linux-user: Remap guest SIGABRT
Distinguish host SIGABRT from guest SIGABRT by mapping the guest signal onto one of the host RT signals. This prevents a cycle by which a host assertion failure is caught and handled by host_signal_handler, queued for the guest, and then we attempt to continue past the host abort. What happens next depends on the host libc, but is neither good nor helpful. Acked-by: Helge Deller <deller@gmx.de> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
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@ -522,8 +522,21 @@ static void signal_table_init(void)
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* multiplexed over a single host signal.
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* Attempts for configure "missing" signals via sigaction will be
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* silently ignored.
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*
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* Remap the target SIGABRT, so that we can distinguish host abort
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* from guest abort. When the guest registers a signal handler or
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* calls raise(SIGABRT), the host will raise SIG_RTn. If the guest
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* arrives at dump_core_and_abort(), we will map back to host SIGABRT
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* so that the parent (native or emulated) sees the correct signal.
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* Finally, also map host to guest SIGABRT so that the emulated
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* parent sees the correct mapping from wait status.
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*/
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for (hsig = SIGRTMIN; hsig <= SIGRTMAX; hsig++) {
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hsig = SIGRTMIN;
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host_to_target_signal_table[SIGABRT] = 0;
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host_to_target_signal_table[hsig++] = TARGET_SIGABRT;
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for (; hsig <= SIGRTMAX; hsig++) {
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tsig = hsig - SIGRTMIN + TARGET_SIGRTMIN;
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if (tsig <= TARGET_NSIG) {
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host_to_target_signal_table[hsig] = tsig;
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@ -539,6 +552,8 @@ static void signal_table_init(void)
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}
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}
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host_to_target_signal_table[SIGABRT] = TARGET_SIGABRT;
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/* Map everything else out-of-bounds. */
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for (hsig = 1; hsig < _NSIG; hsig++) {
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if (host_to_target_signal_table[hsig] == 0) {
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@ -582,14 +597,22 @@ void signal_init(void)
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int hsig = target_to_host_signal(tsig);
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abi_ptr thand = TARGET_SIG_IGN;
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if (hsig < _NSIG) {
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struct sigaction *iact = core_dump_signal(tsig) ? &act : NULL;
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if (hsig >= _NSIG) {
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continue;
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}
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/* As we force remap SIGABRT, cannot probe and install in one step. */
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if (tsig == TARGET_SIGABRT) {
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sigaction(SIGABRT, NULL, &oact);
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sigaction(hsig, &act, NULL);
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} else {
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struct sigaction *iact = core_dump_signal(tsig) ? &act : NULL;
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sigaction(hsig, iact, &oact);
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}
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if (oact.sa_sigaction != (void *)SIG_IGN) {
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thand = TARGET_SIG_DFL;
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}
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}
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sigact_table[tsig - 1]._sa_handler = thand;
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}
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}
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@ -711,7 +734,12 @@ void dump_core_and_abort(CPUArchState *env, int target_sig)
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TaskState *ts = (TaskState *)cpu->opaque;
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int host_sig, core_dumped = 0;
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/* On exit, undo the remapping of SIGABRT. */
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if (target_sig == TARGET_SIGABRT) {
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host_sig = SIGABRT;
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} else {
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host_sig = target_to_host_signal(target_sig);
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}
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trace_user_dump_core_and_abort(env, target_sig, host_sig);
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gdb_signalled(env, target_sig);
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