[v1.06][RISCV] Support for fetching mvendorid, marchid and mimpid (#286)

Getting these 3 RISC-V cpuinfo fields allows the detection of
microarchitecture (and other information), extending the RISC-V
detection capabilities. In particular, this is used here to detect
the marchid of Spacemit X60 uarch.

This commit also changes how the microarchitecture is fetched
(i.e., get_uarch) so that it does not rely only in the uarch field
in cpuinfo, but also on the marchid value.

src/common/cpu.h

@@ -25,6 +25,7 @@ enum {
   CPU_VENDOR_RISCV,
   CPU_VENDOR_SIFIVE,
   CPU_VENDOR_THEAD,
+  CPU_VENDOR_SPACEMIT,
 // OTHERS
   CPU_VENDOR_UNKNOWN,
   CPU_VENDOR_INVALID

src/riscv/riscv.c

@@ -101,8 +101,8 @@ struct extensions* get_extensions_from_str(char* str) {
     return ext;
   }
 
-  int len = strlen(str);
-  ext->str = ecalloc(len+1, sizeof(char));
+  int len = strlen(str)+1;
+  ext->str = emalloc(len * sizeof(char));
   strncpy(ext->str, str, sizeof(char) * len);
 
   // Code inspired in Linux kernel (riscv_fill_hwcap):
@@ -157,13 +157,12 @@ struct cpuInfo* get_cpu_info(void) {
   topo->cach = NULL;
   cpu->topo = topo;
 
-  char* cpuinfo_str = get_uarch_from_cpuinfo();
   char* ext_str = get_extensions_from_cpuinfo();
   cpu->hv = emalloc(sizeof(struct hypervisor));
   cpu->hv->present = false;
   cpu->ext = get_extensions_from_str(ext_str);
   if(cpu->ext->str != NULL && cpu->ext->mask == 0) return NULL;
-  cpu->arch = get_uarch_from_cpuinfo_str(cpuinfo_str, cpu);
+  cpu->arch = get_uarch(cpu);
   cpu->soc = get_soc(cpu);
   cpu->freq = get_frequency_info(0);
   cpu->peak_performance = get_peak_performance(cpu);

src/riscv/uarch.c

@@ -4,6 +4,7 @@
 #include <string.h>
 
 #include "uarch.h"
+#include "udev.h"
 #include "../common/global.h"
 
 typedef uint32_t MICROARCH;
@@ -12,6 +13,7 @@ struct uarch {
   MICROARCH uarch;
   char* uarch_str;
   char* cpuinfo_str;
+  struct riscv_cpuinfo* ci;
 };
 
 enum {
@@ -21,13 +23,20 @@ enum {
   UARCH_U74,
   // THEAD
   UARCH_C906,
-  UARCH_C910
+  UARCH_C910,
+  // SPACEMIT
+  UARCH_X60
 };
 
 #define UARCH_START if (false) {}
 #define CHECK_UARCH(arch, cpu, cpuinfo_str, uarch_str, str, uarch, vendor) \
    else if (strcmp(cpuinfo_str, uarch_str) == 0) fill_uarch(arch, cpu, str, uarch, vendor);
-#define UARCH_END else { printBug("Unknown microarchitecture detected: uarch='%s'", cpuinfo_str); fill_uarch(arch, cpu, "Unknown", UARCH_UNKNOWN, CPU_VENDOR_UNKNOWN); }
+#define UARCH_END else { printWarn("Unknown microarchitecture detected: uarch='%s'", cpuinfo_str); fill_uarch(arch, cpu, "Unknown", UARCH_UNKNOWN, CPU_VENDOR_UNKNOWN); }
+
+#define ARCHID_START if (false) {}
+#define CHECK_ARCHID(arch, marchid_val, str, uarch, vendor) \
+  else if (arch->ci->marchid == (unsigned long) marchid_val) fill_uarch(arch, cpu, str, uarch, vendor);
+#define ARCHID_END else { printWarn("Unknown microarchitecture detected: marchid=0x%.8X", arch->ci->marchid); fill_uarch(arch, cpu, "Unknown", UARCH_UNKNOWN, CPU_VENDOR_UNKNOWN); }
 
