ptrace: add ability to get/set signal-blocked mask (29000cae) · Commits · 戴 / test

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>

include/uapi/linux/ptrace.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -61,6 +61,9 @@ struct ptrace_peeksiginfo_args {
		__s32 nr; /* how may siginfos to take */
		};

		#define PTRACE_GETSIGMASK 0x420a
		#define PTRACE_SETSIGMASK 0x420b

		/* Read signals from a shared (process wide) queue */
		#define PTRACE_PEEKSIGINFO_SHARED (1 << 0)

kernel/ptrace.c

+42 −2

Original line number	Diff line number	Diff line
		@@ -844,6 +844,47 @@ int ptrace_request(struct task_struct *child, long request,
		ret = ptrace_setsiginfo(child, &siginfo);
		break;

		case PTRACE_GETSIGMASK:
		if (addr != sizeof(sigset_t)) {
		ret = -EINVAL;
		break;
		}

		if (copy_to_user(datavp, &child->blocked, sizeof(sigset_t)))
		ret = -EFAULT;
		else
		ret = 0;

		break;

		case PTRACE_SETSIGMASK: {
		sigset_t new_set;

		if (addr != sizeof(sigset_t)) {
		ret = -EINVAL;
		break;
		}

		if (copy_from_user(&new_set, datavp, sizeof(sigset_t))) {
		ret = -EFAULT;
		break;
		}

		sigdelsetmask(&new_set, sigmask(SIGKILL)\|sigmask(SIGSTOP));

		/*
		* Every thread does recalc_sigpending() after resume, so
		* retarget_shared_pending() and recalc_sigpending() are not
		* called here.
		*/
		spin_lock_irq(&child->sighand->siglock);
		child->blocked = new_set;
		spin_unlock_irq(&child->sighand->siglock);

		ret = 0;
		break;
		}

		case PTRACE_INTERRUPT:
		/*
		* Stop tracee without any side-effect on signal or job
		@@ -948,8 +989,7 @@ int ptrace_request(struct task_struct *child, long request,

		#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
		case PTRACE_GETREGSET:
		case PTRACE_SETREGSET:
		{
		case PTRACE_SETREGSET: {
		struct iovec kiov;
		struct iovec __user *uiov = datavp;

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