Messages in this thread Patch in this message | | | From | Charlie Jenkins <> | Date | Tue, 07 May 2024 18:36:31 -0700 | Subject | [PATCH v2 5/8] riscv: Add PLATFORM_SUPPORTS_RISCV_ISA_ZBB Kconfig option |
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Zbb can optimize kernel instruction sequences. Add a config option PLATFORM_SUPPORTS_RISCV_ISA_ZBB that allows arbitrary Zbb instruction sequences to be emitted by the compiler. This assumption also allows the alternatives to become evaluated at compile time for Zbb.
The existing "RISCV_ISA_ZBB" option is repurposed to be used to by kernel code to determine if either PLATFORM_MAY_SUPPORT_RISCV_ISA_ZBB or PLATFORM_SUPPORTS_RISCV_ISA_ZBB has been set.
Signed-off-by: Charlie Jenkins <charlie@rivosinc.com> --- arch/riscv/Kconfig | 24 ---------------- arch/riscv/Kconfig.isa | 54 ++++++++++++++++++++++++++++++++++- arch/riscv/Makefile | 1 + arch/riscv/include/asm/arch_hweight.h | 33 ++++++++++----------- arch/riscv/include/asm/checksum.h | 18 ++++++------ arch/riscv/lib/csum.c | 48 +++++++++++++++---------------- arch/riscv/lib/strcmp.S | 4 +-- arch/riscv/lib/strlen.S | 4 +-- arch/riscv/lib/strncmp.S | 4 +-- arch/riscv/net/bpf_jit.h | 4 ++- 10 files changed, 113 insertions(+), 81 deletions(-)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 47a1d28bbb64..df620e534b3f 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -484,14 +484,6 @@ config RISCV_ALTERNATIVE_EARLY help Allows early patching of the kernel for special errata -config TOOLCHAIN_HAS_ZBB - bool - default y - depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zbb) - depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zbb) - depends on LLD_VERSION >= 150000 || LD_VERSION >= 23900 - depends on AS_HAS_OPTION_ARCH - # This symbol indicates that the toolchain supports all v1.0 vector crypto # extensions, including Zvk*, Zvbb, and Zvbc. LLVM added all of these at once. # binutils added all except Zvkb, then added Zvkb. So we just check for Zvkb. @@ -499,22 +491,6 @@ config TOOLCHAIN_HAS_VECTOR_CRYPTO def_bool $(as-instr, .option arch$(comma) +v$(comma) +zvkb) depends on AS_HAS_OPTION_ARCH -config RISCV_ISA_ZBB - bool "Zbb extension support for bit manipulation instructions" - depends on TOOLCHAIN_HAS_ZBB - depends on MMU - depends on RISCV_ALTERNATIVE - default y - help - Add support for enabling optimisations in the kernel when the - Zbb extension is detected at boot. - - The Zbb extension provides instructions to accelerate a number - of bit-specific operations (count bit population, sign extending, - bitrotation, etc). - - If you don't know what to do here, say Y. - config RISCV_ISA_ZICBOM bool "Zicbom extension support for non-coherent DMA operation" depends on MMU diff --git a/arch/riscv/Kconfig.isa b/arch/riscv/Kconfig.isa index 50e217dc5719..49bed8c75263 100644 --- a/arch/riscv/Kconfig.isa +++ b/arch/riscv/Kconfig.isa @@ -169,7 +169,7 @@ config PLATFORM_SUPPORTS_RISCV_ISA_SVNAPOT endchoice -config RISCV_ISA_SVPBMT +config PLATFORM_MAY_SUPPORT_RISCV_ISA_SVPBMT bool "Svpbmt extension support for supervisor mode page-based memory types" depends on 64BIT && MMU depends on RISCV_ALTERNATIVE @@ -185,3 +185,55 @@ config RISCV_ISA_SVPBMT The Svpbmt extension is only available on 64-bit cpus. If