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>
16 #include <linux/of_device.h>
18 #include <asm/alternative.h>
19 #include <asm/cacheflush.h>
20 #include <asm/cpufeature.h>
21 #include <asm/hwcap.h>
22 #include <asm/patch.h>
23 #include <asm/processor.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 /* Performance information */
33 DEFINE_PER_CPU(long, misaligned_access_speed);
36 * riscv_isa_extension_base() - Get base extension word
38 * @isa_bitmap: ISA bitmap to use
39 * Return: base extension word as unsigned long value
41 * NOTE: If isa_bitmap is NULL then Host ISA bitmap will be used.
43 unsigned long riscv_isa_extension_base(const unsigned long *isa_bitmap)
49 EXPORT_SYMBOL_GPL(riscv_isa_extension_base);
52 * __riscv_isa_extension_available() - Check whether given extension
55 * @isa_bitmap: ISA bitmap to use
56 * @bit: bit position of the desired extension
57 * Return: true or false
59 * NOTE: If isa_bitmap is NULL then Host ISA bitmap will be used.
61 bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, int bit)
63 const unsigned long *bmap = (isa_bitmap) ? isa_bitmap : riscv_isa;
65 if (bit >= RISCV_ISA_EXT_MAX)
68 return test_bit(bit, bmap) ? true : false;
70 EXPORT_SYMBOL_GPL(__riscv_isa_extension_available);
72 static bool riscv_isa_extension_check(int id)
75 case RISCV_ISA_EXT_ZICBOM:
76 if (!riscv_cbom_block_size) {
77 pr_err("Zicbom detected in ISA string, but no cbom-block-size found\n");
79 } else if (!is_power_of_2(riscv_cbom_block_size)) {
80 pr_err("cbom-block-size present, but is not a power-of-2\n");
84 case RISCV_ISA_EXT_ZICBOZ:
85 if (!riscv_cboz_block_size) {
86 pr_err("Zicboz detected in ISA string, but no cboz-block-size found\n");
88 } else if (!is_power_of_2(riscv_cboz_block_size)) {
89 pr_err("cboz-block-size present, but is not a power-of-2\n");
98 void __init riscv_fill_hwcap(void)
100 struct device_node *node;
102 char print_str[NUM_ALPHA_EXTS + 1];
104 unsigned long isa2hwcap[26] = {0};
105 struct acpi_table_header *rhct;
109 isa2hwcap['i' - 'a'] = COMPAT_HWCAP_ISA_I;
110 isa2hwcap['m' - 'a'] = COMPAT_HWCAP_ISA_M;
111 isa2hwcap['a' - 'a'] = COMPAT_HWCAP_ISA_A;
112 isa2hwcap['f' - 'a'] = COMPAT_HWCAP_ISA_F;
113 isa2hwcap['d' - 'a'] = COMPAT_HWCAP_ISA_D;
114 isa2hwcap['c' - 'a'] = COMPAT_HWCAP_ISA_C;
118 bitmap_zero(riscv_isa, RISCV_ISA_EXT_MAX);
120 if (!acpi_disabled) {
121 status = acpi_get_table(ACPI_SIG_RHCT, 0, &rhct);
122 if (ACPI_FAILURE(status))
126 for_each_possible_cpu(cpu) {
127 unsigned long this_hwcap = 0;
128 DECLARE_BITMAP(this_isa, RISCV_ISA_EXT_MAX);
131 node = of_cpu_device_node_get(cpu);
133 pr_warn("Unable to find cpu node\n");
137 rc = of_property_read_string(node, "riscv,isa", &isa);
140 pr_warn("Unable to find \"riscv,isa\" devicetree entry\n");
144 rc = acpi_get_riscv_isa(rhct, cpu, &isa);
146 pr_warn("Unable to get ISA for the hart - %d\n", cpu);
152 * For all possible cpus, we have already validated in
153 * the boot process that they at least contain "rv" and
154 * whichever of "32"/"64" this kernel supports, and so this
155 * section can be skipped.
159 bitmap_zero(this_isa, RISCV_ISA_EXT_MAX);
160 for (; *isa; ++isa) {
161 const char *ext = isa++;
162 const char *ext_end = isa;
163 bool ext_long = false, ext_err = false;
168 * Workaround for invalid single-letter 's' & 'u'(QEMU).
