From: deraadt <deraadt@openbsd.org>
Date: Tue, 2 Apr 2024 08:39:16 +0000 (+0000)
Subject: Delete the msyscall mechanism entirely, since mimmutable+pinsyscalls has
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=30d2057940fb9e9627ddc71bfc4fe05f8825fcec;p=openbsd

Delete the msyscall mechanism entirely, since mimmutable+pinsyscalls has
replaced it with a more strict mechanism, which happens to be lockless O(1)
rather than micro-lock O(1)+O(log N).  Also nop-out the sys_msyscall(2) guts,
but leave the syscall around for a bit longer so that people can build through
it, since ld.so(1) still wants to call it.
---

diff --git a/sys/kern/exec_elf.c b/sys/kern/exec_elf.c
index 33e5cadb76a..0cb3b15968f 100644
--- a/sys/kern/exec_elf.c
+++ b/sys/kern/exec_elf.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: exec_elf.c,v 1.185 2024/01/17 22:22:25 kurt Exp $	*/
+/*	$OpenBSD: exec_elf.c,v 1.186 2024/04/02 08:39:16 deraadt Exp $	*/
 
 /*
  * Copyright (c) 1996 Per Fogelstrom
@@ -494,10 +494,15 @@ elf_load_file(struct proc *p, char *path, struct exec_package *epp,
 				addr = ph[i].p_vaddr - base_ph->p_vaddr;
 			}
 			elf_load_psection(&epp->ep_vmcmds, nd.ni_vp,
-			    &ph[i], &addr, &size, &prot, flags | VMCMD_SYSCALL);
+			    &ph[i], &addr, &size, &prot, flags);
 			/* If entry is within this section it must be text */
 			if (eh.e_entry >= ph[i].p_vaddr &&
 			    eh.e_entry < (ph[i].p_vaddr + size)) {
+				/* LOAD containing e_entry may not be writable */
+				if (prot & PROT_WRITE) {
+					error = ENOEXEC;
+					goto bad1;
+				}
  				epp->ep_entry = addr + eh.e_entry -
 				    ELF_TRUNC(ph[i].p_vaddr,ph[i].p_align);
 				if (flags == VMCMD_RELATIVE)
@@ -715,7 +720,7 @@ exec_elf_makecmds(struct proc *p, struct exec_package *epp)
 	 */
 	for (i = 0, pp = ph; i < eh->e_phnum; i++, pp++) {
 		Elf_Addr addr, size = 0;
-		int prot = 0, syscall = 0;
+		int prot = 0;
 		int flags = 0;
 
 		switch (pp->p_type) {
@@ -731,16 +736,9 @@ exec_elf_makecmds(struct proc *p, struct exec_package *epp)
 			} else
 				addr = ELF_NO_ADDR;
 
-			/*
-			 * Permit system calls in main-text static binaries.
-			 * static binaries may not call msyscall() or
-			 * pinsyscalls()
-			 */
-			if (interp == NULL) {
-				syscall = VMCMD_SYSCALL;
-				p->p_vmspace->vm_map.flags |= VM_MAP_SYSCALL_ONCE;
+			/* Static binaries may not call pinsyscalls() */
+			if (interp == NULL)
 				p->p_vmspace->vm_map.flags |= VM_MAP_PINSYSCALL_ONCE;
-			}
 
 			/*
 			 * Calculates size of text and data segments
@@ -750,7 +748,7 @@ exec_elf_makecmds(struct proc *p, struct exec_package *epp)
 			 * for DATA_PLT, is fine for TEXT_PLT.
 			 */
 			elf_load_psection(&epp->ep_vmcmds, epp->ep_vp,
-			    pp, &addr, &size, &prot, flags | textrel | syscall);
+			    pp, &addr, &size, &prot, flags | textrel);
 
 			/*
 			 * Update exe_base in case alignment was off.
diff --git a/sys/kern/exec_subr.c b/sys/kern/exec_subr.c
index a02566bf797..4ebca1b981d 100644
--- a/sys/kern/exec_subr.c
+++ b/sys/kern/exec_subr.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: exec_subr.c,v 1.66 2023/03/19 20:32:13 kettenis Exp $	*/
+/*	$OpenBSD: exec_subr.c,v 1.67 2024/04/02 08:39:16 deraadt Exp $	*/
 /*	$NetBSD: exec_subr.c,v 1.9 1994/12/04 03:10:42 mycroft Exp $	*/
 
