jcs.org
qemu with hax to log dma reads & writes
jcs.org/2018/11/12/vfio
linux-user: fix use of SIGRTMIN
Some RT signals can be in use by glibc,
it's why SIGRTMIN (34) is generally greater than __SIGRTMIN (32).
So SIGRTMIN cannot be mapped to TARGET_SIGRTMIN.
Instead of swapping only SIGRTMIN and SIGRTMAX, map all the
range [TARGET_SIGRTMIN ... TARGET_SIGRTMAX - X] to
[__SIGRTMIN + X ... SIGRTMAX ]
(SIGRTMIN is __SIGRTMIN + X).
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Taylor Simson <tsimpson@quicinc.com>
Tested-by: Taylor Simpson <tsimpson@quicinc.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20200212125658.644558-5-laurent@vivier.eu>
+48
-5
+45
-5
linux-user/signal.c
+45
-5
linux-user/signal.c
···
498
498
499
499
static void signal_table_init(void)
500
500
{
501
-
int host_sig, target_sig;
501
+
int host_sig, target_sig, count;
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/*
504
-
* Nasty hack: Reverse SIGRTMIN and SIGRTMAX to avoid overlap with
505
-
* host libpthread signals. This assumes no one actually uses SIGRTMAX :-/
504
+
* Signals are supported starting from TARGET_SIGRTMIN and going up
505
+
* until we run out of host realtime signals.
506
+
* glibc at least uses only the lower 2 rt signals and probably
507
+
* nobody's using the upper ones.
508
+
* it's why SIGRTMIN (34) is generally greater than __SIGRTMIN (32)
506
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* To fix this properly we need to do manual signal delivery multiplexed
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510
* over a single host signal.
511
+
* Attempts for configure "missing" signals via sigaction will be
512
+
* silently ignored.
508
513
*/
509
-
host_to_target_signal_table[__SIGRTMIN] = __SIGRTMAX;
510
-
host_to_target_signal_table[__SIGRTMAX] = __SIGRTMIN;
514
+
for (host_sig = SIGRTMIN; host_sig <= SIGRTMAX; host_sig++) {
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+
target_sig = host_sig - SIGRTMIN + TARGET_SIGRTMIN;
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+
if (target_sig <= TARGET_NSIG) {
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+
host_to_target_signal_table[host_sig] = target_sig;
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+
}
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+
}
511
520
512
521
/* generate signal conversion tables */
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+
for (target_sig = 1; target_sig <= TARGET_NSIG; target_sig++) {
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+
target_to_host_signal_table[target_sig] = _NSIG; /* poison */
524
+
}
513
525
for (host_sig = 1; host_sig < _NSIG; host_sig++) {
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if (host_to_target_signal_table[host_sig] == 0) {
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host_to_target_signal_table[host_sig] = host_sig;
···
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if (target_sig <= TARGET_NSIG) {
519
531
target_to_host_signal_table[target_sig] = host_sig;
520
532
}
533
+
}
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+
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+
if (trace_event_get_state_backends(TRACE_SIGNAL_TABLE_INIT)) {
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+
for (target_sig = 1, count = 0; target_sig <= TARGET_NSIG; target_sig++) {
537
+
if (target_to_host_signal_table[target_sig] == _NSIG) {
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+
count++;
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+
}
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+
}
541
+
trace_signal_table_init(count);
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542
}
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}
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···
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838
int host_sig;
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839
int ret = 0;
819
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+
trace_signal_do_sigaction_guest(sig, TARGET_NSIG);
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+
820
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if (sig < 1 || sig > TARGET_NSIG || sig == TARGET_SIGKILL || sig == TARGET_SIGSTOP) {
821
844
return -TARGET_EINVAL;
822
845
}
···
847
870
848
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/* we update the host linux signal state */
849
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host_sig = target_to_host_signal(sig);
873
+
trace_signal_do_sigaction_host(host_sig, TARGET_NSIG);
874
+
if (host_sig > SIGRTMAX) {
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+
/* we don't have enough host signals to map all target signals */
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+
qemu_log_mask(LOG_UNIMP, "Unsupported target signal #%d, ignored\n",
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+
sig);
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+
/*
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+
* we don't return an error here because some programs try to
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+
* register an handler for all possible rt signals even if they
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+
* don't need it.
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+
* An error here can abort them whereas there can be no problem
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+
* to not have the signal available later.
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+
* This is the case for golang,
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+
* See https://github.com/golang/go/issues/33746
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+
* So we silently ignore the error.
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+
*/
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+
return 0;
889
+
}
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890
if (host_sig != SIGSEGV && host_sig != SIGBUS) {
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sigfillset(&act1.sa_mask);
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act1.sa_flags = SA_SIGINFO;
+3
linux-user/trace-events
+3
linux-user/trace-events
···
1
1
# See docs/devel/tracing.txt for syntax documentation.
2
2
3
3
# signal.c
4
+
signal_table_init(int i) "number of unavailable signals: %d"
5
+
signal_do_sigaction_guest(int sig, int max) "target signal %d (MAX %d)"
6
+
signal_do_sigaction_host(int sig, int max) "host signal %d (MAX %d)"
4
7
# */signal.c
5
8
user_setup_frame(void *env, uint64_t frame_addr) "env=%p frame_addr=0x%"PRIx64
6
9
user_setup_rt_frame(void *env, uint64_t frame_addr) "env=%p frame_addr=0x%"PRIx64