Build on Jeff Roberson's linker-set based dynamic per-CPU allocator

(DPCPU), as suggested by Peter Wemm, and implement a new per-virtual
network stack memory allocator.  Modify vnet to use the allocator
instead of monolithic global container structures (vinet, ...).  This
change solves many binary compatibility problems associated with
VIMAGE, and restores ELF symbols for virtualized global variables.

Each virtualized global variable exists as a "reference copy", and also
once per virtual network stack.  Virtualized global variables are
tagged at compile-time, placing the in a special linker set, which is
loaded into a contiguous region of kernel memory.  Virtualized global
variables in the base kernel are linked as normal, but those in modules
are copied and relocated to a reserved portion of the kernel's vnet
region with the help of a the kernel linker.

Virtualized global variables exist in per-vnet memory set up when the
network stack instance is created, and are initialized statically from
the reference copy.  Run-time access occurs via an accessor macro, which
converts from the current vnet and requested symbol to a per-vnet
address.  When "options VIMAGE" is not compiled into the kernel, normal
global ELF symbols will be used instead and indirection is avoided.

This change restores static initialization for network stack global
variables, restores support for non-global symbols and types, eliminates
the need for many subsystem constructors, eliminates large per-subsystem
structures that caused many binary compatibility issues both for
monitoring applications (netstat) and kernel modules, removes the
per-function INIT_VNET_*() macros throughout the stack, eliminates the
need for vnet_symmap ksym(2) munging, and eliminates duplicate
definitions of virtualized globals under VIMAGE_GLOBALS.

Bump __FreeBSD_version and update UPDATING.

Portions submitted by:  bz
Reviewed by:            bz, zec
Discussed with:         gnn, jamie, jeff, jhb, julian, sam
Suggested by:           peter
Approved by:            re (kensmith)

1 files changed, 61 insertions, 31 deletions

diff --git a/sys/netinet6/ip6_var.h b/sys/netinet6/ip6_var.h
index 414880b..b61da42 100644
--- a/sys/netinet6/ip6_var.h
+++ b/sys/netinet6/ip6_var.h
@@ -291,42 +291,72 @@ struct ip6aux {
 #define IP6_HDR_ALIGNED_P(ip)	((((intptr_t) (ip)) & 3) == 0)
 #endif
 
-#ifdef VIMAGE_GLOBALS
-extern struct	ip6stat ip6stat;	/* statistics */
-extern int	ip6_defhlim;		/* default hop limit */
-extern int	ip6_defmcasthlim;	/* default multicast hop limit */
-extern int	ip6_forwarding;		/* act as router? */
-extern int	ip6_gif_hlim;		/* Hop limit for gif encap packet */
-extern int	ip6_use_deprecated;	/* allow deprecated addr as source */
-extern int	ip6_rr_prune;		/* router renumbering prefix
+VNET_DECLARE(struct ip6stat, ip6stat);	/* statistics */
+VNET_DECLARE(int, ip6_defhlim);		/* default hop limit */
+VNET_DECLARE(int, ip6_defmcasthlim);	/* default multicast hop limit */
+VNET_DECLARE(int, ip6_forwarding);	/* act as router? */
+VNET_DECLARE(int, ip6_gif_hlim);	/* Hop limit for gif encap packet */
+VNET_DECLARE(int, ip6_use_deprecated);	/* allow deprecated addr as source */
+VNET_DECLARE(int, ip6_rr_prune);	/* router renumbering prefix
 					 * walk list every 5 sec.    */
-extern int	ip6_mcast_pmtu;		/* enable pMTU discovery for multicast? */
-extern int	ip6_v6only;
-extern struct socket *ip6_mrouter;	/* multicast routing daemon */
-extern int	ip6_sendredirects;	/* send IP redirects when forwarding? */
-extern int	ip6_maxfragpackets; /* Maximum packets in reassembly queue */
-extern int	ip6_maxfrags;	/* Maximum fragments in reassembly queue */
-extern int	ip6_accept_rtadv;	/* Acts as a host not a router */
-extern int	ip6_keepfaith;		/* Firewall Aided Internet Translator */
-extern int	ip6_log_interval;
-extern time_t	ip6_log_time;
-extern int	ip6_hdrnestlimit; /* upper limit of # of extension headers */
-extern int	ip6_dad_count;		/* DupAddrDetectionTransmits */
-
-extern int	ip6_auto_flowlabel;
-extern int	ip6_auto_linklocal;
-
-extern int	ip6_use_tempaddr; /* whether to use temporary addresses. */
-extern int	ip6_prefer_tempaddr; /* whether to prefer temporary addresses
-					in the source address selection */
+VNET_DECLARE(int, ip6_mcast_pmtu);	/* enable pMTU discovery for multicast? */
+VNET_DECLARE(int, ip6_v6only);
+VNET_DECLARE(struct socket *, ip6_mrouter);	/* multicast routing daemon */
+VNET_DECLARE(int, ip6_sendredirects);	/* send IP redirects when forwarding? */
+VNET_DECLARE(int, ip6_maxfragpackets);	/* Maximum packets in reassembly
+					 * queue */
+VNET_DECLARE(int, ip6_maxfrags);	/* Maximum fragments in reassembly
+					 * queue */
+VNET_DECLARE(int, ip6_accept_rtadv);	/* Acts as a host not a router */
+VNET_DECLARE(int, ip6_keepfaith);	/* Firewall Aided Internet Translator */
+VNET_DECLARE(int, ip6_log_interval);
+VNET_DECLARE(time_t, ip6_log_time);
+VNET_DECLARE(int, ip6_hdrnestlimit);	/* upper limit of # of extension
+					 * headers */
+VNET_DECLARE(int, ip6_dad_count);	/* DupAddrDetectionTransmits */
+
+VNET_DECLARE(int, ip6_auto_flowlabel);
+VNET_DECLARE(int, ip6_auto_linklocal);
+
+VNET_DECLARE(int, ip6_use_tempaddr);	/* Whether to use temporary addresses */
+VNET_DECLARE(int, ip6_prefer_tempaddr);	/* Whether to prefer temporary
+					 * addresses in the source address
+					 * selection */
 