169 * No need to set the bit in riscv_isa as 's' & 'u' are
170 * not valid ISA extensions. It works until multi-letter
171 * extension starting with "Su" appears.
173 if (ext[-1] != '_' && ext[1] == 'u') {
185 * Before attempting to parse the extension itself, we find its end.
186 * As multi-letter extensions must be split from other multi-letter
187 * extensions with an "_", the end of a multi-letter extension will
188 * either be the null character or the "_" at the start of the next
189 * multi-letter extension.
191 * Next, as the extensions version is currently ignored, we
192 * eliminate that portion. This is done by parsing backwards from
193 * the end of the extension, removing any numbers. This may be a
194 * major or minor number however, so the process is repeated if a
195 * minor number was found.
197 * ext_end is intended to represent the first character *after* the
198 * name portion of an extension, but will be decremented to the last
199 * character itself while eliminating the extensions version number.
200 * A simple re-increment solves this problem.
203 for (; *isa && *isa != '_'; ++isa)
204 if (unlikely(!isalnum(*isa)))
208 if (unlikely(ext_err))
211 if (!isdigit(ext_end[-1]))
214 while (isdigit(*--ext_end))
217 if (tolower(ext_end[0]) != 'p' || !isdigit(ext_end[-1])) {
222 while (isdigit(*--ext_end))
229 * Things are a little easier for single-letter extensions, as they
230 * are parsed forwards.
232 * After checking that our starting position is valid, we need to
233 * ensure that, when isa was incremented at the start of the loop,
234 * that it arrived at the start of the next extension.
236 * If we are already on a non-digit, there is nothing to do. Either
237 * we have a multi-letter extension's _, or the start of an
240 * Otherwise we have found the current extension's major version
241 * number. Parse past it, and a subsequent p/minor version number
242 * if present. The `p` extension must not appear immediately after
243 * a number, so there is no fear of missing it.
246 if (unlikely(!isalpha(*ext))) {
254 while (isdigit(*++isa))
257 if (tolower(*isa) != 'p')
260 if (!isdigit(*++isa)) {
265 while (isdigit(*++isa))
272 * The parser expects that at the start of an iteration isa points to the
273 * character before the start of the next extension. This will not be the
274 * case if we have just parsed a single-letter extension and the next
275 * extension is not a multi-letter extension prefixed with an "_". It is
276 * also not the case at the end of the string, where it will point to the
277 * terminating null character.
282 #define SET_ISA_EXT_MAP(name, bit) \
284 if ((ext_end - ext == sizeof(name) - 1) && \
285 !strncasecmp(ext, name, sizeof(name) - 1) && \
286 riscv_isa_extension_check(bit)) \
287 set_bit(bit, this_isa); \
290 if (unlikely(ext_err))
293 int nr = tolower(*ext) - 'a';
295 if (riscv_isa_extension_check(nr)) {
296 this_hwcap |= isa2hwcap[nr];
297 set_bit(nr, this_isa);
300 /* sorted alphabetically */
301 SET_ISA_EXT_MAP("smaia", RISCV_ISA_EXT_SMAIA);
302 SET_ISA_EXT_MAP("ssaia", RISCV_ISA_EXT_SSAIA);
303 SET_ISA_EXT_MAP("sscofpmf", RISCV_ISA_EXT_SSCOFPMF);
304 SET_ISA_EXT_MAP("sstc", RISCV_ISA_EXT_SSTC);
305 SET_ISA_EXT_MAP("svinval", RISCV_ISA_EXT_SVINVAL);
306 SET_ISA_EXT_MAP("svnapot", RISCV_ISA_EXT_SVNAPOT);
307 SET_ISA_EXT_MAP("svpbmt", RISCV_ISA_EXT_SVPBMT);
308 SET_ISA_EXT_MAP("zbb", RISCV_ISA_EXT_ZBB);
