Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fixes from Thomas Gleixner:
 "A small set of fixes for x86:

   - Make the tsc=reliable/nowatchdog command line parameter work again.
     It was broken with the introduction of the early TSC clocksource.

   - Prevent the evaluation of exception stacks before they are set up.
     This causes a crash in dumpstack because the stack walk termination
     gets screwed up.

   - Prevent a NULL pointer dereference in the rescource control file
     system.

   - Avoid bogus warnings about APIC id mismatch related to the LDR
     which can happen when the LDR is not in use and therefore not
     initialized. Only evaluate that when the APIC is in logical
     destination mode"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/tsc: Respect tsc command line paraemeter for clocksource_tsc_early
  x86/dumpstack/64: Don't evaluate exception stacks before setup
  x86/apic/32: Avoid bogus LDR warnings
  x86/resctrl: Prevent NULL pointer dereference when reading mondata

4 files changed, 29 insertions, 13 deletions

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 9e2dd2b296cd..2b0faf86da1b 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1586,9 +1586,6 @@ static void setup_local_APIC(void)
 {
 	int cpu = smp_processor_id();
 	unsigned int value;
-#ifdef CONFIG_X86_32
-	int logical_apicid, ldr_apicid;
-#endif
 
 	if (disable_apic) {
 		disable_ioapic_support();
@@ -1626,16 +1623,21 @@ static void setup_local_APIC(void)
 	apic->init_apic_ldr();
 
 #ifdef CONFIG_X86_32
-	/*
-	 * APIC LDR is initialized.  If logical_apicid mapping was
-	 * initialized during get_smp_config(), make sure it matches the
-	 * actual value.
-	 */
-	logical_apicid = early_per_cpu(x86_cpu_to_logical_apicid, cpu);
-	ldr_apicid = GET_APIC_LOGICAL_ID(apic_read(APIC_LDR));
-	WARN_ON(logical_apicid != BAD_APICID && logical_apicid != ldr_apicid);
-	/* always use the value from LDR */
-	early_per_cpu(x86_cpu_to_logical_apicid, cpu) = ldr_apicid;
+	if (apic->dest_logical) {
+		int logical_apicid, ldr_apicid;
+
+		/*
+		 * APIC LDR is initialized.  If logical_apicid mapping was
+		 * initialized during get_smp_config(), make sure it matches
+		 * the actual value.
+		 */
+		logical_apicid = early_per_cpu(x86_cpu_to_logical_apicid, cpu);
+		ldr_apicid = GET_APIC_LOGICAL_ID(apic_read(APIC_LDR));
+		if (logical_apicid != BAD_APICID)
+			WARN_ON(logical_apicid != ldr_apicid);
+		/* Always use the value from LDR. */
+		early_per_cpu(x86_cpu_to_logical_apicid, cpu) = ldr_apicid;
+	}
 #endif
 
 	/*
diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
index efbd54cc4e69..055c8613b531 100644
--- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
+++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
@@ -522,6 +522,10 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg)
 	int ret = 0;
 
 	rdtgrp = rdtgroup_kn_lock_live(of->kn);
+	if (!rdtgrp) {
+		ret = -ENOENT;
+		goto out;
+	}
 
 	md.priv = of->kn->priv;
 	resid = md.u.rid;
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index 753b8cfe8b8a..87b97897a881 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -94,6 +94,13 @@ static bool in_exception_stack(unsigned long *stack, struct stack_info *info)
 	BUILD_BUG_ON(N_EXCEPTION_STACKS != 6);
 
 	begin = (unsigned long)__this_cpu_read(cea_exception_stacks);
+	/*
+	 * Handle the case where stack trace is collected _before_
+	 * cea_exception_stacks had been initialized.
+	 */
+	if (!begin)
+		return false;
+
 	end = begin + sizeof(struct cea_exception_stacks);
 	/* Bail if @stack is outside the exception stack area. */
 	if (stk < begin || stk >= end)
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index c59454c382fd..7e322e2daaf5 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -1505,6 +1505,9 @@ void __init tsc_init(void)
 		return;
 	}
 
+	if (tsc_clocksource_reliable || no_tsc_watchdog)
+		clocksource_tsc_early.flags &= ~CLOCK_SOURCE_MUST_VERIFY;
+
 	clocksource_register_khz(&clocksource_tsc_early, tsc_khz);
 	detect_art();
 }