 #ifdef IPSTEALTH
-extern int	ip6stealth;
+VNET_DECLARE(int, ip6stealth);
 #endif
 
-extern int	ip6_use_defzone; /* whether to use the default scope zone
-				    when unspecified */
-#endif /* VIMAGE_GLOBALS */
+VNET_DECLARE(int, ip6_use_defzone);	/* Whether to use the default scope
+					 * zone when unspecified */
+
+#define	V_ip6stat			VNET_GET(ip6stat)
+#define	V_ip6_defhlim			VNET_GET(ip6_defhlim)
+#define	V_ip6_defmcasthlim		VNET_GET(ip6_defmcasthlim)
+#define	V_ip6_forwarding		VNET_GET(ip6_forwarding)
+#define	V_ip6_gif_hlim			VNET_GET(ip6_gif_hlim)
+#define	V_ip6_use_deprecated		VNET_GET(ip6_use_deprecated)
+#define	V_ip6_rr_prune			VNET_GET(ip6_rr_prune)
+#define	V_ip6_mcast_pmtu		VNET_GET(ip6_mcast_pmtu)
+#define	V_ip6_v6only			VNET_GET(ip6_v6only)
+#define	V_ip6_mrouter			VNET_GET(ip6_mrouter)
+#define	V_ip6_sendredirects		VNET_GET(ip6_sendredirects)
+#define	V_ip6_maxfragpackets		VNET_GET(ip6_maxfragpackets)
+#define	V_ip6_maxfrags			VNET_GET(ip6_maxfrags)
+#define	V_ip6_accept_rtadv		VNET_GET(ip6_accept_rtadv)
+#define	V_ip6_keepfaith			VNET_GET(ip6_keepfaith)
+#define	V_ip6_log_interval		VNET_GET(ip6_log_interval)
+#define	V_ip6_log_time			VNET_GET(ip6_log_time)
+#define	V_ip6_hdrnestlimit		VNET_GET(ip6_hdrnestlimit)
+#define	V_ip6_dad_count			VNET_GET(ip6_dad_count)
+#define	V_ip6_auto_flowlabel		VNET_GET(ip6_auto_flowlabel)
+#define	V_ip6_auto_linklocal		VNET_GET(ip6_auto_linklocal)
+#define	V_ip6_use_tempaddr		VNET_GET(ip6_use_tempaddr)
+#define	V_ip6_prefer_tempaddr		VNET_GET(ip6_prefer_tempaddr)
+#ifdef IPSTEALTH
+#define	V_ip6stealth			VNET_GET(ip6stealth)
+#endif
+#define	V_ip6_use_defzone		VNET_GET(ip6_use_defzone)
 
 extern	struct pfil_head inet6_pfil_hook;	/* packet filter hooks */