[v1.00][X86] Retrieve topology from udev when APIC fails (like #119)

src/arm/udev.c

@@ -3,7 +3,6 @@
 #include "midr.h"
 
 #define _PATH_DEVICETREE_MODEL       "/sys/firmware/devicetree/base/model"
-#define _PATH_CPUS_PRESENT           _PATH_SYS_SYSTEM _PATH_SYS_CPU "/present"
 #define _PATH_CPUINFO                "/proc/cpuinfo"
 //#define _PATH_CPUINFO                "cpuinfo_debug"
 
@@ -17,48 +16,6 @@
 
 #define CPUINFO_CPU_STRING "processor"
 
-// https://www.kernel.org/doc/html/latest/core-api/cpu_hotplug.html
-int get_ncores_from_cpuinfo() {
-  // Examples:
-  // 0-271
-  // 0-7
-  // 0
-
-  int filelen;
-  char* buf;
-  if((buf = read_file(_PATH_CPUS_PRESENT, &filelen)) == NULL) {
-    printWarn("read_file: %s: %s\n", _PATH_CPUS_PRESENT, strerror(errno));
-    return UNKNOWN;
-  }
-
-  int ncores;
-  char* tmp1;
-  if((tmp1 = strstr(buf, "-")) == NULL) {
-    // file contains no - character, we assume that it contains 0,
-    // which means that the CPU contains only one core
-    return 1;
-  }
-  else {
-    tmp1++;
-  }
-  char* tmp2 = strstr(buf, "\n");
-  char ncores_str[filelen];
-  memset(ncores_str, 0, sizeof(char) * filelen);
-  memcpy(ncores_str, tmp1, tmp2-tmp1);
-
-  char* end;
-  errno = 0;
-  ncores = strtol(ncores_str, &end, 10) + 1;
-  if(errno != 0) {
-    printWarn("strtol: %s:\n", strerror(errno));
-    return UNKNOWN;
-  }
-
-  free(buf);
-
-  return ncores;
-}
-
 long parse_cpuinfo_field(char* buf, char* field_str, int field_base) {
   char* tmp = strstr(buf, field_str);
   if(tmp == NULL) return -1;

src/common/udev.c

@@ -2,6 +2,48 @@
 #include "global.h"
 #include "cpu.h"
 
+// https://www.kernel.org/doc/html/latest/core-api/cpu_hotplug.html
+int get_ncores_from_cpuinfo() {
+  // Examples:
+  // 0-271
+  // 0-7
+  // 0
+
+  int filelen;
+  char* buf;
+  if((buf = read_file(_PATH_CPUS_PRESENT, &filelen)) == NULL) {
+    printWarn("read_file: %s: %s\n", _PATH_CPUS_PRESENT, strerror(errno));
+    return -1;
+  }
+
+  int ncores;
+  char* tmp1;
+  if((tmp1 = strstr(buf, "-")) == NULL) {
+    // file contains no - character, we assume that it contains 0,
+    // which means that the CPU contains only one core
+    return 1;
+  }
+  else {
+    tmp1++;
+  }
+  char* tmp2 = strstr(buf, "\n");
+  char ncores_str[filelen];
+  memset(ncores_str, 0, sizeof(char) * filelen);
+  memcpy(ncores_str, tmp1, tmp2-tmp1);
+
+  char* end;
+  errno = 0;
+  ncores = strtol(ncores_str, &end, 10) + 1;
+  if(errno != 0) {
+    printWarn("strtol: %s:\n", strerror(errno));
+    return -1;
+  }
+
+  free(buf);
+
+  return ncores;
+}
+
 char* read_file(char* path, int* len) {
   int fd = open(path, O_RDONLY);
 

src/common/udev.h

@@ -23,6 +23,7 @@
 #define _PATH_CACHE_L3          "/cache/index3"
 #define _PATH_CACHE_SIZE        "/size"
 #define _PATH_CACHE_SHARED_MAP  "/shared_cpu_map"
+#define _PATH_CPUS_PRESENT           _PATH_SYS_SYSTEM _PATH_SYS_CPU "/present"
 
 #define _PATH_FREQUENCY_MAX_LEN 100
 #define _PATH_CACHE_MAX_LEN     200
@@ -36,5 +37,6 @@ long get_l1d_cache_size(uint32_t core);
 long get_l2_cache_size(uint32_t core);
 long get_l3_cache_size(uint32_t core);
 int get_num_caches_by_level(struct cpuInfo* cpu, uint32_t level);
+int get_ncores_from_cpuinfo();
 
 #endif

src/x86/apic.c

@@ -385,13 +385,8 @@ bool get_topology_from_apic(struct cpuInfo* cpu, struct topology* topo) {
 
   get_cache_topology_from_apic(topo);
 
-  if(!fill_apic_ids(apic_ids, topo->total_cores, x2apic_id)) {
-    topo->logical_cores = UNKNOWN_DATA;
-    topo->physical_cores = UNKNOWN_DATA;
-    topo->smt_available = 1;
-    topo->smt_supported = 1;
+  if(!fill_apic_ids(apic_ids, topo->total_cores, x2apic_id))
     return false;
-  }
 
   for(int i=0; i < topo->total_cores; i++) {
     apic_id = apic_ids[i];

src/x86/cpuid.c

@@ -470,6 +470,16 @@ bool get_cache_topology_amd(struct cpuInfo* cpu, struct topology* topo) {
   return true;
 }
 
+void get_topology_from_udev(struct cpuInfo* cpu, struct topology* topo) {
+  // TODO: To be improved in the future
+  topo->total_cores = get_ncores_from_cpuinfo();
+  topo->logical_cores = topo->total_cores;
+  topo->physical_cores = topo->total_cores;
+  topo->smt_available = 1;
+  topo->smt_supported = 1;
+  topo->sockets = 1;
+}
+
 // Main reference: https://software.intel.com/content/www/us/en/develop/articles/intel-64-architecture-processor-topology-enumeration.html
 // Very interesting resource: https://wiki.osdev.org/Detecting_CPU_Topology_(80x86)
 struct topology* get_topology_info(struct cpuInfo* cpu, struct cache* cach) {
@@ -499,7 +509,19 @@ struct topology* get_topology_info(struct cpuInfo* cpu, struct cache* cach) {
   switch(cpu->cpu_vendor) {
     case CPU_VENDOR_INTEL:
       if (cpu->maxLevels >= 0x00000004) {
-        get_topology_from_apic(cpu, topo);
+        bool toporet = get_topology_from_apic(cpu, topo);
+        if(!toporet) {
+          #ifdef __linux__
+            printWarn("Failed to retrieve topology from APIC, using udev...\n");
+            get_topology_from_udev(cpu, topo);
+          #else
+            printErr("Failed to retrieve topology from APIC, assumming default values...\n");
+            topo->logical_cores = UNKNOWN_DATA;
+            topo->physical_cores = UNKNOWN_DATA;
+            topo->smt_available = 1;
+            topo->smt_supported = 1;
+          #endif
+        }
       }
       else {
         printWarn("Can't read topology information from cpuid (needed level is 0x%.8X, max is 0x%.8X)", 0x00000001, cpu->maxLevels);