 void fill_uarch(struct uarch* arch, struct cpuInfo* cpu, char* str, MICROARCH u, VENDOR vendor) {
   arch->uarch = u;
@@ -39,14 +48,8 @@ void fill_uarch(struct uarch* arch, struct cpuInfo* cpu, char* str, MICROARCH u,
 // https://elixir.bootlin.com/linux/latest/source/Documentation/devicetree/bindings/riscv/cpus.yaml
 // SiFive: https://www.sifive.com/risc-v-core-ip
 // T-Head: https://www.t-head.cn/product/c906
-struct uarch* get_uarch_from_cpuinfo_str(char* cpuinfo_str, struct cpuInfo* cpu) {
-  struct uarch* arch = emalloc(sizeof(struct uarch));
+struct uarch* get_uarch_from_cpuinfo_str(char* cpuinfo_str, struct cpuInfo* cpu, struct uarch* arch) {
   arch->cpuinfo_str = cpuinfo_str;
-  if(cpuinfo_str == NULL) {
-    printWarn("get_uarch_from_cpuinfo: Unable to detect microarchitecture, cpuinfo_str is NULL");
-    fill_uarch(arch, cpu, "Unknown", UARCH_UNKNOWN, CPU_VENDOR_UNKNOWN);
-    return arch;
-  }
 
   // U74/U74-MC:
   // SiFive says that U74-MC is "Multicore: four U74 cores and one S76 core" while
@@ -70,6 +73,41 @@ struct uarch* get_uarch_from_cpuinfo_str(char* cpuinfo_str, struct cpuInfo* cpu)
   return arch;
 }
 
+// Use marchid to get the microarchitecture
+struct uarch* get_uarch_from_riscv_cpuinfo(struct cpuInfo* cpu, struct uarch* arch) {
+
+  ARCHID_START
+  CHECK_ARCHID(arch, 0x8000000058000001, "X60", UARCH_X60, CPU_VENDOR_SPACEMIT) // https://github.com/Dr-Noob/cpufetch/issues/286
+  ARCHID_END
+
+  return arch;
+}
+
+struct uarch* get_uarch(struct cpuInfo* cpu) {
+  char* cpuinfo_str = get_uarch_from_cpuinfo();
+  struct uarch* arch = emalloc(sizeof(struct uarch));
+  arch->uarch = UARCH_UNKNOWN;
+  arch->ci = NULL;
+
+  if (cpuinfo_str == NULL) {
+    printWarn("get_uarch_from_cpuinfo: Unable to detect microarchitecture using uarch: cpuinfo_str is NULL");
+    arch->ci = get_riscv_cpuinfo();
+
+    if (arch->ci == NULL || arch->ci->marchid == 0)
+      printWarn("get_riscv_cpuinfo: Unable to get marchid from udev");
+    else
+      arch = get_uarch_from_riscv_cpuinfo(cpu, arch);
+  }
+  else {
+    arch = get_uarch_from_cpuinfo_str(cpuinfo_str, cpu, arch);
+  }
+
+  if (arch->uarch == UARCH_UNKNOWN)
+    fill_uarch(arch, cpu, "Unknown", UARCH_UNKNOWN, CPU_VENDOR_UNKNOWN);
+
+  return arch;
+}
+
 char* get_str_uarch(struct cpuInfo* cpu) {
   return cpu->arch->uarch_str;
 }

src/riscv/uarch.h

@@ -9,6 +9,6 @@ struct uarch;
 char* get_arch_cpuinfo_str(struct cpuInfo* cpu);
 char* get_str_uarch(struct cpuInfo* cpu);
 void free_uarch_struct(struct uarch* arch);
-struct uarch* get_uarch_from_cpuinfo_str(char* cpuinfo_str, struct cpuInfo* cpu);
+struct uarch* get_uarch(struct cpuInfo* cpu);
 
