linux-kernel - [PATCH v4 37/45] exit: Mark do_group_exit() _

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Message-ID: <20220308154319.351270711@infradead.org>
Date:   Tue, 08 Mar 2022 16:30:48 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     x86@...nel.org, joao@...rdrivepizza.com, hjl.tools@...il.com,
        jpoimboe@...hat.com, andrew.cooper3@...rix.com
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org,
        ndesaulniers@...gle.com, keescook@...omium.org,
        samitolvanen@...gle.com, mark.rutland@....com,
        alyssa.milburn@...el.com, mbenes@...e.cz, rostedt@...dmis.org,
        mhiramat@...nel.org, alexei.starovoitov@...il.com
Subject: [PATCH v4 37/45] 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@...radead.org>
---
 include/linux/sched/task.h |    2 +-
 kernel/exit.c              |    2 +-
 tools/objtool/check.c      |    1 +
 3 files changed, 3 insertions(+), 2 deletions(-)

--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -79,7 +79,7 @@ static inline void exit_thread(struct ta
 {
 }
 #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 *);
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -907,7 +907,7 @@ 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;
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -181,6 +181,7 @@ static bool __dead_end_function(struct o
 		"kunit_try_catch_throw",
 		"xen_start_kernel",
 		"cpu_bringup_and_idle",
+		"do_group_exit",
 		"stop_this_cpu",
 	};