The ARM Exception Handling ABI requires personality functions in
phase1 to initialize barrier_cache before returning
_URC_HANDLER_FOUND, and we don't.
Although our own ARM personality function does not use barrier_cache
at all, other languages' ARM personality functions, during phase2, are
allowed and expected to test barrier_cache.sp to check whether the
handler frame was reached, which implies that personality functions is
in charge of the frame, and the remaining fields of barrier_cache hold
whatever values it put there in phase1.
Since we did not set barrier_cache.sp, an earlier exception, already
handled by a non-Ada handler and then released, may have its storage
reused for a new exception, that phase1 matches to an Ada frame, but
if that leaves barrier_cache.sp alone, the phase2 personality function
that handled the earlier exception, upon reaching the frame that
handled the earlier exception, may believe the information in
barrier_cache applies to the current exception. The C++ personality
function, for example, would take the information in the barrier_cache
and end up activating the handler that handled the earlier exception:
try {
throw 1;
} catch (int i) {
std::cout << "caught " << i << " by c++" << std::endl;
}
raise_ada_exception (); // might loop back to the handler above
Regstrapped on x86_64-linux-gnu (no change expected), and tested on
ARM-based systems that use the ARM EH ABI. I'm checking this in.
for gcc/ada/ChangeLog
* raise-gcc.c (personality_body) [__ARM_EABI_UNWINDER__]:
Initialize barrier_cache.sp when ending phase1.
---
ada/raise-gcc.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git gcc/ada/raise-gcc.c gcc/ada/raise-gcc.c
index 1ba8af1..3b6c21fc 100644
--- gcc/ada/raise-gcc.c
+++ gcc/ada/raise-gcc.c
@@ -1211,6 +1211,16 @@ personality_body (_Unwind_Action uw_phases,
}
else
{
+#ifdef __ARM_EABI_UNWINDER__
+ /* Though we do not use this field ourselves, initializing
+ it is required by the ARM EH ABI before a personality
+ function in phase1 returns _URC_HANDLER_FOUND, so that
+ any personality function can use it in phase2 to test
+ whether the handler frame was reached. */
+ uw_exception->barrier_cache.sp
+ = _Unwind_GetGR (uw_context, UNWIND_STACK_REG);
+#endif
+
#ifndef CERT
/* Trigger the appropriate notification routines before the second
phase starts, when the stack is still intact. First install what
--
Alexandre Oliva, freedom fighter he/him https://FSFLA.org/blogs/lxo
Free Software Evangelist Stallman was right, but he's left :(
GNU Toolchain Engineer FSMatrix: It was he who freed the first of us
FSF & FSFLA board member The Savior shall return (true);
