Hi Pierrick,
On 13/2/23 17:13, Pierrick Bouvier wrote:
Windows implementation of setjmp/longjmp is done in
C:/WINDOWS/system32/ucrtbase.dll. Alas, on arm64, it seems to *always*
perform stack unwinding, which crashes from generated code.
By using alternative implementation built in mingw, we avoid doing stack
unwinding and this fixes crash when calling longjmp.
Signed-off-by: Pierrick Bouvier <[email protected]>
---
include/sysemu/os-win32.h | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)
diff --git a/include/sysemu/os-win32.h b/include/sysemu/os-win32.h
index 5b38c7bd04..84f62d0a17 100644
--- a/include/sysemu/os-win32.h
+++ b/include/sysemu/os-win32.h
@@ -51,14 +51,28 @@ typedef struct sockaddr_un {
extern "C" {
#endif
-#if defined(_WIN64)
+#if defined(__aarch64__)
Shouldn't we check for __MINGW64__?
#if defined(__aarch64__) && defined(__MINGW64__)
+/* On windows-arm64, setjmp is available in only one variant, and longjmp
always
+ * does stack unwinding. This crash with generated code.
+ * Thus, we use another implementation of setjmp (not windows one), coming from
+ * mingw, which never performs stack unwinding. */
+#undef setjmp
+#undef longjmp
+/* These functions are not declared in setjmp.h because __aarch64__ defines
+ * setjmp to _setjmpex instead. However, they are still defined in
libmingwex.a,
+ * which gets linked automatically. */
So this is not stable. Better would be to check the symbols availability
at link-time via meson; see for example glusterfs_ftruncate_has_stat
which defines CONFIG_GLUSTERFS_FTRUNCATE_HAS_STAT.
A similar check could define CONFIG_MINGW64_HAS_SETJMP_LONGJMP.
+extern int __mingw_setjmp(jmp_buf);
+extern void __attribute__((noreturn)) __mingw_longjmp(jmp_buf, int);
+#define setjmp(env) __mingw_setjmp(env)
+#define longjmp(env, val) __mingw_longjmp(env, val)
+#elif 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
+#endif /* __aarch64__ */
/* QEMU uses sigsetjmp()/siglongjmp() as the portable way to specify
* "longjmp and don't touch the signal masks". Since we know that the
* savemask parameter will always be zero we can safely define these
Regards,
Phil.