 /*
@@ -194,9 +194,6 @@ vmcmd_map_pagedvn(struct proc *p, struct exec_vmcmd *cmd)
 	/*
 	 * do the map
 	 */
-	if ((cmd->ev_flags & VMCMD_SYSCALL) && (cmd->ev_prot & PROT_EXEC))
-		flags |= UVM_FLAG_SYSCALL;
-
 	error = uvm_map(&p->p_vmspace->vm_map, &cmd->ev_addr, cmd->ev_len,
 	    uobj, cmd->ev_offset, 0,
 	    UVM_MAPFLAG(cmd->ev_prot, PROT_MASK, MAP_INHERIT_COPY,
@@ -217,8 +214,7 @@ vmcmd_map_pagedvn(struct proc *p, struct exec_vmcmd *cmd)
 			    round_page(cmd->ev_addr + cmd->ev_len), 1);
 #ifdef PMAP_CHECK_COPYIN
 		if (PMAP_CHECK_COPYIN &&
-		    ((flags & UVM_FLAG_SYSCALL) ||
-		    ((cmd->ev_flags & VMCMD_IMMUTABLE) && (cmd->ev_prot & PROT_EXEC))))
+		    ((cmd->ev_flags & VMCMD_IMMUTABLE) && (cmd->ev_prot & PROT_EXEC)))
 			uvm_map_check_copyin_add(&p->p_vmspace->vm_map,
 			    cmd->ev_addr, round_page(cmd->ev_addr + cmd->ev_len));
 #endif
diff --git a/sys/kern/init_main.c b/sys/kern/init_main.c
index b4816b2e9a0..d571b0855cf 100644
--- a/sys/kern/init_main.c
+++ b/sys/kern/init_main.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: init_main.c,v 1.325 2024/02/14 06:17:51 miod Exp $	*/
+/*	$OpenBSD: init_main.c,v 1.326 2024/04/02 08:39:16 deraadt Exp $	*/
 /*	$NetBSD: init_main.c,v 1.84.4.1 1996/06/02 09:08:06 mrg Exp $	*/
 
 /*
@@ -626,7 +626,7 @@ start_init(void *arg)
 	    NULL, UVM_UNKNOWN_OFFSET, 0,
 	    UVM_MAPFLAG(PROT_READ | PROT_WRITE, PROT_MASK, MAP_INHERIT_COPY,
 	    MADV_NORMAL,
-	    UVM_FLAG_FIXED|UVM_FLAG_OVERLAY|UVM_FLAG_COPYONW|UVM_FLAG_STACK|UVM_FLAG_SYSCALL)))
+	    UVM_FLAG_FIXED|UVM_FLAG_OVERLAY|UVM_FLAG_COPYONW|UVM_FLAG_STACK)))
 		panic("init: couldn't allocate argument space");
 
 	for (pathp = &initpaths[0]; (path = *pathp) != NULL; pathp++) {
diff --git a/sys/kern/kern_exec.c b/sys/kern/kern_exec.c
index a00e2372145..7d87a4cbcb9 100644
--- a/sys/kern/kern_exec.c
+++ b/sys/kern/kern_exec.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_exec.c,v 1.254 2024/01/17 18:56:13 deraadt Exp $	*/
+/*	$OpenBSD: kern_exec.c,v 1.255 2024/04/02 08:39:16 deraadt Exp $	*/
 /*	$NetBSD: kern_exec.c,v 1.75 1996/02/09 18:59:28 christos Exp $	*/
 
 /*-
@@ -905,7 +905,7 @@ exec_sigcode_map(struct process *pr)
 	if (uvm_map(&pr->ps_vmspace->vm_map, &pr->ps_sigcode, round_page(sz),
 	    sigobject, 0, 0, UVM_MAPFLAG(PROT_EXEC,
 	    PROT_READ | PROT_WRITE | PROT_EXEC, MAP_INHERIT_COPY,
-	    MADV_RANDOM, UVM_FLAG_COPYONW | UVM_FLAG_SYSCALL))) {
+	    MADV_RANDOM, UVM_FLAG_COPYONW))) {
 		uao_detach(sigobject);
 		return (ENOMEM);
 	}
diff --git a/sys/sys/exec.h b/sys/sys/exec.h
index d6b5c645713..801181f2c98 100644
--- a/sys/sys/exec.h
+++ b/sys/sys/exec.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: exec.h,v 1.53 2024/01/16 19:05:00 deraadt Exp $	*/
+/*	$OpenBSD: exec.h,v 1.54 2024/04/02 08:39:16 deraadt Exp $	*/
 /*	$NetBSD: exec.h,v 1.59 1996/02/09 18:25:09 christos Exp $	*/
 
