This adds runtime support for Zabha in cmpxchg8/16() operations. Note that in the absence of Zacas support in the toolchain, CAS instructions from Zabha won't be used. Signed-off-by: Alexandre Ghiti <alexghiti@xxxxxxxxxxxx> Reviewed-by: Andrew Jones <ajones@xxxxxxxxxxxxxxxx> --- arch/riscv/Kconfig | 18 ++++++++ arch/riscv/Makefile | 3 ++ arch/riscv/include/asm/cmpxchg.h | 78 ++++++++++++++++++++------------ arch/riscv/include/asm/hwcap.h | 1 + arch/riscv/kernel/cpufeature.c | 1 + 5 files changed, 72 insertions(+), 29 deletions(-) diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index d955c64d50c2..212ec2aab389 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -613,6 +613,24 @@ config RISCV_ISA_ZAWRS use of these instructions in the kernel when the Zawrs extension is detected at boot. +config TOOLCHAIN_HAS_ZABHA + bool + default y + depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zabha) + depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zabha) + depends on AS_HAS_OPTION_ARCH + +config RISCV_ISA_ZABHA + bool "Zabha extension support for atomic byte/halfword operations" + depends on TOOLCHAIN_HAS_ZABHA + depends on RISCV_ALTERNATIVE + default y + help + Enable the use of the Zabha ISA-extension to implement kernel + byte/halfword atomic memory operations when it is detected at boot. + + If you don't know what to do here, say Y. + config TOOLCHAIN_HAS_ZACAS bool default y diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile index f1788131d5fe..f6dc5ba7c526 100644 --- a/arch/riscv/Makefile +++ b/arch/riscv/Makefile @@ -85,6 +85,9 @@ endif # Check if the toolchain supports Zacas riscv-march-$(CONFIG_TOOLCHAIN_HAS_ZACAS) := $(riscv-march-y)_zacas +# Check if the toolchain supports Zabha +riscv-march-$(CONFIG_TOOLCHAIN_HAS_ZABHA) := $(riscv-march-y)_zabha + # Remove F,D,V from isa string for all. Keep extensions between "fd" and "v" by # matching non-v and non-multi-letter extensions out with the filter ([^v_]*) KBUILD_CFLAGS += -march=$(shell echo $(riscv-march-y) | sed -E 's/(rv32ima|rv64ima)fd([^v_]*)v?/\1\2/') diff --git a/arch/riscv/include/asm/cmpxchg.h b/arch/riscv/include/asm/cmpxchg.h index 39c1daf39f6a..1f4cd12e4664 100644 --- a/arch/riscv/include/asm/cmpxchg.h +++ b/arch/riscv/include/asm/cmpxchg.h @@ -108,34 +108,49 @@ * indicated by comparing RETURN with OLD. */ -#define __arch_cmpxchg_masked(sc_sfx, prepend, append, r, p, o, n) \ -({ \ - 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) \ - << __s; \ - ulong __newx = (ulong)(n) << __s; \ - ulong __oldx = (ulong)(o) << __s; \ - ulong __retx; \ - ulong __rc; \ - \ - __asm__ __volatile__ ( \ - prepend \ - "0: lr.w %0, %2\n" \ - " and %1, %0, %z5\n" \ - " bne %1, %z3, 1f\n" \ - " and %1, %0, %z6\n" \ - " or %1, %1, %z4\n" \ - " sc.w" sc_sfx " %1, %1, %2\n" \ - " bnez %1, 0b\n" \ - append \ - "1:\n" \ - : "=&r" (__retx), "=&r" (__rc), "+A" (*(__ptr32b)) \ - : "rJ" ((long)__oldx), "rJ" (__newx), \ - "rJ" (__mask), "rJ" (~__mask) \ - : "memory"); \ - \ - r = (__typeof__(*(p)))((__retx & __mask) >> __s); \ +#define __arch_cmpxchg_masked(sc_sfx, cas_sfx, prepend, append, r, p, o, n) \ +({ \ + if (IS_ENABLED(CONFIG_RISCV_ISA_ZABHA) && \ + IS_ENABLED(CONFIG_RISCV_ISA_ZACAS) && \ + riscv_has_extension_unlikely(RISCV_ISA_EXT_ZABHA) && \ + riscv_has_extension_unlikely(RISCV_ISA_EXT_ZACAS)) { \ + r = o; \ + \ + __asm__ __volatile__ ( \ + prepend \ + " amocas" cas_sfx " %0, %z2, %1\n" \ + 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) \ + << __s; \ + ulong __newx = (ulong)(n) << __s; \ + ulong __oldx = (ulong)(o) << __s; \ + ulong __retx; \ + ulong __rc; \ + \ + __asm__ __volatile__ ( \ + prepend \ + "0: lr.w %0, %2\n" \ + " and %1, %0, %z5\n" \ + " bne %1, %z3, 1f\n" \ + " and %1, %0, %z6\n" \ + " or %1, %1, %z4\n" \ + " sc.w" sc_sfx " %1, %1, %2\n" \ + " bnez %1, 0b\n" \ + append \ + "1:\n" \ + : "=&r" (__retx), "=&r" (__rc), "+A" (*(__ptr32b)) \ + : "rJ" ((long)__oldx), "rJ" (__newx), \ + "rJ" (__mask), "rJ" (~__mask) \ + : "memory"); \ + \ + r = (__typeof__(*(p)))((__retx & __mask) >> __s); \ + } \ }) #define __arch_cmpxchg(lr_sfx, sc_cas_sfx, prepend, append, r, p, co, o, n) \ @@ -177,8 +192,13 @@ \ switch (sizeof(*__ptr)) { \ case 1: \ + __arch_cmpxchg_masked(sc_cas_sfx, ".b" sc_cas_sfx, \ + prepend, append, \ + __ret, __ptr, __old, __new); \ + break; \ case 2: \ - __arch_cmpxchg_masked(sc_cas_sfx, prepend, append, \ + __arch_cmpxchg_masked(sc_cas_sfx, ".h" sc_cas_sfx, \ + prepend, append, \ __ret, __ptr, __old, __new); \ break; \ case 4: \ diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h index 5a0bd27fd11a..f5d53251c947 100644 --- a/arch/riscv/include/asm/hwcap.h +++ b/arch/riscv/include/asm/hwcap.h @@ -92,6 +92,7 @@ #define RISCV_ISA_EXT_ZCF 83 #define RISCV_ISA_EXT_ZCMOP 84 #define RISCV_ISA_EXT_ZAWRS 85 +#define RISCV_ISA_EXT_ZABHA 86 #define RISCV_ISA_EXT_XLINUXENVCFG 127 diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c index b427188b28fc..67ebcc4c9424 100644 --- a/arch/riscv/kernel/cpufeature.c +++ b/arch/riscv/kernel/cpufeature.c @@ -322,6 +322,7 @@ 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(zimop, RISCV_ISA_EXT_ZIMOP), + __RISCV_ISA_EXT_DATA(zabha, RISCV_ISA_EXT_ZABHA), __RISCV_ISA_EXT_DATA(zacas, RISCV_ISA_EXT_ZACAS), __RISCV_ISA_EXT_DATA(zawrs, RISCV_ISA_EXT_ZAWRS), __RISCV_ISA_EXT_DATA(zfa, RISCV_ISA_EXT_ZFA), -- 2.39.2