309 SET_ISA_EXT_MAP("zicbom", RISCV_ISA_EXT_ZICBOM);
310 SET_ISA_EXT_MAP("zicboz", RISCV_ISA_EXT_ZICBOZ);
311 SET_ISA_EXT_MAP("zihintpause", RISCV_ISA_EXT_ZIHINTPAUSE);
313 #undef SET_ISA_EXT_MAP
317 * All "okay" hart should have same isa. Set HWCAP based on
318 * common capabilities of every "okay" hart, in case they don't
322 elf_hwcap &= this_hwcap;
324 elf_hwcap = this_hwcap;
326 if (bitmap_empty(riscv_isa, RISCV_ISA_EXT_MAX))
327 bitmap_copy(riscv_isa, this_isa, RISCV_ISA_EXT_MAX);
329 bitmap_and(riscv_isa, riscv_isa, this_isa, RISCV_ISA_EXT_MAX);
332 if (!acpi_disabled && rhct)
333 acpi_put_table((struct acpi_table_header *)rhct);
335 /* We don't support systems with F but without D, so mask those out
337 if ((elf_hwcap & COMPAT_HWCAP_ISA_F) && !(elf_hwcap & COMPAT_HWCAP_ISA_D)) {
338 pr_info("This kernel does not support systems with F but not D\n");
339 elf_hwcap &= ~COMPAT_HWCAP_ISA_F;
342 memset(print_str, 0, sizeof(print_str));
343 for (i = 0, j = 0; i < NUM_ALPHA_EXTS; i++)
344 if (riscv_isa[0] & BIT_MASK(i))
345 print_str[j++] = (char)('a' + i);
346 pr_info("riscv: base ISA extensions %s\n", print_str);
348 memset(print_str, 0, sizeof(print_str));
349 for (i = 0, j = 0; i < NUM_ALPHA_EXTS; i++)
350 if (elf_hwcap & BIT_MASK(i))
351 print_str[j++] = (char)('a' + i);
352 pr_info("riscv: ELF capabilities %s\n", print_str);
355 #ifdef CONFIG_RISCV_ALTERNATIVE
357 * Alternative patch sites consider 48 bits when determining when to patch
358 * the old instruction sequence with the new. These bits are broken into a
359 * 16-bit vendor ID and a 32-bit patch ID. A non-zero vendor ID means the
360 * patch site is for an erratum, identified by the 32-bit patch ID. When
361 * the vendor ID is zero, the patch site is for a cpufeature. cpufeatures
362 * further break down patch ID into two 16-bit numbers. The lower 16 bits
363 * are the cpufeature ID and the upper 16 bits are used for a value specific
364 * to the cpufeature and patch site. If the upper 16 bits are zero, then it
365 * implies no specific value is specified. cpufeatures that want to control
366 * patching on a per-site basis will provide non-zero values and implement
367 * checks here. The checks return true when patching should be done, and
370 static bool riscv_cpufeature_patch_check(u16 id, u16 value)
376 case RISCV_ISA_EXT_ZICBOZ:
378 * Zicboz alternative applications provide the maximum
379 * supported block size order, or zero when it doesn't
380 * matter. If the current block size exceeds the maximum,
381 * then the alternative cannot be applied.
383 return riscv_cboz_block_size <= (1U << value);
389 void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
390 struct alt_entry *end,
393 struct alt_entry *alt;
394 void *oldptr, *altptr;
397 if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
400 for (alt = begin; alt < end; alt++) {
401 if (alt->vendor_id != 0)
404 id = PATCH_ID_CPUFEATURE_ID(alt->patch_id);
406 if (id >= RISCV_ISA_EXT_MAX) {
407 WARN(1, "This extension id:%d is not in ISA extension list", id);
411 if (!__riscv_isa_extension_available(NULL, id))
414 value = PATCH_ID_CPUFEATURE_VALUE(alt->patch_id);
415 if (!riscv_cpufeature_patch_check(id, value))
418 oldptr = ALT_OLD_PTR(alt);
419 altptr = ALT_ALT_PTR(alt);
421 mutex_lock(&text_mutex);
422 patch_text_nosync(oldptr, altptr, alt->alt_len);
423 riscv_alternative_fix_offsets(oldptr, alt->alt_len, oldptr - altptr);
424 mutex_unlock(&text_mutex);