ptrace: add ability to get/set signal-blocked mask
crtools uses a parasite code for dumping processes. The parasite code is injected into a process with help PTRACE_SEIZE. Currently crtools blocks signals from a parasite code. If a process has pending signals, crtools wait while a process handles these signals. This method is not suitable for stopped tasks. A stopped task can have a few pending signals, when we will try to execute a parasite code, we will need to drop SIGSTOP, but all other signals must remain pending, because a state of processes must not be changed during checkpointing. This patch adds two ptrace commands to set/get signal-blocked mask. I think gdb can use this commands too. [akpm@linux-foundation.org: be consistent with brace layout] Signed-off-by: Andrey Vagin <avagin@openvz.org> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Cc: Roland McGrath <roland@redhat.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Pavel Emelyanov <xemul@parallels.com> Cc: Cyrill Gorcunov <gorcunov@openvz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -61,6 +61,9 @@ struct ptrace_peeksiginfo_args {
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__s32 nr; /* how may siginfos to take */
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};
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#define PTRACE_GETSIGMASK 0x420a
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#define PTRACE_SETSIGMASK 0x420b
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/* Read signals from a shared (process wide) queue */
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#define PTRACE_PEEKSIGINFO_SHARED (1 << 0)
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@ -844,6 +844,47 @@ int ptrace_request(struct task_struct *child, long request,
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ret = ptrace_setsiginfo(child, &siginfo);
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break;
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case PTRACE_GETSIGMASK:
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if (addr != sizeof(sigset_t)) {
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ret = -EINVAL;
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break;
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}
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if (copy_to_user(datavp, &child->blocked, sizeof(sigset_t)))
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ret = -EFAULT;
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else
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ret = 0;
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break;
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case PTRACE_SETSIGMASK: {
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sigset_t new_set;
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if (addr != sizeof(sigset_t)) {
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ret = -EINVAL;
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break;
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}
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if (copy_from_user(&new_set, datavp, sizeof(sigset_t))) {
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ret = -EFAULT;
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break;
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}
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sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
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/*
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* Every thread does recalc_sigpending() after resume, so
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* retarget_shared_pending() and recalc_sigpending() are not
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* called here.
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*/
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spin_lock_irq(&child->sighand->siglock);
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child->blocked = new_set;
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spin_unlock_irq(&child->sighand->siglock);
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ret = 0;
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break;
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}
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case PTRACE_INTERRUPT:
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/*
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* Stop tracee without any side-effect on signal or job
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@ -948,8 +989,7 @@ int ptrace_request(struct task_struct *child, long request,
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#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
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case PTRACE_GETREGSET:
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case PTRACE_SETREGSET:
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{
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case PTRACE_SETREGSET: {
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struct iovec kiov;
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struct iovec __user *uiov = datavp;
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