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-rw-r--r--arch/riscv/kernel/cpufeature.c327
1 files changed, 327 insertions, 0 deletions
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
new file mode 100644
index 000000000..fd1238df6
--- /dev/null
+++ b/arch/riscv/kernel/cpufeature.c
@@ -0,0 +1,327 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copied from arch/arm64/kernel/cpufeature.c
+ *
+ * Copyright (C) 2015 ARM Ltd.
+ * Copyright (C) 2017 SiFive
+ */
+
+#include <linux/bitmap.h>
+#include <linux/ctype.h>
+#include <linux/libfdt.h>
+#include <linux/memory.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <asm/alternative.h>
+#include <asm/cacheflush.h>
+#include <asm/errata_list.h>
+#include <asm/hwcap.h>
+#include <asm/patch.h>
+#include <asm/pgtable.h>
+#include <asm/processor.h>
+#include <asm/smp.h>
+#include <asm/switch_to.h>
+
+#define NUM_ALPHA_EXTS ('z' - 'a' + 1)
+
+unsigned long elf_hwcap __read_mostly;
+
+/* Host ISA bitmap */
+static DECLARE_BITMAP(riscv_isa, RISCV_ISA_EXT_MAX) __read_mostly;
+
+DEFINE_STATIC_KEY_ARRAY_FALSE(riscv_isa_ext_keys, RISCV_ISA_EXT_KEY_MAX);
+EXPORT_SYMBOL(riscv_isa_ext_keys);
+
+/**
+ * riscv_isa_extension_base() - Get base extension word
+ *
+ * @isa_bitmap: ISA bitmap to use
+ * Return: base extension word as unsigned long value
+ *
+ * NOTE: If isa_bitmap is NULL then Host ISA bitmap will be used.
+ */
+unsigned long riscv_isa_extension_base(const unsigned long *isa_bitmap)
+{
+ if (!isa_bitmap)
+ return riscv_isa[0];
+ return isa_bitmap[0];
+}
+EXPORT_SYMBOL_GPL(riscv_isa_extension_base);
+
+/**
+ * __riscv_isa_extension_available() - Check whether given extension
+ * is available or not
+ *
+ * @isa_bitmap: ISA bitmap to use
+ * @bit: bit position of the desired extension
+ * Return: true or false
+ *
+ * NOTE: If isa_bitmap is NULL then Host ISA bitmap will be used.
+ */
+bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, int bit)
+{
+ const unsigned long *bmap = (isa_bitmap) ? isa_bitmap : riscv_isa;
+
+ if (bit >= RISCV_ISA_EXT_MAX)
+ return false;
+
+ return test_bit(bit, bmap) ? true : false;
+}
+EXPORT_SYMBOL_GPL(__riscv_isa_extension_available);
+
+void __init riscv_fill_hwcap(void)
+{
+ struct device_node *node;
+ const char *isa;
+ char print_str[NUM_ALPHA_EXTS + 1];
+ int i, j, rc;
+ static unsigned long isa2hwcap[256] = {0};
+ unsigned long hartid;
+
+ isa2hwcap['i'] = isa2hwcap['I'] = COMPAT_HWCAP_ISA_I;
+ isa2hwcap['m'] = isa2hwcap['M'] = COMPAT_HWCAP_ISA_M;
+ isa2hwcap['a'] = isa2hwcap['A'] = COMPAT_HWCAP_ISA_A;
+ isa2hwcap['f'] = isa2hwcap['F'] = COMPAT_HWCAP_ISA_F;
+ isa2hwcap['d'] = isa2hwcap['D'] = COMPAT_HWCAP_ISA_D;
+ isa2hwcap['c'] = isa2hwcap['C'] = COMPAT_HWCAP_ISA_C;
+
+ elf_hwcap = 0;
+
+ bitmap_zero(riscv_isa, RISCV_ISA_EXT_MAX);
+
+ for_each_of_cpu_node(node) {
+ unsigned long this_hwcap = 0;
+ DECLARE_BITMAP(this_isa, RISCV_ISA_EXT_MAX);
+ const char *temp;
+
+ rc = riscv_of_processor_hartid(node, &hartid);
+ if (rc < 0)
+ continue;
+
+ if (of_property_read_string(node, "riscv,isa", &isa)) {
+ pr_warn("Unable to find \"riscv,isa\" devicetree entry\n");
+ continue;
+ }
+
+ temp = isa;
+#if IS_ENABLED(CONFIG_32BIT)
+ if (!strncmp(isa, "rv32", 4))
+ isa += 4;
+#elif IS_ENABLED(CONFIG_64BIT)
+ if (!strncmp(isa, "rv64", 4))
+ isa += 4;
+#endif
+ /* The riscv,isa DT property must start with rv64 or rv32 */
+ if (temp == isa)
+ continue;
+ bitmap_zero(this_isa, RISCV_ISA_EXT_MAX);
+ for (; *isa; ++isa) {
+ const char *ext = isa++;
+ const char *ext_end = isa;
+ bool ext_long = false, ext_err = false;
+
+ switch (*ext) {
+ case 's':
+ /**
+ * Workaround for invalid single-letter 's' & 'u'(QEMU).
