[v3,14/14] RISC-V: add zbb support to string functions

Message ID	20221130225614.1594256-15-heiko@sntech.de (mailing list archive)
State	Superseded
Headers	show Return-Path: <linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org> From: Heiko Stuebner <heiko@sntech.de> To: linux-riscv@lists.infradead.org, palmer@dabbelt.com Cc: christoph.muellner@vrull.eu, prabhakar.csengg@gmail.com, conor@kernel.org, philipp.tomsich@vrull.eu, ajones@ventanamicro.com, heiko@sntech.de, emil.renner.berthing@canonical.com, ardb@kernel.org, linux-efi@vger.kernel.org, Heiko Stuebner <heiko.stuebner@vrull.eu> Subject: [PATCH v3 14/14] RISC-V: add zbb support to string functions Date: Wed, 30 Nov 2022 23:56:14 +0100 Message-Id: <20221130225614.1594256-15-heiko@sntech.de> In-Reply-To: <20221130225614.1594256-1-heiko@sntech.de> References: <20221130225614.1594256-1-heiko@sntech.de> MIME-Version: 1.0 Precedence: list Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" <linux-riscv-bounces@lists.infradead.org> Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org
Series	Zbb string optimizations and call support in alternatives \| expand [v3,0/14] Zbb string optimizations and call support in alternatives [v3,01/14] RISC-V: fix funct4 definition for c.jalr in parse_asm.h [v3,02/14] RISC-V: add prefix to all constants/macros in parse_asm.h [v3,03/14] RISC-V: detach funct-values from their offset [v3,04/14] RISC-V: add ebreak instructions to definitions [v3,05/14] RISC-V: add auipc elements to parse_asm header [v3,06/14] RISC-V: Move riscv_insn_is_* macros into a common header [v3,07/14] RISC-V: rename parse_asm.h to insn.h [v3,08/14] RISC-V: kprobes: use central defined funct3 constants [v3,09/14] RISC-V: add U-type imm parsing to insn.h header [v3,10/14] RISC-V: add rd reg parsing to insn.h header [v3,11/14] RISC-V: fix auipc-jalr addresses in patched alternatives [v3,12/14] efi/riscv: libstub: mark when compiling libstub [v3,13/14] RISC-V: add infrastructure to allow different str* implementations [v3,14/14] RISC-V: add zbb support to string functions

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diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index fa78595a6089..5703c44da5f9 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -411,6 +411,30 @@ config RISCV_ISA_SVPBMT 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_IS_GNU + +config RISCV_ISA_ZBB + bool "Zbb extension support for bit manipulation instructions" + depends on TOOLCHAIN_HAS_ZBB + depends on !XIP_KERNEL && MMU + select RISCV_ALTERNATIVE + default y + help + Adds support to dynamically detect the presence of the ZBB + extension (basic bit manipulation) and enable its usage. + + 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 TOOLCHAIN_HAS_ZICBOM bool default y diff --git a/arch/riscv/include/asm/errata_list.h b/arch/riscv/include/asm/errata_list.h index 19a771085781..e0a49b9b7627 100644 --- a/arch/riscv/include/asm/errata_list.h +++ b/arch/riscv/include/asm/errata_list.h @@ -22,7 +22,8 @@ #define CPUFEATURE_SVPBMT 0 #define CPUFEATURE_ZICBOM 1 -#define CPUFEATURE_NUMBER 2 +#define CPUFEATURE_ZBB 2 +#define CPUFEATURE_NUMBER 3 #ifdef __ASSEMBLY__ diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h index b22525290073..ac5555fd9788 100644 --- a/arch/riscv/include/asm/hwcap.h +++ b/arch/riscv/include/asm/hwcap.h @@ -59,6 +59,7 @@ enum riscv_isa_ext_id { RISCV_ISA_EXT_ZIHINTPAUSE, RISCV_ISA_EXT_SSTC, RISCV_ISA_EXT_SVINVAL, + RISCV_ISA_EXT_ZBB, RISCV_ISA_EXT_ID_MAX = RISCV_ISA_EXT_MAX, }; diff --git a/arch/riscv/include/asm/string.h b/arch/riscv/include/asm/string.h index b98481d2d154..806c402c874e 100644 --- a/arch/riscv/include/asm/string.h +++ b/arch/riscv/include/asm/string.h @@ -6,6 +6,8 @@ #ifndef _ASM_RISCV_STRING_H #define _ASM_RISCV_STRING_H +#include <asm/alternative-macros.h> +#include <asm/errata_list.h> #include <linux/types.h> #include <linux/linkage.h> @@ -21,6 +23,7 @@ extern asmlinkage void *__memmove(void *, const void *, size_t); #define __HAVE_ARCH_STRCMP extern asmlinkage int __strcmp_generic(const char *cs, const char *ct); +extern asmlinkage int __strcmp_zbb(const char *cs, const char *ct); static inline int strcmp(const char *cs, const char *ct) { @@ -31,10 +34,14 @@ static inline int strcmp(const char *cs, const char *ct) register const char *a1 asm("a1") = ct; register int a0_out asm("a0"); - asm volatile("call __strcmp_generic\n\t" + asm volatile( + ALTERNATIVE( + "call __strcmp_generic\n\t", + "call __strcmp_zbb\n\t", + 0, CPUFEATURE_ZBB, CONFIG_RISCV_ISA_ZBB) : "=r"(a0_out) : "r"(a0), "r"(a1) - : "ra", "t0", "t1", "t2"); + : "ra", "t0", "t1", "t2", "t3", "t4", "t5"); return a0_out; #endif @@ -43,6 +50,8 @@ static inline int strcmp(const char *cs, const char *ct) #define __HAVE_ARCH_STRNCMP extern asmlinkage int __strncmp_generic(const char *cs, const char *ct, size_t count); +extern asmlinkage int __strncmp_zbb(const char *cs, + const char *ct, size_t count); static inline int strncmp(const char *cs, const char *ct, size_t count) { @@ -54,10 +63,14 @@ static inline int strncmp(const char *cs, const char *ct, size_t count) register size_t a2 asm("a2") = count; register int a0_out asm("a0"); - asm volatile("call __strncmp_generic\n\t" + asm volatile( + ALTERNATIVE( + "call __strncmp_generic\n\t", + "call __strncmp_zbb\n\t", + 0, CPUFEATURE_ZBB, CONFIG_RISCV_ISA_ZBB) : "=r"(a0_out) : "r"(a0), "r"(a1), "r"(a2) - : "ra", "t0", "t1", "t2"); + : "ra", "t0", "t1", "t2", "t3", "t4", "t5", "t6"); return a0_out; #endif @@ -65,6 +78,7 @@ static inline int strncmp(const char *cs, const char *ct, size_t count) #define __HAVE_ARCH_STRLEN extern asmlinkage __kernel_size_t __strlen_generic(const char *); +extern asmlinkage __kernel_size_t __strlen_zbb(const char *); static inline __kernel_size_t strlen(const char *s) { @@ -75,10 +89,13 @@ static inline __kernel_size_t strlen(const char *s) register int a0_out asm("a0"); asm volatile( - "call __strlen_generic\n\t" + ALTERNATIVE( + "call __strlen_generic\n\t", + "call __strlen_zbb\n\t", + 0, CPUFEATURE_ZBB, CONFIG_RISCV_ISA_ZBB) : "=r"(a0_out) : "r"(a0) - : "ra", "t0", "t1"); + : "ra", "t0", "t1", "t2", "t3"); return a0_out; #endif diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c index 852ecccd8920..e93e098f34fe 100644 --- a/arch/riscv/kernel/cpu.c +++ b/arch/riscv/kernel/cpu.c @@ -138,6 +138,7 @@ device_initcall(riscv_cpuinfo_init); * extensions by an underscore. */ static struct riscv_isa_ext_data isa_ext_arr[] = { + __RISCV_ISA_EXT_DATA(zbb, RISCV_ISA_EXT_ZBB), __RISCV_ISA_EXT_DATA(sscofpmf, RISCV_ISA_EXT_SSCOFPMF), __RISCV_ISA_EXT_DATA(sstc, RISCV_ISA_EXT_SSTC), __RISCV_ISA_EXT_DATA(svinval, RISCV_ISA_EXT_SVINVAL), diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c index ba62a4ff5ccd..2ec60794293f 100644 --- a/arch/riscv/kernel/cpufeature.c +++ b/arch/riscv/kernel/cpufeature.c @@ -199,6 +199,7 @@ void __init riscv_fill_hwcap(void) this_hwcap |= isa2hwcap[(unsigned char)(*ext)]; set_bit(*ext - 'a', this_isa); } else { + SET_ISA_EXT_MAP("zbb", RISCV_ISA_EXT_ZBB); SET_ISA_EXT_MAP("sscofpmf", RISCV_ISA_EXT_SSCOFPMF); SET_ISA_EXT_MAP("svpbmt", RISCV_ISA_EXT_SVPBMT); SET_ISA_EXT_MAP("zicbom", RISCV_ISA_EXT_ZICBOM); @@ -278,6 +279,20 @@ static bool __init_or_module cpufeature_probe_zicbom(unsigned int stage) return true; } +static bool __init_or_module cpufeature_probe_zbb(unsigned int stage) +{ + if (!IS_ENABLED(CONFIG_RISCV_ISA_ZBB)) + return false; + + if (stage == RISCV_ALTERNATIVES_EARLY_BOOT) + return false; + + if (!riscv_isa_extension_available(NULL, ZBB)) + return false; + + return true; +} + /* * Probe presence of individual extensions. * @@ -295,6 +310,9 @@ static u32 __init_or_module cpufeature_probe(unsigned int stage) if (cpufeature_probe_zicbom(stage)) cpu_req_feature |= BIT(CPUFEATURE_ZICBOM); + if (cpufeature_probe_zbb(stage)) + cpu_req_feature |= BIT(CPUFEATURE_ZBB); + return cpu_req_feature; } diff --git a/arch/riscv/lib/Makefile b/arch/riscv/lib/Makefile index 6c74b0bedd60..b632483f851c 100644 --- a/arch/riscv/lib/Makefile +++ b/arch/riscv/lib/Makefile @@ -4,8 +4,11 @@ lib-y += memcpy.o lib-y += memset.o lib-y += memmove.o lib-y += strcmp.o +lib-$(CONFIG_RISCV_ISA_ZBB) += strcmp_zbb.o lib-y += strlen.o +lib-$(CONFIG_RISCV_ISA_ZBB) += strlen_zbb.o lib-y += strncmp.o +lib-$(CONFIG_RISCV_ISA_ZBB) += strncmp_zbb.o lib-$(CONFIG_MMU) += uaccess.o lib-$(CONFIG_64BIT) += tishift.o diff --git a/arch/riscv/lib/strcmp_zbb.S b/arch/riscv/lib/strcmp_zbb.S new file mode 100644 index 000000000000..654f17dabd67 --- /dev/null +++ b/arch/riscv/lib/strcmp_zbb.S @@ -0,0 +1,96 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (c) 2022 VRULL GmbH + * Author: Christoph Muellner <christoph.muellner@vrull.eu> + */ + +#include <linux/linkage.h> +#include <asm/asm.h> +#include <asm-generic/export.h> + +#define src1 a0 +#define result a0 +#define src2 t5 +#define data1 t0 +#define data2 t1 +#define align t2 +#define data1_orcb t3 +#define m1 t4 + +.option push +.option arch,+zbb + +/* int __strcmp_zbb(const char *cs, const char *ct) */ +ENTRY(__strcmp_zbb) + /* + * Returns + * a0 - comparison result, value like strcmp + * + * Parameters + * a0 - string1 + * a1 - string2 + * + * Clobbers + * t0, t1, t2, t3, t4, t5 + */ + mv src2, a1 + + or align, src1, src2 + li m1, -1 + and align, align, SZREG-1 + bnez align, 3f + + /* Main loop for aligned string. */ + .p2align 3 +1: + REG_L data1, 0(src1) + REG_L data2, 0(src2) + orc.b data1_orcb, data1 + bne data1_orcb, m1, 2f + addi src1, src1, SZREG + addi src2, src2, SZREG + beq data1, data2, 1b + + /* + * Words don't match, and no null byte in the first + * word. Get bytes in big-endian order and compare. + */ +#ifndef CONFIG_CPU_BIG_ENDIAN + rev8 data1, data1 + rev8 data2, data2 +#endif + + /* Synthesize (data1 >= data2) ? 1 : -1 in a branchless sequence. */ + sltu result, data1, data2 + neg result, result + ori result, result, 1 + ret + +2: + /* + * Found a null byte. + * If words don't match, fall back to simple loop. + */ + bne data1, data2, 3f + + /* Otherwise, strings are equal. */ + li result, 0 + ret + + /* Simple loop for misaligned strings. */ + .p2align 3 +3: + lbu data1, 0(src1) + lbu data2, 0(src2) + addi src1, src1, 1 + addi src2, src2, 1 + bne data1, data2, 4f + bnez data1, 3b + +4: + sub result, data1, data2 + ret +END(__strcmp_zbb) +EXPORT_SYMBOL(__strcmp_zbb) + +.option pop diff --git a/arch/riscv/lib/strlen_zbb.S b/arch/riscv/lib/strlen_zbb.S new file mode 100644 index 000000000000..49a396567819 --- /dev/null +++ b/arch/riscv/lib/strlen_zbb.S @@ -0,0 +1,115 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (c) 2022 VRULL GmbH + * Author: Christoph Muellner <christoph.muellner@vrull.eu> + */ + +#include <linux/linkage.h> +#include <asm/asm.h> +#include <asm-generic/export.h> + +#define src a0 +#define result a0 +#define addr t0 +#define data t1 +#define offset t2 +#define offset_bits t2 +#define valid_bytes t3 +#define m1 t3 + +#ifdef CONFIG_CPU_BIG_ENDIAN +# define CZ clz +# define SHIFT sll +#else +# define CZ ctz +# define SHIFT srl +#endif + +.option push +.option arch,+zbb + +/* int __strlen_zbb(const char *s) */ +ENTRY(__strlen_zbb) + /* + * Returns + * a0 - string length + * + * Parameters + * a0 - String to measure + * + * Clobbers + * t0, t1, t2, t3 + */ + + /* Number of irrelevant bytes in the first word. */ + andi offset, src, SZREG-1 + + /* Align pointer. */ + andi addr, src, -SZREG + + li valid_bytes, SZREG + sub valid_bytes, valid_bytes, offset + slli offset_bits, offset, RISCV_LGPTR + + /* Get the first word. */ + REG_L data, 0(addr) + + /* + * Shift away the partial data we loaded to remove the irrelevant bytes + * preceding the string with the effect of adding NUL bytes at the + * end of the string. + */ + SHIFT data, data, offset_bits + + /* Convert non-NUL into 0xff and NUL into 0x00. */ + orc.b data, data + + /* Convert non-NUL into 0x00 and NUL into 0xff. */ + not data, data + + /* + * Search for the first set bit (corresponding to a NUL byte in the + * original chunk). + */ + CZ data, data + + /* + * The first chunk is special: commpare against the number + * of valid bytes in this chunk. + */ + srli result, data, 3 + bgtu valid_bytes, result, 3f + + /* Prepare for the word comparison loop. */ + addi offset, addr, SZREG + li m1, -1 + + /* + * Our critical loop is 4 instructions and processes data in + * 4 byte or 8 byte chunks. + */ + .p2align 3 +1: + REG_L data, SZREG(addr) + addi addr, addr, SZREG + orc.b data, data + beq data, m1, 1b +2: + not data, data + CZ data, data + + /* Get number of processed words. */ + sub offset, addr, offset + + /* Add number of characters in the first word. */ + add result, result, offset + srli data, data, 3 + + /* Add number of characters in the last word. */ + add result, result, data +3: + ret +END(__strlen_zbb) +EXPORT_SYMBOL(__strlen_zbb) + +.option pop diff --git a/arch/riscv/lib/strncmp_zbb.S b/arch/riscv/lib/strncmp_zbb.S new file mode 100644 index 000000000000..0cd4b84b7d27 --- /dev/null +++ b/arch/riscv/lib/strncmp_zbb.S @@ -0,0 +1,112 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (c) 2022 VRULL GmbH + * Author: Christoph Muellner <christoph.muellner@vrull.eu> + */ + +#include <linux/linkage.h> +#include <asm/asm.h> +#include <asm-generic/export.h> + +#define src1 a0 +#define result a0 +#define src2 t6 +#define len a2 +#define data1 t0 +#define data2 t1 +#define align t2 +#define data1_orcb t3 +#define limit t4 +#define m1 t5 + +.option push +.option arch,+zbb + +/* int __strncmp_zbb(const char *cs, const char *ct, size_t count) */ +ENTRY(__strncmp_zbb) + /* + * Returns + * a0 - comparison result, like strncmp + * + * Parameters + * a0 - string1 + * a1 - string2 + * a2 - number of characters to compare + * + * Clobbers + * t0, t1, t2, t3, t4, t5, t6 + */ + mv src2, a1 + + or align, src1, src2 + li m1, -1 + and align, align, SZREG-1 + add limit, src1, len + bnez align, 4f + + /* Adjust limit for fast-path. */ + addi limit, limit, -SZREG + + /* Main loop for aligned string. */ + .p2align 3 +1: + bgt src1, limit, 3f + REG_L data1, 0(src1) + REG_L data2, 0(src2) + orc.b data1_orcb, data1 + bne data1_orcb, m1, 2f + addi src1, src1, SZREG + addi src2, src2, SZREG + beq data1, data2, 1b + + /* + * Words don't match, and no null byte in the first + * word. Get bytes in big-endian order and compare. + */ +#ifndef CONFIG_CPU_BIG_ENDIAN + rev8 data1, data1 + rev8 data2, data2 +#endif + + /* Synthesize (data1 >= data2) ? 1 : -1 in a branchless sequence. */ + sltu result, data1, data2 + neg result, result + ori result, result, 1 + ret + +2: + /* + * Found a null byte. + * If words don't match, fall back to simple loop. + */ + bne data1, data2, 3f + + /* Otherwise, strings are equal. */ + li result, 0 + ret + + /* Simple loop for misaligned strings. */ +3: + /* Restore limit for slow-path. */ + addi limit, limit, SZREG + .p2align 3 +4: + bge src1, limit, 6f + lbu data1, 0(src1) + lbu data2, 0(src2) + addi src1, src1, 1 + addi src2, src2, 1 + bne data1, data2, 5f + bnez data1, 4b + +5: + sub result, data1, data2 + ret + +6: + li result, 0 + ret +END(__strncmp_zbb) +EXPORT_SYMBOL(__strncmp_zbb) + +.option pop

[v3,14/14] RISC-V: add zbb support to string functions

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