perf: Tidy up after the big rename

 - provide compatibility Kconfig entry for existing PERF_COUNTERS .config's

 - provide courtesy copy of old perf_counter.h, for user-space projects

 - small indentation fixups

 - fix up MAINTAINERS

 - fix small x86 printout fallout

 - fix up small PowerPC comment fallout (use 'counter' as in register)

Reviewed-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

MAINTAINERS

@@ -4000,7 +4000,7 @@ S:	Maintained
 F:	include/linux/delayacct.h
 F:	kernel/delayacct.c
 
-PERFORMANCE COUNTER SUBSYSTEM
+PERFORMANCE EVENTS SUBSYSTEM
 M:	Peter Zijlstra <a.p.zijlstra@chello.nl>
 M:	Paul Mackerras <paulus@samba.org>
 M:	Ingo Molnar <mingo@elte.hu>

arch/powerpc/include/asm/paca.h

@@ -122,7 +122,7 @@ struct paca_struct {
 	u8 soft_enabled;		/* irq soft-enable flag */
 	u8 hard_enabled;		/* set if irqs are enabled in MSR */
 	u8 io_sync;			/* writel() needs spin_unlock sync */
-	u8 perf_event_pending;	/* PM interrupt while soft-disabled */
+	u8 perf_event_pending;		/* PM interrupt while soft-disabled */
 
 	/* Stuff for accurate time accounting */
 	u64 user_time;			/* accumulated usermode TB ticks */

arch/powerpc/kernel/perf_event.c

@@ -41,7 +41,7 @@ DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events);
 struct power_pmu *ppmu;
 
 /*
- * Normally, to ignore kernel events we set the FCS (freeze events
+ * Normally, to ignore kernel events we set the FCS (freeze counters
  * in supervisor mode) bit in MMCR0, but if the kernel runs with the
  * hypervisor bit set in the MSR, or if we are running on a processor
  * where the hypervisor bit is forced to 1 (as on Apple G5 processors),
@@ -159,7 +159,7 @@ void perf_event_print_debug(void)
 }
 
 /*
- * Read one performance monitor event (PMC).
+ * Read one performance monitor counter (PMC).
  */
 static unsigned long read_pmc(int idx)
 {
@@ -409,7 +409,7 @@ static void power_pmu_read(struct perf_event *event)
 		val = read_pmc(event->hw.idx);
 	} while (atomic64_cmpxchg(&event->hw.prev_count, prev, val) != prev);
 
-	/* The events are only 32 bits wide */
+	/* The counters are only 32 bits wide */
 	delta = (val - prev) & 0xfffffffful;
 	atomic64_add(delta, &event->count);
 	atomic64_sub(delta, &event->hw.period_left);
@@ -543,7 +543,7 @@ void hw_perf_disable(void)
 		}
 
 		/*
-		 * Set the 'freeze events' bit.
+		 * Set the 'freeze counters' bit.
 		 * The barrier is to make sure the mtspr has been
 		 * executed and the PMU has frozen the events
 		 * before we return.
@@ -1124,7 +1124,7 @@ const struct pmu *hw_perf_event_init(struct perf_event *event)
 }
 
 /*
- * A event has overflowed; update its count and record
+ * A counter has overflowed; update its count and record
  * things if requested.  Note that interrupts are hard-disabled
  * here so there is no possibility of being interrupted.
  */
@@ -1271,7 +1271,7 @@ static void perf_event_interrupt(struct pt_regs *regs)
 
 	/*
 	 * Reset MMCR0 to its normal value.  This will set PMXE and
-	 * clear FC (freeze events) and PMAO (perf mon alert occurred)
+	 * clear FC (freeze counters) and PMAO (perf mon alert occurred)
 	 * and thus allow interrupts to occur again.
 	 * XXX might want to use MSR.PM to keep the events frozen until
 	 * we get back out of this interrupt.

arch/x86/kernel/cpu/perf_event.c

@@ -2081,13 +2081,13 @@ void __init init_hw_perf_events(void)
 	perf_events_lapic_init();
 	register_die_notifier(&perf_event_nmi_notifier);
 
-	pr_info("... version:                 %d\n",     x86_pmu.version);
-	pr_info("... bit width:               %d\n",     x86_pmu.event_bits);
-	pr_info("... generic events:        %d\n",     x86_pmu.num_events);
-	pr_info("... value mask:              %016Lx\n", x86_pmu.event_mask);
-	pr_info("... max period:              %016Lx\n", x86_pmu.max_period);
-	pr_info("... fixed-purpose events:  %d\n",     x86_pmu.num_events_fixed);
-	pr_info("... event mask:            %016Lx\n", perf_event_mask);
+	pr_info("... version:                %d\n",     x86_pmu.version);
+	pr_info("... bit width:              %d\n",     x86_pmu.event_bits);
+	pr_info("... generic registers:      %d\n",     x86_pmu.num_events);
+	pr_info("... value mask:             %016Lx\n", x86_pmu.event_mask);
+	pr_info("... max period:             %016Lx\n", x86_pmu.max_period);
+	pr_info("... fixed-purpose events:   %d\n",     x86_pmu.num_events_fixed);
+	pr_info("... event mask:             %016Lx\n", perf_event_mask);
 }
 
 static inline void x86_pmu_read(struct perf_event *event)