[PATCH v2 06/10] riscv: Implement xchg8/16() using Zabha

[Alexandre Ghiti]

On 27/06/2024 15:45, Andrea Parri wrote:
>> -#define __arch_xchg_masked(sc_sfx, prepend, append, r, p, n)		\
>> +#define __arch_xchg_masked(sc_sfx, swap_sfx, prepend, sc_append,	\
>> +			   swap_append, r, p, n)			\
>>   ({									\
>> +	__label__ zabha, end;						\
>> +									\
>> +	if (IS_ENABLED(CONFIG_RISCV_ISA_ZABHA)) {			\
>> +		asm goto(ALTERNATIVE("nop", "j %[zabha]", 0,		\
>> +				     RISCV_ISA_EXT_ZABHA, 1)		\
>> +			 : : : : zabha);				\
>> +	}								\
>> +									\
>>   	u32 *__ptr32b = (u32 *)((ulong)(p) & ~0x3);			\
>>   	ulong __s = ((ulong)(p) & (0x4 - sizeof(*p))) * BITS_PER_BYTE;	\
>>   	ulong __mask = GENMASK(((sizeof(*p)) * BITS_PER_BYTE) - 1, 0)	\
>> @@ -28,12 +37,25 @@
>>   	       "	or   %1, %1, %z3\n"				\
>>   	       "	sc.w" sc_sfx " %1, %1, %2\n"			\
>>   	       "	bnez %1, 0b\n"					\
>> -	       append							\
>> +	       sc_append							\
>>   	       : "=&r" (__retx), "=&r" (__rc), "+A" (*(__ptr32b))	\
>>   	       : "rJ" (__newx), "rJ" (~__mask)				\
>>   	       : "memory");						\
>>   									\
>>   	r = (__typeof__(*(p)))((__retx & __mask) >> __s);		\
>> +	goto end;							\
>> +									\
>> +zabha:									\
>> +	if (IS_ENABLED(CONFIG_RISCV_ISA_ZABHA)) {			\
>> +		__asm__ __volatile__ (					\
>> +			prepend						\
>> +			"	amoswap" swap_sfx " %0, %z2, %1\n"	\
>> +			swap_append						\
>> +			: "=&r" (r), "+A" (*(p))			\
>> +			: "rJ" (n)					\
>> +			: "memory");					\
>> +	}								\
>> +end:;									\
>>   })
> As for patch #1: why the semicolon? and should the second IS_ENABLED()
> be kept?
>
>
>> diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
>> index e17d0078a651..f71ddd2ca163 100644
>> --- a/arch/riscv/include/asm/hwcap.h
>> +++ b/arch/riscv/include/asm/hwcap.h
>> @@ -81,6 +81,7 @@
>>   #define RISCV_ISA_EXT_ZTSO		72
>>   #define RISCV_ISA_EXT_ZACAS		73
>>   #define RISCV_ISA_EXT_XANDESPMU		74
>> +#define RISCV_ISA_EXT_ZABHA		75
>>   
>>   #define RISCV_ISA_EXT_XLINUXENVCFG	127
>>   
>> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
>> index 5ef48cb20ee1..c125d82c894b 100644
>> --- a/arch/riscv/kernel/cpufeature.c
>> +++ b/arch/riscv/kernel/cpufeature.c
>> @@ -257,6 +257,7 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
>>   	__RISCV_ISA_EXT_DATA(zihintpause, RISCV_ISA_EXT_ZIHINTPAUSE),
>>   	__RISCV_ISA_EXT_DATA(zihpm, RISCV_ISA_EXT_ZIHPM),
>>   	__RISCV_ISA_EXT_DATA(zacas, RISCV_ISA_EXT_ZACAS),
>> +	__RISCV_ISA_EXT_DATA(zabha, RISCV_ISA_EXT_ZABHA),
>>   	__RISCV_ISA_EXT_DATA(zfa, RISCV_ISA_EXT_ZFA),
>>   	__RISCV_ISA_EXT_DATA(zfh, RISCV_ISA_EXT_ZFH),
>>   	__RISCV_ISA_EXT_DATA(zfhmin, RISCV_ISA_EXT_ZFHMIN),
> To be squashed into patch #3?


Yep, done, thanks.


>
>    Andrea
>
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