Fix gdb debugging of hypervisor.

This patch:
  * enables the gdbstubs to properly access hypervisor memory;
  * prevents an assertion failure in __spurious_page_fault's call
    to map_domain_page if such accesses fail, by testing in_irq();
  * prints some additional helpful messages;
  * fixes the endianness of register transfers from the gdbstubs
    so that gdb is much less confused.
  * fixes the documentation in docs/misc/crashdb.txt

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/xen/arch/x86/gdbstub.c b/xen/arch/x86/gdbstub.c
index a3af473ee2..3d0d0d0429 100644
--- a/xen/arch/x86/gdbstub.c
+++ b/xen/arch/x86/gdbstub.c
@@ -71,18 +71,20 @@ gdb_arch_read_reg(unsigned long regnum, struct cpu_user_regs *regs,
     gdb_send_reply("", ctx);
 }
 
-/* Like copy_from_user, but safe to call with interrupts disabled.
-   Trust me, and don't look behind the curtain. */
+/*
+ * Use __copy_*_user to make us page-fault safe, but not otherwise restrict
+ * our access to the full virtual address space.
+ */
 unsigned int
 gdb_arch_copy_from_user(void *dest, const void *src, unsigned len)
 {
-    return copy_from_user(dest, src, len);
+    return __copy_from_user(dest, src, len);
 }
 
 unsigned int 
 gdb_arch_copy_to_user(void *dest, const void *src, unsigned len)
 {
-    return copy_to_user(dest, src, len);
+    return __copy_to_user(dest, src, len);
 }
 
 void