1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copied from arch/arm64/kernel/cpufeature.c
5 * Copyright (C) 2015 ARM Ltd.
6 * Copyright (C) 2017 SiFive
9 #include <linux/acpi.h>
10 #include <linux/bitmap.h>
11 #include <linux/ctype.h>
12 #include <linux/log2.h>
13 #include <linux/memory.h>
14 #include <linux/module.h>
17 #include <asm/alternative.h>
18 #include <asm/cacheflush.h>
19 #include <asm/cpufeature.h>
20 #include <asm/hwcap.h>
21 #include <asm/patch.h>
22 #include <asm/processor.h>
23 #include <asm/vector.h>
25 #define NUM_ALPHA_EXTS ('z' - 'a' + 1)
27 unsigned long elf_hwcap __read_mostly;
30 static DECLARE_BITMAP(riscv_isa, RISCV_ISA_EXT_MAX) __read_mostly;
32 /* Per-cpu ISA extensions. */
33 struct riscv_isainfo hart_isa[NR_CPUS];
35 /* Performance information */
36 DEFINE_PER_CPU(long, misaligned_access_speed);
39 * riscv_isa_extension_base() - Get base extension word
41 * @isa_bitmap: ISA bitmap to use
42 * Return: base extension word as unsigned long value
44 * NOTE: If isa_bitmap is NULL then Host ISA bitmap will be used.
46 unsigned long riscv_isa_extension_base(const unsigned long *isa_bitmap)
52 EXPORT_SYMBOL_GPL(riscv_isa_extension_base);
55 * __riscv_isa_extension_available() - Check whether given extension
58 * @isa_bitmap: ISA bitmap to use
59 * @bit: bit position of the desired extension
60 * Return: true or false
62 * NOTE: If isa_bitmap is NULL then Host ISA bitmap will be used.
64 bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, int bit)
66 const unsigned long *bmap = (isa_bitmap) ? isa_bitmap : riscv_isa;
68 if (bit >= RISCV_ISA_EXT_MAX)
71 return test_bit(bit, bmap) ? true : false;
73 EXPORT_SYMBOL_GPL(__riscv_isa_extension_available);
75 static bool riscv_isa_extension_check(int id)
78 case RISCV_ISA_EXT_ZICBOM:
79 if (!riscv_cbom_block_size) {
80 pr_err("Zicbom detected in ISA string, disabling as no cbom-block-size found\n");
82 } else if (!is_power_of_2(riscv_cbom_block_size)) {
83 pr_err("Zicbom disabled as cbom-block-size present, but is not a power-of-2\n");
87 case RISCV_ISA_EXT_ZICBOZ:
88 if (!riscv_cboz_block_size) {
89 pr_err("Zicboz detected in ISA string, but no cboz-block-size found\n");
91 } else if (!is_power_of_2(riscv_cboz_block_size)) {
92 pr_err("cboz-block-size present, but is not a power-of-2\n");
101 #define __RISCV_ISA_EXT_DATA(_name, _id) { \
103 .property = #_name, \
108 * The canonical order of ISA extension names in the ISA string is defined in
109 * chapter 27 of the unprivileged specification.
111 * Ordinarily, for in-kernel data structures, this order is unimportant but
112 * isa_ext_arr defines the order of the ISA string in /proc/cpuinfo.
114 * The specification uses vague wording, such as should, when it comes to
115 * ordering, so for our purposes the following rules apply:
117 * 1. All multi-letter extensions must be separated from other extensions by an
120 * 2. Additional standard extensions (starting with 'Z') must be sorted after
121 * single-letter extensions and before any higher-privileged extensions.
123 * 3. The first letter following the 'Z' conventionally indicates the most
124 * closely related alphabetical extension category, IMAFDQLCBKJTPVH.
125 * If multiple 'Z' extensions are named, they must be ordered first by
126 * category, then alphabetically within a category.
128 * 3. Standard supervisor-level extensions (starting with 'S') must be listed
129 * after standard unprivileged extensions. If multiple supervisor-level
130 * extensions are listed, they must be ordered alphabetically.
132 * 4. Standard machine-level extensions (starting with 'Zxm') must be listed
133 * after any lower-privileged, standard extensions. If multiple
134 * machine-level extensions are listed, they must be ordered
137 * 5. Non-standard extensions (starting with 'X') must be listed after all
138 * standard extensions. If multiple non-standard extensions are listed, they
139 * must be ordered alphabetically.
