Place a cpu-dependent trap/illegal instruction over the remainder of the

sigtramp page, so that it will generate a nice kernel fault if touched.
While here, move most of the sigtramps to the .rodata segment, because
they are not executed in the kernel.
Also some preparation for sliding the actual sigtramp forward (will need
some gdb changes)
ok mlarkin kettenis

12 files changed, 166 insertions, 21 deletions

diff --git a/sys/arch/alpha/alpha/locore.s b/sys/arch/alpha/alpha/locore.s
index 6d6354f079f..61445b260d6 100644
--- a/sys/arch/alpha/alpha/locore.s
+++ b/sys/arch/alpha/alpha/locore.s
@@ -1,4 +1,4 @@
-/* $OpenBSD: locore.s,v 1.44 2016/05/10 18:39:40 deraadt Exp $ */
+/* $OpenBSD: locore.s,v 1.45 2016/05/23 20:11:48 deraadt Exp $ */
 /* $NetBSD: locore.s,v 1.94 2001/04/26 03:10:44 ross Exp $ */
 
 /*-
@@ -266,6 +266,7 @@ backtolocore1:
  *      scp+0	beginning of signal context frame
  */
 
+	.section .rodata
 NESTED(sigcode,0,0,ra,0,0)
 	lda	sp, -16(sp)		/* save the sigcontext pointer */
 	stq	a2, 0(sp)
@@ -280,6 +281,17 @@ sigcoderet:
 XNESTED(esigcode,0)
 	END(sigcode)
 
+	.globl	sigfill
+sigfill:
+	halt
+esigfill:
+
+	.globl	sigfillsiz
+sigfillsiz:
+	.quad	esigfill - sigfill
+
+	.text
+
 /**************************************************************************/
 
 /*
diff --git a/sys/arch/amd64/amd64/locore.S b/sys/arch/amd64/amd64/locore.S
index bad043377b4..11b886740d1 100644
--- a/sys/arch/amd64/amd64/locore.S
+++ b/sys/arch/amd64/amd64/locore.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: locore.S,v 1.78 2016/05/10 18:39:42 deraadt Exp $	*/
+/*	$OpenBSD: locore.S,v 1.79 2016/05/23 20:11:49 deraadt Exp $	*/
 /*	$NetBSD: locore.S,v 1.13 2004/03/25 18:33:17 drochner Exp $	*/
 
 /*
@@ -756,20 +756,31 @@ longmode_hi:
  * Signal trampoline; copied to top of user stack.
  * gdb's backtrace logic matches against the instructions in this.
  */
-NENTRY(sigcode)
+	.section .rodata
+	.globl	_C_LABEL(sigcode)
+_C_LABEL(sigcode):
 	call	*%rax
 
 	movq	%rsp,%rdi
 	pushq	%rdi			/* fake return address */
 	movq	$SYS_sigreturn,%rax
 	syscall
-	.globl  _C_LABEL(sigcoderet)
+	.globl	_C_LABEL(sigcoderet)
 _C_LABEL(sigcoderet):
 	movq	$SYS_exit,%rax
 	syscall
 	.globl	_C_LABEL(esigcode)
 _C_LABEL(esigcode):
 
+	.globl	_C_LABEL(sigfill)
+_C_LABEL(sigfill):
+	int3
+_C_LABEL(esigfill):
+	.globl	_C_LABEL(sigfillsiz)
+_C_LABEL(sigfillsiz):
+	.long	_C_LABEL(esigfill) - _C_LABEL(sigfill)
+
+	.text
 /*
  * void lgdt(struct region_descriptor *rdp);
  * Change the global descriptor table.
diff --git a/sys/arch/arm/arm/sigcode.S b/sys/arch/arm/arm/sigcode.S
index dc38068e482..2e0cfef9aa7 100644
--- a/sys/arch/arm/arm/sigcode.S
+++ b/sys/arch/arm/arm/sigcode.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: sigcode.S,v 1.3 2016/05/10 18:39:43 deraadt Exp $	*/
+/*	$OpenBSD: sigcode.S,v 1.4 2016/05/23 20:11:49 deraadt Exp $	*/
 /*	$NetBSD: sigcode.S,v 1.6 2003/10/05 19:44:58 matt Exp $	*/
 
