ddk: missing chkstk.S

git-svn-id: svn://kolibrios.org@1873 a494cfbc-eb01-0410-851d-a64ba20cac60

drivers/ddk/debug/chkstk.S

@@ -0,0 +1,31 @@
+
+.global ___chkstk
+.global __alloca
+
+.section .text
+
+.align 4
+___chkstk:
+__alloca:
+        pushl   %ecx            /* save temp */
+        leal    8(%esp), %ecx   /* point past return addr */
+        subl    %eax, %ecx
+        call *__imp__GetStackBase
+        cmpl    %eax, %ecx      # check low stack limit
+        jb      1f
+
+        movl    %esp, %eax      /* save old stack pointer */
+        movl    %ecx, %esp      /* decrement stack */
+        movl    (%eax), %ecx    /* recover saved temp */
+        movl    4(%eax), %eax   /* recover return address */
+
+        /* Push the return value back.  Doing this instead of just
+           jumping to %eax preserves the cached call-return stack
+           used by most modern processors.  */
+        pushl   %eax
+        ret
+1:
+        int3                    #trap to debugger.
+                                #Oh wait... there is no kernel debugger
+        .ascii "Stack overflow"
+