141 * An example string following the order is:
142 * rv64imadc_zifoo_zigoo_zafoo_sbar_scar_zxmbaz_xqux_xrux
144 * New entries to this struct should follow the ordering rules described above.
146 const struct riscv_isa_ext_data riscv_isa_ext[] = {
147 __RISCV_ISA_EXT_DATA(i, RISCV_ISA_EXT_i),
148 __RISCV_ISA_EXT_DATA(m, RISCV_ISA_EXT_m),
149 __RISCV_ISA_EXT_DATA(a, RISCV_ISA_EXT_a),
150 __RISCV_ISA_EXT_DATA(f, RISCV_ISA_EXT_f),
151 __RISCV_ISA_EXT_DATA(d, RISCV_ISA_EXT_d),
152 __RISCV_ISA_EXT_DATA(q, RISCV_ISA_EXT_q),
153 __RISCV_ISA_EXT_DATA(c, RISCV_ISA_EXT_c),
154 __RISCV_ISA_EXT_DATA(b, RISCV_ISA_EXT_b),
155 __RISCV_ISA_EXT_DATA(k, RISCV_ISA_EXT_k),
156 __RISCV_ISA_EXT_DATA(j, RISCV_ISA_EXT_j),
157 __RISCV_ISA_EXT_DATA(p, RISCV_ISA_EXT_p),
158 __RISCV_ISA_EXT_DATA(v, RISCV_ISA_EXT_v),
159 __RISCV_ISA_EXT_DATA(h, RISCV_ISA_EXT_h),
160 __RISCV_ISA_EXT_DATA(zicbom, RISCV_ISA_EXT_ZICBOM),
161 __RISCV_ISA_EXT_DATA(zicboz, RISCV_ISA_EXT_ZICBOZ),
162 __RISCV_ISA_EXT_DATA(zicntr, RISCV_ISA_EXT_ZICNTR),
163 __RISCV_ISA_EXT_DATA(zicsr, RISCV_ISA_EXT_ZICSR),
164 __RISCV_ISA_EXT_DATA(zifencei, RISCV_ISA_EXT_ZIFENCEI),
165 __RISCV_ISA_EXT_DATA(zihintpause, RISCV_ISA_EXT_ZIHINTPAUSE),
166 __RISCV_ISA_EXT_DATA(zihpm, RISCV_ISA_EXT_ZIHPM),
167 __RISCV_ISA_EXT_DATA(zba, RISCV_ISA_EXT_ZBA),
168 __RISCV_ISA_EXT_DATA(zbb, RISCV_ISA_EXT_ZBB),
169 __RISCV_ISA_EXT_DATA(zbs, RISCV_ISA_EXT_ZBS),
170 __RISCV_ISA_EXT_DATA(smaia, RISCV_ISA_EXT_SMAIA),
171 __RISCV_ISA_EXT_DATA(ssaia, RISCV_ISA_EXT_SSAIA),
172 __RISCV_ISA_EXT_DATA(sscofpmf, RISCV_ISA_EXT_SSCOFPMF),
173 __RISCV_ISA_EXT_DATA(sstc, RISCV_ISA_EXT_SSTC),
174 __RISCV_ISA_EXT_DATA(svinval, RISCV_ISA_EXT_SVINVAL),
175 __RISCV_ISA_EXT_DATA(svnapot, RISCV_ISA_EXT_SVNAPOT),
176 __RISCV_ISA_EXT_DATA(svpbmt, RISCV_ISA_EXT_SVPBMT),
179 const size_t riscv_isa_ext_count = ARRAY_SIZE(riscv_isa_ext);
181 static void __init riscv_parse_isa_string(unsigned long *this_hwcap, struct riscv_isainfo *isainfo,
182 unsigned long *isa2hwcap, const char *isa)
185 * For all possible cpus, we have already validated in
186 * the boot process that they at least contain "rv" and
187 * whichever of "32"/"64" this kernel supports, and so this
188 * section can be skipped.
193 const char *ext = isa++;
194 const char *ext_end = isa;
195 bool ext_long = false, ext_err = false;
200 * Workaround for invalid single-letter 's' & 'u'(QEMU).
