Move sig_kernel_* et al macros to linux/signal.h
This patch moves the sig_kernel_* and related macros from kernel/signal.c
to linux/signal.h, and cleans them up slightly. I need the sig_kernel_*
macros for default signal behavior in the utrace code, and want to avoid
duplication or overhead to share the knowledge.
Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/signal.h b/include/linux/signal.h
index 1474905..3fa0fab 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -243,6 +243,131 @@
extern struct kmem_cache *sighand_cachep;
+/*
+ * In POSIX a signal is sent either to a specific thread (Linux task)
+ * or to the process as a whole (Linux thread group). How the signal
+ * is sent determines whether it's to one thread or the whole group,
+ * which determines which signal mask(s) are involved in blocking it
+ * from being delivered until later. When the signal is delivered,
+ * either it's caught or ignored by a user handler or it has a default
+ * effect that applies to the whole thread group (POSIX process).
+ *
+ * The possible effects an unblocked signal set to SIG_DFL can have are:
+ * ignore - Nothing Happens
+ * terminate - kill the process, i.e. all threads in the group,
+ * similar to exit_group. The group leader (only) reports
+ * WIFSIGNALED status to its parent.
+ * coredump - write a core dump file describing all threads using
+ * the same mm and then kill all those threads
+ * stop - stop all the threads in the group, i.e. TASK_STOPPED state
+ *
+ * SIGKILL and SIGSTOP cannot be caught, blocked, or ignored.
+ * Other signals when not blocked and set to SIG_DFL behaves as follows.
+ * The job control signals also have other special effects.
+ *
+ * +--------------------+------------------+
+ * | POSIX signal | default action |
+ * +--------------------+------------------+
+ * | SIGHUP | terminate |
+ * | SIGINT | terminate |
+ * | SIGQUIT | coredump |
+ * | SIGILL | coredump |
+ * | SIGTRAP | coredump |
+ * | SIGABRT/SIGIOT | coredump |
+ * | SIGBUS | coredump |
+ * | SIGFPE | coredump |
+ * | SIGKILL | terminate(+) |
+ * | SIGUSR1 | terminate |
+ * | SIGSEGV | coredump |
+ * | SIGUSR2 | terminate |
+ * | SIGPIPE | terminate |
+ * | SIGALRM | terminate |
+ * | SIGTERM | terminate |
+ * | SIGCHLD | ignore |
+ * | SIGCONT | ignore(*) |
+ * | SIGSTOP | stop(*)(+) |
+ * | SIGTSTP | stop(*) |
+ * | SIGTTIN | stop(*) |
+ * | SIGTTOU | stop(*) |
+ * | SIGURG | ignore |
+ * | SIGXCPU | coredump |
+ * | SIGXFSZ | coredump |
+ * | SIGVTALRM | terminate |
+ * | SIGPROF | terminate |
+ * | SIGPOLL/SIGIO | terminate |
+ * | SIGSYS/SIGUNUSED | coredump |
+ * | SIGSTKFLT | terminate |
+ * | SIGWINCH | ignore |
+ * | SIGPWR | terminate |
+ * | SIGRTMIN-SIGRTMAX | terminate |
+ * +--------------------+------------------+
+ * | non-POSIX signal | default action |
+ * +--------------------+------------------+
+ * | SIGEMT | coredump |
+ * +--------------------+------------------+
+ *
+ * (+) For SIGKILL and SIGSTOP the action is "always", not just "default".
+ * (*) Special job control effects:
+ * When SIGCONT is sent, it resumes the process (all threads in the group)
+ * from TASK_STOPPED state and also clears any pending/queued stop signals
+ * (any of those marked with "stop(*)"). This happens regardless of blocking,
+ * catching, or ignoring SIGCONT. When any stop signal is sent, it clears
+ * any pending/queued SIGCONT signals; this happens regardless of blocking,
+ * catching, or ignored the stop signal, though (except for SIGSTOP) the
+ * default action of stopping the process may happen later or never.
+ */
+
+#ifdef SIGEMT
+#define SIGEMT_MASK rt_sigmask(SIGEMT)
+#else
+#define SIGEMT_MASK 0
+#endif
+
+#if SIGRTMIN > BITS_PER_LONG
+#define rt_sigmask(sig) (1ULL << ((sig)-1))
+#else
+#define rt_sigmask(sig) sigmask(sig)
+#endif
+#define siginmask(sig, mask) (rt_sigmask(sig) & (mask))
+
+#define SIG_KERNEL_ONLY_MASK (\
+ rt_sigmask(SIGKILL) | rt_sigmask(SIGSTOP))
+
+#define SIG_KERNEL_STOP_MASK (\
+ rt_sigmask(SIGSTOP) | rt_sigmask(SIGTSTP) | \
+ rt_sigmask(SIGTTIN) | rt_sigmask(SIGTTOU) )
+
+#define SIG_KERNEL_COREDUMP_MASK (\
+ rt_sigmask(SIGQUIT) | rt_sigmask(SIGILL) | \
+ rt_sigmask(SIGTRAP) | rt_sigmask(SIGABRT) | \
+ rt_sigmask(SIGFPE) | rt_sigmask(SIGSEGV) | \
+ rt_sigmask(SIGBUS) | rt_sigmask(SIGSYS) | \
+ rt_sigmask(SIGXCPU) | rt_sigmask(SIGXFSZ) | \
+ SIGEMT_MASK )
+
+#define SIG_KERNEL_IGNORE_MASK (\
+ rt_sigmask(SIGCONT) | rt_sigmask(SIGCHLD) | \
+ rt_sigmask(SIGWINCH) | rt_sigmask(SIGURG) )
+
+#define sig_kernel_only(sig) \
+ (((sig) < SIGRTMIN) && siginmask(sig, SIG_KERNEL_ONLY_MASK))
+#define sig_kernel_coredump(sig) \
+ (((sig) < SIGRTMIN) && siginmask(sig, SIG_KERNEL_COREDUMP_MASK))
+#define sig_kernel_ignore(sig) \
+ (((sig) < SIGRTMIN) && siginmask(sig, SIG_KERNEL_IGNORE_MASK))
+#define sig_kernel_stop(sig) \
+ (((sig) < SIGRTMIN) && siginmask(sig, SIG_KERNEL_STOP_MASK))
+
+#define sig_needs_tasklist(sig) ((sig) == SIGCONT)
+
+#define sig_user_defined(t, signr) \
+ (((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_DFL) && \
+ ((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_IGN))
+
+#define sig_fatal(t, signr) \
+ (!siginmask(signr, SIG_KERNEL_IGNORE_MASK|SIG_KERNEL_STOP_MASK) && \
+ (t)->sighand->action[(signr)-1].sa.sa_handler == SIG_DFL)
+
#endif /* __KERNEL__ */
#endif /* _LINUX_SIGNAL_H */