diff mbox

[07/17] w64: Fix definition of setjmp

Message ID 1334519723-28632-8-git-send-email-sw@weilnetz.de
State Accepted
Headers show

Commit Message

Stefan Weil April 15, 2012, 7:55 p.m. UTC 
The default definition of setjmp which is implemented in MinGW-w64
cannot be used with programs like QEMU which call longjmp from
code without structured exception handling (SEH).

This code therefore disables stack unwinding.

We could also implement SEH for QEMU's generated JIT code, but
that is much more difficult. Stack unwinding would also cost
execution time.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
---
 qemu-os-win32.h |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)
diff mbox

Patch

diff --git a/qemu-os-win32.h b/qemu-os-win32.h
index b6533c0..753679b 100644
--- a/qemu-os-win32.h
+++ b/qemu-os-win32.h
@@ -56,6 +56,15 @@ 
 # define EWOULDBLOCK  WSAEWOULDBLOCK
 #endif
 
+#if defined(_WIN64)
+/* On w64, setjmp is implemented by _setjmp which needs a second parameter.
+ * If this parameter is NULL, longjump does no stack unwinding.
+ * That is what we need for QEMU. Passing the value of register rsp (default)
+ * lets longjmp try a stack unwinding which will crash with generated code. */
+# undef setjmp
+# define setjmp(env) _setjmp(env, NULL)
+#endif
+
 /* Declaration of ffs() is missing in MinGW's strings.h. */
 int ffs(int i);