On Sun, 9 Jan 2022 at 16:44, Warner Losh <i...@bsdimp.com> wrote:
>
> Force delivering a signal and generating a core file.
>
> Signed-off-by: Stacey Son <s...@freebsd.org>
> Signed-off-by: Kyle Evans <kev...@freebsd.org>
> Signed-off-by: Warner Losh <i...@bsdimp.com>
> ---
> bsd-user/qemu.h | 1 +
> bsd-user/signal.c | 59 +++++++++++++++++++++++++++++++++++++++++
> bsd-user/syscall_defs.h | 1 +
> 3 files changed, 61 insertions(+)
>
> diff --git a/bsd-user/qemu.h b/bsd-user/qemu.h
> index 7c54a933eb8..e12617f5d69 100644
> --- a/bsd-user/qemu.h
> +++ b/bsd-user/qemu.h
> @@ -223,6 +223,7 @@ void queue_signal(CPUArchState *env, int sig,
> target_siginfo_t *info);
> abi_long do_sigaltstack(abi_ulong uss_addr, abi_ulong uoss_addr, abi_ulong
> sp);
> int target_to_host_signal(int sig);
> int host_to_target_signal(int sig);
> +void QEMU_NORETURN force_sig(int target_sig);
>
> /* mmap.c */
> int target_mprotect(abi_ulong start, abi_ulong len, int prot);
> diff --git a/bsd-user/signal.c b/bsd-user/signal.c
> index 824535be8b8..97f42f9c45e 100644
> --- a/bsd-user/signal.c
> +++ b/bsd-user/signal.c
> @@ -109,6 +109,65 @@ static int core_dump_signal(int sig)
> }
> }
>
> +/* Abort execution with signal. */
> +void QEMU_NORETURN force_sig(int target_sig)
In linux-user we call this dump_core_and_abort(), which is
a name that better describes what it's actually doing.
(Today's linux-user's force_sig() does what the Linux kernel's
function of that name does -- it's a wrapper around
queue_signal() which delivers a signal to the guest with
.si_code = SI_KERNEL , si_pid = si_uid = 0.
Whether you want one of those or not depends on what BSD
kernels do in that kind of "we have to kill this process"
situation.)
> +{
> + CPUArchState *env = thread_cpu->env_ptr;
> + CPUState *cpu = env_cpu(env);
> + TaskState *ts = cpu->opaque;
> + int core_dumped = 0;
> + int host_sig;
> + struct sigaction act;
> +
> + host_sig = target_to_host_signal(target_sig);
> + gdb_signalled(env, target_sig);
> +
> + /* Dump core if supported by target binary format */
> + if (core_dump_signal(target_sig) && (ts->bprm->core_dump != NULL)) {
> + stop_all_tasks();
> + core_dumped =
> + ((*ts->bprm->core_dump)(target_sig, env) == 0);
> + }
> + if (core_dumped) {
> + struct rlimit nodump;
> +
> + /*
> + * We already dumped the core of target process, we don't want
> + * a coredump of qemu itself.
> + */
> + getrlimit(RLIMIT_CORE, &nodump);
> + nodump.rlim_cur = 0;
> + setrlimit(RLIMIT_CORE, &nodump);
> + (void) fprintf(stderr, "qemu: uncaught target signal %d (%s) "
> + "- %s\n", target_sig, strsignal(host_sig), "core dumped");
> + }
> +
> + /*
> + * The proper exit code for dying from an uncaught signal is
> + * -<signal>. The kernel doesn't allow exit() or _exit() to pass
> + * a negative value. To get the proper exit code we need to
> + * actually die from an uncaught signal. Here the default signal
> + * handler is installed, we send ourself a signal and we wait for
> + * it to arrive.
> + */
> + memset(&act, 0, sizeof(act));
> + sigfillset(&act.sa_mask);
> + act.sa_handler = SIG_DFL;
> + sigaction(host_sig, &act, NULL);
> +
> + kill(getpid(), host_sig);
> +
> + /*
> + * Make sure the signal isn't masked (just reuse the mask inside
> + * of act).
> + */
> + sigdelset(&act.sa_mask, host_sig);
> + sigsuspend(&act.sa_mask);
> +
> + /* unreachable */
> + abort();
> +}
> +
> /*
> * Queue a signal so that it will be send to the virtual CPU as soon as
> * possible.
> diff --git a/bsd-user/syscall_defs.h b/bsd-user/syscall_defs.h
> index 04a1a886d7b..62b472b990b 100644
> --- a/bsd-user/syscall_defs.h
> +++ b/bsd-user/syscall_defs.h
> @@ -21,6 +21,7 @@
> #define _SYSCALL_DEFS_H_
>
> #include <sys/syscall.h>
> +#include <sys/resource.h>
>
> #include "errno_defs.h"
>
-- PMM
