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, 9 insertions, 14 deletions

diff --git a/sys/net/if_loop.c b/sys/net/if_loop.c
index 82c68ff..c2acacd 100644
--- a/sys/net/if_loop.c
+++ b/sys/net/if_loop.c
@@ -108,25 +108,26 @@ static int	vnet_loif_iattach(const void *);
 static int	vnet_loif_idetach(const void *);
 #endif
 
-#ifdef VIMAGE_GLOBALS
-struct ifnet *loif;			/* Used externally */
-#endif
+VNET_DEFINE(struct ifnet *, loif);	/* Used externally */
 
 #ifdef VIMAGE
+static VNET_DEFINE(struct ifc_simple_data *, lo_cloner_data);
+static VNET_DEFINE(struct if_clone *, lo_cloner);
+#define	V_lo_cloner_data	VNET_GET(lo_cloner_data)
+#define	V_lo_cloner		VNET_GET(lo_cloner)
+
 MALLOC_DEFINE(M_LO_CLONER, "lo_cloner", "lo_cloner");
 #endif
 
-#ifndef VIMAGE_GLOBALS
+#ifdef VIMAGE
 static const vnet_modinfo_t vnet_loif_modinfo = {
 	.vmi_id		= VNET_MOD_LOIF,
 	.vmi_dependson	= VNET_MOD_IF_CLONE,
 	.vmi_name	= "loif",
 	.vmi_iattach	= vnet_loif_iattach,
-#ifdef VIMAGE
 	.vmi_idetach	= vnet_loif_idetach
-#endif
 };
-#endif /* !VIMAGE_GLOBALS */
+#endif
 
 IFC_SIMPLE_DECLARE(lo, 1);
 
@@ -147,7 +148,6 @@ lo_clone_destroy(struct ifnet *ifp)
 static int
 lo_clone_create(struct if_clone *ifc, int unit, caddr_t params)
 {
-	INIT_VNET_NET(curvnet);
 	struct ifnet *ifp;
 
 	ifp = if_alloc(IFT_LOOP);
@@ -173,10 +173,7 @@ lo_clone_create(struct if_clone *ifc, int unit, caddr_t params)
 static int
 vnet_loif_iattach(const void *unused __unused)
 {
-	INIT_VNET_NET(curvnet);
 
-	V_loif = NULL;
-	
 #ifdef VIMAGE
 	V_lo_cloner = malloc(sizeof(*V_lo_cloner), M_LO_CLONER,
 	    M_WAITOK | M_ZERO);
@@ -196,7 +193,6 @@ vnet_loif_iattach(const void *unused __unused)
 static int
 vnet_loif_idetach(const void *unused __unused)
 {
-	INIT_VNET_NET(curvnet);
 
 	if_clone_detach(V_lo_cloner);
 	free(V_lo_cloner, M_LO_CLONER);
@@ -213,7 +209,7 @@ loop_modevent(module_t mod, int type, void *data)
 
 	switch (type) {
 	case MOD_LOAD:
-#ifndef VIMAGE_GLOBALS
+#ifdef VIMAGE
 		vnet_mod_register(&vnet_loif_modinfo);
 #else
 		vnet_loif_iattach(NULL);
@@ -309,7 +305,6 @@ looutput(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 int
 if_simloop(struct ifnet *ifp, struct mbuf *m, int af, int hlen)
 {
-	INIT_VNET_NET(ifp->if_vnet);
 	int isr;
 
 	M_ASSERTPKTHDR(m);