1 files changed, 160 insertions, 12 deletions

diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index 67cf22083f4c..4520c9356b54 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -78,6 +78,7 @@ static unsigned int freeze_events_kernel = MMCR0_FCS;
 #define MMCR0_FC56		0
 #define MMCR0_PMAO		0
 #define MMCR0_EBE		0
+#define MMCR0_BHRBA		0
 #define MMCR0_PMCC		0
 #define MMCR0_PMCC_U6		0
 
@@ -120,6 +121,7 @@ static inline void power_pmu_bhrb_enable(struct perf_event *event) {}
 static inline void power_pmu_bhrb_disable(struct perf_event *event) {}
 void power_pmu_flush_branch_stack(void) {}
 static inline void power_pmu_bhrb_read(struct cpu_hw_events *cpuhw) {}
+static void pmao_restore_workaround(bool ebb) { }
 #endif /* CONFIG_PPC32 */
 
 static bool regs_use_siar(struct pt_regs *regs)
@@ -502,8 +504,11 @@ static int ebb_event_check(struct perf_event *event)
 		if (!leader->attr.pinned || !leader->attr.exclusive)
 			return -EINVAL;
 
-		if (event->attr.inherit || event->attr.sample_period ||
-		    event->attr.enable_on_exec || event->attr.freq)
+		if (event->attr.freq ||
+		    event->attr.inherit ||
+		    event->attr.sample_type ||
+		    event->attr.sample_period ||
+		    event->attr.enable_on_exec)
 			return -EINVAL;
 	}
 
@@ -542,13 +547,21 @@ static unsigned long ebb_switch_in(bool ebb, unsigned long mmcr0)
 	if (!ebb)
 		goto out;
 
-	/* Enable EBB and read/write to all 6 PMCs for userspace */
-	mmcr0 |= MMCR0_EBE | MMCR0_PMCC_U6;
+	/* Enable EBB and read/write to all 6 PMCs and BHRB for userspace */
+	mmcr0 |= MMCR0_EBE | MMCR0_BHRBA | MMCR0_PMCC_U6;
 
-	/* Add any bits from the user reg, FC or PMAO */
+	/*
+	 * Add any bits from the user MMCR0, FC or PMAO. This is compatible
+	 * with pmao_restore_workaround() because we may add PMAO but we never
+	 * clear it here.
+	 */
 	mmcr0 |= current->thread.mmcr0;
 
-	/* Be careful not to set PMXE if userspace had it cleared */
+	/*
+	 * Be careful not to set PMXE if userspace had it cleared. This is also
+	 * compatible with pmao_restore_workaround() because it has already
+	 * cleared PMXE and we leave PMAO alone.
+	 */
 	if (!(current->thread.mmcr0 & MMCR0_PMXE))
 		mmcr0 &= ~MMCR0_PMXE;
 
@@ -559,13 +572,94 @@ static unsigned long ebb_switch_in(bool ebb, unsigned long mmcr0)
 out:
 	return mmcr0;
 }
-#endif /* CONFIG_PPC64 */
-
-static void perf_event_interrupt(struct pt_regs *regs);
 
-void perf_event_print_debug(void)
+static void pmao_restore_workaround(bool ebb)
 {
+	unsigned pmcs[6];
+
+	if (!cpu_has_feature(CPU_FTR_PMAO_BUG))
+		return;
+
+	/*
+	 * On POWER8E there is a hardware defect which affects the PMU context
+	 * switch logic, ie. power_pmu_disable/enable().
+	 *
+	 * When a counter overflows PMXE is cleared and FC/PMAO is set in MMCR0
+	 * by the hardware. Sometime later the actual PMU exception is
+	 * delivered.
+	 *
+	 * If we context switch, or simply disable/enable, the PMU prior to the
+	 * exception arriving, the exception will be lost when we clear PMAO.
+	 *
+	 * When we reenable the PMU, we will write the saved MMCR0 with PMAO
+	 * set, and this _should_ generate an exception. However because of the
+	 * defect no exception is generated when we write PMAO, and we get
+	 * stuck with no counters counting but no exception delivered.
+	 *
+	 * The workaround is to detect this case and tweak the hardware to
+	 * create another pending PMU exception.
+	 *
+	 * We do that by setting up PMC6 (cycles) for an imminent overflow and
+	 * enabling the PMU. That causes a new exception to be generated in the
+	 * chip, but we don't take it yet because we have interrupts hard
+	 * disabled. We then write back the PMU state as we want it to be seen
+	 * by the exception handler. When we reenable interrupts the exception
+	 * handler will be called and see the correct state.
+	 *
+	 * The logic is the same for EBB, except that the exception is gated by
+	 * us having interrupts hard disabled as well as the fact that we are
+	 * not in userspace. The exception is finally delivered when we return
+	 * to userspace.
+	 */
+
+	/* Only if PMAO is set and PMAO_SYNC is clear */
+	if ((current->thread.mmcr0 & (MMCR0_PMAO | MMCR0_PMAO_SYNC)) != MMCR0_PMAO)
+		return;
+
+	/* If we're doing EBB, only if BESCR[GE] is set */
+	if (ebb && !(current->thread.bescr & BESCR_GE))
+		return;
+
+	/*
+	 * We are already soft-disabled in power_pmu_enable(). We need to hard
+	 * enable to actually prevent the PMU exception from firing.
+	 */
+	hard_irq_disable();
+
+	/*
+	 * This is a bit gross, but we know we're on POWER8E and have 6 PMCs.
+	 * Using read/write_pmc() in a for loop adds 12 function calls and
+	 * almost doubles our code size.
+	 */
+	pmcs[0] = mfspr(SPRN_PMC1);
+	pmcs[1] = mfspr(SPRN_PMC2);
+	pmcs[2] = mfspr(SPRN_PMC3);
+	pmcs[3] = mfspr(SPRN_PMC4);
+	pmcs[4] = mfspr(SPRN_PMC5);
+	pmcs[5] = mfspr(SPRN_PMC6);
+
+	/* Ensure all freeze bits are unset */
+	mtspr(SPRN_MMCR2, 0);
+
+	/* Set up PMC6 to overflow in one cycle */
+	mtspr(SPRN_PMC6, 0x7FFFFFFE);
+
+	/* Enable exceptions and unfreeze PMC6 */
+	mtspr(SPRN_MMCR0, MMCR0_PMXE | MMCR0_PMCjCE | MMCR0_PMAO);
+
+	/* Now we need to refreeze and restore the PMCs */
+	mtspr(SPRN_MMCR0, MMCR0_FC | MMCR0_PMAO);
+
+	mtspr(SPRN_PMC1, pmcs[0]);
+	mtspr(SPRN_PMC2, pmcs[1]);
+	mtspr(SPRN_PMC3, pmcs[2]);
+	mtspr(SPRN_PMC4, pmcs[3]);
+	mtspr(SPRN_PMC5, pmcs[4]);
+	mtspr(SPRN_PMC6, pmcs[5]);
 }
+#endif /* CONFIG_PPC64 */
+
+static void perf_event_interrupt(struct pt_regs *regs);
 
