[tip: x86/core] exit: Mark do_group_exit() __noreturn

[tip-bot2 for Peter Zijlstra]

The following commit has been merged into the x86/core branch of tip:

Commit-ID:     fb604370c4b1c1c17fa9c3f0d60bbe8c9494edd9
Gitweb:        https://git.kernel.org/tip/fb604370c4b1c1c17fa9c3f0d60bbe8c9494edd9
Author:        Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate:    Tue, 08 Mar 2022 16:30:48 +01:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Tue, 08 Mar 2022 23:53:37 +01:00

exit: Mark do_group_exit() __noreturn

vmlinux.o: warning: objtool: get_signal()+0x108: unreachable instruction

0000 000000000007f930 <get_signal>:
...
0103    7fa33:  e8 00 00 00 00          call   7fa38 <get_signal+0x108> 7fa34: R_X86_64_PLT32   do_group_exit-0x4
0108    7fa38:  41 8b 45 74             mov    0x74(%r13),%eax

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220308154319.351270711@xxxxxxxxxxxxx
---
 include/linux/sched/task.h | 2 +-
 kernel/exit.c              | 2 +-
 tools/objtool/check.c      | 1 +
 3 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index e84e54d..719c9a6 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -79,7 +79,7 @@ static inline void exit_thread(struct task_struct *tsk)
 {
 }
 #endif
-extern void do_group_exit(int);
+extern __noreturn void do_group_exit(int);
 
 extern void exit_files(struct task_struct *);
 extern void exit_itimers(struct signal_struct *);
diff --git a/kernel/exit.c b/kernel/exit.c
index b00a25b..b71f9df 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -906,7 +906,7 @@ SYSCALL_DEFINE1(exit, int, error_code)
  * Take down every thread in the group.  This is called by fatal signals
  * as well as by sys_exit_group (below).
  */
-void
+void __noreturn
 do_group_exit(int exit_code)
 {
 	struct signal_struct *sig = current->signal;
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index c3ddcec..9896562 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -181,6 +181,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
 		"kunit_try_catch_throw",
 		"xen_start_kernel",
 		"cpu_bringup_and_idle",
+		"do_group_exit",
 		"stop_this_cpu",
 	};