you don't know what to do here, say Y. + +config TOOLCHAIN_HAS_ZBB + bool + default y + depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zbb) + depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zbb) + depends on LLD_VERSION >= 150000 || LD_VERSION >= 23900 + depends on AS_HAS_OPTION_ARCH + +config RISCV_ISA_ZBB + bool + +choice + prompt "Zbb extension for bit manipulation instructions support" + default PLATFORM_MAY_SUPPORT_RISCV_ISA_ZBB + help + This selects the level of support for Zbb instructions to be + built into the Linux Kernel. This does not impact whether Zbb + instructions are allowed to be emitted by user-space code. + + The Zbb extension provides instructions to accelerate a number + of bit-specific operations (count bit population, sign extending, + bitrotation, etc). + +config PROHIBIT_RISCV_ISA_ZBB + bool "Prohibit Zbb instruction sequences" + depends on NONPORTABLE + help + Regardless of if the platform supports Zbb instructions, + prohibit the kernel from emitting Zbb instructions. + +config PLATFORM_MAY_SUPPORT_RISCV_ISA_ZBB + bool "Allow Zbb instruction sequences if supported" + depends on TOOLCHAIN_HAS_ZBB + depends on RISCV_ALTERNATIVE + select RISCV_ISA_ZBB + help + Add support for enabling optimisations in the kernel when the + Zbb extension is detected at boot. + +config PLATFORM_SUPPORTS_RISCV_ISA_ZBB + bool "Emit Zbb instructions when building Linux" + depends on TOOLCHAIN_HAS_ZBB + depends on NONPORTABLE + select RISCV_ISA_ZBB + help + Adds "zbb" to the ISA subsets that the toolchain is allowed to emit + when building Linux, which results in Zbb instructions in the + Linux binary. This option produces a kernel that will not run on + systems that do not support the Zbb extension. + +endchoice diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile index e1111e62ca20..6b0c3a782f99 100644 --- a/arch/riscv/Makefile +++ b/arch/riscv/Makefile @@ -66,6 +66,7 @@ riscv-march-$(CONFIG_ARCH_RV32I) := rv32ima riscv-march-$(CONFIG_ARCH_RV64I) := rv64ima riscv-march-$(CONFIG_FPU) := $(riscv-march-y)fd riscv-march-$(CONFIG_PLATFORM_SUPPORTS_RISCV_ISA_C) := $(riscv-march-y)c +riscv-march-$(CONFIG_PLATFORM_SUPPORTS_RISCV_ISA_ZBB) := $(riscv-march-y)_zbb ifdef CONFIG_TOOLCHAIN_NEEDS_OLD_ISA_SPEC KBUILD_CFLAGS += -Wa,-misa-spec=2.2 diff --git a/arch/riscv/include/asm/arch_hweight.h b/arch/riscv/include/asm/arch_hweight.h index 85b2c443823e..d89a18d5104f 100644 --- a/arch/riscv/include/asm/arch_hweight.h +++ b/arch/riscv/include/asm/arch_hweight.h @@ -19,21 +19,20 @@ static __always_inline unsigned int __arch_hweight32(unsigned int w) { -#ifdef CONFIG_RISCV_ISA_ZBB - asm goto(ALTERNATIVE("j %l[legacy]", "nop", 0, - RISCV_ISA_EXT_ZBB, 1) - : : : : legacy); - - asm (".option push\n" - ".option arch,+zbb\n" - CPOPW "%0, %0\n" - ".option pop\n" - : "+r" (w) : :); - - return w; + if (IS_ENABLED(CONFIG_RISCV_ISA_ZBB)) { + if (!IS_ENABLED(CONFIG_PLATFORM_SUPPORTS_RISCV_ISA_ZBB)) + asm goto(ALTERNATIVE("j %l[legacy]", "nop", 0, + RISCV_ISA_EXT_ZBB, 1) + : : : : legacy); + asm (".option push\n" + ".option arch,+zbb\n" + CPOPW "%0, %0\n" + ".option pop\n" + : "+r" (w) : :); + return w; + } legacy: -#endif return __sw_hweight32(w); } @@ -50,11 +49,12 @@ static inline unsigned int __arch_hweight8(unsigned