+ * No need to set the bit in riscv_isa as 's' & 'u' are
+ * not valid ISA extensions. It works until multi-letter
+ * extension starting with "Su" appears.
+ */
+ if (ext[-1] != '_' && ext[1] == 'u') {
+ ++isa;
+ ext_err = true;
+ break;
+ }
+ fallthrough;
+ case 'x':
+ case 'z':
+ ext_long = true;
+ /* Multi-letter extension must be delimited */
+ for (; *isa && *isa != '_'; ++isa)
+ if (unlikely(!islower(*isa)
+ && !isdigit(*isa)))
+ ext_err = true;
+ /* Parse backwards */
+ ext_end = isa;
+ if (unlikely(ext_err))
+ break;
+ if (!isdigit(ext_end[-1]))
+ break;
+ /* Skip the minor version */
+ while (isdigit(*--ext_end))
+ ;
+ if (ext_end[0] != 'p'
+ || !isdigit(ext_end[-1])) {
+ /* Advance it to offset the pre-decrement */
+ ++ext_end;
+ break;
+ }
+ /* Skip the major version */
+ while (isdigit(*--ext_end))
+ ;
+ ++ext_end;
+ break;
+ default:
+ if (unlikely(!islower(*ext))) {
+ ext_err = true;
+ break;
+ }
+ /* Find next extension */
+ if (!isdigit(*isa))
+ break;
+ /* Skip the minor version */
+ while (isdigit(*++isa))
+ ;
+ if (*isa != 'p')
+ break;
+ if (!isdigit(*++isa)) {
+ --isa;
+ break;
+ }
+ /* Skip the major version */
+ while (isdigit(*++isa))
+ ;
+ break;
+ }
+ if (*isa != '_')
+ --isa;
+
+#define SET_ISA_EXT_MAP(name, bit) \
+ do { \
+ if ((ext_end - ext == sizeof(name) - 1) && \
+ !memcmp(ext, name, sizeof(name) - 1)) \
+ set_bit(bit, this_isa); \
+ } while (false) \
+
+ if (unlikely(ext_err))
+ continue;
+ if (!ext_long) {
+ this_hwcap |= isa2hwcap[(unsigned char)(*ext)];
+ set_bit(*ext - 'a', this_isa);
+ } else {
+ 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);
+ SET_ISA_EXT_MAP("zihintpause", RISCV_ISA_EXT_ZIHINTPAUSE);
+ SET_ISA_EXT_MAP("sstc", RISCV_ISA_EXT_SSTC);
+ SET_ISA_EXT_MAP("svinval", RISCV_ISA_EXT_SVINVAL);
+ }
+#undef SET_ISA_EXT_MAP
+ }
+
+ /*
+ * All "okay" hart should have same isa. Set HWCAP based on
+ * common capabilities of every "okay" hart, in case they don't
+ * have.
