arch/riscv/kernel/cpufeature.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copied from arch/arm64/kernel/cpufeature.c
   4  *
   5  * Copyright (C) 2015 ARM Ltd.
   6  * Copyright (C) 2017 SiFive
   7  */
   8
   9 #include <linux/bitmap.h>
  10 #include <linux/ctype.h>
  11 #include <linux/of.h>
  12 #include <asm/processor.h>
  13 #include <asm/hwcap.h>
  14 #include <asm/smp.h>
  15 #include <asm/switch_to.h>
  16
  17 #define NUM_ALPHA_EXTS ('z' - 'a' + 1)
  18
  19 unsigned long elf_hwcap __read_mostly;
  20
  21 /* Host ISA bitmap */
  22 static DECLARE_BITMAP(riscv_isa, RISCV_ISA_EXT_MAX) __read_mostly;
  23
  24 #ifdef CONFIG_FPU
  25 __ro_after_init DEFINE_STATIC_KEY_FALSE(cpu_hwcap_fpu);
  26 #endif
  27
  28 /**
  29  * riscv_isa_extension_base() - Get base extension word
  30  *
  31  * @isa_bitmap: ISA bitmap to use
  32  * Return: base extension word as unsigned long value
  33  *
  34  * NOTE: If isa_bitmap is NULL then Host ISA bitmap will be used.
  35  */
  36 unsigned long riscv_isa_extension_base(const unsigned long *isa_bitmap)
  37 {
  38         if (!isa_bitmap)
  39                 return riscv_isa[0];
  40         return isa_bitmap[0];
  41 }
  42 EXPORT_SYMBOL_GPL(riscv_isa_extension_base);
  43
  44 /**
  45  * __riscv_isa_extension_available() - Check whether given extension
  46  * is available or not
  47  *
  48  * @isa_bitmap: ISA bitmap to use
  49  * @bit: bit position of the desired extension
  50  * Return: true or false
  51  *
  52  * NOTE: If isa_bitmap is NULL then Host ISA bitmap will be used.
  53  */
  54 bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, int bit)
  55 {
  56         const unsigned long *bmap = (isa_bitmap) ? isa_bitmap : riscv_isa;
  57
  58         if (bit >= RISCV_ISA_EXT_MAX)
  59                 return false;
  60
  61         return test_bit(bit, bmap) ? true : false;
  62 }
  63 EXPORT_SYMBOL_GPL(__riscv_isa_extension_available);
  64
  65 void __init riscv_fill_hwcap(void)
  66 {
  67         struct device_node *node;
  68         const char *isa;
  69         char print_str[NUM_ALPHA_EXTS + 1];
  70         int i, j;
  71         static unsigned long isa2hwcap[256] = {0};
  72
  73         isa2hwcap['i'] = isa2hwcap['I'] = COMPAT_HWCAP_ISA_I;
  74         isa2hwcap['m'] = isa2hwcap['M'] = COMPAT_HWCAP_ISA_M;
  75         isa2hwcap['a'] = isa2hwcap['A'] = COMPAT_HWCAP_ISA_A;
  76         isa2hwcap['f'] = isa2hwcap['F'] = COMPAT_HWCAP_ISA_F;
  77         isa2hwcap['d'] = isa2hwcap['D'] = COMPAT_HWCAP_ISA_D;
  78         isa2hwcap['c'] = isa2hwcap['C'] = COMPAT_HWCAP_ISA_C;
  79
  80         elf_hwcap = 0;
  81
  82         bitmap_zero(riscv_isa, RISCV_ISA_EXT_MAX);
  83
  84         for_each_of_cpu_node(node) {
  85                 unsigned long this_hwcap = 0;
  86                 unsigned long this_isa = 0;
  87
  88                 if (riscv_of_processor_hartid(node) < 0)
  89                         continue;
  90
  91                 if (of_property_read_string(node, "riscv,isa", &isa)) {
  92                         pr_warn("Unable to find \"riscv,isa\" devicetree entry\n");
  93                         continue;
  94                 }
  95
  96 #if IS_ENABLED(CONFIG_32BIT)
  97                 if (!strncmp(isa, "rv32", 4))
  98                         isa += 4;
  99 #elif IS_ENABLED(CONFIG_64BIT)
 100                 if (!strncmp(isa, "rv64", 4))
 101                         isa += 4;
 102 #endif
 103                 for (; *isa; ++isa) {
 104                         const char *ext = isa++;
 105                         const char *ext_end = isa;
 106                         bool ext_long = false, ext_err = false;
 107
 108                         switch (*ext) {
 109                         case 's':
 110                         case 'x':
 111                         case 'z':
 112                                 /**
 113                                  * Workaround for invalid single-letter 's' (QEMU).
