x86, bts: detect size of DS fields

Impact: more robust DS feature enumeration

Detect the size of the pointer-type fields in the DS area
configuration via the DTES64 features rather than based on
the cpuid.

Rename a variable to denote that size to reflect that it only
covers the pointer-type fields.

Add more boot-time diagnostics giving the detected size and
the sizes of BTS and PEBS records.

Use the size of the BTS/PEBS record to indicate that the
respective feature is not available (if the record size is zero).

Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
LKML-Reference: <20090313104218.A30096@sedona.ch.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 44 insertions, 40 deletions

diff --git a/arch/x86/kernel/ds.c b/arch/x86/kernel/ds.c
index 87b67e3a765a..6e5ec679a0cd 100644
--- a/arch/x86/kernel/ds.c
+++ b/arch/x86/kernel/ds.c
@@ -39,7 +39,7 @@ struct ds_configuration {
         /* the size of one pointer-typed field in the DS structure and
            in the BTS and PEBS buffers in bytes;
            this covers the first 8 DS fields related to buffer management. */
-        unsigned char  sizeof_field;
+        unsigned char  sizeof_ptr_field;
         /* the size of a BTS/PEBS record in bytes */
         unsigned char  sizeof_rec[2];
         /* a series of bit-masks to control various features indexed
@@ -142,14 +142,14 @@ enum ds_qualifier {
 static inline unsigned long ds_get(const unsigned char *base,
                                    enum ds_qualifier qual, enum ds_field field)
 {
-        base += (ds_cfg.sizeof_field * (field + (4 * qual)));
+        base += (ds_cfg.sizeof_ptr_field * (field + (4 * qual)));
         return *(unsigned long *)base;
 }
 
 static inline void ds_set(unsigned char *base, enum ds_qualifier qual,
                           enum ds_field field, unsigned long value)
 {
-        base += (ds_cfg.sizeof_field * (field + (4 * qual)));
+        base += (ds_cfg.sizeof_ptr_field * (field + (4 * qual)));
         (*(unsigned long *)base) = value;
 }
 
@@ -410,7 +410,7 @@ static int ds_write(struct ds_context *context, enum ds_qualifier qual,
  * Later architectures use 64bit pointers throughout, whereas earlier
  * architectures use 32bit pointers in 32bit mode.
  *
- * We compute the base address for the first 8 fields based on:
+ * We compute the base address for the fields based on:
  * - the field size stored in the DS configuration
  * - the relative field position
  *
@@ -441,13 +441,13 @@ enum bts_field {
 
 static inline unsigned long bts_get(const char *base, enum bts_field field)
 {
-        base += (ds_cfg.sizeof_field * field);
+        base += (ds_cfg.sizeof_ptr_field * field);
         return *(unsigned long *)base;
 }
 
 static inline void bts_set(char *base, enum bts_field field, unsigned long val)
 {
-        base += (ds_cfg.sizeof_field * field);;
+        base += (ds_cfg.sizeof_ptr_field * field);;
         (*(unsigned long *)base) = val;
 }
 
@@ -593,6 +593,10 @@ static int ds_request(struct ds_tracer *tracer, struct ds_trace *trace,
         struct ds_context *context;
         int error;
 
+        error = -EOPNOTSUPP;
+        if (!ds_cfg.sizeof_rec[qual])
+                goto out;
+
         error = -EINVAL;
         if (!base)
                 goto out;
@@ -635,10 +639,6 @@ struct bts_tracer *ds_request_bts(struct task_struct *task,
         unsigned long irq;
         int error;
 
-        error = -EOPNOTSUPP;
-        if (!ds_cfg.ctl[dsf_bts])
-                goto out;
-
         /* buffer overflow notification is not yet implemented */
         error = -EOPNOTSUPP;
         if (ovfl)
@@ -848,7 +848,8 @@ const struct pebs_trace *ds_read_pebs(struct pebs_tracer *tracer)
 
         ds_read_config(tracer->ds.context, &tracer->trace.ds, ds_pebs);
         tracer->trace.reset_value =
-                *(u64 *)(tracer->ds.context->ds + (ds_cfg.sizeof_field * 8));
+                *(u64 *)(tracer->ds.context->ds +
+                         (ds_cfg.sizeof_ptr_field * 8));
 
         return &tracer->trace;
 }
@@ -884,7 +885,8 @@ int ds_set_pebs_reset(struct pebs_tracer *tracer, u64 value)
         if (!tracer)
                 return -EINVAL;
 