 /*-
@@ -92,7 +92,6 @@ struct exec_vmcmd {
 #define VMCMD_RELATIVE  0x0001  /* ev_addr is relative to base entry */
 #define VMCMD_BASE      0x0002  /* marks a base entry */
 #define VMCMD_STACK     0x0004  /* create with UVM_FLAG_STACK */
-#define VMCMD_SYSCALL   0x0008  /* create with UVM_FLAG_SYSCALL */
 #define VMCMD_IMMUTABLE	0x0010  /* create with UVM_ET_IMMUTABLE */
 #define VMCMD_TEXTREL	0x0020  /* terrible binary contains terrible textrel */
 };
diff --git a/sys/sys/proc.h b/sys/sys/proc.h
index c98ea17b594..4333914bf6e 100644
--- a/sys/sys/proc.h
+++ b/sys/sys/proc.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: proc.h,v 1.357 2024/03/30 13:33:21 mpi Exp $	*/
+/*	$OpenBSD: proc.h,v 1.358 2024/04/02 08:39:16 deraadt Exp $	*/
 /*	$NetBSD: proc.h,v 1.44 1996/04/22 01:23:21 christos Exp $	*/
 
 /*-
@@ -337,7 +337,6 @@ struct proc {
 	struct	filedesc *p_fd;		/* copy of p_p->ps_fd */
 	struct	vmspace *p_vmspace;	/* [I] copy of p_p->ps_vmspace */
 	struct	p_inentry p_spinentry;	/* [o] cache for SP check */
-	struct	p_inentry p_pcinentry;	/* [o] cache for PC check */
 
 	int	p_flag;			/* P_* flags. */
 	u_char	p_spare;		/* unused */
diff --git a/sys/uvm/uvm.h b/sys/uvm/uvm.h
index 3078d2cfed9..79dd17e35d4 100644
--- a/sys/uvm/uvm.h
+++ b/sys/uvm/uvm.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm.h,v 1.72 2024/03/30 12:47:47 mpi Exp $	*/
+/*	$OpenBSD: uvm.h,v 1.73 2024/04/02 08:39:17 deraadt Exp $	*/
 /*	$NetBSD: uvm.h,v 1.24 2000/11/27 08:40:02 chs Exp $	*/
 
 /*
@@ -92,7 +92,6 @@ struct uvm {
 #define UVM_ET_STACK		0x0040	/* this is a stack */
 #define UVM_ET_WC		0x0080	/* write combining */
 #define UVM_ET_CONCEAL		0x0100	/* omit from dumps */
-#define UVM_ET_SYSCALL		0x0200	/* syscall text segment */
 #define UVM_ET_IMMUTABLE	0x0400	/* entry may not be changed */
 #define UVM_ET_FREEMAPPED	0x8000	/* map entry is on free list (DEBUG) */
 
diff --git a/sys/uvm/uvm_extern.h b/sys/uvm/uvm_extern.h
index 7fd732396c5..0b9a135d3ad 100644
--- a/sys/uvm/uvm_extern.h
+++ b/sys/uvm/uvm_extern.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_extern.h,v 1.173 2024/01/19 21:20:35 deraadt Exp $	*/
+/*	$OpenBSD: uvm_extern.h,v 1.174 2024/04/02 08:39:17 deraadt Exp $	*/
 /*	$NetBSD: uvm_extern.h,v 1.57 2001/03/09 01:02:12 chs Exp $	*/
 
 /*
@@ -111,7 +111,6 @@ typedef int		vm_prot_t;
 #define UVM_FLAG_STACK   0x2000000 /* page may contain a stack */
 #define UVM_FLAG_WC      0x4000000 /* write combining */
 #define UVM_FLAG_CONCEAL 0x8000000 /* omit from dumps */
-#define UVM_FLAG_SYSCALL 0x10000000 /* system calls allowed */
 #define UVM_FLAG_SIGALTSTACK 0x20000000 /* sigaltstack validation required */
 
