diff options
author | Mike Pall <mike> | 2012-10-21 19:15:03 +0200 |
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committer | Mike Pall <mike> | 2012-10-21 19:17:14 +0200 |
commit | 1d5c2ce4e295562daddfe6ce8e470749f0d42542 (patch) | |
tree | e56ef2c9b51a466654548bb52a0ebaf7f9cb6e3d | |
parent | f6536c6696deca9fb7b9744573406c83f0f893a4 (diff) | |
download | luajit2-1d5c2ce4e295562daddfe6ce8e470749f0d42542.tar.gz |
Replace error with PANIC for callbacks from JIT-compiled code.
-rw-r--r-- | doc/ext_ffi_semantics.html | 16 | ||||
-rw-r--r-- | src/lj_ccallback.c | 10 |
2 files changed, 23 insertions, 3 deletions
diff --git a/doc/ext_ffi_semantics.html b/doc/ext_ffi_semantics.html index f8da1e60..ab02f2b8 100644 --- a/doc/ext_ffi_semantics.html +++ b/doc/ext_ffi_semantics.html @@ -934,6 +934,22 @@ advisable in general. Do this only if you know the C function, that called the callback, copes with the forced stack unwinding and doesn't leak resources. </p> +<p> +One thing that's not allowed, is to let an FFI call into a C function +get JIT-compiled, which in turn calls a callback, calling into Lua again. +Usually this attempt is caught by the interpreter first and the +C function is blacklisted for compilation. +</p> +<p> +However, this heuristic may fail under specific circumstances: e.g. a +message polling function might not run Lua callbacks right away and the call +gets JIT-compiled. If it later happens to call back into Lua, you'll get a +VM PANIC with the message <tt>"bad callback"</tt>. Then you'll need to +manually turn off JIT-compilation with +<a href="ext_jit.html#jit_onoff_func"><tt>jit.off()</tt></a> for the +surrounding Lua function that invokes such a message polling function (or +similar). +</p> <h3 id="callback_resources">Callback resource handling</h3> <p> diff --git a/src/lj_ccallback.c b/src/lj_ccallback.c index 430643ee..e1d03fcf 100644 --- a/src/lj_ccallback.c +++ b/src/lj_ccallback.c @@ -527,10 +527,14 @@ static void callback_conv_result(CTState *cts, lua_State *L, TValue *o) lua_State * LJ_FASTCALL lj_ccallback_enter(CTState *cts, void *cf) { lua_State *L = cts->L; + global_State *g = cts->g; lua_assert(L != NULL); - if (gcref(cts->g->jit_L)) - lj_err_caller(gco2th(gcref(cts->g->jit_L)), LJ_ERR_FFI_BADCBACK); - lj_trace_abort(cts->g); /* Never record across callback. */ + if (gcref(g->jit_L)) { + setstrV(L, L->top++, lj_err_str(L, LJ_ERR_FFI_BADCBACK)); + if (g->panic) g->panic(L); + exit(EXIT_FAILURE); + } + lj_trace_abort(g); /* Never record across callback. */ /* Setup C frame. */ cframe_prev(cf) = L->cframe; setcframe_L(cf, L); |