[src/trunk]: src/sys/arch/usermode/usermode Prevent nested SIGIOs ruining the...

[reinoud <reinoud%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/e2bac85966e8
branches:  trunk
changeset: 319788:e2bac85966e8
user:      reinoud <reinoud%NetBSD.org@localhost>
date:      Mon Jun 11 19:23:21 2018 +0000

description:
Prevent nested SIGIOs ruining the system stack

diffstat:

 sys/arch/usermode/usermode/trap.c |  14 ++++++++++----
 1 files changed, 10 insertions(+), 4 deletions(-)

diffs (42 lines):

diff -r b62ff1b4718b -r e2bac85966e8 sys/arch/usermode/usermode/trap.c
--- a/sys/arch/usermode/usermode/trap.c Mon Jun 11 19:13:38 2018 +0000
+++ b/sys/arch/usermode/usermode/trap.c Mon Jun 11 19:23:21 2018 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: trap.c,v 1.67 2018/05/18 20:24:16 reinoud Exp $ */
+/* $NetBSD: trap.c,v 1.68 2018/06/11 19:23:21 reinoud Exp $ */
 
 /*-
  * Copyright (c) 2011 Reinoud Zandijk <reinoud%netbsd.org@localhost>
@@ -27,7 +27,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: trap.c,v 1.67 2018/05/18 20:24:16 reinoud Exp $");
+__KERNEL_RCSID(0, "$NetBSD: trap.c,v 1.68 2018/06/11 19:23:21 reinoud Exp $");
 
 #include <sys/types.h>
 #include <sys/param.h>
@@ -335,7 +335,9 @@
        if (sig == SIGILL)
                print_illegal_instruction_siginfo(sig, info, ctx, pc, va, sp);
 
-       /* if we're running on a stack of our own, use the system stack */
+       /* currently running on the dedicated signal stack */
+
+       /* if we're running on a userland stack, switch to the system stack */
        from_userland = 0;
        if ((sp < (vaddr_t) pcb->sys_stack) ||
            (sp > (vaddr_t) pcb->sys_stack_top)) {
@@ -361,7 +363,11 @@
        jump_ucp.uc_stack.ss_size = sp - (vaddr_t) pcb->sys_stack;
        jump_ucp.uc_link = (void *) fp; /* link to old frame on stack */
 
-       thunk_sigemptyset(&jump_ucp.uc_sigmask);
+       /* prevent multiple nested SIGIOs */
+       if (sig == SIGIO)
+               thunk_sigfillset(&jump_ucp.uc_sigmask);
+       else
+               thunk_sigemptyset(&jump_ucp.uc_sigmask);
        jump_ucp.uc_flags = _UC_STACK | _UC_CPU | _UC_SIGMASK;
 
        thunk_makecontext(&jump_ucp,