Commit 0ccf30fc authored by Thorsten Blum's avatar Thorsten Blum Committed by Josh Poimboeuf
Browse files

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: default avatarThorsten Blum <thorsten.blum@linux.dev>
Link: https://patch.msgid.link/20251027155107.183136-1-thorsten.blum@linux.dev


Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
parent f6af8690

arch/x86/include/asm/smp.h

+1 −1
Original line number Diff line number Diff line
@@ -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);

arch/x86/kernel/smpboot.c

+2 −6
Original line number Diff line number Diff line
@@ -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();

}

tools/objtool/noreturns.h

+1 −0
Original line number Diff line number Diff line
@@ -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)