diff mbox series

[v4,2/4] sysemu/os-win32: fix setjmp/longjmp on windows-arm64

Message ID 20230221153006.20300-3-pierrick.bouvier@linaro.org
State Superseded
Headers show
Series Adds support for running QEMU natively on windows-arm64 | expand

Commit Message

Pierrick Bouvier Feb. 21, 2023, 3:30 p.m. UTC
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.bouvier@linaro.org>
Acked-by: Richard Henderson <richard.henderson@linaro.org>
---
 include/sysemu/os-win32.h | 28 ++++++++++++++++++++++++----
 meson.build               | 21 +++++++++++++++++++++
 2 files changed, 45 insertions(+), 4 deletions(-)

Comments

Philippe Mathieu-Daudé Feb. 21, 2023, 10:27 p.m. UTC | #1
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.bouvier@linaro.org>
> Acked-by: Richard Henderson <richard.henderson@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?

Otherwise,
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Richard Henderson Feb. 21, 2023, 11:45 p.m. UTC | #2
On 2/21/23 05:30, 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.bouvier@linaro.org>
> Acked-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>   include/sysemu/os-win32.h | 28 ++++++++++++++++++++++++----
>   meson.build               | 21 +++++++++++++++++++++
>   2 files changed, 45 insertions(+), 4 deletions(-)

Queueing this to tcg-next.


r~
Pierrick Bouvier Feb. 22, 2023, 4:08 p.m. UTC | #3
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.bouvier@linaro.org>
>> Acked-by: Richard Henderson <richard.henderson@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.

Pierrick

> 
> Otherwise,
> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
>
Philippe Mathieu-Daudé Feb. 22, 2023, 4:17 p.m. UTC | #4
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.bouvier@linaro.org>
>>> Acked-by: Richard Henderson <richard.henderson@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 :)
diff mbox series

Patch

diff --git a/include/sysemu/os-win32.h b/include/sysemu/os-win32.h
index 5b38c7bd04..97d0243aee 100644
--- a/include/sysemu/os-win32.h
+++ b/include/sysemu/os-win32.h
@@ -51,14 +51,34 @@  typedef struct sockaddr_un {
 extern "C" {
 #endif
 
-#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__ */
 /* 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
diff --git a/meson.build b/meson.build
index a76c855312..b676c831b3 100644
--- a/meson.build
+++ b/meson.build
@@ -2470,6 +2470,27 @@  if targetos == 'windows'
     }''', name: '_lock_file and _unlock_file'))
 endif
 
+if targetos == 'windows'
+  mingw_has_setjmp_longjmp = cc.links('''
+    #include <setjmp.h>
+    int main(void) {
+      /*
+       * These functions are not available in setjmp header, but may be
+       * available at link time, from libmingwex.a.
+       */
+      extern int __mingw_setjmp(jmp_buf);
+      extern void __attribute__((noreturn)) __mingw_longjmp(jmp_buf, int);
+      jmp_buf env;
+      __mingw_setjmp(env);
+      __mingw_longjmp(env, 0);
+    }
+  ''', name: 'mingw setjmp and longjmp')
+
+  if cpu == 'aarch64' and not mingw_has_setjmp_longjmp
+    error('mingw must provide setjmp/longjmp for windows-arm64')
+  endif
+endif
+
 ########################
 # Target configuration #
 ########################