On 22/2/23 17:08, Pierrick Bouvier wrote:
On 2/21/23 23:27, Philippe Mathieu-Daudé wrote:
On 21/2/23 16:30, 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 <pierrick.bouv...@linaro.org>
Acked-by: Richard Henderson <richard.hender...@linaro.org>
---
include/sysemu/os-win32.h | 28 ++++++++++++++++++++++++----
meson.build | 21 +++++++++++++++++++++
2 files changed, 45 insertions(+), 4 deletions(-)
-#if defined(_WIN64)
-/* On w64, setjmp is implemented by _setjmp which needs a second
parameter.
+#if defined(__aarch64__)
+/*
+ * 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.
+ */
+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 windows-x64, 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. */
+ * lets longjmp try a stack unwinding which will crash with
generated code.
+ */
# undef setjmp
# define setjmp(env) _setjmp(env, NULL)
-#endif
+#endif /* __aarch64__ */
This comment is confusing, the previous if ladder is about i86. Maybe
better not add any comment?
If I am not mistaken, before we had:
#if x64
define setjmp as _setjmp(env, 0)
#endif
// nothing done for x86
and now we have:
#if aarch64
define setjmp as __mingw_setjmp
define longjmp as __mingw_longjmp
#elif x64
define setjmp as _setjmp(env, 0)
#endif
// nothing done for x86
Maybe the patch format is confusing, or I missed what you pointed.
Oh OK, we are good then, sorry :)
