tests/win32-stack-unwind.c

   1 /* Compiled and loaded by win32-foreign-stack-unwind.impure.lisp
   2  *
   3  * establish_return_frame(callback_ptr) establishes an SEH frame
   4  * that will cause an unwind to itself followed by a return on
   5  * any exception, and then calls the callback_ptr.
   6  *
   7  * perform_test_unwind() does an unwind to the SEH frame
   8  * established by establish_return_frame().
   9  *
  10  * The name of the game for the tests is to establish a callback
  11  * that establishes something with a dynamic contour and
  12  * possibly a control transfer semantic (such as a binding or an
  13  * unwind-protect) and then call perform_test_unwind() or cause
  14  * an exception that should be handled by SBCL and see what
  15  * breaks.
  16  */
  17
  18 /* This software is part of the SBCL system. See the README file for
  19  * more information.
  20  *
  21  * While most of SBCL is derived from the CMU CL system, the test
  22  * files (like this one) were written from scratch after the fork
  23  * from CMU CL.
  24  *
  25  * This software is in the public domain and is provided with
  26  * absolutely no warranty. See the COPYING and CREDITS files for
  27  * more information.
  28  */
  29
  30 #include <stdio.h>
  31 #include <stdlib.h>
  32
  33 #define WIN32_LEAN_AND_MEAN
  34 #include <windows.h>
  35 #include <excpt.h>
  36
  37 #include <setjmp.h>
  38
  39 /* The "public" API */
  40
  41 typedef void (*callback_ptr)(void);
  42
  43 void establish_return_frame(callback_ptr callback);
  44 void perform_test_unwind(void);
  45
  46
  47 /* The implementation */
  48
  49 static
  50 void **saved_exception_frame;
  51
  52 static
  53 DWORD saved_ebp;
  54
  55 static void *get_seh_frame(void)
  56 {
  57     void* retval;
  58     asm volatile ("movl %%fs:0,%0": "=r" (retval));
  59     return retval;
  60 }
  61
  62 static void set_seh_frame(void *frame)
  63 {
  64     asm volatile ("movl %0,%%fs:0": : "r" (frame));
  65 }
  66
  67
  68 static
  69 EXCEPTION_DISPOSITION handle_exception(EXCEPTION_RECORD *exception_record,
  70                                        void **exception_frame,
  71                                        CONTEXT *context,
  72                                        void *dc)
  73 {
  74     /* If an exception occurs and is passed to us to handle, just
  75      * unwind.  One or more test cases check for SBCL handling
  76      * breakpoint exceptions properly.  This makes sure that it
  77      * doesn't unless a new exception frame is estabished when a
  78      * callback occurs. */
  79     if (!(exception_record->ExceptionFlags
  80           & (EH_UNWINDING | EH_EXIT_UNWIND))) {
  81         perform_test_unwind();
  82     }
  83
  84     return ExceptionContinueSearch;
  85 }
  86
  87 static void
  88   __attribute__((returns_twice))
  89   invoke_callback(callback_ptr callback, DWORD *unwind_token);
  90
  91 asm("_invoke_callback:"
  92     "pushl %ebp; movl %esp, %ebp;"
  93     "movl 12(%ebp), %eax;"
  94     "movl %ebp, (%eax);"
  95     "call *8(%ebp);"
  96     "movl %ebp, %esp; popl %ebp; ret");
  97
  98 static void do_unwind(void *target_frame, DWORD unwind_token);
  99 asm("_do_unwind:"
 100     "pushl $target; pushl %ebp; movl %esp, %ebp;"
 101     "pushl $0xcafe; pushl $0; pushl $-1; pushl 12(%ebp); call _RtlUnwind@16;"
 102     "target:"
 103     "movl 16(%ebp), %esp; popl %ebp; ret");
 104
 105
 106 void establish_return_frame(callback_ptr callback)
 107 {
 108     void *exception_frame[2];
 109
 110     saved_exception_frame = exception_frame;
 111     exception_frame[0] = get_seh_frame();
 112     exception_frame[1] = handle_exception;
 113     set_seh_frame(exception_frame);
 114
 115     /* Do a setjmp just to explicitly spill callee-saved registers, i.e.
 116      * the portable equivalent of:
 117      *   asm("" : : : "%esi", "%edi", "%ebx");
 118      * which is needed because otherwise those registers would be trashed
 119      * following the stack unwind, and leave us with a likely crash upon
 120      * return to call_into_c.
 121      *
 122      * The returns_twice attribute on invoke_callback should take care
 123      * of this already, but does not seem to take effect, at least with
 124      * the version of gcc I am using.
 125      *
 126      * Note: __builtin_setjmp, not setjmp, because only the former has
 127      * the desired effect on the immediate call site. */
 128     jmp_buf env;
 129     __builtin_setjmp(env);
 130
 131     invoke_callback(callback, &saved_ebp);
 132
 133     if (exception_frame != get_seh_frame()) {
 134         /* It is never good for this to happen. */
 135         printf("exception frame mismatch on callback return.\n");
 136     }
 137
 138     set_seh_frame(exception_frame[0]);
 139 }
 140
 141 void perform_test_unwind(void)
 142 {
 143     do_unwind(saved_exception_frame, saved_ebp);
 144 }
 145
 146 /* EOF */