On 9/16/23 15:49, Mikulas Patocka wrote:
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 <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <signal.h>
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 <mpatocka@xxxxxxxxxx>
Acked-by: Helge Deller <deller@xxxxxx>
Thank you!
Helge
---
linux-user/hppa/signal.c | 1 +
1 file changed, 1 insertion(+)
Index: qemu/linux-user/hppa/signal.c
===================================================================
--- qemu.orig/linux-user/hppa/signal.c
+++ qemu/linux-user/hppa/signal.c
@@ -159,6 +159,7 @@ void setup_rt_frame(int sig, struct targ
}
env->iaoq_f = haddr;
env->iaoq_b = haddr + 4;
+ env->psw_n = 0;
return;
give_sigsegv:
