[PATCH] x86_64: add support for Intel dual-core detection and displaying

Appended patch adds the support for Intel dual-core detection and displaying
the core related information in /proc/cpuinfo.  

It adds two new fields "core id" and "cpu cores" to x86 /proc/cpuinfo and the
"core id" field for x86_64("cpu cores" field is already present in x86_64).

Number of processor cores in a die is detected using cpuid(4) and this is
documented in IA-32 Intel Architecture Software Developer's Manual (vol 2a)
(http://developer.intel.com/design/pentium4/manuals/index_new.htm#sdm_vol2a)

This patch also adds cpu_core_map similar to cpu_sibling_map.

Slightly hacked by AK.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 72 insertions, 16 deletions

diff --git a/arch/x86_64/kernel/setup.c b/arch/x86_64/kernel/setup.c
index 57f619052bad..ef74564eedeb 100644
--- a/arch/x86_64/kernel/setup.c
+++ b/arch/x86_64/kernel/setup.c
@@ -774,7 +774,7 @@ static void __init detect_ht(struct cpuinfo_x86 *c)
 {
 #ifdef CONFIG_SMP
         u32     eax, ebx, ecx, edx;
-        int     index_lsb, index_msb, tmp;
+        int     index_msb, tmp;
         int     cpu = smp_processor_id();
         
         if (!cpu_has(c, X86_FEATURE_HT))
@@ -786,7 +786,6 @@ static void __init detect_ht(struct cpuinfo_x86 *c)
         if (smp_num_siblings == 1) {
                 printk(KERN_INFO  "CPU: Hyper-Threading is disabled\n");
         } else if (smp_num_siblings > 1) {
-                index_lsb = 0;
                 index_msb = 31;
                 /*
                  * At this point we only support two siblings per
@@ -798,21 +797,33 @@ static void __init detect_ht(struct cpuinfo_x86 *c)
                         return;
                 }
                 tmp = smp_num_siblings;
-                while ((tmp & 1) == 0) {
-                        tmp >>=1 ;
-                        index_lsb++;
-                }
-                tmp = smp_num_siblings;
                 while ((tmp & 0x80000000 ) == 0) {
                         tmp <<=1 ;
                         index_msb--;
                 }
-                if (index_lsb != index_msb )
+                if (smp_num_siblings & (smp_num_siblings - 1))
                         index_msb++;
                 phys_proc_id[cpu] = phys_pkg_id(index_msb);
                 
                 printk(KERN_INFO  "CPU: Physical Processor ID: %d\n",
                        phys_proc_id[cpu]);
+
+                smp_num_siblings = smp_num_siblings / c->x86_num_cores;
+
+                tmp = smp_num_siblings;
+                index_msb = 31;
+                while ((tmp & 0x80000000) == 0) {
+                        tmp <<=1 ;
+                        index_msb--;
+                }
+                if (smp_num_siblings & (smp_num_siblings - 1))
+                        index_msb++;
+
+                cpu_core_id[cpu] = phys_pkg_id(index_msb);
+
+                if (c->x86_num_cores > 1)
+                        printk(KERN_INFO  "CPU: Processor Core ID: %d\n",
+                               cpu_core_id[cpu]);
         }
 #endif
 }
@@ -829,7 +840,28 @@ static void __init sched_cmp_hack(struct cpuinfo_x86 *c)
                 smp_num_siblings = 1;
 #endif
 }
-        
+
+/*
+ * find out the number of processor cores on the die
+ */
+static int __init intel_num_cpu_cores(struct cpuinfo_x86 *c)
+{
+        unsigned int eax;
+
+        if (c->cpuid_level < 4)
+                return 1;
+
+        __asm__("cpuid"
+                : "=a" (eax)
+                : "0" (4), "c" (0)
+                : "bx", "dx");
+
+        if (eax & 0x1f)
+                return ((eax >> 26) + 1);
+        else
+                return 1;
+}
+
 static void __init init_intel(struct cpuinfo_x86 *c)
 {
         /* Cache sizes */
@@ -847,6 +879,7 @@ static void __init init_intel(struct cpuinfo_x86 *c)
                 c->x86_cache_alignment = c->x86_clflush_size * 2;
         if (c->x86 >= 15)
                 set_bit(X86_FEATURE_CONSTANT_TSC, &c->x86_capability);
+        c->x86_num_cores = intel_num_cpu_cores(c);
 }
 
 void __init get_cpu_vendor(struct cpuinfo_x86 *c)
@@ -1153,13 +1186,16 @@ static int show_cpuinfo(struct seq_file *m, void *v)
                                         seq_printf(m, " [%d]", i);
                         }
         }
-        seq_printf(m, "\n");
 
-        if (c->x86_num_cores > 1)
-                seq_printf(m, "cpu cores\t: %d\n", c->x86_num_cores);
-
-        seq_printf(m, "\n\n"); 
+        seq_printf(m, "\n");
 
