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 #ifndef EH_UNWINDING
  40 #define EH_UNWINDING 0x02
  41 #define EH_EXIT_UNWIND 0x04
  42 #endif
  43
  44 /* The "public" API */
  45
  46 typedef void (*callback_ptr)(void);
  47
  48 void establish_return_frame(callback_ptr callback);
  49 void perform_test_unwind(void);
  50
  51
  52 /* The implementation */
  53
  54 static
  55 void **saved_exception_frame;
  56
  57 static
  58 DWORD saved_ebp;
  59
  60 static void *get_seh_frame(void)
  61 {
  62     void* retval;
  63     asm volatile ("movl %%fs:0,%0": "=r" (retval));
  64     return retval;
  65 }
  66
  67 static void set_seh_frame(void *frame)
  68 {
  69     asm volatile ("movl %0,%%fs:0": : "r" (frame));
  70 }
  71
  72
  73 static
  74 EXCEPTION_DISPOSITION handle_exception(EXCEPTION_RECORD *exception_record,
  75                                        void **exception_frame,
  76                                        CONTEXT *context,
  77                                        void *dc)
  78 {
  79     /* If an exception occurs and is passed to us to handle, just
  80      * unwind.  One or more test cases check for SBCL handling
  81      * breakpoint exceptions properly.  This makes sure that it
  82      * doesn't unless a new exception frame is estabished when a
  83      * callback occurs. */
  84     if (!(exception_record->ExceptionFlags
  85           & (EH_UNWINDING | EH_EXIT_UNWIND))) {
  86         perform_test_unwind();
  87     }
  88
  89     return ExceptionContinueSearch;
  90 }
  91
  92 static void
  93   __attribute__((returns_twice))
  94   invoke_callback(callback_ptr callback, DWORD *unwind_token);
  95
  96 asm("_invoke_callback:"
  97     "pushl %ebp; movl %esp, %ebp;"
  98     "movl 12(%ebp), %eax;"
  99     "movl %ebp, (%eax);"
 100     "call *8(%ebp);"
 101     "movl %ebp, %esp; popl %ebp; ret");
 102
 103 static void do_unwind(void *target_frame, DWORD unwind_token);
 104 asm("_do_unwind:"
 105     "pushl $target; pushl %ebp; movl %esp, %ebp;"
 106     "pushl $0xcafe; pushl $0; pushl $-1; pushl 12(%ebp); call _RtlUnwind@16;"
 107     "target:"
 108     "movl 16(%ebp), %esp; popl %ebp; ret");
 109
 110
 111 void establish_return_frame(callback_ptr callback)
 112 {
 113     void *exception_frame[2];
 114
 115     saved_exception_frame = exception_frame;
 116     exception_frame[0] = get_seh_frame();
 117     exception_frame[1] = handle_exception;
 118     set_seh_frame(exception_frame);
 119
 120     /* Do a setjmp just to explicitly spill callee-saved registers, i.e.
 121      * the portable equivalent of:
 122      *   asm("" : : : "%esi", "%edi", "%ebx");
 123      * which is needed because otherwise those registers would be trashed
 124      * following the stack unwind, and leave us with a likely crash upon
 125      * return to call_into_c.
 126      *
 127      * The returns_twice attribute on invoke_callback should take care
 128      * of this already, but does not seem to take effect, at least with
 129      * the version of gcc I am using.
 130      *
 131      * Note: __builtin_setjmp, not setjmp, because only the former has
 132      * the desired effect on the immediate call site. */
 133     jmp_buf env;
 134     __builtin_setjmp(env);
 135
 136     invoke_callback(callback, &saved_ebp);
 137
 138     if (exception_frame != get_seh_frame()) {
 139         /* It is never good for this to happen. */
 140         printf("exception frame mismatch on callback return.\n");
 141     }
 142
 143     set_seh_frame(exception_frame[0]);
 144 }
 145
 146 void perform_test_unwind(void)
 147 {
 148     do_unwind(saved_exception_frame, saved_ebp);
 149 }
 150
 151 /* EOF */