git: 88b4d124efc5 - main - riscv: Rework CPU identification (first part)
- Go to: [ bottom of page ] [ top of archives ] [ this month ]
Date: Tue, 23 May 2023 13:23:19 UTC
The branch main has been updated by mhorne:
URL: https://cgit.FreeBSD.org/src/commit/?id=88b4d124efc5a2d45660551fe0750acc0be6d3cd
commit 88b4d124efc5a2d45660551fe0750acc0be6d3cd
Author: Mitchell Horne <mhorne@FreeBSD.org>
AuthorDate: 2023-05-22 23:48:41 +0000
Commit: Mitchell Horne <mhorne@FreeBSD.org>
CommitDate: 2023-05-23 13:00:25 +0000
riscv: Rework CPU identification (first part)
Make better use of the RISC-V identification CSRs: mvendorid, marchid,
and mimpid. This code was written before these registers were
well-specified, or even available to the kernel. It currently fails to
recognize any CPU or platform.
Per the privileged specification, mvendorid contains the JEDEC vendor ID,
or zero.
The marchid register denotes the CPU microarchitecture. This is either
one of the globally allocated open-source implementation IDs, or the
field has a custom encoding. Therefore, for known vendors (SiFive) we
can also maintain a list of known marchid values. If we can not give a
name to the CPU but marchid is non-zero, then just print its value in
the report.
The mimpid (implementation ID) could be used in the future to more
uniquely identify the micro-architecture, but it really remains to be
seen how it gets used. For now we just print its value.
Thank you to Danjel Qyteza <danq1222@gmail.com> who submitted an early
version of this change to me, although it has been almost entirely
rewritten.
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D39809
---
sys/riscv/include/cpu.h | 45 +++++++++-------
sys/riscv/riscv/identcpu.c | 128 ++++++++++++++++++++++++++-------------------
2 files changed, 101 insertions(+), 72 deletions(-)
diff --git a/sys/riscv/include/cpu.h b/sys/riscv/include/cpu.h
index ee7b1111af56..b33e34d350fb 100644
--- a/sys/riscv/include/cpu.h
+++ b/sys/riscv/include/cpu.h
@@ -52,27 +52,36 @@
#ifdef _KERNEL
/*
- * 0x0000 CPU ID unimplemented
- * 0x0001 UC Berkeley Rocket repo
- * 0x00020x7FFE Reserved for open-source repos
- * 0x7FFF Reserved for extension
- * 0x8000 Reserved for anonymous source
- * 0x80010xFFFE Reserved for proprietary implementations
- * 0xFFFF Reserved for extension
+ * Core manufacturer IDs, as reported by the mvendorid CSR.
*/
+#define MVENDORID_UNIMPL 0x0
+#define MVENDORID_SIFIVE 0x489
+#define MVENDORID_THEAD 0x5b7
-#define CPU_IMPL_SHIFT 0
-#define CPU_IMPL_MASK (0xffff << CPU_IMPL_SHIFT)
-#define CPU_IMPL(mimpid) ((mimpid & CPU_IMPL_MASK) >> CPU_IMPL_SHIFT)
-#define CPU_IMPL_UNIMPLEMEN 0x0
-#define CPU_IMPL_UCB_ROCKET 0x1
+/*
+ * Micro-architecture ID register, marchid.
+ *
+ * IDs for open-source implementations are allocated globally. Commercial IDs
+ * will have the most-significant bit set.
+ */
+#define MARCHID_UNIMPL 0x0
+#define MARCHID_MSB (1ul << (XLEN - 1))
+#define MARCHID_OPENSOURCE(v) (v)
+#define MARCHID_COMMERCIAL(v) (MARCHID_MSB | (v))
+#define MARCHID_IS_OPENSOURCE(m) (((m) & MARCHID_MSB) == 0)
+
+/*
+ * Open-source marchid values.
+ *
+ * https://github.com/riscv/riscv-isa-manual/blob/master/marchid.md
+ */
+#define MARCHID_UCB_ROCKET MARCHID_OPENSOURCE(1)
+#define MARCHID_UCB_BOOM MARCHID_OPENSOURCE(2)
+#define MARCHID_UCB_SPIKE MARCHID_OPENSOURCE(5)
+#define MARCHID_UCAM_RVBS MARCHID_OPENSOURCE(10)
-#define CPU_PART_SHIFT 62
-#define CPU_PART_MASK (0x3ul << CPU_PART_SHIFT)
-#define CPU_PART(misa) ((misa & CPU_PART_MASK) >> CPU_PART_SHIFT)
-#define CPU_PART_RV32 0x1
-#define CPU_PART_RV64 0x2
-#define CPU_PART_RV128 0x3
+/* SiFive marchid values */
+#define MARCHID_SIFIVE_U7 MARCHID_COMMERCIAL(7)
extern char btext[];
extern char etext[];
diff --git a/sys/riscv/riscv/identcpu.c b/sys/riscv/riscv/identcpu.c
index c57a22c1b51a..9b2330ee7051 100644
--- a/sys/riscv/riscv/identcpu.c
+++ b/sys/riscv/riscv/identcpu.c
@@ -67,42 +67,47 @@ register_t marchid; /* The architecture ID */
register_t mimpid; /* The implementation ID */
struct cpu_desc {
- u_int cpu_impl;
- u_int cpu_part_num;
- const char *cpu_impl_name;
- const char *cpu_part_name;
+ const char *cpu_mvendor_name;
+ const char *cpu_march_name;
};
struct cpu_desc cpu_desc[MAXCPU];
-struct cpu_parts {
- u_int part_id;
- const char *part_name;
+/*
+ * Micro-architecture tables.
