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

commands/service/parse.c

@@ -731,6 +731,7 @@ struct
 	{ "INFO",		VM_INFO },
 	{ "RS_UPDATE",		VM_RS_UPDATE },
 	{ "RS_MEMCTL",		VM_RS_MEMCTL },
+	{ "PROCCTL",		VM_PROCCTL },
 	{ NULL,			0 },
 };
 

etc/system.conf

@@ -11,6 +11,7 @@ service rs
 		RS_SET_PRIV	# 37
 		RS_UPDATE	# 41
 		RS_MEMCTL	# 42
+		PROCCTL
 		;
 	io	NONE;		# No I/O range allowed
 	irq	NONE;		# No IRQ allowed
@@ -93,7 +94,7 @@ service vfs
 		UMAP		# 14
 		VIRCOPY		# 15
 		;
-	vm	BASIC;		# Only basic VM calls allowed
+	vm	PROCCTL;
 	io	NONE;		# No I/O range allowed
 	irq	NONE;		# No IRQ allowed
 	sigmgr          rs;	# Signal manager is RS

include/minix/com.h

@@ -942,6 +942,7 @@
 #	define VMM_FLAGS		m5_s2
 #	define VMM_FD			m5_i1
 #	define VMM_OFFSET		m5_i2
+#	define VMM_FORWHOM		m5_l3
 #	define VMM_RETADDR		m5_l1	/* result */
 #define VM_UMAP			(VM_RQ_BASE+11)
 #	define VMU_SEG			m1_i1
@@ -1076,8 +1077,14 @@
 #define VM_REMAP_RO		(VM_RQ_BASE+44)
 /* same args as VM_REMAP */
 
+#define VM_PROCCTL		(VM_RQ_BASE+45)
+#define VMPCTL_PARAM		m1_i1
+#define VMPCTL_WHO		m1_i2
+
+#define VMPPARAM_CLEAR		1	/* values for VMPCTL_PARAM */
+
 /* Total. */
-#define NR_VM_CALLS				45
+#define NR_VM_CALLS				46
 #define VM_CALL_MASK_SIZE			BITMAP_CHUNKS(NR_VM_CALLS)
 
 /* not handled as a normal VM call, thus at the end of the reserved rage */

include/minix/vm.h

@@ -70,6 +70,7 @@ int vm_info_stats(struct vm_stats_info *vfi);
 int vm_info_usage(endpoint_t who, struct vm_usage_info *vui);
 int vm_info_region(endpoint_t who, struct vm_region_info *vri, int
 	count, vir_bytes *next);
+int vm_procctl(endpoint_t ep, int param);
 
 #endif /* _MINIX_VM_H */
 

include/sys/mman.h

@@ -4,6 +4,7 @@
 #include <sys/featuretest.h>
 
 #include <machine/ansi.h>
+#include <minix/type.h>
 
 #ifdef	_BSD_SIZE_T_
 typedef	_BSD_SIZE_T_	size_t;
@@ -54,9 +55,10 @@ typedef	__off_t		off_t;		/* file offset */
 #define MAP_ALIGN64K	0x0040		/* physically aligned at 64kB */
 #define MAP_LOWER1M	0x0080		/* physically below 16MB */
 #define	MAP_ALIGNMENT_64KB	MAP_ALIGN64K
-#define	MAP_IPC_SHARED	0x0100	/* share changes */
+#define	MAP_IPC_SHARED	0x0100		/* share changes */
 
 #define MAP_FIXED      0x0200  /* require mapping to happen at hint */
+#define MAP_THIRDPARTY	0x0400		/* perform on behalf of any process */
 
 /*
  * Error indicator returned by mmap(2)
@@ -71,6 +73,7 @@ void *	mmap(void *, size_t, int, int, int, off_t);
 int	munmap(void *, size_t);
 #else
 void *	minix_mmap(void *, size_t, int, int, int, off_t);
+void *	minix_mmap_for(endpoint_t, void *, size_t, int, int, int, off_t);
 int	minix_munmap(void *, size_t);
 int 		minix_munmap_text(void *, size_t);
 void *		vm_remap(int d, int s, void *da, void *sa, size_t si);

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,
+void *minix_mmap_for(endpoint_t forwhom,
-	int fd, off_t offset)
+	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);
+}

servers/vm/exit.c

@@ -114,3 +114,33 @@ int do_willexit(message *msg)
 	return OK;
 }
 
+int do_procctl(message *msg)
+{
+	endpoint_t proc;
+	struct vmproc *vmp;
+
+	if(vm_isokendpt(msg->VMPCTL_WHO, &proc) != OK) {
+		printf("VM: bogus endpoint VM_PROCCTL %d\n",
+			msg->VMPCTL_WHO);
+		return EINVAL;
+	}
+	vmp = &vmproc[proc];
+
+	switch(msg->VMPCTL_PARAM) {
+		case VMPPARAM_CLEAR:
+			if(msg->m_source != RS_PROC_NR
+				&& msg->m_source != VFS_PROC_NR)
+				return EPERM;
+			free_proc(vmp);
+			pt_new(&vmp->vm_pt);
+			vmp->vm_flags |= VMF_HASPT;
+			pt_bind(&vmp->vm_pt, vmp);
+			return OK;
+		default:
+			return EINVAL;
+	}
+
+
+	return OK;
+}
+

servers/vm/main.c

@@ -357,6 +357,9 @@ static int sef_cb_init_fresh(int type, sef_init_info_t *info)
 	CALLMAP(VM_RS_UPDATE, do_rs_update);
 	CALLMAP(VM_RS_MEMCTL, do_rs_memctl);
 
+	/* Calls from RS/VFS */
+	CALLMAP(VM_PROCCTL, do_procctl);
+
 	/* Generic calls. */
 	CALLMAP(VM_REMAP, do_remap);
 	CALLMAP(VM_REMAP_RO, do_remap);

servers/vm/mmap.c

@@ -43,8 +43,18 @@ int do_mmap(message *m)
 	vir_bytes addr;
 	struct vir_region *vr = NULL;
 
-	if((r=vm_isokendpt(m->m_source, &n)) != OK) {
+	if(m->VMM_FLAGS & MAP_THIRDPARTY) {
-		panic("do_mmap: message from strange source: %d", m->m_source);
+		/* exec()ers, i.e. RS & VFS, can mmap() on behalf of anyone. */
+		if(m->m_source != VFS_PROC_NR && m->m_source != RS_PROC_NR)
+			return EPERM;
+		if((r=vm_isokendpt(m->VMM_FORWHOM, &n)) != OK)
+			return ESRCH;
+	} else {
+		/* regular mmap, i.e. for caller */
+		if((r=vm_isokendpt(m->m_source, &n)) != OK) {
+			panic("do_mmap: message from strange source: %d",
+				m->m_source);
+		}
 	}
 
 	vmp = &vmproc[n];

servers/vm/proto.h

@@ -52,6 +52,7 @@ int swap_proc_dyn_data(struct vmproc *src_vmp, struct vmproc *dst_vmp);
 void clear_proc(struct vmproc *vmp);
 int do_exit(message *msg);
 int do_willexit(message *msg);
+int do_procctl(message *msg);
 void free_proc(struct vmproc *vmp);
 
 /* fork.c */