201 * No need to set the bit in riscv_isa as 's' & 'u' are
202 * not valid ISA extensions. It works until multi-letter
203 * extension starting with "Su" appears.
205 if (ext[-1] != '_' && ext[1] == 'u') {
217 * Before attempting to parse the extension itself, we find its end.
218 * As multi-letter extensions must be split from other multi-letter
219 * extensions with an "_", the end of a multi-letter extension will
220 * either be the null character or the "_" at the start of the next
221 * multi-letter extension.
223 * Next, as the extensions version is currently ignored, we
224 * eliminate that portion. This is done by parsing backwards from
225 * the end of the extension, removing any numbers. This may be a
226 * major or minor number however, so the process is repeated if a
227 * minor number was found.
229 * ext_end is intended to represent the first character *after* the
230 * name portion of an extension, but will be decremented to the last
231 * character itself while eliminating the extensions version number.
232 * A simple re-increment solves this problem.
235 for (; *isa && *isa != '_'; ++isa)
236 if (unlikely(!isalnum(*isa)))
240 if (unlikely(ext_err))
243 if (!isdigit(ext_end[-1]))
246 while (isdigit(*--ext_end))
249 if (tolower(ext_end[0]) != 'p' || !isdigit(ext_end[-1])) {
254 while (isdigit(*--ext_end))
261 * Things are a little easier for single-letter extensions, as they
262 * are parsed forwards.
264 * After checking that our starting position is valid, we need to
265 * ensure that, when isa was incremented at the start of the loop,
266 * that it arrived at the start of the next extension.
268 * If we are already on a non-digit, there is nothing to do. Either
269 * we have a multi-letter extension's _, or the start of an
272 * Otherwise we have found the current extension's major version
273 * number. Parse past it, and a subsequent p/minor version number
274 * if present. The `p` extension must not appear immediately after
275 * a number, so there is no fear of missing it.
278 if (unlikely(!isalpha(*ext))) {
286 while (isdigit(*++isa))
289 if (tolower(*isa) != 'p')
292 if (!isdigit(*++isa)) {
297 while (isdigit(*++isa))
304 * The parser expects that at the start of an iteration isa points to the
305 * first character of the next extension. As we stop parsing an extension
306 * on meeting a non-alphanumeric character, an extra increment is needed
307 * where the succeeding extension is a multi-letter prefixed with an "_".
312 #define SET_ISA_EXT_MAP(name, bit) \
314 if ((ext_end - ext == strlen(name)) && \
315 !strncasecmp(ext, name, strlen(name)) && \
316 riscv_isa_extension_check(bit)) \
317 set_bit(bit, isainfo->isa); \
320 if (unlikely(ext_err))
323 int nr = tolower(*ext) - 'a';
325 if (riscv_isa_extension_check(nr)) {
326 *this_hwcap |= isa2hwcap[nr];
327 set_bit(nr, isainfo->isa);
330 for (int i = 0; i < riscv_isa_ext_count; i++)
331 SET_ISA_EXT_MAP(riscv_isa_ext[i].name,
332 riscv_isa_ext[i].id);
334 #undef SET_ISA_EXT_MAP
338 static void __init riscv_fill_hwcap_from_isa_string(unsigned long *isa2hwcap)
340 struct device_node *node;
343 struct acpi_table_header *rhct;
347 if (!acpi_disabled) {
348 status = acpi_get_table(ACPI_SIG_RHCT, 0, &rhct);
349 if (ACPI_FAILURE(status))
353 for_each_possible_cpu(cpu) {
354 struct riscv_isainfo *isainfo = &hart_isa[cpu];
355 unsigned long this_hwcap = 0;
358 node = of_cpu_device_node_get(cpu);
360 pr_warn("Unable to find cpu node\n");
364 rc = of_property_read_string(node, "riscv,isa", &isa);
367 pr_warn("Unable to find \"riscv,isa\" devicetree entry\n");
371 rc = acpi_get_riscv_isa(rhct, cpu, &isa);
373 pr_warn("Unable to get ISA for the hart - %d\n", cpu);
378 riscv_parse_isa_string(&this_hwcap, isainfo, isa2hwcap, isa);
381 * These ones were as they were part of the base ISA when the
382 * port & dt-bindings were upstreamed, and so can be set
383 * unconditionally where `i` is in riscv,isa on DT systems.
386 set_bit(RISCV_ISA_EXT_ZICSR, isainfo->isa);
387 set_bit(RISCV_ISA_EXT_ZIFENCEI, isainfo->isa);
388 set_bit(RISCV_ISA_EXT_ZICNTR, isainfo->isa);
389 set_bit(RISCV_ISA_EXT_ZIHPM, isainfo->isa);
393 * All "okay" hart should have same isa. Set HWCAP based on
394 * common capabilities of every "okay" hart, in case they don't
398 elf_hwcap &= this_hwcap;
400 elf_hwcap = this_hwcap;
402 if (bitmap_empty(riscv_isa, RISCV_ISA_EXT_MAX))
403 bitmap_copy(riscv_isa, isainfo->isa, RISCV_ISA_EXT_MAX);
405 bitmap_and(riscv_isa, riscv_isa, isainfo->isa, RISCV_ISA_EXT_MAX);
408 if (!acpi_disabled && rhct)
409 acpi_put_table((struct acpi_table_header *)rhct);
412 static int __init riscv_fill_hwcap_from_ext_list(unsigned long *isa2hwcap)
416 for_each_possible_cpu(cpu) {
417 unsigned long this_hwcap = 0;
418 struct device_node *cpu_node;
419 struct riscv_isainfo *isainfo = &hart_isa[cpu];
421 cpu_node = of_cpu_device_node_get(cpu);
423 pr_warn("Unable to find cpu node\n");
427 if (!of_property_present(cpu_node, "riscv,isa-extensions")) {
428 of_node_put(cpu_node);
432 for (int i = 0; i < riscv_isa_ext_count; i++) {
433 if (of_property_match_string(cpu_node, "riscv,isa-extensions",
434 riscv_isa_ext[i].property) < 0)
437 if (!riscv_isa_extension_check(riscv_isa_ext[i].id))
440 /* Only single letter extensions get set in hwcap */
441 if (strnlen(riscv_isa_ext[i].name, 2) == 1)
442 this_hwcap |= isa2hwcap[riscv_isa_ext[i].id];
444 set_bit(riscv_isa_ext[i].id, isainfo->isa);
447 of_node_put(cpu_node);
450 * All "okay" harts should have same isa. Set HWCAP based on
451 * common capabilities of every "okay" hart, in case they don't.
454 elf_hwcap &= this_hwcap;
456 elf_hwcap = this_hwcap;
458 if (bitmap_empty(riscv_isa, RISCV_ISA_EXT_MAX))
459 bitmap_copy(riscv_isa, isainfo->isa, RISCV_ISA_EXT_MAX);
461 bitmap_and(riscv_isa, riscv_isa, isainfo->isa, RISCV_ISA_EXT_MAX);
464 if (bitmap_empty(riscv_isa, RISCV_ISA_EXT_MAX))
470 #ifdef CONFIG_RISCV_ISA_FALLBACK
471 bool __initdata riscv_isa_fallback = true;
473 bool __initdata riscv_isa_fallback;
474 static int __init riscv_isa_fallback_setup(char *__unused)
476 riscv_isa_fallback = true;
479 early_param("riscv_isa_fallback", riscv_isa_fallback_setup);
482 void __init riscv_fill_hwcap(void)
484 char print_str[NUM_ALPHA_EXTS + 1];
485 unsigned long isa2hwcap[26] = {0};
488 isa2hwcap['i' - 'a'] = COMPAT_HWCAP_ISA_I;
489 isa2hwcap['m' - 'a'] = COMPAT_HWCAP_ISA_M;
490 isa2hwcap['a' - 'a'] = COMPAT_HWCAP_ISA_A;
491 isa2hwcap['f' - 'a'] = COMPAT_HWCAP_ISA_F;
492 isa2hwcap['d' - 'a'] = COMPAT_HWCAP_ISA_D;
493 isa2hwcap['c' - 'a'] = COMPAT_HWCAP_ISA_C;
494 isa2hwcap['v' - 'a'] = COMPAT_HWCAP_ISA_V;
496 if (!acpi_disabled) {
497 riscv_fill_hwcap_from_isa_string(isa2hwcap);
499 int ret = riscv_fill_hwcap_from_ext_list(isa2hwcap);
501 if (ret && riscv_isa_fallback) {
502 pr_info("Falling back to deprecated \"riscv,isa\"\n");
503 riscv_fill_hwcap_from_isa_string(isa2hwcap);
508 * We don't support systems with F but without D, so mask those out
511 if ((elf_hwcap & COMPAT_HWCAP_ISA_F) && !(elf_hwcap & COMPAT_HWCAP_ISA_D)) {
512 pr_info("This kernel does not support systems with F but not D\n");
513 elf_hwcap &= ~COMPAT_HWCAP_ISA_F;
516 if (elf_hwcap & COMPAT_HWCAP_ISA_V) {
517 riscv_v_setup_vsize();
519 * ISA string in device tree might have 'v' flag, but
520 * CONFIG_RISCV_ISA_V is disabled in kernel.