-        *(u64 *)(tracer->ds.context->ds + (ds_cfg.sizeof_field * 8)) = value;
+        *(u64 *)(tracer->ds.context->ds +
+                 (ds_cfg.sizeof_ptr_field * 8)) = value;
 
         return 0;
 }
@@ -894,52 +896,54 @@ static const struct ds_configuration ds_cfg_netburst = {
         .ctl[dsf_bts]           = (1 << 2) | (1 << 3),
         .ctl[dsf_bts_kernel]    = (1 << 5),
         .ctl[dsf_bts_user]      = (1 << 6),
-
-        .sizeof_field           = sizeof(long),
-        .sizeof_rec[ds_bts]     = sizeof(long) * 3,
-#ifdef __i386__
-        .sizeof_rec[ds_pebs]    = sizeof(long) * 10,
-#else
-        .sizeof_rec[ds_pebs]    = sizeof(long) * 18,
-#endif
 };
 static const struct ds_configuration ds_cfg_pentium_m = {
         .name = "Pentium M",
         .ctl[dsf_bts]           = (1 << 6) | (1 << 7),
-
-        .sizeof_field           = sizeof(long),
-        .sizeof_rec[ds_bts]     = sizeof(long) * 3,
-#ifdef __i386__
-        .sizeof_rec[ds_pebs]    = sizeof(long) * 10,
-#else
-        .sizeof_rec[ds_pebs]    = sizeof(long) * 18,
-#endif
 };
 static const struct ds_configuration ds_cfg_core2_atom = {
         .name = "Core 2/Atom",
         .ctl[dsf_bts]           = (1 << 6) | (1 << 7),
         .ctl[dsf_bts_kernel]    = (1 << 9),
         .ctl[dsf_bts_user]      = (1 << 10),
-
-        .sizeof_field           = 8,
-        .sizeof_rec[ds_bts]     = 8 * 3,
-        .sizeof_rec[ds_pebs]    = 8 * 18,
 };
 
 static void
-ds_configure(const struct ds_configuration *cfg)
+ds_configure(const struct ds_configuration *cfg,
+             struct cpuinfo_x86 *cpu)
 {
+        unsigned long nr_pebs_fields = 0;
+
+        printk(KERN_INFO "[ds] using %s configuration\n", cfg->name);
+
+#ifdef __i386__
+        nr_pebs_fields = 10;
+#else
+        nr_pebs_fields = 18;
+#endif
+
         memset(&ds_cfg, 0, sizeof(ds_cfg));
         ds_cfg = *cfg;
 
-        printk(KERN_INFO "[ds] using %s configuration\n", ds_cfg.name);
+        ds_cfg.sizeof_ptr_field =
+                (cpu_has(cpu, X86_FEATURE_DTES64) ? 8 : 4);
 
-        if (!cpu_has_bts) {
-                ds_cfg.ctl[dsf_bts] = 0;
+        ds_cfg.sizeof_rec[ds_bts]  = ds_cfg.sizeof_ptr_field * 3;
+        ds_cfg.sizeof_rec[ds_pebs] = ds_cfg.sizeof_ptr_field * nr_pebs_fields;
+
+        if (!cpu_has(cpu, X86_FEATURE_BTS)) {
+                ds_cfg.sizeof_rec[ds_bts] = 0;
                 printk(KERN_INFO "[ds] bts not available\n");
         }
-        if (!cpu_has_pebs)
+        if (!cpu_has(cpu, X86_FEATURE_PEBS)) {
+                ds_cfg.sizeof_rec[ds_pebs] = 0;
                 printk(KERN_INFO "[ds] pebs not available\n");
+        }
+
+        printk(KERN_INFO "[ds] sizes: address: %u bit, ",
+               8 * ds_cfg.sizeof_ptr_field);
+        printk("bts/pebs record: %u/%u bytes\n",
+               ds_cfg.sizeof_rec[ds_bts], ds_cfg.sizeof_rec[ds_pebs]);
 
         WARN_ON_ONCE(MAX_SIZEOF_DS < (12 * ds_cfg.sizeof_field));
 }
@@ -951,12 +955,12 @@ void __cpuinit ds_init_intel(struct cpuinfo_x86 *c)
                 switch (c->x86_model) {
                 case 0x9:
                 case 0xd: /* Pentium M */
-                        ds_configure(&ds_cfg_pentium_m);
+                        ds_configure(&ds_cfg_pentium_m, c);
                         break;
                 case 0xf:
                 case 0x17: /* Core2 */
                 case 0x1c: /* Atom */
-                        ds_configure(&ds_cfg_core2_atom);
+                        ds_configure(&ds_cfg_core2_atom, c);
                         break;
                 case 0x1a: /* i7 */
                 default:
@@ -969,7 +973,7 @@ void __cpuinit ds_init_intel(struct cpuinfo_x86 *c)
                 case 0x0:
                 case 0x1:
                 case 0x2: /* Netburst */
-                        ds_configure(&ds_cfg_netburst);
+                        ds_configure(&ds_cfg_netburst, c);
                         break;
                 default:
                         /* sorry, don't know about them */