+ */
+struct marchid_entry {
+ register_t march_id;
+ const char *march_name;
};
-#define CPU_PART_NONE { -1, "Unknown Processor" }
-struct cpu_implementers {
- u_int impl_id;
- const char *impl_name;
+#define MARCHID_END { -1ul, NULL }
+
+/* Open-source RISC-V architecture IDs; globally allocated. */
+static const struct marchid_entry global_marchids[] = {
+ { MARCHID_UCB_ROCKET, "UC Berkeley Rocket" },
+ { MARCHID_UCB_BOOM, "UC Berkeley Boom" },
+ { MARCHID_UCB_SPIKE, "UC Berkeley Spike" },
+ { MARCHID_UCAM_RVBS, "University of Cambridge RVBS" },
+ MARCHID_END
};
-#define CPU_IMPLEMENTER_NONE { 0, "Unknown Implementer" }
-/*
- * CPU base
- */
-static const struct cpu_parts cpu_parts_std[] = {
- { CPU_PART_RV32, "RV32" },
- { CPU_PART_RV64, "RV64" },
- { CPU_PART_RV128, "RV128" },
- CPU_PART_NONE,
+static const struct marchid_entry sifive_marchids[] = {
+ { MARCHID_SIFIVE_U7, "6/7/P200/X200-Series Processor" },
+ MARCHID_END
};
/*
- * Implementers table.
+ * Known CPU vendor/manufacturer table.
*/
-const struct cpu_implementers cpu_implementers[] = {
- { CPU_IMPL_UCB_ROCKET, "UC Berkeley Rocket" },
- CPU_IMPLEMENTER_NONE,
+static const struct {
+ register_t mvendor_id;
+ const char *mvendor_name;
+ const struct marchid_entry *marchid_table;
+} mvendor_ids[] = {
+ { MVENDORID_UNIMPL, "Unspecified", NULL },
+ { MVENDORID_SIFIVE, "SiFive", sifive_marchids },
+ { MVENDORID_THEAD, "T-Head", NULL },
};
/*
@@ -319,48 +324,63 @@ fill_elf_hwcap(void *dummy __unused)
SYSINIT(identcpu, SI_SUB_CPU, SI_ORDER_ANY, fill_elf_hwcap, NULL);
#endif
-void
-identify_cpu(void)
+static void
+identify_cpu_ids(struct cpu_desc *desc)
{
- const struct cpu_parts *cpu_partsp;
- uint32_t part_id;
- uint32_t impl_id;
- uint64_t misa;
- u_int cpu;
- size_t i;
-
- cpu_partsp = NULL;
+ const struct marchid_entry *table = NULL;
+ int i;
- /* TODO: can we get misa somewhere ? */
- misa = 0;
+ desc->cpu_mvendor_name = "Unknown";
+ desc->cpu_march_name = "Unknown";
- cpu = PCPU_GET(cpuid);
-
- impl_id = CPU_IMPL(mimpid);
- for (i = 0; i < nitems(cpu_implementers); i++) {
- if (impl_id == cpu_implementers[i].impl_id ||
- cpu_implementers[i].impl_id == 0) {
- cpu_desc[cpu].cpu_impl = impl_id;
- cpu_desc[cpu].cpu_impl_name = cpu_implementers[i].impl_name;
- cpu_partsp = cpu_parts_std;
+ /*
+ * Search for a recognized vendor, and possibly obtain the secondary
+ * table for marchid lookup.
+ */
+ for (i = 0; i < nitems(mvendor_ids); i++) {
+ if (mvendorid == mvendor_ids[i].mvendor_id) {
+ desc->cpu_mvendor_name = mvendor_ids[i].mvendor_name;
+ table = mvendor_ids[i].marchid_table;
break;
}
}
- part_id = CPU_PART(misa);
- for (i = 0; &cpu_partsp[i] != NULL; i++) {
- if (part_id == cpu_partsp[i].part_id ||
- cpu_partsp[i].part_id == -1) {
- cpu_desc[cpu].cpu_part_num = part_id;
- cpu_desc[cpu].cpu_part_name = cpu_partsp[i].part_name;
+ if (marchid == MARCHID_UNIMPL) {
+ desc->cpu_march_name = "Unspecified";
+ return;
+ }
+
+ if (MARCHID_IS_OPENSOURCE(marchid)) {
+ table = global_marchids;
+ } else if (table == NULL)
+ return;
+
+ for (i = 0; table[i].march_name != NULL; i++) {
+ if (marchid == table[i].march_id) {
+ desc->cpu_march_name = table[i].march_name;
break;
}
}
+}
+
+void
+identify_cpu(void)
+{
+ struct cpu_desc *desc;
+ u_int cpu, hart;
+
+ cpu = PCPU_GET(cpuid);
+ hart = PCPU_GET(hart);
+ desc = &cpu_desc[cpu];
+
+ identify_cpu_ids(desc);
/* Print details for boot CPU or if we want verbose output */
if (cpu == 0 || bootverbose) {
- printf("CPU(%d): %s %s\n", cpu,
- cpu_desc[cpu].cpu_impl_name,
- cpu_desc[cpu].cpu_part_name);
+ /* Summary line. */
+ printf("CPU %-3u: Vendor=%s Core=%s (Hart %u)\n", cpu,
+ desc->cpu_mvendor_name, desc->cpu_march_name, hart);
+
+ printf(" marchid=%#lx, mimpid=%#lx\n", marchid, mimpid);
}
}