int w) #if BITS_PER_LONG == 64 static __always_inline unsigned long __arch_hweight64(__u64 w) { -# ifdef CONFIG_RISCV_ISA_ZBB +#ifdef CONFIG_PLATFORM_MAY_SUPPORT_RISCV_ISA_ZBB asm goto(ALTERNATIVE("j %l[legacy]", "nop", 0, RISCV_ISA_EXT_ZBB, 1) : : : : legacy); - +#endif +#ifdef CONFIG_RISCV_ISA_ZBB asm (".option push\n" ".option arch,+zbb\n" "cpop %0, %0\n" @@ -62,7 +62,8 @@ static __always_inline unsigned long __arch_hweight64(__u64 w) : "+r" (w) : :); return w; - +#endif +#ifdef CONFIG_PLATFORM_MAY_SUPPORT_RISCV_ISA_ZBB legacy: # endif return __sw_hweight64(w); diff --git a/arch/riscv/include/asm/checksum.h b/arch/riscv/include/asm/checksum.h index 88e6f1499e88..2fe92abf5525 100644 --- a/arch/riscv/include/asm/checksum.h +++ b/arch/riscv/include/asm/checksum.h @@ -2,7 +2,7 @@ /* * Checksum routines * - * Copyright (C) 2023 Rivos Inc. + * Copyright (C) 2023-2024 Rivos Inc. */ #ifndef __ASM_RISCV_CHECKSUM_H #define __ASM_RISCV_CHECKSUM_H @@ -49,16 +49,16 @@ static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl) * ZBB only saves three instructions on 32-bit and five on 64-bit so not * worth checking if supported without Alternatives. */ - if (IS_ENABLED(CONFIG_RISCV_ISA_ZBB) && - IS_ENABLED(CONFIG_RISCV_ALTERNATIVE)) { + if (IS_ENABLED(CONFIG_RISCV_ISA_ZBB)) { unsigned long fold_temp; - asm goto(ALTERNATIVE("j %l[no_zbb]", "nop", 0, - RISCV_ISA_EXT_ZBB, 1) - : - : - : - : no_zbb); + if (!IS_ENABLED(CONFIG_PLATFORM_SUPPORTS_RISCV_ISA_ZBB)) + asm goto(ALTERNATIVE("j %l[no_zbb]", "nop", 0, + RISCV_ISA_EXT_ZBB, 1) + : + : + : + : no_zbb); if (IS_ENABLED(CONFIG_32BIT)) { asm(".option push \n\ diff --git a/arch/riscv/lib/csum.c b/arch/riscv/lib/csum.c index 7fb12c59e571..5ea2bf71c963 100644 --- a/arch/riscv/lib/csum.c +++ b/arch/riscv/lib/csum.c @@ -44,8 +44,7 @@ __sum16 csum_ipv6_magic(const struct in6_addr *saddr, * Zbb support saves 4 instructions, so not worth checking without * alternatives if supported */ - if (IS_ENABLED(CONFIG_RISCV_ISA_ZBB) && - IS_ENABLED(CONFIG_RISCV_ALTERNATIVE)) { + if (IS_ENABLED(CONFIG_RISCV_ISA_ZBB)) { unsigned long fold_temp; /* @@ -53,12 +52,13 @@ __sum16 csum_ipv6_magic(const struct in6_addr *saddr, * support, so nop when Zbb is available and jump when Zbb is * not available. */ - asm goto(ALTERNATIVE("j %l[no_zbb]", "nop", 0, - RISCV_ISA_EXT_ZBB, 1) - : - : - : - : no_zbb); + if (!IS_ENABLED(CONFIG_PLATFORM_SUPPORTS_RISCV_ISA_ZBB)) + asm goto(ALTERNATIVE("j %l[no_zbb]", "nop", 0, + RISCV_ISA_EXT_ZBB, 1) + : + : + : + : no_zbb); asm(".option push \n\ .option arch,+zbb \n\ rori %[fold_temp], %[sum], 32 \n\ @@ -161,8 +161,7 @@ do_csum_with_alignment(const unsigned char *buff, int len) * Zbb support saves 6 instructions, so not worth checking without * alternatives if supported */ - if (IS_ENABLED(CONFIG_RISCV_ISA_ZBB) && - IS_ENABLED(CONFIG_RISCV_ALTERNATIVE)) { + if (IS_ENABLED(CONFIG_RISCV_ISA_ZBB)) { unsigned long fold_temp; /* @@ -170,12 +169,13 @@ do_csum_with_alignment(const unsigned char *buff, int len) * support, so nop when Zbb is available and jump when Zbb is * not available. */ - asm goto(ALTERNATIVE("j %l[no_zbb]", "nop", 0, - RISCV_ISA_EXT_ZBB, 1) - : - : - : - : no_zbb); + if (!IS_ENABLED(CONFIG_PLATFORM_SUPPORTS_RISCV_ISA_ZBB)) + asm goto(ALTERNATIVE("j %l[no_zbb]", "nop", 0, + RISCV_ISA_EXT_ZBB, 1) + : + : + : + : no_zbb); #ifdef CONFIG_32BIT asm_goto_output(".option push \n\ @@ -248,8 +248,7 @@ do_csum_no_alignment(const unsigned char *buff, int len) * Zbb support saves 6 instructions, so not worth checking without * alternatives if supported */ - if (IS_ENABLED(CONFIG_RISCV_ISA_ZBB) && - IS_ENABLED(CONFIG_RISCV_ALTERNATIVE)) { + if (IS_ENABLED(CONFIG_RISCV_ISA_ZBB)) { unsigned long fold_temp; /* @@ -257,12 +256,13 @@ do_csum_no_alignment(const unsigned char *buff, int len) * support, so nop when Zbb is available and jump when Zbb is * not available. */ - asm goto(ALTERNATIVE("j %l[no_zbb]", "nop", 0, - RISCV_ISA_EXT_ZBB, 1) - : - : - : - : no_zbb); + if (!IS_ENABLED(CONFIG_PLATFORM_SUPPORTS_RISCV_ISA_ZBB)) + asm goto(ALTERNATIVE("j %l[no_zbb]", "nop", 0, + RISCV_ISA_EXT_ZBB, 1) + : + : + : + : no_zbb); #ifdef CONFIG_32BIT asm (".option push \n\ diff --git a/arch/riscv/lib/strcmp.S b/arch/riscv/lib/strcmp.S index 687b2bea5c43..5798ef7e73fc 100644 --- a/arch/riscv/lib/strcmp.S +++ b/arch/riscv/lib/strcmp.S @@ -7,7 +7,7 @@ /* int strcmp(const char *cs, const char *ct) */ SYM_FUNC_START(strcmp) - +#ifndef CONFIG_PLATFORM_SUPPORTS_RISCV_ISA_ZBB ALTERNATIVE("nop", "j strcmp_zbb", 0, RISCV_ISA_EXT_ZBB, CONFIG_RISCV_ISA_ZBB) /* @@ -37,7 +37,7 @@ SYM_FUNC_START(strcmp) */ sub a0, t0, t1 ret - +#endif /* !CONFIG_PLATFORM_SUPPORTS_RISCV_ISA_ZBB */ /* * Variant of strcmp using the ZBB extension if available. * The code was published as part of the bitmanip manual diff --git a/arch/riscv/lib/strlen.S b/arch/riscv/lib/strlen.S index 8ae3064e45ff..b63b91f74084 100644 --- a/arch/riscv/lib/strlen.S +++ b/arch/riscv/lib/strlen.S @@ -7,7 +7,7 @@ /* int strlen(const char *s) */ SYM_FUNC_START(strlen) - +#ifndef CONFIG_PLATFORM_SUPPORTS_RISCV_ISA_ZBB ALTERNATIVE("nop", "j strlen_zbb", 0, RISCV_ISA_EXT_ZBB, CONFIG_RISCV_ISA_ZBB) /* @@ -29,7 +29,7 @@ SYM_FUNC_START(strlen) 2: sub a0, t1, a0 ret - +#endif /* !CONFIG_PLATFORM_SUPPORTS_RISCV_ISA_ZBB */ /* * Variant of strlen using the ZBB extension if available */ diff --git a/arch/riscv/lib/strncmp.S b/arch/riscv/lib/strncmp.S index aba5b3148621..3a1330d7d4a2 100644 --- a/arch/riscv/lib/strncmp.S +++ b/arch/riscv/lib/strncmp.S @@ -7,7 +7,7 @@ /* int strncmp(const char *cs, const char *ct, size_t count) */ SYM_FUNC_START(strncmp) - +#ifndef CONFIG_PLATFORM_SUPPORTS_RISCV_ISA_ZBB ALTERNATIVE("nop", "j strncmp_zbb", 0, RISCV_ISA_EXT_ZBB, CONFIG_RISCV_ISA_ZBB) /* @@ -42,7 +42,7 @@ SYM_FUNC_START(strncmp) */ sub a0, t0, t1 ret - +#endif /* !CONFIG_PLATFORM_SUPPORTS_RISCV_ISA_ZBB */ /* * Variant of strncmp using the ZBB extension if available */ diff --git a/arch/riscv/net/bpf_jit.h b/arch/riscv/net/bpf_jit.h index 259294bdbc3a..61892044124e 100644 --- a/arch/riscv/net/bpf_jit.h +++ b/arch/riscv/net/bpf_jit.h @@ -22,7 +22,9 @@ static inline bool rvc_enabled(void) static inline bool rvzbb_enabled(void) { - return IS_ENABLED(CONFIG_RISCV_ISA_ZBB) && riscv_has_extension_likely(RISCV_ISA_EXT_ZBB); + return IS_ENABLED(CONFIG_PLATFORM_SUPPORTS_RISCV_ISA_ZBB) || + (IS_ENABLED(CONFIG_PLATFORM_MAY_SUPPORT_RISCV_ISA_ZBB) && + riscv_has_extension_likely(RISCV_ISA_EXT_ZBB)); } enum { -- 2.44.0
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