int msync(void *addr, size_t len, \
 				    int flags); }
 66	AUE_VFORK	NOPROTO	{ int vfork(void); }
@@ -210,7 +214,8 @@
 100	AUE_GETPRIORITY	NOPROTO	{ int getpriority(int which, int who); }
 101	AUE_NULL	OBSOL	osend
 102	AUE_NULL	OBSOL	orecv
-103	AUE_NULL	OBSOL	osigreturn
+103	AUE_NULL	COMPAT	{ int freebsd32_sigreturn( \
+				    struct ia32_sigcontext3 *sigcntxp); }
 104	AUE_BIND	NOPROTO	{ int bind(int s, caddr_t name, \
 				    int namelen); }
 105	AUE_SETSOCKOPT	NOPROTO	{ int setsockopt(int s, int level, \
@@ -292,7 +297,8 @@
 ; 155 is initialized by the NFS code, if present.
 ; XXX this is a problem!!!
 155	AUE_NFS_SVC	UNIMPL	nfssvc
-156	AUE_GETDIRENTRIES	OBSOL	ogetdirentries
+156	AUE_GETDIRENTRIES COMPAT { int freebsd32_getdirentries(int fd, \
+				    char *buf, u_int count, uint32_t *basep); }
 157	AUE_STATFS	COMPAT4	{ int freebsd32_statfs(char *path, \
 				    struct statfs32 *buf); }
 158	AUE_FSTATFS	COMPAT4	{ int freebsd32_fstatfs(int fd, \