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authorAndrey Vagin <avagin@openvz.org>2013-07-03 15:08:12 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-07-03 16:08:01 -0700
commit29000caecbe87b6b66f144f72111f0d02fbbf0c1 (patch)
tree91d178abd9543a49c087af857a3cfabececfd71e
parent37f07655522042399db7a4b54aee830bdb52ce2c (diff)
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>
-rw-r--r--include/uapi/linux/ptrace.h3
-rw-r--r--kernel/ptrace.c44
2 files changed, 45 insertions, 2 deletions
diff --git a/include/uapi/linux/ptrace.h b/include/uapi/linux/ptrace.h
index 52ebcc89f306..cf1019e15f5b 100644
--- a/include/uapi/linux/ptrace.h
+++ b/include/uapi/linux/ptrace.h
@@ -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)
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 335a7ae697f5..ba5e6cea181a 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -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;