+#ifdef CONFIG_SMP
+        /* Put new fields at the end to lower the probability of
+           breaking user space parsers. */
+        seq_printf(m, "core id\t\t: %d\n", cpu_core_id[c - cpu_data]);
+        seq_printf(m, "cpu cores\t: %d\n", c->x86_num_cores);
+#endif
+        seq_printf(m, "\n");
         return 0;
 }
 
diff --git a/arch/x86_64/kernel/smpboot.c b/arch/x86_64/kernel/smpboot.c
index e5714090b00d..7e2de8925b0f 100644
--- a/arch/x86_64/kernel/smpboot.c
+++ b/arch/x86_64/kernel/smpboot.c
@@ -58,7 +58,10 @@
 int smp_num_siblings = 1;
 /* Package ID of each logical CPU */
 u8 phys_proc_id[NR_CPUS] = { [0 ... NR_CPUS-1] = BAD_APICID };
+/* Core ID of each logical CPU */
+u8 cpu_core_id[NR_CPUS] = { [0 ... NR_CPUS-1] = BAD_APICID };
 EXPORT_SYMBOL(phys_proc_id);
+EXPORT_SYMBOL(cpu_core_id);
 
 /* Bitmask of currently online CPUs */
 cpumask_t cpu_online_map;
@@ -71,6 +74,7 @@ static cpumask_t smp_commenced_mask;
 struct cpuinfo_x86 cpu_data[NR_CPUS] __cacheline_aligned;
 
 cpumask_t cpu_sibling_map[NR_CPUS] __cacheline_aligned;
+cpumask_t cpu_core_map[NR_CPUS] __cacheline_aligned;
 
 /*
  * Trampoline 80x86 program as an array.
@@ -713,6 +717,7 @@ static void __init smp_boot_cpus(unsigned int max_cpus)
                 io_apic_irqs = 0;
                 cpu_online_map = cpumask_of_cpu(0);
                 cpu_set(0, cpu_sibling_map[0]);
+                cpu_set(0, cpu_core_map[0]);
                 phys_cpu_present_map = physid_mask_of_physid(0);
                 if (APIC_init_uniprocessor())
                         printk(KERN_NOTICE "Local APIC not detected."
@@ -740,6 +745,7 @@ static void __init smp_boot_cpus(unsigned int max_cpus)
                 io_apic_irqs = 0;
                 cpu_online_map = cpumask_of_cpu(0);
                 cpu_set(0, cpu_sibling_map[0]);
+                cpu_set(0, cpu_core_map[0]);
                 phys_cpu_present_map = physid_mask_of_physid(0);
                 disable_apic = 1;
                 goto smp_done;
@@ -756,6 +762,7 @@ static void __init smp_boot_cpus(unsigned int max_cpus)
                 io_apic_irqs = 0;
                 cpu_online_map = cpumask_of_cpu(0);
                 cpu_set(0, cpu_sibling_map[0]);
+                cpu_set(0, cpu_core_map[0]);
                 phys_cpu_present_map = physid_mask_of_physid(0);
                 disable_apic = 1;
                 goto smp_done;
@@ -833,10 +840,13 @@ static void __init smp_boot_cpus(unsigned int max_cpus)
          * Construct cpu_sibling_map[], so that we can tell the
          * sibling CPU efficiently.
          */
-        for (cpu = 0; cpu < NR_CPUS; cpu++)
+        for (cpu = 0; cpu < NR_CPUS; cpu++) {
                 cpus_clear(cpu_sibling_map[cpu]);
+                cpus_clear(cpu_core_map[cpu]);
+        }
 
         for (cpu = 0; cpu < NR_CPUS; cpu++) {
+                struct cpuinfo_x86 *c = cpu_data + cpu;
                 int siblings = 0;
                 int i;
                 if (!cpu_isset(cpu, cpu_callout_map))
@@ -846,7 +856,7 @@ static void __init smp_boot_cpus(unsigned int max_cpus)
                         for (i = 0; i < NR_CPUS; i++) {
                                 if (!cpu_isset(i, cpu_callout_map))
                                         continue;
-                                if (phys_proc_id[cpu] == phys_proc_id[i]) {
+                                if (phys_proc_id[cpu] == cpu_core_id[i]) {
                                         siblings++;
                                         cpu_set(i, cpu_sibling_map[cpu]);
                                 }
@@ -862,6 +872,16 @@ static void __init smp_boot_cpus(unsigned int max_cpus)
                                siblings, cpu, smp_num_siblings);
                         smp_num_siblings = siblings;
                 }       
+                if (c->x86_num_cores > 1) {
+                        for (i = 0; i < NR_CPUS; i++) {
+                                if (!cpu_isset(i, cpu_callout_map))
+                                        continue;
+                                if (phys_proc_id[cpu] == phys_proc_id[i]) {
+                                        cpu_set(i, cpu_core_map[cpu]);
+                                }
+                        }
+                } else
+                        cpu_core_map[cpu] = cpu_sibling_map[cpu];
         }
 
         Dprintk("Boot done.\n");