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From: Peter Maydell <peter.maydell@linaro.org>
To: Warner Losh <imp@bsdimp.com>
Cc: Kyle Evans <kevans@freebsd.org>, Stacey Son <sson@freebsd.org>,
	qemu-devel@nongnu.org
Subject: Re: [PATCH 25/30] bsd-user/signal.c: handle_pending_signal
Date: Fri, 14 Jan 2022 11:50:22 +0000	[thread overview]
Message-ID: <CAFEAcA9_saH9MgsU5G6R=N6guZNx9YQ3vJfyD-CXZB3CY04GbA@mail.gmail.com> (raw)
In-Reply-To: <20220109161923.85683-26-imp@bsdimp.com>

On Sun, 9 Jan 2022 at 16:47, Warner Losh <imp@bsdimp.com> wrote:
>
> Handle a queued signal.
>
> Signed-off-by: Stacey Son <sson@FreeBSD.org>
> Signed-off-by: Kyle Evans <kevans@freebsd.org>
> Signed-off-by: Warner Losh <imp@bsdimp.com>


> +static void handle_pending_signal(CPUArchState *cpu_env, int sig,
> +                                  struct emulated_sigtable *k)
> +{
> +    CPUState *cpu = env_cpu(cpu_env);
> +    TaskState *ts = cpu->opaque;
> +    struct qemu_sigqueue *q;
> +    struct target_sigaction *sa;
> +    int code;
> +    sigset_t set;
> +    abi_ulong handler;
> +    target_siginfo_t tinfo;
> +    target_sigset_t target_old_set;
> +
> +    trace_user_handle_signal(cpu_env, sig);
> +
> +    /* Dequeue signal. */
> +    q = k->first;
> +    k->first = q->next;
> +    if (!k->first) {
> +        k->pending = 0;
> +    }

(The dequeue simplifies if you follow linux-user's way of handling
"queueing" a signal.)

> +
> +    sig = gdb_handlesig(cpu, sig);
> +    if (!sig) {
> +        sa = NULL;
> +        handler = TARGET_SIG_IGN;
> +    } else {
> +        sa = &sigact_table[sig - 1];
> +        handler = sa->_sa_handler;
> +    }
> +
> +    if (do_strace) {
> +        print_taken_signal(sig, &q->info);
> +    }
> +
> +    if (handler == TARGET_SIG_DFL) {
> +        /*
> +         * default handler : ignore some signal. The other are job
> +         * control or fatal.
> +         */
> +        if (TARGET_SIGTSTP == sig || TARGET_SIGTTIN == sig ||
> +                TARGET_SIGTTOU == sig) {
> +            kill(getpid(), SIGSTOP);
> +        } else if (TARGET_SIGCHLD != sig && TARGET_SIGURG != sig &&
> +            TARGET_SIGINFO != sig &&
> +            TARGET_SIGWINCH != sig && TARGET_SIGCONT != sig) {
> +            force_sig(sig);
> +        }
> +    } else if (TARGET_SIG_IGN == handler) {

Avoid the yoda-conditionals, please.

> +        /* ignore sig */
> +    } else if (TARGET_SIG_ERR == handler) {
> +        force_sig(sig);

Note that if you follow linux-user and my suggestion on
patch 21, these force_sig() calls become calls to
dump_core_and_abort(), unlike the one in setup_frame(),
which should be a "queue this signal". (The difference is
that here we know the process is definitely going to die,
because it has no valid handler for a fatal signal. In
setup_frame() the process might be able to continue, if it
has a signal handler for the SIGILL or SIGSEGV or whatever.)

> +    } else {
> +        /* compute the blocked signals during the handler execution */
> +        sigset_t *blocked_set;
> +
> +        target_to_host_sigset(&set, &sa->sa_mask);
> +        /*
> +         * SA_NODEFER indicates that the current signal should not be
> +         * blocked during the handler.
> +         */
> +        if (!(sa->sa_flags & TARGET_SA_NODEFER)) {
> +            sigaddset(&set, target_to_host_signal(sig));
> +        }
> +
> +        /*
> +         * Save the previous blocked signal state to restore it at the
> +         * end of the signal execution (see do_sigreturn).
> +         */
> +        host_to_target_sigset_internal(&target_old_set, &ts->signal_mask);
> +
> +        blocked_set = ts->in_sigsuspend ?
> +            &ts->sigsuspend_mask : &ts->signal_mask;
> +        qemu_sigorset(&ts->signal_mask, blocked_set, &set);
> +        ts->in_sigsuspend = false;
> +        sigprocmask(SIG_SETMASK, &ts->signal_mask, NULL);
> +
> +        /* XXX VM86 on x86 ??? */
> +
> +        code = q->info.si_code;
> +        /* prepare the stack frame of the virtual CPU */
> +        if (sa->sa_flags & TARGET_SA_SIGINFO) {
> +            tswap_siginfo(&tinfo, &q->info);

Oh, you're doing the tswap_siginfo() here. If you really want to
do that, then the setup_frame() should be able to do a simple
structure-copy I think and doesn't need the logic to figure out
which union fields are relevant. But putting the tswap_siginfo()
inside setup_frame() would match where linux-user does it.

> +            setup_frame(sig, code, sa, &target_old_set, &tinfo, cpu_env);
> +        } else {
> +            setup_frame(sig, code, sa, &target_old_set, NULL, cpu_env);
> +        }
> +        if (sa->sa_flags & TARGET_SA_RESETHAND) {
> +            sa->_sa_handler = TARGET_SIG_DFL;
> +        }
> +    }
> +    if (q != &k->info) {
> +        free_sigqueue(cpu_env, q);
> +    }
> +}
> +
>  void process_pending_signals(CPUArchState *cpu_env)
>  {
>  }
> --
> 2.33.1

thanks
-- PMM


  reply	other threads:[~2022-01-14 11:53 UTC|newest]

Thread overview: 105+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-09 16:18 [PATCH 00/30] bsd-user: upstream our signal implementation Warner Losh
2022-01-09 16:18 ` [PATCH 01/30] bsd-user/arm/target_arch_cpu.h: Move EXCP_ATOMIC to match linux-user Warner Losh
2022-01-13 15:47   ` Peter Maydell
2022-01-23 21:30   ` Richard Henderson
2022-01-09 16:18 ` [PATCH 02/30] bsd-user/signal.c: implement force_sig_fault Warner Losh
2022-01-13 16:43   ` Peter Maydell
2022-01-23 21:36   ` Richard Henderson
2022-01-09 16:18 ` [PATCH 03/30] bsd-user/signal.c: Implement cpu_loop_exit_sigsegv Warner Losh
2022-01-13 17:00   ` Peter Maydell
2022-01-23 21:38   ` Richard Henderson
2022-01-09 16:18 ` [PATCH 04/30] bsd-user/signal.c: implement cpu_loop_exit_sigbus Warner Losh
2022-01-13 17:00   ` Peter Maydell
2022-01-23 21:38   ` Richard Henderson
2022-01-09 16:18 ` [PATCH 05/30] bsd-user/arm/arget_arch_cpu.h: Move EXCP_DEBUG and EXCP_BKPT together Warner Losh
2022-01-13 17:13   ` Peter Maydell
2022-01-14  6:33     ` Warner Losh
2022-01-23 21:40   ` Richard Henderson
2022-01-09 16:18 ` [PATCH 06/30] bsd-user/arm/target_arch_cpu.h: Correct code pointer Warner Losh
2022-01-13 17:15   ` Peter Maydell
2022-01-14  6:38     ` Warner Losh
2022-01-14 10:22       ` Peter Maydell
2022-01-17  4:12         ` Warner Losh
2022-01-23 21:43   ` Richard Henderson
2022-01-09 16:19 ` [PATCH 07/30] bsd-user/arm/target_arch_cpu.h: Use force_sig_fault for EXCP_UDEF Warner Losh
2022-01-13 17:19   ` Peter Maydell
2022-01-23 22:07     ` Richard Henderson
2022-01-09 16:19 ` [PATCH 08/30] bsd-user/arm/target_arch_cpu.h: Implement data faults Warner Losh
2022-01-13 17:40   ` Peter Maydell
2022-01-14 18:13     ` Warner Losh
2022-01-14 18:21       ` Peter Maydell
2022-01-24  1:12   ` Richard Henderson
2022-01-09 16:19 ` [PATCH 09/30] bsd-user/signal.c: implement abstract target / host signal translation Warner Losh
2022-01-13 17:44   ` Peter Maydell
2022-01-14 18:27     ` Warner Losh
2022-01-09 16:19 ` [PATCH 10/30] bsd-user/signal.c: Implement signal_init() Warner Losh
2022-01-13 19:28   ` Peter Maydell
2022-01-14 18:51     ` Warner Losh
2022-01-24  1:38   ` Richard Henderson
2022-01-24 21:35     ` Warner Losh
2022-01-09 16:19 ` [PATCH 11/30] bsd-user/host/arm/host-signal.h: Implement host_signal_* Warner Losh
2022-01-13 19:32   ` Peter Maydell
2022-01-17  3:53     ` Warner Losh
2022-01-09 16:19 ` [PATCH 12/30] bsd-user/host/i386/host-signal.h: " Warner Losh
2022-01-13 19:33   ` Peter Maydell
2022-01-24  1:49   ` Richard Henderson
2022-01-09 16:19 ` [PATCH 13/30] bsd-user/host/x86_64/host-signal.h: " Warner Losh
2022-01-13 19:33   ` Peter Maydell
2022-01-24  1:52   ` Richard Henderson
2022-01-09 16:19 ` [PATCH 14/30] bsd-user: Add host signals to the build Warner Losh
2022-01-13 19:35   ` Peter Maydell
2022-01-24  1:56   ` Richard Henderson
2022-01-09 16:19 ` [PATCH 15/30] bsd-user: Add trace events for bsd-usr Warner Losh
2022-01-13 19:37   ` Peter Maydell
2022-01-24  1:57   ` Richard Henderson
2022-01-09 16:19 ` [PATCH 16/30] bsd-user/signal.c: host_to_target_siginfo_noswap Warner Losh
2022-01-13 19:43   ` Peter Maydell
2022-01-15  6:19     ` Warner Losh
2022-01-15 11:08       ` Peter Maydell
2022-01-24  2:05   ` Richard Henderson
2022-01-24 21:45     ` Warner Losh
2022-01-09 16:19 ` [PATCH 17/30] bsd-user/signal.c: Implement rewind_if_in_safe_syscall Warner Losh
2022-01-13 19:44   ` Peter Maydell
2022-01-24  2:09   ` Richard Henderson
2022-01-09 16:19 ` [PATCH 18/30] bsd-user/signal.c: Implement host_signal_handler Warner Losh
2022-01-13 20:17   ` Peter Maydell
2022-01-16 20:52     ` Warner Losh
2022-01-09 16:19 ` [PATCH 19/30] bsd-user/strace.c: print_taken_signal Warner Losh
2022-01-13 20:20   ` Peter Maydell
2022-01-24  2:45   ` Richard Henderson
2022-01-09 16:19 ` [PATCH 20/30] bsd-user/signal.c: core_dump_signal Warner Losh
2022-01-13 20:22   ` Peter Maydell
2022-01-13 20:28     ` Warner Losh
2022-01-13 20:40       ` Peter Maydell
2022-01-24  3:01   ` Richard Henderson
2022-01-09 16:19 ` [PATCH 21/30] bsd-user/signal.c: force_sig Warner Losh
2022-01-13 20:29   ` Peter Maydell
2022-01-13 20:53     ` Peter Maydell
2022-01-13 23:04       ` Kyle Evans
2022-01-18 22:27         ` Warner Losh
2022-01-09 16:19 ` [PATCH 22/30] bsd-user/signal.c: Fill in queue_signal Warner Losh
2022-01-13 20:37   ` Peter Maydell
2022-01-17 16:22     ` Warner Losh
2022-01-17 16:33       ` Peter Maydell
2022-01-09 16:19 ` [PATCH 23/30] bsd-user/signal.c: sigset manipulation routines Warner Losh
2022-01-14 11:13   ` Peter Maydell
2022-01-22 16:44     ` Warner Losh
2022-01-22 18:00       ` Kyle Evans
2022-01-09 16:19 ` [PATCH 24/30] bsd-user/signal.c: setup_frame Warner Losh
2022-01-14 11:40   ` Peter Maydell
2022-01-17  6:58     ` Warner Losh
2022-01-17  7:24       ` Warner Losh
2022-01-09 16:19 ` [PATCH 25/30] bsd-user/signal.c: handle_pending_signal Warner Losh
2022-01-14 11:50   ` Peter Maydell [this message]
2022-01-09 16:19 ` [PATCH 26/30] bsd-user/signal.c: tswap_siginfo Warner Losh
2022-01-14 11:54   ` Peter Maydell
2022-01-09 16:19 ` [PATCH 27/30] bsd-user/signal.c: process_pending_signals Warner Losh
2022-01-14 11:55   ` Peter Maydell
2022-01-17  2:09     ` Warner Losh
2022-01-09 16:19 ` [PATCH 28/30] bsd-user/signal.c: implement do_sigreturn Warner Losh
2022-01-14 12:12   ` Peter Maydell
2022-01-09 16:19 ` [PATCH 29/30] bsd-user/signal.c: implement do_sigaction Warner Losh
2022-01-14 13:13   ` Peter Maydell
2022-01-09 16:19 ` [PATCH 30/30] bsd-user/signal.c: do_sigaltstack Warner Losh
2022-01-14 13:18   ` Peter Maydell
2022-01-22 22:20     ` Warner Losh

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