 /*
@@ -41,7 +41,11 @@
  * Signal trampoline; 
  */
 
-ENTRY_NP(sigcode)
+	.section .rodata
+	.align	0
+	.globl	sigcode
+	.type	x,_ASM_TYPE_FUNCTION
+sigcode:
 /*
  * The kernel arranges for the handler to be invoked directly.  This
  * trampoline is used only to return from the signal.
@@ -63,3 +67,15 @@ _C_LABEL(sigcoderet):
 	.align	0
         .global _C_LABEL(esigcode)
 _C_LABEL(esigcode):
+
+	.globl	sigfill
+sigfill:
+	.word	0xa000f7f0		/* illegal on all cpus? */
+esigfill:
+
+	.data
+	.globl	sigfillsiz
+sigfillsiz:
+	.word	esigfill - sigfill
+
+	.text
diff --git a/sys/arch/hppa/hppa/locore.S b/sys/arch/hppa/hppa/locore.S
index 037e3b8e72a..785da2d1daf 100644
--- a/sys/arch/hppa/hppa/locore.S
+++ b/sys/arch/hppa/hppa/locore.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: locore.S,v 1.194 2016/05/10 18:39:44 deraadt Exp $	*/
+/*	$OpenBSD: locore.S,v 1.195 2016/05/23 20:11:49 deraadt Exp $	*/
 
 /*
  * Copyright (c) 1998-2004 Michael Shalayeff
@@ -3027,7 +3027,14 @@ EXIT(hw_cpu_spinup_trampoline)
 /*
  * Signal "trampoline" code. Invoked from RTE setup by sendsig().
  */
-ENTRY(sigcode,0)
+	.section .rodata
+	.align 4
+	.export	sigcode, entry
+	.label sigcode
+	.proc
+	.callinfo frame=0,calls, save_rp, save_sp
+	.entry
+sigcode:
 	bb,>=,n	arg3, 30, sigcode_call
 	dep	r0, 31, 2, arg3
 	ldw	4(arg3), r19
@@ -3053,4 +3060,15 @@ sigcoderet:
 ALTENTRY(esigcode)
 EXIT(sigcode)
 
+	.globl	sigfill
+sigfill:
+	break	0,0
+esigfill:
+	.align	4
+	.globl	sigfillsiz
+sigfillsiz:
+	.word	esigfill - sigfill
+
+	.text
+
 	.end
diff --git a/sys/arch/i386/i386/locore.s b/sys/arch/i386/i386/locore.s
index f143d75008d..73221f8d86d 100644
--- a/sys/arch/i386/i386/locore.s
+++ b/sys/arch/i386/i386/locore.s
@@ -1,4 +1,4 @@
-/*	$OpenBSD: locore.s,v 1.168 2016/05/10 18:39:45 deraadt Exp $	*/
+/*	$OpenBSD: locore.s,v 1.169 2016/05/23 20:11:49 deraadt Exp $	*/
 /*	$NetBSD: locore.s,v 1.145 1996/05/03 19:41:19 christos Exp $	*/
 
 /*-
@@ -689,7 +689,9 @@ _C_LABEL(codepatch_end):
 /*
  * Signal trampoline; copied to top of user stack.
  */
-NENTRY(sigcode)
+	.section .rodata
+	.globl	_C_LABEL(sigcode)
+_C_LABEL(sigcode):
 	call	*SIGF_HANDLER(%esp)
 	leal	SIGF_SC(%esp),%eax	# scp (the call may have clobbered the
 					# copy at SIGF_SCP(%esp))
@@ -697,13 +699,25 @@ NENTRY(sigcode)
 	pushl	%eax			# junk to fake return address
 	movl	$SYS_sigreturn,%eax
 	int	$0x80			# enter kernel with args on stack
-	.globl  _C_LABEL(sigcoderet)
+	.globl	_C_LABEL(sigcoderet)
 _C_LABEL(sigcoderet):
 	movl	$SYS_exit,%eax
 	int	$0x80			# exit if sigreturn fails
 	.globl	_C_LABEL(esigcode)
 _C_LABEL(esigcode):
 
+	.globl	_C_LABEL(sigfill)
+_C_LABEL(sigfill):
+	int3
+_C_LABEL(esigfill):
+
+	.data
+	.globl	_C_LABEL(sigfillsiz)
+_C_LABEL(sigfillsiz):
+	.long	_C_LABEL(esigfill) - _C_LABEL(sigfill)
+
+	.text
+
 /*****************************************************************************/
 
 /*
diff --git a/sys/arch/macppc/macppc/locore.S b/sys/arch/macppc/macppc/locore.S
index f042f47acc6..ce18aaf1f2b 100644
--- a/sys/arch/macppc/macppc/locore.S
+++ b/sys/arch/macppc/macppc/locore.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: locore.S,v 1.54 2016/05/10 18:39:46 deraadt Exp $	*/
+/*	$OpenBSD: locore.S,v 1.55 2016/05/23 20:11:49 deraadt Exp $	*/
 /*	$NetBSD: locore.S,v 1.2 1996/10/16 19:33:09 ws Exp $	*/
 