521 * Clear V flag in elf_hwcap if CONFIG_RISCV_ISA_V is disabled.
523 if (!IS_ENABLED(CONFIG_RISCV_ISA_V))
524 elf_hwcap &= ~COMPAT_HWCAP_ISA_V;
527 memset(print_str, 0, sizeof(print_str));
528 for (i = 0, j = 0; i < NUM_ALPHA_EXTS; i++)
529 if (riscv_isa[0] & BIT_MASK(i))
530 print_str[j++] = (char)('a' + i);
531 pr_info("riscv: base ISA extensions %s\n", print_str);
533 memset(print_str, 0, sizeof(print_str));
534 for (i = 0, j = 0; i < NUM_ALPHA_EXTS; i++)
535 if (elf_hwcap & BIT_MASK(i))
536 print_str[j++] = (char)('a' + i);
537 pr_info("riscv: ELF capabilities %s\n", print_str);
540 unsigned long riscv_get_elf_hwcap(void)
544 hwcap = (elf_hwcap & ((1UL << RISCV_ISA_EXT_BASE) - 1));
546 if (!riscv_v_vstate_ctrl_user_allowed())
547 hwcap &= ~COMPAT_HWCAP_ISA_V;
552 #ifdef CONFIG_RISCV_ALTERNATIVE
554 * Alternative patch sites consider 48 bits when determining when to patch
555 * the old instruction sequence with the new. These bits are broken into a
556 * 16-bit vendor ID and a 32-bit patch ID. A non-zero vendor ID means the
557 * patch site is for an erratum, identified by the 32-bit patch ID. When
558 * the vendor ID is zero, the patch site is for a cpufeature. cpufeatures
559 * further break down patch ID into two 16-bit numbers. The lower 16 bits
560 * are the cpufeature ID and the upper 16 bits are used for a value specific
561 * to the cpufeature and patch site. If the upper 16 bits are zero, then it
562 * implies no specific value is specified. cpufeatures that want to control
563 * patching on a per-site basis will provide non-zero values and implement
564 * checks here. The checks return true when patching should be done, and
567 static bool riscv_cpufeature_patch_check(u16 id, u16 value)
573 case RISCV_ISA_EXT_ZICBOZ:
575 * Zicboz alternative applications provide the maximum
576 * supported block size order, or zero when it doesn't
577 * matter. If the current block size exceeds the maximum,
578 * then the alternative cannot be applied.
580 return riscv_cboz_block_size <= (1U << value);
586 void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
587 struct alt_entry *end,
590 struct alt_entry *alt;
591 void *oldptr, *altptr;
594 if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
597 for (alt = begin; alt < end; alt++) {
598 if (alt->vendor_id != 0)
601 id = PATCH_ID_CPUFEATURE_ID(alt->patch_id);
603 if (id >= RISCV_ISA_EXT_MAX) {
604 WARN(1, "This extension id:%d is not in ISA extension list", id);
608 if (!__riscv_isa_extension_available(NULL, id))
611 value = PATCH_ID_CPUFEATURE_VALUE(alt->patch_id);
612 if (!riscv_cpufeature_patch_check(id, value))
615 oldptr = ALT_OLD_PTR(alt);
616 altptr = ALT_ALT_PTR(alt);
618 mutex_lock(&text_mutex);
619 patch_text_nosync(oldptr, altptr, alt->alt_len);
620 riscv_alternative_fix_offsets(oldptr, alt->alt_len, oldptr - altptr);
621 mutex_unlock(&text_mutex);