 /* macros to extract info */
diff --git a/sys/uvm/uvm_map.c b/sys/uvm/uvm_map.c
index 0e84e2a1e3f..a0c17ee18f4 100644
--- a/sys/uvm/uvm_map.c
+++ b/sys/uvm/uvm_map.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_map.c,v 1.327 2024/02/21 03:28:29 deraadt Exp $	*/
+/*	$OpenBSD: uvm_map.c,v 1.328 2024/04/02 08:39:17 deraadt Exp $	*/
 /*	$NetBSD: uvm_map.c,v 1.86 2000/11/27 08:40:03 chs Exp $	*/
 
 /*
@@ -871,12 +871,6 @@ uvm_mapanon(struct vm_map *map, vaddr_t *addr, vsize_t sz,
 	entry->inheritance = inherit;
 	entry->wired_count = 0;
 	entry->advice = advice;
-	if (prot & PROT_WRITE)
-		map->wserial++;
-	if (flags & UVM_FLAG_SYSCALL) {
-		entry->etype |= UVM_ET_SYSCALL;
-		map->wserial++;
-	}
 	if (flags & UVM_FLAG_STACK) {
 		entry->etype |= UVM_ET_STACK;
 		if (flags & (UVM_FLAG_FIXED | UVM_FLAG_UNMAP))
@@ -1146,12 +1140,6 @@ uvm_map(struct vm_map *map, vaddr_t *addr, vsize_t sz,
 	entry->inheritance = inherit;
 	entry->wired_count = 0;
 	entry->advice = advice;
-	if (prot & PROT_WRITE)
-		map->wserial++;
-	if (flags & UVM_FLAG_SYSCALL) {
-		entry->etype |= UVM_ET_SYSCALL;
-		map->wserial++;
-	}
 	if (flags & UVM_FLAG_STACK) {
 		entry->etype |= UVM_ET_STACK;
 		if (flags & UVM_FLAG_UNMAP)
@@ -1613,23 +1601,6 @@ uvm_map_inentry_sp(vm_map_entry_t entry)
 	return (1);
 }
 
-/*
- * The system call must not come from a writeable entry, W^X is violated.
- * (Would be nice if we can spot aliasing, which is also kind of bad)
- *
- * The system call must come from an syscall-labeled entry (which are
- * the text regions of the main program, sigtramp, ld.so, or libc).
- */
-int
-uvm_map_inentry_pc(vm_map_entry_t entry)
-{
-	if (entry->protection & PROT_WRITE)
-		return (0);	/* not permitted */
-	if ((entry->etype & UVM_ET_SYSCALL) == 0)
-		return (0);	/* not permitted */
-	return (1);
-}
-
 int
 uvm_map_inentry_recheck(u_long serial, vaddr_t addr, struct p_inentry *ie)
 {
@@ -1747,8 +1718,6 @@ uvm_map_is_stack_remappable(struct vm_map *map, vaddr_t addr, vaddr_t sz,
 			return FALSE;
 		}
 		if (sigaltstack_check) {
-			if ((iter->etype & UVM_ET_SYSCALL))
-				return FALSE;
 			if (iter->protection != (PROT_READ | PROT_WRITE))
 				return FALSE;
 		}
@@ -2937,13 +2906,12 @@ uvm_map_printit(struct vm_map *map, boolean_t full,
 		    (long long)entry->offset, entry->aref.ar_amap,
 		    entry->aref.ar_pageoff);
 		(*pr)("\tsubmap=%c, cow=%c, nc=%c, stack=%c, "
-		    "syscall=%c, prot(max)=%d/%d, inh=%d, "
+		    "prot(max)=%d/%d, inh=%d, "
 		    "wc=%d, adv=%d\n",
 		    (entry->etype & UVM_ET_SUBMAP) ? 'T' : 'F',
 		    (entry->etype & UVM_ET_COPYONWRITE) ? 'T' : 'F',
 		    (entry->etype & UVM_ET_NEEDSCOPY) ? 'T' : 'F',
 		    (entry->etype & UVM_ET_STACK) ? 'T' : 'F',
-		    (entry->etype & UVM_ET_SYSCALL) ? 'T' : 'F',
 		    entry->protection, entry->max_protection,
 		    entry->inheritance, entry->wired_count, entry->advice);
 