 /*
@@ -1206,6 +1206,7 @@ _C_LABEL(setfault):
  * On entry r1 points to a struct sigframe at bottom of current stack.
  * All other registers are unchanged.
  */
+	.section .rodata
 	.globl	_C_LABEL(sigcode),_C_LABEL(esigcode)
 	.type	_C_LABEL(sigcode),@function
 	.type	_C_LABEL(esigcode),@function
@@ -1256,6 +1257,16 @@ _C_LABEL(sigcoderet):
 	sc				/* exit(errno) */
 _C_LABEL(esigcode):
 
+	.globl  _C_LABEL(sigfill)
+_C_LABEL(sigfill):
+	.long	0		# illegal
+_C_LABEL(esigfill):
+	.align	4
+	.globl	_C_LABEL(sigfillsiz)
+_C_LABEL(sigfillsiz):
+	.long	_C_LABEL(esigfill) - _C_LABEL(sigfill)
+
+	.text
 
 #ifdef DDB
 /*
diff --git a/sys/arch/mips64/mips64/lcore_access.S b/sys/arch/mips64/mips64/lcore_access.S
index e6c9a53143e..cbc8aa7bcb8 100644
--- a/sys/arch/mips64/mips64/lcore_access.S
+++ b/sys/arch/mips64/mips64/lcore_access.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: lcore_access.S,v 1.25 2016/05/10 18:39:47 deraadt Exp $ */
+/*	$OpenBSD: lcore_access.S,v 1.26 2016/05/23 20:11:49 deraadt Exp $ */
 
 /*
  * Copyright (c) 2001-2003 Opsycon AB  (www.opsycon.se / www.opsycon.com)
@@ -83,6 +83,18 @@ _C_LABEL(sigcoderet):
 	.globl	esigcode
 esigcode:
 
+	.globl	sigfill
+sigfill:
+	break	0
+esigfill:
+
+	.data
+	.globl	sigfillsiz
+sigfillsiz:
+	.long	esigfill - sigfill
+
+	.text
+
 /*
  * Copy a null terminated string within the kernel address space.
  * Maxlength may be null if count not wanted.
diff --git a/sys/arch/sh/sh/locore_subr.S b/sys/arch/sh/sh/locore_subr.S
index ec1d1e6b87f..616a11e7f6a 100644
--- a/sys/arch/sh/sh/locore_subr.S
+++ b/sys/arch/sh/sh/locore_subr.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: locore_subr.S,v 1.11 2016/05/10 18:39:47 deraadt Exp $	*/
+/*	$OpenBSD: locore_subr.S,v 1.12 2016/05/23 20:11:49 deraadt Exp $	*/
 /*	$NetBSD: locore_subr.S,v 1.28 2006/01/23 22:52:09 uwe Exp $	*/
 
 /*
@@ -508,6 +508,18 @@ _C_LABEL(sigcoderet):
 _C_LABEL(esigcode):
 	SET_ENTRY_SIZE(sigcode)
 
+	.globl	sigfill
+sigfill:
+	sleep		/* priviledged -> illegal? */
+esigfill:
+
+	.data
+	.globl	sigfillsiz
+sigfillsiz:
+	.word	esigfill - sigfill
+
+	.text
+
 /*
  * LINTSTUB: Func: void savectx(struct pcb *pcb)
  *	save struct switchframe.
diff --git a/sys/arch/socppc/socppc/locore.S b/sys/arch/socppc/socppc/locore.S
index 38a5bb01731..eb70347517c 100644
--- a/sys/arch/socppc/socppc/locore.S
+++ b/sys/arch/socppc/socppc/locore.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: locore.S,v 1.21 2016/05/10 18:39:48 deraadt Exp $	*/
+/*	$OpenBSD: locore.S,v 1.22 2016/05/23 20:11:49 deraadt Exp $	*/
 /*	$NetBSD: locore.S,v 1.2 1996/10/16 19:33:09 ws Exp $	*/
 
 /*
@@ -1225,6 +1225,7 @@ _C_LABEL(setfault):
  * On entry r1 points to a struct sigframe at bottom of current stack.
  * All other registers are unchanged.
  */
+	.section .rodata
 	.globl	_C_LABEL(sigcode),_C_LABEL(esigcode)
 	.type	_C_LABEL(sigcode),@function
 	.type	_C_LABEL(esigcode),@function
@@ -1275,6 +1276,16 @@ _C_LABEL(sigcoderet):
 	sc				/* exit(errno) */
 _C_LABEL(esigcode):
 
+	.globl  _C_LABEL(sigfill)
+_C_LABEL(sigfill):
+	.long	0		# illegal
+_C_LABEL(esigfill):
+	.align	4
+	.globl	_C_LABEL(sigfillsiz)
+_C_LABEL(sigfillsiz):
+	.long	_C_LABEL(esigfill) - _C_LABEL(sigfill)
+
+	.text
 
