# HG changeset patch
# User john.levon@sun.com
# Date 1179888079 25200
# Node ID 16f72321a6fc567d9764faef5729263b5101dbe8
# Parent 01982a3f30dcb842e493e1252d85d970a7055ab2
Prevent an infinite series of traps
In some cases, we can end up in a vicious cycle of fatal_trap()s
within fatal_trap()s. Panic after a certain number of attempts.
Signed-off-by: Nils Nieuwejaar <nils.nieuwejaar@sun.com>
diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -375,16 +375,25 @@ char *trapstr(int trapnr)
*/
asmlinkage void fatal_trap(int trapnr, struct cpu_user_regs *regs)
{
- watchdog_disable();
- console_start_sync();
-
- show_execution_state(regs);
-
- if ( trapnr == TRAP_page_fault )
- {
- unsigned long cr2 = read_cr2();
- printk("Faulting linear address: %p\n", _p(cr2));
- show_page_walk(cr2);
+ static int depth = 0;
+
+ /*
+ * In some cases, we can end up in a vicious cycle of fatal_trap()s
+ * within fatal_trap()s. We give the problem a couple of iterations to
+ * bottom out, and then we just panic.
+ */
+ if (depth++ < 3) {
+ watchdog_disable();
+ console_start_sync();
+
+ show_execution_state(regs);
+
+ if ( trapnr == TRAP_page_fault )
+ {
+ unsigned long cr2 = read_cr2();
+ printk("Faulting linear address: %p\n", _p(cr2));
+ show_page_walk(cr2);
+ }
}
panic("FATAL TRAP: vector = %d (%s)\n"
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Jan Beulich
2007-May-23 09:42 UTC
Re: [Xen-devel] [PATCH] Prevent an infinite series of traps
Could the depth variable at least be made a per-CPU one, to prevent missing simultaneous traps on many different CPUs? Jan>>> John Levon <levon@movementarian.org> 05/23/07 4:53 AM >>># HG changeset patch # User john.levon@sun.com # Date 1179888079 25200 # Node ID 16f72321a6fc567d9764faef5729263b5101dbe8 # Parent 01982a3f30dcb842e493e1252d85d970a7055ab2 Prevent an infinite series of traps In some cases, we can end up in a vicious cycle of fatal_trap()s within fatal_trap()s. Panic after a certain number of attempts. Signed-off-by: Nils Nieuwejaar <nils.nieuwejaar@sun.com> diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c --- a/xen/arch/x86/traps.c +++ b/xen/arch/x86/traps.c @@ -375,16 +375,25 @@ char *trapstr(int trapnr) */ asmlinkage void fatal_trap(int trapnr, struct cpu_user_regs *regs) { - watchdog_disable(); - console_start_sync(); - - show_execution_state(regs); - - if ( trapnr == TRAP_page_fault ) - { - unsigned long cr2 = read_cr2(); - printk("Faulting linear address: %p\n", _p(cr2)); - show_page_walk(cr2); + static int depth = 0; + + /* + * In some cases, we can end up in a vicious cycle of fatal_trap()s + * within fatal_trap()s. We give the problem a couple of iterations to + * bottom out, and then we just panic. + */ + if (depth++ < 3) { + watchdog_disable(); + console_start_sync(); + + show_execution_state(regs); + + if ( trapnr == TRAP_page_fault ) + { + unsigned long cr2 = read_cr2(); + printk("Faulting linear address: %p\n", _p(cr2)); + show_page_walk(cr2); + } } panic("FATAL TRAP: vector = %d (%s)\n" _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel