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Re: [PATCH 28/30] bsd-user/signal.c: implement do_sigreturn
From: |
Peter Maydell |
Subject: |
Re: [PATCH 28/30] bsd-user/signal.c: implement do_sigreturn |
Date: |
Fri, 14 Jan 2022 12:12:14 +0000 |
On Sun, 9 Jan 2022 at 17:00, Warner Losh <imp@bsdimp.com> wrote:
>
> Implements the meat of a sigreturn(2) system call via do_sigreturn, and
> helper reset_signal_mask. Fix the prototype of do_sigreturn in qemu.h
> and remove do_rt_sigreturn since it's linux only.
>
> Signed-off-by: Stacey Son <sson@FreeBSD.org>
> Signed-off-by: Kyle Evans <kevans@freebsd.org>
> Signed-off-by: Warner Losh <imp@bsdimp.com>
> ---
> bsd-user/qemu.h | 3 +--
> bsd-user/signal.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 57 insertions(+), 2 deletions(-)
>
> diff --git a/bsd-user/qemu.h b/bsd-user/qemu.h
> index 011fdfebbaa..b8c64ca0e5b 100644
> --- a/bsd-user/qemu.h
> +++ b/bsd-user/qemu.h
> @@ -219,14 +219,13 @@ extern int do_strace;
> /* signal.c */
> void process_pending_signals(CPUArchState *cpu_env);
> void signal_init(void);
> -long do_sigreturn(CPUArchState *env);
> -long do_rt_sigreturn(CPUArchState *env);
> 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 host_to_target_sigset(target_sigset_t *d, const sigset_t *s);
> void target_to_host_sigset(sigset_t *d, const target_sigset_t *s);
> +long do_sigreturn(CPUArchState *regs, abi_ulong addr);
Please always call CPUArchState* arguments 'env'.
> void QEMU_NORETURN force_sig(int target_sig);
> int qemu_sigorset(sigset_t *dest, const sigset_t *left, const sigset_t
> *right);
>
> diff --git a/bsd-user/signal.c b/bsd-user/signal.c
> index 1dd6dbb4ee1..d11f5eddd7e 100644
> --- a/bsd-user/signal.c
> +++ b/bsd-user/signal.c
> @@ -640,6 +640,62 @@ give_sigsegv:
> force_sig(TARGET_SIGSEGV);
> }
>
> +static int reset_signal_mask(target_ucontext_t *ucontext)
> +{
> + int i;
> + sigset_t blocked;
> + target_sigset_t target_set;
> + TaskState *ts = (TaskState *)thread_cpu->opaque;
> +
> + for (i = 0; i < TARGET_NSIG_WORDS; i++)
> + if (__get_user(target_set.__bits[i],
> + &ucontext->uc_sigmask.__bits[i])) {
> + return -TARGET_EFAULT;
> + }
> + target_to_host_sigset_internal(&blocked, &target_set);
> + ts->signal_mask = blocked;
> + sigprocmask(SIG_SETMASK, &ts->signal_mask, NULL);
do_sigreturn() itself shouldn't be setting the active signal
mask, at least if you follow the linux-user design. It just
sets the thread's signal_mask field in the TaskState by
calling set_sigmask(), and then on our way out in the
main cpu loop we'll call process_pending_signals() which
sets the real thread signal mask to that value. (This, together
with do_sigreturn() calling block_signals() before it starts
work, avoids some race conditions where a host signal is delivered
as soon as we unblock, I think.)
-- PMM
- Re: [PATCH 20/30] bsd-user/signal.c: core_dump_signal, (continued)
[PATCH 22/30] bsd-user/signal.c: Fill in queue_signal, Warner Losh, 2022/01/09
[PATCH 26/30] bsd-user/signal.c: tswap_siginfo, Warner Losh, 2022/01/09
[PATCH 28/30] bsd-user/signal.c: implement do_sigreturn, Warner Losh, 2022/01/09
- Re: [PATCH 28/30] bsd-user/signal.c: implement do_sigreturn,
Peter Maydell <=
[PATCH 29/30] bsd-user/signal.c: implement do_sigaction, Warner Losh, 2022/01/09
[PATCH 27/30] bsd-user/signal.c: process_pending_signals, Warner Losh, 2022/01/09
[PATCH 30/30] bsd-user/signal.c: do_sigaltstack, Warner Losh, 2022/01/09
[PATCH 16/30] bsd-user/signal.c: host_to_target_siginfo_noswap, Warner Losh, 2022/01/09