[Tarantool-patches] [PATCH luajit 1/2] Fix handling of errors during snapshot restore.
Sergey Kaplun
skaplun at tarantool.org
Sun Jul 31 13:58:30 MSK 2022
From: Mike Pall <mike>
(cherry picked from commit 12ab596997b9cb27846a5b254d11230c3f9c50c8)
When an error is raised during snapshot restore, `err_unwind()` skipped the
correct cframe to stop unwinding. It happens due this frame is C frame
without Lua frame and the special negative value of `cfram_nres()` for
this frame isn't set.
This patch sets `cframe_nres()` for cframe with snap restoration to
`-2*LUAI_MAXSTACK` to guarantee that an error will be always caught
here.
Sergey Kaplun:
* added the description and the test for the problem
Part of tarantool/tarantool#7230
---
src/lj_trace.c | 2 ++
.../lj-603-err-snap-restore.test.lua | 30 +++++++++++++++++++
2 files changed, 32 insertions(+)
create mode 100644 test/tarantool-tests/lj-603-err-snap-restore.test.lua
diff --git a/src/lj_trace.c b/src/lj_trace.c
index d7a78d4d..68a657a7 100644
--- a/src/lj_trace.c
+++ b/src/lj_trace.c
@@ -803,6 +803,8 @@ static TValue *trace_exit_cp(lua_State *L, lua_CFunction dummy, void *ud)
{
ExitDataCP *exd = (ExitDataCP *)ud;
cframe_errfunc(L->cframe) = -1; /* Inherit error function. */
+ /* Always catch error here. */
+ cframe_nres(L->cframe) = -2*LUAI_MAXSTACK*(int)sizeof(TValue);
exd->pc = lj_snap_restore(exd->J, exd->exptr);
UNUSED(dummy);
return NULL;
diff --git a/test/tarantool-tests/lj-603-err-snap-restore.test.lua b/test/tarantool-tests/lj-603-err-snap-restore.test.lua
new file mode 100644
index 00000000..82ce6a8f
--- /dev/null
+++ b/test/tarantool-tests/lj-603-err-snap-restore.test.lua
@@ -0,0 +1,30 @@
+local tap = require('tap')
+
+-- Test file to demonstrate the incorrect JIT behaviour when an
+-- error is raised on restoration from the snapshot.
+-- See also https://github.com/LuaJIT/LuaJIT/issues/603.
+local test = tap.test('lj-603-err-snap-restore.test.lua')
+test:plan(1)
+
+local recursive_f
+local function errfunc()
+ xpcall(recursive_f, errfunc)
+end
+
+-- A recursive call to itself leads to trace with up-recursion.
+-- When the Lua stack can't be grown more, error is raised on
+-- restoration from the snapshot.
+recursive_f = function()
+ xpcall(recursive_f, errfunc)
+ errfunc = function() end
+ recursive_f = function() end
+end
+recursive_f()
+
+test:ok(true)
+
+-- XXX: Don't use `os.exit()` here intense. When error on snap
+-- restoration is raised, `err_unwind()` doesn't stop on correct
+-- cframe. So later, on exit from VM this corrupted cframe chain
+-- shows itself. `os.exit()` literally calls `exit()` and doesn't
+-- show the issue.
--
2.34.1
More information about the Tarantool-patches
mailing list