Commit c337c849 authored by Tiezhu Yang's avatar Tiezhu Yang Committed by Huacai Chen
Browse files

LoongArch: Put the body of play_dead() into arch_cpu_idle_dead() 



The initial aim is to silence the following objtool warning:

arch/loongarch/kernel/process.o: warning: objtool: arch_cpu_idle_dead() falls through to next function start_thread()

According to tools/objtool/Documentation/objtool.txt, this is because
the last instruction of arch_cpu_idle_dead() is a call to a noreturn
function play_dead(). In order to silence the warning, one simple way
is to add the noreturn function play_dead() to objtool's hard-coded
global_noreturns array, that is to say, just put "NORETURN(play_dead)"
into tools/objtool/noreturns.h, it works well.

But I noticed that play_dead() is only defined once and only called by
arch_cpu_idle_dead(), so put the body of play_dead() into the caller
arch_cpu_idle_dead(), then remove the noreturn function play_dead() is
an alternative way which can reduce the overhead of the function call
at the same time.

Signed-off-by: default avatarTiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: default avatarHuacai Chen <chenhuacai@loongson.cn>
parent 8879515e

arch/loongarch/include/asm/smp.h

+0 −2
Original line number Diff line number Diff line
@@ -98,8 +98,6 @@ static inline void __cpu_die(unsigned int cpu) 
{

	loongson_cpu_die(cpu);

}



extern void __noreturn play_dead(void);

#endif



#endif /* __ASM_SMP_H */

arch/loongarch/kernel/process.c

+0 −7
Original line number Diff line number Diff line
@@ -61,13 +61,6 @@ EXPORT_SYMBOL(__stack_chk_guard); 
unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE;

EXPORT_SYMBOL(boot_option_idle_override);



#ifdef CONFIG_HOTPLUG_CPU

void __noreturn arch_cpu_idle_dead(void)

{

	play_dead();

}

#endif



asmlinkage void ret_from_fork(void);

asmlinkage void ret_from_kernel_thread(void);

arch/loongarch/kernel/smp.c

+1 −1
Original line number Diff line number Diff line
@@ -317,7 +317,7 @@ void loongson_cpu_die(unsigned int cpu) 
	mb();

}



void play_dead(void)

void __noreturn arch_cpu_idle_dead(void)

{

	register uint64_t addr;

	register void (*init_fn)(void);