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From: | Philippe Mathieu-Daudé |
Subject: | Re: [PATCH v3 2/4] sysemu/os-win32: fix setjmp/longjmp on windows-arm64 |
Date: | Tue, 21 Feb 2023 11:33:17 +0100 |
User-agent: | Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 |
On 21/2/23 10:47, Pierrick Bouvier wrote:
@Philippe Mathieu-Daudé, is that version satisfying for you, regarding your initial comments about setjmp/longjmp detection in meson?
Yes, the meson check is what I had in mind.
I can integrate more changes if needed. Thanks, Pierrick On 2/20/23 16:16, Pierrick Bouvier wrote:Acked-by: Richard Henderson <richard.henderson@linaro.org> On 2/20/23 12:12, 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> --- include/sysemu/os-win32.h | 25 +++++++++++++++++++++++-- meson.build | 24 ++++++++++++++++++++++++ 2 files changed, 47 insertions(+), 2 deletions(-) diff --git a/include/sysemu/os-win32.h b/include/sysemu/os-win32.h index 5b38c7bd04..1f6c141d39 100644 --- a/include/sysemu/os-win32.h +++ b/include/sysemu/os-win32.h @@ -51,14 +51,35 @@ typedef struct sockaddr_un { extern "C" { #endif -#if defined(_WIN64) +#if defined(__aarch64__) +#ifndef CONFIG_MINGW64_HAS_SETJMP_LONGJMP +#error mingw must provide setjmp/longjmp for windows-arm64
Per the meson error [*], this now seems impossible, thus we can simply drop the CONFIG_MINGW64_HAS_SETJMP_LONGJMP definition?
+#endif +/*+ * 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 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__ */
This comment doesn't seem accurate. Maybe "64-bit"?
/* 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 4ba3bf3431..e968ed9e7a 100644 --- a/meson.build +++ b/meson.build @@ -2450,6 +2450,30 @@ 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') + + config_host_data.set('CONFIG_MINGW64_HAS_SETJMP_LONGJMP', + mingw_has_setjmp_longjmp) + + if cpu == 'aarch64' and not mingw_has_setjmp_longjmp + error('mingw must provide setjmp/longjmp for windows-arm64')
(This is the [*] error I mentioned earlier).
+ endif +endif + ######################## # Target configuration # ########################
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