 #endif

src/riscv/udev.c

@@ -7,6 +7,9 @@
 #define _PATH_DEVTREE          "/proc/device-tree/compatible"
 #define CPUINFO_UARCH_STR      "uarch\t\t: "
 #define CPUINFO_EXTENSIONS_STR "isa\t\t: "
+#define CPUINFO_RISCV_MVENDORID "mvendorid\t:"
+#define CPUINFO_RISCV_MARCHID   "marchid\t\t:"
+#define CPUINFO_RISCV_MIMPID    "mimpid\t\t:"
 #define DEVTREE_HARDWARE_FIELD 0
 
 char* get_field_from_devtree(int DEVTREE_FIELD) {
@@ -75,6 +78,52 @@ char* parse_cpuinfo_field(char* field_str) {
   return ret;
 }
 
+unsigned long parse_cpuinfo_field_uint64(char* field_str) {
+  int filelen;
+  char* buf;
+  if((buf = read_file(_PATH_CPUINFO, &filelen)) == NULL) {
+    printWarn("read_file: %s: %s", _PATH_CPUINFO, strerror(errno));
+    return 0;
+  }
+
+  char* tmp = strstr(buf, field_str);
+  if(tmp == NULL) return 0;
+  tmp += strlen(field_str);
+
+  char* end;
+  errno = 0;
+  unsigned long ret = strtoul(tmp, &end, 16);
+  if (errno != 0) {
+    printWarn("strtoul: %s: %s", strerror(errno), tmp);
+    return 0;
+  }
+
+  return ret;
+}
+
+// Creates and fills in the riscv_cpuinfo struct (which contains
+// mvendorid, marchid and mimpid) using cpuinfo to fetch the values.
+//
+// Every RISC-V hart (hardware thread) [1] provides a
+// marchid (Machine Architecture ID register) CSR that encodes its
+// base microarchitecture [2]. For more information about
+// marchid and the rest of values, see [3].
+// [1] https://groups.google.com/a/groups.riscv.org/g/sw-dev/c/QKjUDjz_vKo
+// [2] https://github.com/riscv/riscv-isa-manual/blob/main/marchid.md
+// [3] https://five-embeddev.com/riscv-priv-isa-manual/Priv-v1.12/machine.html#machine-architecture-id-register-marchid
+struct riscv_cpuinfo *get_riscv_cpuinfo(void) {
+  struct riscv_cpuinfo* ci = emalloc(sizeof(struct riscv_cpuinfo));
+
+  ci->mvendorid = parse_cpuinfo_field_uint64(CPUINFO_RISCV_MVENDORID);
+  ci->marchid = parse_cpuinfo_field_uint64(CPUINFO_RISCV_MARCHID);
+  ci->mimpid = parse_cpuinfo_field_uint64(CPUINFO_RISCV_MIMPID);
+
+  if (ci->mvendorid == 0 && ci->mvendorid == 0 && ci->mvendorid == 0)
+    return NULL;
+
+  return ci;
+}
+
 char* get_hardware_from_devtree(void) {
   return get_field_from_devtree(DEVTREE_HARDWARE_FIELD);
 }

src/riscv/udev.h

@@ -5,8 +5,16 @@
 
 #define UNKNOWN -1
 
+// https://elixir.bootlin.com/linux/v6.10.6/source/arch/riscv/include/asm/cpufeature.h#L21
+struct riscv_cpuinfo {
+  unsigned long mvendorid;
+  unsigned long marchid;
+  unsigned long mimpid;
+};
+
 char* get_hardware_from_devtree(void);
 char* get_uarch_from_cpuinfo(void);
 char* get_extensions_from_cpuinfo(void);
+struct riscv_cpuinfo *get_riscv_cpuinfo(void);
 
 #endif