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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>
This commit is contained in:
Andrey Vagin 2013-07-03 15:08:12 -07:00 committed by Linus Torvalds
parent 37f0765552
commit 29000caecb
2 changed files with 45 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/uapi/linux/ptrace.h
View File

@ -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)

44
kernel/ptrace.c
View File

@ -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;