[CRIU] [PATCH] compel: compel_emergency_sigframe() helper introduced

[Stanislav Kinsburskiy]

This helper constructs sigframe, which can be used to resume process from the
point where it was stopped.
Result has to be copied to the process manually and then used with rt_sigreturn.

Signed-off-by: Stanislav Kinsburskiy <skinsbursky at virtuozzo.com>
---
 compel/include/uapi/infect.h |    3 +++
 compel/src/lib/infect.c      |   14 ++++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/compel/include/uapi/infect.h b/compel/include/uapi/infect.h
index aebb77c..08e9c54 100644
--- a/compel/include/uapi/infect.h
+++ b/compel/include/uapi/infect.h
@@ -95,6 +95,9 @@ extern k_rtsigset_t *compel_thread_sigmask(struct parasite_thread_ctl *tctl);
 
 struct rt_sigframe;
 
+extern int compel_emergency_sigframe(struct parasite_ctl *ctl, struct rt_sigframe *f,
+				     struct rt_sigframe *rtf);
+
 typedef int (*open_proc_fn)(int pid, int mode, const char *fmt, ...)
 	__attribute__ ((__format__ (__printf__, 3, 4)));
 
diff --git a/compel/src/lib/infect.c b/compel/src/lib/infect.c
index a2cb5d6..f6cedc5 100644
--- a/compel/src/lib/infect.c
+++ b/compel/src/lib/infect.c
@@ -1162,6 +1162,20 @@ static int make_sigframe_plain(void *from, struct rt_sigframe *f, struct rt_sigf
 	return 0;
 }
 
+int compel_emergency_sigframe(struct parasite_ctl *ctl, struct rt_sigframe *f,
+			      struct rt_sigframe *rtf)
+{
+	pid_t pid = ctl->rpid;
+	struct thread_ctx *thread = &ctl->orig;
+	struct plain_regs_struct regs;
+
+	if (get_task_regs(pid, &thread->regs, save_regs_plain, &regs)) {
+		pr_err("Can't obtain regs for thread %d\n", pid);
+		return -1;
+	}
+	return make_sigframe_plain(&regs, f, rtf, &thread->sigmask);
+}
+
 struct parasite_ctl *compel_prepare(int pid)
 {
 	struct parasite_ctl *ctl;