@@ -3222,10 +3190,6 @@ uvm_map_protect(struct vm_map *map, vaddr_t start, vaddr_t end,
 			mask = UVM_ET_ISCOPYONWRITE(iter) ?
 			    ~PROT_WRITE : PROT_MASK;
 
-			/* XXX should only wserial++ if no split occurs */
-			if (iter->protection & PROT_WRITE)
-				map->wserial++;
-
 			if (map->flags & VM_MAP_ISVMSPACE) {
 				if (old_prot == PROT_NONE) {
 					((struct vmspace *)map)->vm_dused +=
@@ -3401,7 +3365,7 @@ uvmspace_exec(struct proc *p, vaddr_t start, vaddr_t end)
 		 */
 		vm_map_lock(map);
 		vm_map_modflags(map, 0, VM_MAP_WIREFUTURE |
-		    VM_MAP_SYSCALL_ONCE | VM_MAP_PINSYSCALL_ONCE);
+		    VM_MAP_PINSYSCALL_ONCE);
 
 		/*
 		 * now unmap the old program
@@ -3938,8 +3902,7 @@ uvmspace_fork(struct process *pr)
 			    new_map, new_entry->start, new_entry->end);
 		}
 	}
-	new_map->flags |= old_map->flags &
-	    (VM_MAP_SYSCALL_ONCE | VM_MAP_PINSYSCALL_ONCE);
+	new_map->flags |= old_map->flags & VM_MAP_PINSYSCALL_ONCE;
 #ifdef PMAP_CHECK_COPYIN
 	if (PMAP_CHECK_COPYIN) {
 		memcpy(&new_map->check_copyin, &old_map->check_copyin,
@@ -4244,48 +4207,6 @@ uvm_map_check_copyin_add(struct vm_map *map, vaddr_t start, vaddr_t end)
 }
 #endif /* PMAP_CHECK_COPYIN */
 
-/* 
- * uvm_map_syscall: permit system calls for range of addrs in map.
- *
- * => map must be unlocked
- */
-int
-uvm_map_syscall(struct vm_map *map, vaddr_t start, vaddr_t end)
-{
-	struct vm_map_entry *entry;
-
-	if (start > end)
-		return EINVAL;
-	start = MAX(start, map->min_offset);
-	end = MIN(end, map->max_offset);
-	if (start >= end)
-		return 0;
-	if (map->flags & VM_MAP_SYSCALL_ONCE)	/* only allowed once */
-		return (EPERM);
-
-	vm_map_lock(map);
-
-	entry = uvm_map_entrybyaddr(&map->addr, start);
-	if (entry->end > start)
-		UVM_MAP_CLIP_START(map, entry, start);
-	else
-		entry = RBT_NEXT(uvm_map_addr, entry);
-
-	while (entry != NULL && entry->start < end) {
-		UVM_MAP_CLIP_END(map, entry, end);
-		entry->etype |= UVM_ET_SYSCALL;
-		entry = RBT_NEXT(uvm_map_addr, entry);
-	}
-
-#ifdef PMAP_CHECK_COPYIN
-	check_copyin_add(map, start, end);	/* Add libc's text segment */
-#endif
-	map->wserial++;
-	map->flags |= VM_MAP_SYSCALL_ONCE;
-	vm_map_unlock(map);
-	return (0);
-}
-
 /* 
  * uvm_map_immutable: block mapping/mprotect for range of addrs in map.
  *
@@ -4328,8 +4249,6 @@ uvm_map_immutable(struct vm_map *map, vaddr_t start, vaddr_t end, int imut)
 			entry->etype &= ~UVM_ET_IMMUTABLE;
 		entry = RBT_NEXT(uvm_map_addr, entry);
 	}
-
-	map->wserial++;
 	error = 0;
 out:
 	vm_map_unlock(map);
diff --git a/sys/uvm/uvm_map.h b/sys/uvm/uvm_map.h
index b1f53696f7a..2fd80e85888 100644
--- a/sys/uvm/uvm_map.h
+++ b/sys/uvm/uvm_map.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_map.h,v 1.88 2024/01/16 19:05:01 deraadt Exp $	*/
+/*	$OpenBSD: uvm_map.h,v 1.89 2024/04/02 08:39:17 deraadt Exp $	*/
 /*	$NetBSD: uvm_map.h,v 1.24 2001/02/18 21:19:08 chs Exp $	*/
 
