From 0ccf30fc64acca8e43a54a4f54fb3a4f155d4692 Mon Sep 17 00:00:00 2001 From: Thorsten Blum Date: Mon, 27 Oct 2025 16:51:02 +0100 Subject: [PATCH] x86/smpboot: Mark native_play_dead() as __noreturn native_play_dead() ends by calling the non-returning function hlt_play_dead() and therefore also never returns. The !CONFIG_HOTPLUG_CPU stub version of native_play_dead() unconditionally calls BUG() and does not return either. Add the __noreturn attribute to both function definitions and their declaration to document this behavior and to potentially improve compiler optimizations. Remove the obsolete comment, and add native_play_dead() to the objtool's list of __noreturn functions. Signed-off-by: Thorsten Blum Link: https://patch.msgid.link/20251027155107.183136-1-thorsten.blum@linux.dev Signed-off-by: Josh Poimboeuf --- arch/x86/include/asm/smp.h | 2 +- arch/x86/kernel/smpboot.c | 8 ++------ tools/objtool/noreturns.h | 1 + 3 files changed, 4 insertions(+), 7 deletions(-) diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h index 22bfebe6776da..84951572ab817 100644 --- a/arch/x86/include/asm/smp.h +++ b/arch/x86/include/asm/smp.h @@ -109,7 +109,7 @@ int common_cpu_up(unsigned int cpunum, struct task_struct *tidle); int native_kick_ap(unsigned int cpu, struct task_struct *tidle); int native_cpu_disable(void); void __noreturn hlt_play_dead(void); -void native_play_dead(void); +void __noreturn native_play_dead(void); void play_dead_common(void); void wbinvd_on_cpu(int cpu); void wbinvd_on_all_cpus(void); diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index eb289abece237..a4ba735842a8a 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1328,11 +1328,7 @@ void __noreturn hlt_play_dead(void) native_halt(); } -/* - * native_play_dead() is essentially a __noreturn function, but it can't - * be marked as such as the compiler may complain about it. - */ -void native_play_dead(void) +void __noreturn native_play_dead(void) { if (cpu_feature_enabled(X86_FEATURE_KERNEL_IBRS)) __update_spec_ctrl(0); @@ -1351,7 +1347,7 @@ int native_cpu_disable(void) return -ENOSYS; } -void native_play_dead(void) +void __noreturn native_play_dead(void) { BUG(); } diff --git a/tools/objtool/noreturns.h b/tools/objtool/noreturns.h index 802895fae3cac..14f8ab653449c 100644 --- a/tools/objtool/noreturns.h +++ b/tools/objtool/noreturns.h @@ -36,6 +36,7 @@ NORETURN(machine_real_restart) NORETURN(make_task_dead) NORETURN(mpt_halt_firmware) NORETURN(mwait_play_dead) +NORETURN(native_play_dead) NORETURN(nmi_panic_self_stop) NORETURN(panic) NORETURN(vpanic) -- 2.47.3