Re: [PATCH 1/4] powerpc: convert to copy_thread_tls

[Nicholas Piggin <npiggin@gmail.com>]

Christophe Leroy's on August 27, 2019 4:07 pm:
> 
> 
> Le 27/08/2019 à 05:30, Nicholas Piggin a écrit :
>> Commit 3033f14ab78c3 ("clone: support passing tls argument via C rather
>> than pt_regs magic") introduced the HAVE_COPY_THREAD_TLS option. Use it
>> to avoid a subtle assumption about the argument ordering of clone type
>> syscalls.
>> 
>> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
>> ---
>>   arch/powerpc/Kconfig          | 1 +
>>   arch/powerpc/kernel/process.c | 9 +++++----
>>   2 files changed, 6 insertions(+), 4 deletions(-)
>> 
>> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
>> index d8dcd8820369..7477a3263225 100644
>> --- a/arch/powerpc/Kconfig
>> +++ b/arch/powerpc/Kconfig
>> @@ -182,6 +182,7 @@ config PPC
>>   	select HAVE_STACKPROTECTOR		if PPC64 && $(cc-option,-mstack-protector-guard=tls -mstack-protector-guard-reg=r13)
>>   	select HAVE_STACKPROTECTOR		if PPC32 && $(cc-option,-mstack-protector-guard=tls -mstack-protector-guard-reg=r2)
>>   	select HAVE_CONTEXT_TRACKING		if PPC64
>> +	select HAVE_COPY_THREAD_TLS
>>   	select HAVE_DEBUG_KMEMLEAK
>>   	select HAVE_DEBUG_STACKOVERFLOW
>>   	select HAVE_DYNAMIC_FTRACE
>> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
>> index 8fc4de0d22b4..24621e7e5033 100644
>> --- a/arch/powerpc/kernel/process.c
>> +++ b/arch/powerpc/kernel/process.c
>> @@ -1600,8 +1600,9 @@ static void setup_ksp_vsid(struct task_struct *p, unsigned long sp)
>>   /*
>>    * Copy architecture-specific thread state
>>    */
>> -int copy_thread(unsigned long clone_flags, unsigned long usp,
>> -		unsigned long kthread_arg, struct task_struct *p)
>> +int copy_thread_tls(unsigned long clone_flags, unsigned long usp,
>> +		unsigned long kthread_arg, struct task_struct *p,
>> +		unsigned long tls)
>>   {
>>   	struct pt_regs *childregs, *kregs;
>>   	extern void ret_from_fork(void);
>> @@ -1642,10 +1643,10 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
>>   		if (clone_flags & CLONE_SETTLS) {
>>   #ifdef CONFIG_PPC64
> 
> is_32bit_task() exists and always returns 1 on PPC32 so this gross ifdef 
> in the middle of an if/else is pointless, it should be dropped.

I could do that as another patch in the series.

Thanks,
Nick