Unverified Commit 97ddab7f authored by Alexandre Ghiti's avatar Alexandre Ghiti Committed by Palmer Dabbelt
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riscv: Implement xchg8/16() using Zabha 



This adds runtime support for Zabha in xchg8/16() operations.

Signed-off-by: default avatarAlexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: default avatarAndrew Jones <ajones@ventanamicro.com>
Reviewed-by: default avatarAndrea Parri <parri.andrea@gmail.com>
Link: https://lore.kernel.org/r/20241103145153.105097-9-alexghiti@rivosinc.com


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent f7bd2be7

arch/riscv/include/asm/cmpxchg.h

+41 −24
Original line number Diff line number Diff line
@@ -14,8 +14,19 @@ 
#include <asm/insn-def.h>

#include <asm/cpufeature-macros.h>



#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)				\

({										\

	if (IS_ENABLED(CONFIG_RISCV_ISA_ZABHA) &&				\

	    riscv_has_extension_unlikely(RISCV_ISA_EXT_ZABHA)) {		\

		__asm__ __volatile__ (						\

			prepend							\

			"	amoswap" swap_sfx " %0, %z2, %1\n"		\

			swap_append						\

			: "=&r" (r), "+A" (*(p))				\

			: "rJ" (n)						\

			: "memory");						\

	} else {								\

		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)	\
@@ -31,12 +42,13 @@ 
		       "	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);		\

	}									\

})



#define __arch_xchg(sfx, prepend, append, r, p, n)			\
@@ -59,8 +71,13 @@ 
									\

	switch (sizeof(*__ptr)) {					\

	case 1:								\

		__arch_xchg_masked(sc_sfx, ".b" swap_sfx,		\

				   prepend, sc_append, swap_append,	\

				   __ret, __ptr, __new);		\

		break;							\

	case 2:								\

		__arch_xchg_masked(sc_sfx, prepend, sc_append,		\

		__arch_xchg_masked(sc_sfx, ".h" swap_sfx,		\

				   prepend, sc_append, swap_append,	\

				   __ret, __ptr, __new);		\

		break;							\

	case 4:								\