 114                                  * It works until multi-letter extension starting
 115                                  * with "Su" appears.
 116                                  */
 117                                 if (*ext == 's' && ext[-1] != '_' && ext[1] == 'u')
 118                                         break;
 119                                 ext_long = true;
 120                                 /* Multi-letter extension must be delimited */
 121                                 for (; *isa && *isa != '_'; ++isa)
 122                                         if (unlikely(!islower(*isa)
 123                                                      && !isdigit(*isa)))
 124                                                 ext_err = true;
 125                                 /* Parse backwards */
 126                                 ext_end = isa;
 127                                 if (unlikely(ext_err))
 128                                         break;
 129                                 if (!isdigit(ext_end[-1]))
 130                                         break;
 131                                 /* Skip the minor version */
 132                                 while (isdigit(*--ext_end))
 133                                         ;
 134                                 if (ext_end[0] != 'p'
 135                                     || !isdigit(ext_end[-1])) {
 136                                         /* Advance it to offset the pre-decrement */
 137                                         ++ext_end;
 138                                         break;
 139                                 }
 140                                 /* Skip the major version */
 141                                 while (isdigit(*--ext_end))
 142                                         ;
 143                                 ++ext_end;
 144                                 break;
 145                         default:
 146                                 if (unlikely(!islower(*ext))) {
 147                                         ext_err = true;
 148                                         break;
 149                                 }
 150                                 /* Find next extension */
 151                                 if (!isdigit(*isa))
 152                                         break;
 153                                 /* Skip the minor version */
 154                                 while (isdigit(*++isa))
 155                                         ;
 156                                 if (*isa != 'p')
 157                                         break;
 158                                 if (!isdigit(*++isa)) {
 159                                         --isa;
 160                                         break;
 161                                 }
 162                                 /* Skip the major version */
 163                                 while (isdigit(*++isa))
 164                                         ;
 165                                 break;
 166                         }
 167                         if (*isa != '_')
 168                                 --isa;
 169
 170                         if (unlikely(ext_err))
 171                                 continue;
 172                         if (!ext_long) {
 173                                 this_hwcap |= isa2hwcap[(unsigned char)(*ext)];
 174                                 this_isa |= (1UL << (*ext - 'a'));
 175                         }
 176                 }
 177
 178                 /*
 179                  * All "okay" hart should have same isa. Set HWCAP based on
 180                  * common capabilities of every "okay" hart, in case they don't
 181                  * have.
 182                  */
 183                 if (elf_hwcap)
 184                         elf_hwcap &= this_hwcap;
 185                 else
 186                         elf_hwcap = this_hwcap;
 187
 188                 if (riscv_isa[0])
 189                         riscv_isa[0] &= this_isa;
 190                 else
 191                         riscv_isa[0] = this_isa;
 192         }
 193
 194         /* We don't support systems with F but without D, so mask those out
 195          * here. */
 196         if ((elf_hwcap & COMPAT_HWCAP_ISA_F) && !(elf_hwcap & COMPAT_HWCAP_ISA_D)) {
 197                 pr_info("This kernel does not support systems with F but not D\n");
 198                 elf_hwcap &= ~COMPAT_HWCAP_ISA_F;
 199         }
 200
 201         memset(print_str, 0, sizeof(print_str));
 202         for (i = 0, j = 0; i < NUM_ALPHA_EXTS; i++)
 203                 if (riscv_isa[0] & BIT_MASK(i))
 204                         print_str[j++] = (char)('a' + i);
 205         pr_info("riscv: ISA extensions %s\n", print_str);
 206
 207         memset(print_str, 0, sizeof(print_str));
 208         for (i = 0, j = 0; i < NUM_ALPHA_EXTS; i++)
 209                 if (elf_hwcap & BIT_MASK(i))
 210                         print_str[j++] = (char)('a' + i);
 211         pr_info("riscv: ELF capabilities %s\n", print_str);
 212
 213 #ifdef CONFIG_FPU
 214         if (elf_hwcap & (COMPAT_HWCAP_ISA_F | COMPAT_HWCAP_ISA_D))
 215                 static_branch_enable(&cpu_hwcap_fpu);
 216 #endif
 217 }