 #ifdef DDB
 /*
diff --git a/sys/arch/sparc/sparc/locore.s b/sys/arch/sparc/sparc/locore.s
index 7a4556a59df..d6de7c3f28a 100644
--- a/sys/arch/sparc/sparc/locore.s
+++ b/sys/arch/sparc/sparc/locore.s
@@ -1,4 +1,4 @@
-/*	$OpenBSD: locore.s,v 1.100 2016/05/11 20:21:26 phessler Exp $	*/
+/*	$OpenBSD: locore.s,v 1.101 2016/05/23 20:11:49 deraadt Exp $	*/
 /*	$NetBSD: locore.s,v 1.73 1997/09/13 20:36:48 pk Exp $	*/
 
 /*
@@ -3916,7 +3916,6 @@ Lgandul:	nop
  * work out.
  */
 	.globl	_C_LABEL(sigcode)
-	.globl	_C_LABEL(esigcode)
 _C_LABEL(sigcode):
 	/*
 	 * XXX  the `save' and `restore' below are unnecessary: should
@@ -4022,8 +4021,20 @@ _C_LABEL(suicide):
 	mov	139, %g1		! obsolete syscall, puke...
 	t	ST_SYSCALL
 #endif
+	.globl	_C_LABEL(esigcode)
 _C_LABEL(esigcode):
 
+	.globl	_C_LABEL(sigfill)
+_C_LABEL(sigfill):
+	unimp
+_C_LABEL(esigfill):
+
+	.globl	_C_LABEL(sigfillsiz)
+_C_LABEL(sigfillsiz):
+	.word	_C_LABEL(esigfill) - _C_LABEL(sigfill)
+
+	.text
+
 /*
  * Primitives
  */
diff --git a/sys/arch/sparc64/sparc64/locore.s b/sys/arch/sparc64/sparc64/locore.s
index b1a8a1d9dca..729bb1a8fe4 100644
--- a/sys/arch/sparc64/sparc64/locore.s
+++ b/sys/arch/sparc64/sparc64/locore.s
@@ -1,4 +1,4 @@
-/*	$OpenBSD: locore.s,v 1.182 2016/05/10 18:39:49 deraadt Exp $	*/
+/*	$OpenBSD: locore.s,v 1.183 2016/05/23 20:11:49 deraadt Exp $	*/
 /*	$NetBSD: locore.s,v 1.137 2001/08/13 06:10:10 jdolecek Exp $	*/
 
 /*
@@ -5338,8 +5338,8 @@ dlflush4:
  * will eventually be removed, with a hole left in its place, if things
  * work out.
  */
+	.section .rodata
 	.globl	_C_LABEL(sigcode)
-	.globl	_C_LABEL(esigcode)
 _C_LABEL(sigcode):
 	/*
 	 * XXX  the `save' and `restore' below are unnecessary: should
@@ -5435,8 +5435,19 @@ _C_LABEL(sigcoderet):
 	! sigreturn does not return unless it fails
 	mov	SYS_exit, %g1		! exit(errno)
 	t	ST_SYSCALL
+	.globl	_C_LABEL(esigcode)
 _C_LABEL(esigcode):
 
+	.globl	_C_LABEL(sigfill)
+_C_LABEL(sigfill):
+	unimp
+_C_LABEL(esigfill):
+
+	.globl	_C_LABEL(sigfillsiz)
+_C_LABEL(sigfillsiz):
+	.word	_C_LABEL(esigfill) - _C_LABEL(sigfill)
+
+	.text
 
 /*
  * Primitives
diff --git a/sys/kern/kern_exec.c b/sys/kern/kern_exec.c
index ced0bb86c51..d7b1f3e360a 100644
--- a/sys/kern/kern_exec.c
+++ b/sys/kern/kern_exec.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_exec.c,v 1.177 2016/05/10 18:39:51 deraadt Exp $	*/
+/*	$OpenBSD: kern_exec.c,v 1.178 2016/05/23 20:11:47 deraadt Exp $	*/
 /*	$NetBSD: kern_exec.c,v 1.75 1996/02/09 18:59:28 christos Exp $	*/
 
 /*-
@@ -843,6 +843,9 @@ exec_sigcode_map(struct process *pr, struct emul *e)
 	 * the way sys_mmap would map it.
 	 */
 	if (e->e_sigobject == NULL) {
+		extern int sigfillsiz;
+		extern u_char sigfill[];
+		size_t off;
 		vaddr_t va;
 		int r;
 
@@ -855,7 +858,10 @@ exec_sigcode_map(struct process *pr, struct emul *e)
 			uao_detach(e->e_sigobject);
 			return (ENOMEM);
 		}
-		memcpy((void *)va, e->e_sigcode, sz);
+
+		for (off = 0; off < round_page(sz); off += sigfillsiz)
+			memcpy((caddr_t)va + off, sigfill, sigfillsiz);
+		memcpy((caddr_t)va, e->e_sigcode, sz);
 		uvm_unmap(kernel_map, va, va + round_page(sz));
 	}