Messages in this thread Patch in this message | | | From | Heiko Stuebner <> | Subject | [PATCH 4/4] RISC-V: add support for vendor-extensions via AT_BASE_PLATFORM and xthead | Date | Mon, 24 Apr 2023 21:49:11 +0200 |
| |
From: Heiko Stuebner <heiko.stuebner@vrull.eu>
T-Head cores support a number of own ISA extensions that also include optimized instructions which could benefit userspace to improve performance.
Extensions supported by current T-Head cores are: * XTheadBa - bitmanipulation instructions for address calculation * XTheadBb - conditional basic bit-manipulation instructions * XTheadBs - instructions to access a single bit in a register * XTheadCmo - cache management operations * XTheadCondMov - conditional move instructions * XTheadFMemIdx - indexed memory operations for floating-point registers * XTheadFmv - double-precision floating-point high-bit data transmission intructions for RV32 * XTheadInt - instructions to reduce the code size of ISRs and/or the interrupt latencies that are caused by ISR entry/exit code * XTheadMac - multiply-accumulate instructions * XTheadMemIdx - indexed memory operations for GP registers * XTheadMemPair - two-GPR memory operations * XTheadSync - multi-core synchronization instructions
In-depth descriptions of these extensions can be found on https://github.com/T-head-Semi/thead-extension-spec
Support for those extensions was merged into the relevant toolchains so userspace programs can select necessary optimizations when needed.
So a mechanism to the isa-string generation to export vendor-extension lists via the errata mechanism and implement it for T-Head C9xx cores.
This exposes these vendor extensions then both in AT_BASE_PLATFORM and /proc/cpuinfo.
Signed-off-by: Heiko Stuebner <heiko.stuebner@vrull.eu> --- arch/riscv/errata/thead/errata.c | 43 ++++++++++++++++++++++++++++ arch/riscv/include/asm/alternative.h | 4 +++ arch/riscv/kernel/alternative.c | 21 ++++++++++++++ arch/riscv/kernel/cpu.c | 12 ++++++++ 4 files changed, 80 insertions(+)
diff --git a/arch/riscv/errata/thead/errata.c b/arch/riscv/errata/thead/errata.c index 1036b8f933ec..eb635bf80737 100644 --- a/arch/riscv/errata/thead/errata.c +++ b/arch/riscv/errata/thead/errata.c @@ -15,6 +15,7 @@ #include <asm/errata_list.h> #include <asm/hwprobe.h> #include <asm/patch.h> +#include <asm/switch_to.h> #include <asm/vendorid_list.h> static bool errata_probe_pbmt(unsigned int stage, @@ -125,3 +126,45 @@ void __init_or_module thead_feature_probe_func(unsigned int cpu, if ((archid == 0) && (impid == 0)) per_cpu(misaligned_access_speed, cpu) = RISCV_HWPROBE_MISALIGNED_FAST; } + + +char *thead_extension_list_func(unsigned long archid, + unsigned long impid) +{ + if ((archid == 0) && (impid == 0)) { + const char *xbase1 = "xtheadba_xtheadbb_xtheadbs_xtheadcmo_xtheadcondmov"; + const char *xbase2 = "_xtheadint_xtheadmac_xtheadmemidx_xtheadmempair_xtheadsync"; + const char *xfpu = "_xtheadfmemIdx"; +#ifdef CONFIG_32BIT + const char *xfpu32 = "_xtheadfmv"; +#endif + int len = strlen(xbase1) + strlen(xbase2); + char *str; + + if (has_fpu()) { + len += strlen(xfpu); +#ifdef CONFIG_32BIT + len+= strlen(xfpu32); +#endif + } + + str = kzalloc(len, GFP_KERNEL); + if (!str) + return str; + + strcpy(str, xbase1); + + if (has_fpu()) { + strcat(str, xfpu); +#ifdef CONFIG_32BIT + strcat(str, xfpu32); +#endif + } + + strcat(str, xbase2); + + return str; + } + + return NULL; +} diff --git a/arch/riscv/include/asm/alternative.h b/arch/riscv/include/asm/alternative.h index a8f5cf6694a1..8c9aec196649 100644 --- a/arch/riscv/include/asm/alternative.h +++ b/arch/riscv/include/asm/alternative.h @@ -31,6 +31,7 @@ #define ALT_ALT_PTR(a) __ALT_PTR(a, alt_offset) void __init probe_vendor_features(unsigned int cpu); +char *list_vendor_extensions(void); void __init apply_boot_alternatives(void); void __init apply_early_boot_alternatives(void); void apply_module_alternatives(void *start, size_t length); @@ -55,6 +56,8 @@ void thead_errata_patch_func(struct alt_entry *begin, struct alt_entry *end, void thead_feature_probe_func(unsigned int cpu, unsigned long archid, unsigned long impid); +char *thead_extension_list_func(unsigned long archid, + unsigned long impid); void riscv_cpufeature_patch_func(struct alt_entry *begin, struct alt_entry *end, unsigned int stage); @@ -62,6 +65,7 @@ void riscv_cpufeature_patch_func(struct alt_entry *begin, struct alt_entry *end, #else /* CONFIG_RISCV_ALTERNATIVE */ static inline void probe_vendor_features(unsigned int cpu) { } +static inline char *list_vendor_extensions(void) { return NULL; } static inline void apply_boot_alternatives(void) { } static inline void apply_early_boot_alternatives(void) { } static inline void apply_module_alternatives(void *start, size_t length) { } diff --git a/arch/riscv/kernel/alternative.c b/arch/riscv/kernel/alternative.c index fc65c9293ac5..18913fd1809f 100644 --- a/arch/riscv/kernel/alternative.c +++ b/arch/riscv/kernel/alternative.c @@ -29,6 +29,8 @@ struct cpu_manufacturer_info_t { unsigned int stage); void (*feature_probe_func)(unsigned int cpu, unsigned long archid, unsigned long impid); + char *(*extension_list_func)(unsigned long archid, + unsigned long impid); }; static void __init_or_module riscv_fill_cpu_mfr_info(struct cpu_manufacturer_info_t *cpu_mfr_info) @@ -54,6 +56,7 @@ static void __init_or_module riscv_fill_cpu_mfr_info(struct cpu_manufacturer_inf case THEAD_VENDOR_ID: cpu_mfr_info->patch_func = thead_errata_patch_func; cpu_mfr_info->feature_probe_func = thead_feature_probe_func; + cpu_mfr_info->extension_list_func = thead_extension_list_func; break; #endif default: @@ -157,6 +160,24 @@ void __init_or_module probe_vendor_features(unsigned int cpu) cpu_mfr_info.imp_id); } +/* + * Lists the vendor-specific extensions common to all cores. + * Returns a new underscore "_" concatenated string that the + * caller is supposed to free after use. + */ +char *list_vendor_extensions(void) +{ + struct cpu_manufacturer_info_t cpu_mfr_info; + + riscv_fill_cpu_mfr_info(&cpu_mfr_info); + if (!cpu_mfr_info.extension_list_func) + return NULL; + + return cpu_mfr_info.extension_list_func(cpu_mfr_info.arch_id, + cpu_mfr_info.imp_id); + +} + /* * This is called very early in the boot process (directly after we run * a feature detect on the boot CPU). No need to worry about other CPUs diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c index 71770563199f..6a0a45b2eb20 100644 --- a/arch/riscv/kernel/cpu.c +++ b/arch/riscv/kernel/cpu.c @@ -7,6 +7,7 @@ #include <linux/init.h> #include <linux/seq_file.h> #include <linux/of.h> +#include <asm/alternative.h> #include <asm/cpufeature.h> #include <asm/csr.h> #include <asm/hwcap.h> @@ -260,6 +261,7 @@ static char *riscv_create_isa_string(void) { int maxlen = 4; char *isa_str; + char *vendor_isa; int i; /* calculate the needed string length */ @@ -268,6 +270,10 @@ static char *riscv_create_isa_string(void) maxlen++; maxlen += strlen_isa_ext(); + vendor_isa = list_vendor_extensions(); + if (vendor_isa) + maxlen += strlen(vendor_isa) + 1; + isa_str = kzalloc(maxlen, GFP_KERNEL); if (!isa_str) return ERR_PTR(-ENOMEM); @@ -287,6 +293,12 @@ static char *riscv_create_isa_string(void) strcat_isa_ext(isa_str); + if(vendor_isa) { + strcat(isa_str, "_"); + strcat(isa_str, vendor_isa); + kfree(vendor_isa); + } + return isa_str; } -- 2.39.0
| |