From 2529497cb6b298e732e8dbe5212da7925240b4f4 Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Sat, 16 Sep 2023 15:49:42 +0200 Subject: [PATCH] linux-user/hppa: clear the PSW 'N' bit when delivering signals qemu-hppa may crash when delivering a signal. It can be demonstrated with this program. Compile the program with "hppa-linux-gnu-gcc -O2 signal.c" and run it with "qemu-hppa -one-insn-per-tb a.out". It reports that the address of the flag is 0xb4 and it crashes when attempting to touch it. #include #include #include #include sig_atomic_t flag; void sig(int n) { printf("&flag: %p\n", &flag); flag = 1; } int main(void) { struct sigaction sa; struct itimerval it; sa.sa_handler = sig; sigemptyset(&sa.sa_mask); sa.sa_flags = SA_RESTART; if (sigaction(SIGALRM, &sa, NULL)) perror("sigaction"), exit(1); it.it_interval.tv_sec = 0; it.it_interval.tv_usec = 100; it.it_value.tv_sec = it.it_interval.tv_sec; it.it_value.tv_usec = it.it_interval.tv_usec; if (setitimer(ITIMER_REAL, &it, NULL)) perror("setitimer"), exit(1); while (1) { } } The reason for the crash is that the signal handling routine doesn't clear the 'N' flag in the PSW. If the signal interrupts a thread when the 'N' flag is set, the flag remains set at the beginning of the signal handler and the first instruction of the signal handler is skipped. Signed-off-by: Mikulas Patocka Acked-by: Helge Deller Cc: qemu-stable@nongnu.org Signed-off-by: Helge Deller --- linux-user/hppa/signal.c | 1 + 1 file changed, 1 insertion(+) diff --git a/linux-user/hppa/signal.c b/linux-user/hppa/signal.c index f253a15864..3a976ac693 100644 --- a/linux-user/hppa/signal.c +++ b/linux-user/hppa/signal.c @@ -159,6 +159,7 @@ void setup_rt_frame(int sig, struct target_sigaction *ka, } env->iaoq_f = haddr; env->iaoq_b = haddr + 4; + env->psw_n = 0; return; give_sigsegv: