vm: add third-party mmap() mode and PROCCTL

these two functions will be used to support all exec() functionality
going into a single library shared by RS and VFS and exec() knowledge
leaving VM.

	. third-party mmap: allow certain processes (VFS, RS) to
	  do mmap() on behalf of another process
	. PROCCTL: used to free and clear a process' address space

lib/libc/sys-minix/mmap.c

@@ -21,8 +21,8 @@ __weak_alias(minix_munmap_text, _minix_munmap_text)
 #include <string.h>
 #include <errno.h>
 
-void *minix_mmap(void *addr, size_t len, int prot, int flags,
-	int fd, off_t offset)
+void *minix_mmap_for(endpoint_t forwhom,
+	void *addr, size_t len, int prot, int flags, int fd, off_t offset)
 {
 	message m;
 	int r;
@@ -33,6 +33,11 @@ void *minix_mmap(void *addr, size_t len, int prot, int flags,
 	m.VMM_FLAGS = flags;
 	m.VMM_FD = fd;
 	m.VMM_OFFSET = offset;
+	m.VMM_FORWHOM = forwhom;
+
+	if(forwhom != SELF) {
+		m.VMM_FLAGS |= MAP_THIRDPARTY;
+	}
 
 	r = _syscall(VM_PROC_NR, VM_MMAP, &m);
 
@@ -43,6 +48,12 @@ void *minix_mmap(void *addr, size_t len, int prot, int flags,
 	return (void *) m.VMM_RETADDR;
 }
 
+void *minix_mmap(void *addr, size_t len, int prot, int flags,
+	int fd, off_t offset)
+{
+	return minix_mmap_for(SELF, addr, len, prot, flags, fd, offset);
+}
+
 int minix_munmap(void *addr, size_t len)
 {
 	message m;

lib/libsys/Makefile

@@ -127,6 +127,7 @@ SRCS=  \
 	vm_push_sig.c \
 	vm_umap.c \
 	vm_yield_get_block.c \
+	vm_procctl.c \
 	vprintf.c \
 
 .if ${MKCOVERAGE} != "no"

lib/libsys/vm_procctl.c

@@ -0,0 +1,22 @@
+
+#include "syslib.h"
+
+#include <minix/vm.h>
+#include <string.h>
+
+/*===========================================================================*
+ *                                vm_exit				     *
+ *===========================================================================*/
+int vm_procctl(endpoint_t ep, int param)
+{
+    message m;
+    int result;
+
+    memset(&m, 0, sizeof(m));
+
+    m.VMPCTL_WHO = ep;
+    m.VMPCTL_PARAM = param;
+
+    result = _taskcall(VM_PROC_NR, VM_PROCCTL, &m);
+    return(result);
+}