+ */
+ if (elf_hwcap)
+ elf_hwcap &= this_hwcap;
+ else
+ elf_hwcap = this_hwcap;
+
+ if (bitmap_empty(riscv_isa, RISCV_ISA_EXT_MAX))
+ bitmap_copy(riscv_isa, this_isa, RISCV_ISA_EXT_MAX);
+ else
+ bitmap_and(riscv_isa, riscv_isa, this_isa, RISCV_ISA_EXT_MAX);
+ }
+
+ /* We don't support systems with F but without D, so mask those out
+ * here. */
+ if ((elf_hwcap & COMPAT_HWCAP_ISA_F) && !(elf_hwcap & COMPAT_HWCAP_ISA_D)) {
+ pr_info("This kernel does not support systems with F but not D\n");
+ elf_hwcap &= ~COMPAT_HWCAP_ISA_F;
+ }
+
+ memset(print_str, 0, sizeof(print_str));
+ for (i = 0, j = 0; i < NUM_ALPHA_EXTS; i++)
+ if (riscv_isa[0] & BIT_MASK(i))
+ print_str[j++] = (char)('a' + i);
+ pr_info("riscv: base ISA extensions %s\n", print_str);
+
+ memset(print_str, 0, sizeof(print_str));
+ for (i = 0, j = 0; i < NUM_ALPHA_EXTS; i++)
+ if (elf_hwcap & BIT_MASK(i))
+ print_str[j++] = (char)('a' + i);
+ pr_info("riscv: ELF capabilities %s\n", print_str);
+
+ for_each_set_bit(i, riscv_isa, RISCV_ISA_EXT_MAX) {
+ j = riscv_isa_ext2key(i);
+ if (j >= 0)
+ static_branch_enable(&riscv_isa_ext_keys[j]);
+ }
+}
+
+#ifdef CONFIG_RISCV_ALTERNATIVE
+static bool __init_or_module cpufeature_probe_svpbmt(unsigned int stage)
+{
+ if (!IS_ENABLED(CONFIG_RISCV_ISA_SVPBMT))
+ return false;
+
+ if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
+ return false;
+
+ return riscv_isa_extension_available(NULL, SVPBMT);
+}
+
+static bool __init_or_module cpufeature_probe_zicbom(unsigned int stage)
+{
+ if (!IS_ENABLED(CONFIG_RISCV_ISA_ZICBOM))
+ return false;
+
+ if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
+ return false;
+
+ if (!riscv_isa_extension_available(NULL, ZICBOM))
+ return false;
+
+ riscv_noncoherent_supported();
+ return true;
+}
+
+/*
+ * Probe presence of individual extensions.
+ *
+ * This code may also be executed before kernel relocation, so we cannot use
+ * addresses generated by the address-of operator as they won't be valid in
+ * this context.
+ */
+static u32 __init_or_module cpufeature_probe(unsigned int stage)
+{
+ u32 cpu_req_feature = 0;
+
+ if (cpufeature_probe_svpbmt(stage))
+ cpu_req_feature |= BIT(CPUFEATURE_SVPBMT);
+
+ if (cpufeature_probe_zicbom(stage))
+ cpu_req_feature |= BIT(CPUFEATURE_ZICBOM);
+
+ return cpu_req_feature;
+}
+
+void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
+ struct alt_entry *end,
+ unsigned int stage)
+{
+ u32 cpu_req_feature = cpufeature_probe(stage);
+ struct alt_entry *alt;
+ u32 tmp;
+
+ for (alt = begin; alt < end; alt++) {
+ if (alt->vendor_id != 0)
+ continue;
+ if (alt->errata_id >= CPUFEATURE_NUMBER) {
+ WARN(1, "This feature id:%d is not in kernel cpufeature list",
+ alt->errata_id);
+ continue;
+ }
+
+ tmp = (1U << alt->errata_id);
+ if (cpu_req_feature & tmp) {
+ mutex_lock(&text_mutex);
+ patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len);
+ mutex_unlock(&text_mutex);
+ }
+ }
+}
+#endif
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