[Xen-devel] [xen-devel] [Patch 4/4] DO NOT APPLY: Test code for interesting stack overflows

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

---
 xen/arch/x86/traps.c |   71 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)

diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index 17255d5..f5e99c1 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -34,6 +34,7 @@
 #include <xen/console.h>
 #include <xen/shutdown.h>
 #include <xen/guest_access.h>
+#include <xen/keyhandler.h>
 #include <asm/regs.h>
 #include <xen/delay.h>
 #include <xen/event.h>
@@ -3742,6 +3743,76 @@ unsigned long do_get_debugreg(int reg)
     return -EINVAL;
 }
 
+static noinline void recursion(int depth)
+{
+    /* junk on stack to fool naive algorithm */
+    volatile unsigned long addr1 = (unsigned long)&do_get_debugreg;
+    volatile unsigned long tsc;
+    volatile unsigned long addr2 = (unsigned long)&do_set_debugreg;
+
+    if ( depth == 0 )
+    {
+        printk("Did you mean recursion()?\n");
+        run_in_exception_handler(show_stack);
+        return;
+    }
+    else
+    {
+        rdtscll(tsc);
+        printk("depth %d, addr1 0x%016"PRIx64", addr2 0x%016"PRIx64", tsc 
%"PRIu64"\n",
+               depth, addr1, addr2, tsc);
+        recursion(depth-1);
+        printk("done\n"); /* So GCC cant perform tailcall optimisation */
+    }
+}
+
+static void stacktest1(unsigned char key)
+{
+    printk("In %s()\n", __func__);
+    recursion(5);
+}
+
+static void stacktest2(unsigned char key, struct cpu_user_regs * regs)
+{
+    printk("In %s()\n", __func__);
+    recursion(5);
+}
+
+static void stacktest3(unsigned char key)
+{
+    printk("In %s()\n", __func__);
+    recursion(500);
+}
+
+static struct keyhandler stacktest_handler[] = {
+    {
+        .irq_callback = 0,
+        .u.fn = stacktest1,
+        .desc = "Xen stack #1 - Recurse a little and see trace."
+    },
+
+    {
+        .irq_callback = 1,
+        .u.irq_fn = stacktest2,
+        .desc = "Xen stack #2 - Recurse a little and see trace in irq."
+    },
+
+    {
+        .irq_callback = 0,
+        .u.fn = stacktest3,
+        .desc = "Xen stack #3 - Cause stack overflow."
+    },
+ };
+
+static int __init initialize_crashtable(void)
+{
+    register_keyhandler('1', &stacktest_handler[0]);
+    register_keyhandler('2', &stacktest_handler[1]);
+    register_keyhandler('3', &stacktest_handler[2]);
+    return 1;
+}
+__initcall(initialize_crashtable);
+
 /*
  * Local variables:
  * mode: C
-- 
1.7.10.4


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