Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull arm64 fixes from Will Deacon:

 - Fix panic() when it occurs during secondary CPU startup

 - Fix "kpti=off" when KASLR is enabled

 - Fix howler in compat syscall table for vDSO clock_getres() fallback

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: compat: Fix syscall number of compat_clock_getres
  arm64: kpti: Fix "kpti=off" when KASLR is enabled
  arm64: smp: fix crash_smp_send_stop() behaviour
  arm64: smp: fix smp_send_stop() behaviour

4 files changed, 26 insertions, 11 deletions

diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h
index e4d862420bb4..d79ce6df9e12 100644
--- a/arch/arm64/include/asm/mmu.h
+++ b/arch/arm64/include/asm/mmu.h
@@ -29,11 +29,9 @@ typedef struct {
  */
 #define ASID(mm)	((mm)->context.id.counter & 0xffff)
 
-extern bool arm64_use_ng_mappings;
-
 static inline bool arm64_kernel_unmapped_at_el0(void)
 {
-	return arm64_use_ng_mappings;
+	return cpus_have_const_cap(ARM64_UNMAP_KERNEL_AT_EL0);
 }
 
 typedef void (*bp_hardening_cb_t)(void);
diff --git a/arch/arm64/include/asm/pgtable-prot.h b/arch/arm64/include/asm/pgtable-prot.h
index 6f87839f0249..1305e28225fc 100644
--- a/arch/arm64/include/asm/pgtable-prot.h
+++ b/arch/arm64/include/asm/pgtable-prot.h
@@ -23,11 +23,13 @@
 
 #include <asm/pgtable-types.h>
 
+extern bool arm64_use_ng_mappings;
+
 #define _PROT_DEFAULT		(PTE_TYPE_PAGE | PTE_AF | PTE_SHARED)
 #define _PROT_SECT_DEFAULT	(PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S)
 
-#define PTE_MAYBE_NG		(arm64_kernel_unmapped_at_el0() ? PTE_NG : 0)
-#define PMD_MAYBE_NG		(arm64_kernel_unmapped_at_el0() ? PMD_SECT_NG : 0)
+#define PTE_MAYBE_NG		(arm64_use_ng_mappings ? PTE_NG : 0)
+#define PMD_MAYBE_NG		(arm64_use_ng_mappings ? PMD_SECT_NG : 0)
 
 #define PROT_DEFAULT		(_PROT_DEFAULT | PTE_MAYBE_NG)
 #define PROT_SECT_DEFAULT	(_PROT_SECT_DEFAULT | PMD_MAYBE_NG)
diff --git a/arch/arm64/include/asm/unistd.h b/arch/arm64/include/asm/unistd.h
index 1dd22da1c3a9..803039d504de 100644
--- a/arch/arm64/include/asm/unistd.h
+++ b/arch/arm64/include/asm/unistd.h
@@ -25,8 +25,8 @@
 #define __NR_compat_gettimeofday	78
 #define __NR_compat_sigreturn		119
 #define __NR_compat_rt_sigreturn	173
-#define __NR_compat_clock_getres	247
 #define __NR_compat_clock_gettime	263
+#define __NR_compat_clock_getres	264
 #define __NR_compat_clock_gettime64	403
 #define __NR_compat_clock_getres_time64	406
 
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index d4ed9a19d8fe..5407bf5d98ac 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -958,11 +958,22 @@ void tick_broadcast(const struct cpumask *mask)
 }
 #endif
 
+/*
+ * The number of CPUs online, not counting this CPU (which may not be
+ * fully online and so not counted in num_online_cpus()).
+ */
+static inline unsigned int num_other_online_cpus(void)
+{
+	unsigned int this_cpu_online = cpu_online(smp_processor_id());
+
+	return num_online_cpus() - this_cpu_online;
+}
+
 void smp_send_stop(void)
 {
 	unsigned long timeout;
 
-	if (num_online_cpus() > 1) {
+	if (num_other_online_cpus()) {
 		cpumask_t mask;
 
 		cpumask_copy(&mask, cpu_online_mask);
@@ -975,10 +986,10 @@ void smp_send_stop(void)
 
 	/* Wait up to one second for other CPUs to stop */
 	timeout = USEC_PER_SEC;
-	while (num_online_cpus() > 1 && timeout--)
+	while (num_other_online_cpus() && timeout--)
 		udelay(1);
 
-	if (num_online_cpus() > 1)
+	if (num_other_online_cpus())
 		pr_warn("SMP: failed to stop secondary CPUs %*pbl\n",
 			cpumask_pr_args(cpu_online_mask));
 
@@ -1001,7 +1012,11 @@ void crash_smp_send_stop(void)
 
 	cpus_stopped = 1;
 
-	if (num_online_cpus() == 1) {
+	/*
+	 * If this cpu is the only one alive at this point in time, online or
+	 * not, there are no stop messages to be sent around, so just back out.
+	 */
+	if (num_other_online_cpus() == 0) {
 		sdei_mask_local_cpu();
 		return;
 	}
@@ -1009,7 +1024,7 @@ void crash_smp_send_stop(void)
 	cpumask_copy(&mask, cpu_online_mask);
 	cpumask_clear_cpu(smp_processor_id(), &mask);
 
-	atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1);
+	atomic_set(&waiting_for_crash_ipi, num_other_online_cpus());
 
 	pr_crit("SMP: stopping secondary CPUs\n");
 	smp_cross_call(&mask, IPI_CPU_CRASH_STOP);