 /*
  * Read one performance monitor counter (PMC).
@@ -645,6 +739,57 @@ static void write_pmc(int idx, unsigned long val)
 	}
 }
 
+/* Called from sysrq_handle_showregs() */
+void perf_event_print_debug(void)
+{
+	unsigned long sdar, sier, flags;
+	u32 pmcs[MAX_HWEVENTS];
+	int i;
+
+	if (!ppmu->n_counter)
+		return;
+
+	local_irq_save(flags);
+
+	pr_info("CPU: %d PMU registers, ppmu = %s n_counters = %d",
+		 smp_processor_id(), ppmu->name, ppmu->n_counter);
+
+	for (i = 0; i < ppmu->n_counter; i++)
+		pmcs[i] = read_pmc(i + 1);
+
+	for (; i < MAX_HWEVENTS; i++)
+		pmcs[i] = 0xdeadbeef;
+
+	pr_info("PMC1:  %08x PMC2: %08x PMC3: %08x PMC4: %08x\n",
+		 pmcs[0], pmcs[1], pmcs[2], pmcs[3]);
+
+	if (ppmu->n_counter > 4)
+		pr_info("PMC5:  %08x PMC6: %08x PMC7: %08x PMC8: %08x\n",
+			 pmcs[4], pmcs[5], pmcs[6], pmcs[7]);
+
+	pr_info("MMCR0: %016lx MMCR1: %016lx MMCRA: %016lx\n",
+		mfspr(SPRN_MMCR0), mfspr(SPRN_MMCR1), mfspr(SPRN_MMCRA));
+
+	sdar = sier = 0;
+#ifdef CONFIG_PPC64
+	sdar = mfspr(SPRN_SDAR);
+
+	if (ppmu->flags & PPMU_HAS_SIER)
+		sier = mfspr(SPRN_SIER);
+
+	if (ppmu->flags & PPMU_EBB) {
+		pr_info("MMCR2: %016lx EBBHR: %016lx\n",
+			mfspr(SPRN_MMCR2), mfspr(SPRN_EBBHR));
+		pr_info("EBBRR: %016lx BESCR: %016lx\n",
+			mfspr(SPRN_EBBRR), mfspr(SPRN_BESCR));
+	}
+#endif
+	pr_info("SIAR:  %016lx SDAR:  %016lx SIER:  %016lx\n",
+		mfspr(SPRN_SIAR), sdar, sier);
+
+	local_irq_restore(flags);
+}
+
 /*
  * Check if a set of events can all go on the PMU at once.
  * If they can't, this will look at alternative codes for the events
@@ -973,11 +1118,12 @@ static void power_pmu_disable(struct pmu *pmu)
 		}
 
 		/*
-		 * Set the 'freeze counters' bit, clear EBE/PMCC/PMAO/FC56.
+		 * Set the 'freeze counters' bit, clear EBE/BHRBA/PMCC/PMAO/FC56
 		 */
 		val  = mmcr0 = mfspr(SPRN_MMCR0);
 		val |= MMCR0_FC;
-		val &= ~(MMCR0_EBE | MMCR0_PMCC | MMCR0_PMAO | MMCR0_FC56);
+		val &= ~(MMCR0_EBE | MMCR0_BHRBA | MMCR0_PMCC | MMCR0_PMAO |
+			 MMCR0_FC56);
 
 		/*
 		 * The barrier is to make sure the mtspr has been
@@ -1144,6 +1290,8 @@ static void power_pmu_enable(struct pmu *pmu)
 	cpuhw->mmcr[0] |= MMCR0_PMXE | MMCR0_FCECE;
 
  out_enable:
+	pmao_restore_workaround(ebb);
+
 	mmcr0 = ebb_switch_in(ebb, cpuhw->mmcr[0]);
 
 	mb();