[PATCH 2/8] xen/x86-64: clean up warnings about IST-using traps

Jeremy Fitzhardinge
2009-05-08T00:16:51Z

From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

Ignore known IST-using traps. Aside from the debugger traps, they're
low-level faults which Xen will handle for us, so the kernel needn't
worry about them. Keep warning in case unknown trap starts using IST.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
---
arch/x86/xen/enlighten.c | 22 ++++++++++++++++++++--
1 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 16afbc3..cbb31eb 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -439,12 +439,30 @@ static int cvt_gate_to_trap(int vector, const gate_desc *val,

addr = gate_offset(*val);
#ifdef CONFIG_X86_64
+ /*
+ * Look for known traps using IST, and substitute them
+ * appropriately. The debugger ones are the only ones we care
+ * about. Xen will handle faults like double_fault and
+ * machine_check, so we should never see them. Warn if
+ * there's an unexpected IST-using fault handler.
+ */
if (addr == (unsigned long)debug)
addr = (unsigned long)xen_debug;
else if (addr == (unsigned long)int3)
addr = (unsigned long)xen_int3;
- else
- WARN_ON(val->ist != 0);
+ else if (addr == (unsigned long)double_fault ||
+ addr == (unsigned long)stack_segment) {
+ /* Don't need to handle these */
+ return 0;
+#ifdef CONFIG_X86_MCE
+ } else if (addr == (unsigned long)machine_check) {
+ return 0;
+#endif
+ } else {
+ /* Some other trap using IST? */
+ if (WARN_ON(val->ist != 0))
+ return 0;
+ }
#endif /* CONFIG_X86_64 */
info->address = addr;

--
1.6.0.6