um: Implement TRACE_IRQFLAGS_SUPPORT

UML enables TRACE_IRQFLAGS_SUPPORT but doesn't actually implement
it. It seems to have been added for lockdep support, but that can't
actually really work well without IRQ flags tracing, as is also
very noisily reported when enabling CONFIG_DEBUG_LOCKDEP.

Implement it now.

Fixes: 711553efa5b8 ("[PATCH] uml: declare in Kconfig our partial LOCKDEP support")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

3 files changed, 31 insertions, 3 deletions

diff --git a/arch/um/kernel/signal.c b/arch/um/kernel/signal.c
index 57acbd67d85d..3a8012520e22 100644
--- a/arch/um/kernel/signal.c
+++ b/arch/um/kernel/signal.c
@@ -6,15 +6,43 @@
 #include <linux/module.h>
 #include <linux/ptrace.h>
 #include <linux/sched.h>
+#include <linux/ftrace.h>
 #include <asm/siginfo.h>
 #include <asm/signal.h>
 #include <asm/unistd.h>
 #include <frame_kern.h>
 #include <kern_util.h>
+#include <os.h>
 
 EXPORT_SYMBOL(block_signals);
 EXPORT_SYMBOL(unblock_signals);
 
+void block_signals_trace(void)
+{
+	block_signals();
+	if (current_thread_info())
+		trace_hardirqs_off();
+}
+
+void unblock_signals_trace(void)
+{
+	if (current_thread_info())
+		trace_hardirqs_on();
+	unblock_signals();
+}
+
+void um_trace_signals_on(void)
+{
+	if (current_thread_info())
+		trace_hardirqs_on();
+}
+
+void um_trace_signals_off(void)
+{
+	if (current_thread_info())
+		trace_hardirqs_off();
+}
+
 /*
  * OK, we're invoking a handler
  */
diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c
index 29e7f5f9f188..ace71f805700 100644
--- a/arch/um/kernel/skas/mmu.c
+++ b/arch/um/kernel/skas/mmu.c
@@ -63,12 +63,12 @@ int init_new_context(struct task_struct *task, struct mm_struct *mm)
 	if (current->mm != NULL && current->mm != &init_mm)
 		from_mm = &current->mm->context;
 
-	block_signals();
+	block_signals_trace();
 	if (from_mm)
 		to_mm->id.u.pid = copy_context_skas0(stack,
 						     from_mm->id.u.pid);
 	else to_mm->id.u.pid = start_userspace(stack);
-	unblock_signals();
+	unblock_signals_trace();
 
 	if (to_mm->id.u.pid < 0) {
 		ret = to_mm->id.u.pid;
diff --git a/arch/um/kernel/skas/process.c b/arch/um/kernel/skas/process.c
index d4dbf08722d6..404914627dd6 100644
--- a/arch/um/kernel/skas/process.c
+++ b/arch/um/kernel/skas/process.c
@@ -19,7 +19,7 @@ static int __init start_kernel_proc(void *unused)
 {
 	int pid;
 
-	block_signals();
+	block_signals_trace();
 	pid = os_getpid();
 
 	cpu_tasks[0].pid = pid;