 /*
@@ -261,7 +261,6 @@ RBT_PROTOTYPE(uvm_map_addr, vm_map_entry, daddrs.addr_entry,
 struct vm_map {
 	struct pmap		*pmap;		/* [I] Physical map */
 	u_long			sserial;	/* [v] # stack changes */
-	u_long			wserial;	/* [v] # PROT_WRITE increases */
 
 	struct uvm_map_addr	addr;		/* [v] Entry tree, by addr */
 
@@ -328,7 +327,6 @@ struct vm_map {
 #define	VM_MAP_WANTLOCK		0x10		/* rw: want to write-lock */
 #define	VM_MAP_GUARDPAGES	0x20		/* rw: add guard pgs to map */
 #define	VM_MAP_ISVMSPACE	0x40		/* ro: map is a vmspace */
-#define	VM_MAP_SYSCALL_ONCE	0x80		/* rw: libc syscall registered */
 #define	VM_MAP_PINSYSCALL_ONCE	0x100		/* rw: pinsyscall done */
 
 /* Number of kernel maps and entries to statically allocate */
@@ -358,7 +356,6 @@ struct vm_map *	uvm_map_create(pmap_t, vaddr_t, vaddr_t, int);
 vaddr_t		uvm_map_pie(vaddr_t);
 vaddr_t		uvm_map_hint(struct vmspace *, vm_prot_t, vaddr_t, vaddr_t);
 int		uvm_map_check_copyin_add(struct vm_map *, vaddr_t, vaddr_t);
-int		uvm_map_syscall(struct vm_map *, vaddr_t, vaddr_t);
 int		uvm_map_immutable(struct vm_map *, vaddr_t, vaddr_t, int);
 int		uvm_map_inherit(struct vm_map *, vaddr_t, vaddr_t, vm_inherit_t);
 int		uvm_map_advice(struct vm_map *, vaddr_t, vaddr_t, int);
@@ -385,7 +382,6 @@ int		uvm_map_mquery(struct vm_map*, vaddr_t*, vsize_t, voff_t, int);
 struct p_inentry;
 
 int		uvm_map_inentry_sp(vm_map_entry_t);
-int		uvm_map_inentry_pc(vm_map_entry_t);
 boolean_t	uvm_map_inentry(struct proc *, struct p_inentry *, vaddr_t addr,
 		    const char *fmt, int (*fn)(vm_map_entry_t), u_long serial);
 
diff --git a/sys/uvm/uvm_mmap.c b/sys/uvm/uvm_mmap.c
index c0205f26781..4148367ebad 100644
--- a/sys/uvm/uvm_mmap.c
+++ b/sys/uvm/uvm_mmap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_mmap.c,v 1.186 2024/03/28 02:19:57 deraadt Exp $	*/
+/*	$OpenBSD: uvm_mmap.c,v 1.187 2024/04/02 08:39:17 deraadt Exp $	*/
 /*	$NetBSD: uvm_mmap.c,v 1.49 2001/02/18 21:19:08 chs Exp $	*/
 
 /*
@@ -592,24 +592,7 @@ sys_mprotect(struct proc *p, void *v, register_t *retval)
 int
 sys_msyscall(struct proc *p, void *v, register_t *retval)
 {
-	struct sys_msyscall_args /* {
-		syscallarg(void *) addr;
-		syscallarg(size_t) len;
-	} */ *uap = v;
-	vaddr_t addr;
-	vsize_t size, pageoff;
-
-	addr = (vaddr_t)SCARG(uap, addr);
-	size = (vsize_t)SCARG(uap, len);
-
-	/*
-	 * align the address to a page boundary, and adjust the size accordingly
-	 */
-	ALIGN_ADDR(addr, size, pageoff);
-	if (addr > SIZE_MAX - size)
-		return EINVAL;		/* disallow wrap-around. */
-
-	return uvm_map_syscall(&p->p_vmspace->vm_map, addr, addr+size);
+	return 0;
 }
 
 /*