Re: [PATCH 2/3] loongarch: Introduce sys_loongarch_flush_icache syscall

[Arnd Bergmann]

On Sat, Jan 4, 2025, at 10:04, Jinyang Shen wrote:
> On 2025/1/3 02:34, Jiaxun Yang wrote:
>> +/*
>> + * On LoongArch CPUs with ICACHET, writes automatically sync to both local and
>> + * remote instruction caches. CPUs without this feature lack userspace cache
>> + * flush instructions, requiring a syscall to maintain I/D cache coherence and
>> + * propagate to remote caches.
>> + *
>> + * sys_loongarch_flush_icache() is defined to flush the instruction cache
>> + * over an address range, with the flush applying to either all threads or
>> + * just the caller.
>> + */
>> +SYSCALL_DEFINE3(loongarch_flush_icache, uintptr_t, start, uintptr_t, end,
>> +	uintptr_t, flags)


I think for consistency with other architectures, we want start/length/flags
instead of start/end/flags.

The meaning of the third argument is rather inconsistent between
architectures already, but at least the second argument is always
length so far.


>> diff --git a/scripts/syscall.tbl b/scripts/syscall.tbl
>> index ebbdb3c42e9f74613b003014c0baf44c842bb756..723fe859956809f26d6ec50ad7812933531ef687 100644
>> --- a/scripts/syscall.tbl
>> +++ b/scripts/syscall.tbl
>> @@ -298,6 +298,8 @@
>>   244	csky	set_thread_area			sys_set_thread_area
>>   245	csky	cacheflush			sys_cacheflush
>>   
>> +259	loongarch       loongarch_flush_icache	sys_loongarch_flush_icache
>
> Can we use cacheflush as arc, csky and nios2?

Agreed. I would also use the number 244 instead of 259 here.

     Arnd