21 files changed, 84 insertions, 71 deletions

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index c3daf0aaa0ee..cdaab30880b9 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -239,7 +239,7 @@ void __init arch_init_ideal_nops(void)
 			return;
 		}
 
-		/* fall through */
+		fallthrough;
 
 	default:
 #ifdef CONFIG_X86_64
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 21325a4a78b9..21f9c7f11779 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -800,7 +800,7 @@ static int irq_polarity(int idx)
 		return IOAPIC_POL_HIGH;
 	case MP_IRQPOL_RESERVED:
 		pr_warn("IOAPIC: Invalid polarity: 2, defaulting to low\n");
-		/* fall through */
+		fallthrough;
 	case MP_IRQPOL_ACTIVE_LOW:
 	default: /* Pointless default required due to do gcc stupidity */
 		return IOAPIC_POL_LOW;
@@ -848,7 +848,7 @@ static int irq_trigger(int idx)
 		return IOAPIC_EDGE;
 	case MP_IRQTRIG_RESERVED:
 		pr_warn("IOAPIC: Invalid trigger mode 2 defaulting to level\n");
-		/* fall through */
+		fallthrough;
 	case MP_IRQTRIG_LEVEL:
 	default: /* Pointless default required due to do gcc stupidity */
 		return IOAPIC_LEVEL;
@@ -2243,6 +2243,7 @@ static inline void __init check_timer(void)
 	legacy_pic->init(0);
 	legacy_pic->make_irq(0);
 	apic_write(APIC_LVT0, APIC_DM_EXTINT);
+	legacy_pic->unmask(0);
 
 	unlock_ExtINT_logic();
 
diff --git a/arch/x86/kernel/apic/probe_32.c b/arch/x86/kernel/apic/probe_32.c
index 7bda71def557..99ee61c9ba54 100644
--- a/arch/x86/kernel/apic/probe_32.c
+++ b/arch/x86/kernel/apic/probe_32.c
@@ -149,7 +149,7 @@ void __init default_setup_apic_routing(void)
 				break;
 			}
 			/* P4 and above */
-			/* fall through */
+			fallthrough;
 		case X86_VENDOR_HYGON:
 		case X86_VENDOR_AMD:
 			def_to_bigsmp = 1;
diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
index dae32d948bf2..f8a56b5dc29f 100644
--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -161,6 +161,7 @@ static void apic_update_vector(struct irq_data *irqd, unsigned int newvec,
 		apicd->move_in_progress = true;
 		apicd->prev_vector = apicd->vector;
 		apicd->prev_cpu = apicd->cpu;
+		WARN_ON_ONCE(apicd->cpu == newcpu);
 	} else {
 		irq_matrix_free(vector_matrix, apicd->cpu, apicd->vector,
 				managed);
@@ -910,7 +911,7 @@ void send_cleanup_vector(struct irq_cfg *cfg)
 		__send_cleanup_vector(apicd);
 }
 
-static void __irq_complete_move(struct irq_cfg *cfg, unsigned vector)
+void irq_complete_move(struct irq_cfg *cfg)
 {
 	struct apic_chip_data *apicd;
 
@@ -918,15 +919,16 @@ static void __irq_complete_move(struct irq_cfg *cfg, unsigned vector)
 	if (likely(!apicd->move_in_progress))
 		return;
 
-	if (vector == apicd->vector && apicd->cpu == smp_processor_id())
+	/*
+	 * If the interrupt arrived on the new target CPU, cleanup the
+	 * vector on the old target CPU. A vector check is not required
+	 * because an interrupt can never move from one vector to another
+	 * on the same CPU.
+	 */
+	if (apicd->cpu == smp_processor_id())
 		__send_cleanup_vector(apicd);
 }
 
-void irq_complete_move(struct irq_cfg *cfg)
-{
-	__irq_complete_move(cfg, ~get_irq_regs()->orig_ax);
-}
-
 /*
  * Called from fixup_irqs() with @desc->lock held and interrupts disabled.
  */
diff --git a/arch/x86/kernel/cpu/cacheinfo.c b/arch/x86/kernel/cpu/cacheinfo.c
index c7503be92f35..57074cf3ad7c 100644
--- a/arch/x86/kernel/cpu/cacheinfo.c
+++ b/arch/x86/kernel/cpu/cacheinfo.c
@@ -248,7 +248,7 @@ amd_cpuid4(int leaf, union _cpuid4_leaf_eax *eax,
 	switch (leaf) {
 	case 1:
 		l1 = &l1i;
-		/* fall through */
+		fallthrough;
 	case 0:
 		if (!l1->val)
 			return;
diff --git a/arch/x86/kernel/cpu/mce/inject.c b/arch/x86/kernel/cpu/mce/inject.c
index 7843ab3fde09..3a44346f2276 100644
--- a/arch/x86/kernel/cpu/mce/inject.c
+++ b/arch/x86/kernel/cpu/mce/inject.c
@@ -199,7 +199,7 @@ static int raise_local(void)
 			 * calling irq_enter, but the necessary
 			 * machinery isn't exported currently.
 			 */
-			/*FALL THROUGH*/
+			fallthrough;
 		case MCJ_CTX_PROCESS:
 			raise_exception(m, NULL);
 			break;
diff --git a/arch/x86/kernel/cpu/mce/intel.c b/arch/x86/kernel/cpu/mce/intel.c
index d8f9230d2034..abe9fe0fb851 100644
--- a/arch/x86/kernel/cpu/mce/intel.c
+++ b/arch/x86/kernel/cpu/mce/intel.c
@@ -193,7 +193,7 @@ unsigned long cmci_intel_adjust_timer(unsigned long interval)
 		if (!atomic_sub_return(1, &cmci_storm_on_cpus))
 			pr_notice("CMCI storm subsided: switching to interrupt mode\n");
 
-		/* FALLTHROUGH */
+		fallthrough;
 
 	case CMCI_STORM_SUBSIDED:
 		/*
diff --git a/arch/x86/kernel/cpu/mtrr/cyrix.c b/arch/x86/kernel/cpu/mtrr/cyrix.c
index 72182809b333..ca670919b561 100644
--- a/arch/x86/kernel/cpu/mtrr/cyrix.c
+++ b/arch/x86/kernel/cpu/mtrr/cyrix.c
@@ -98,7 +98,7 @@ cyrix_get_free_region(unsigned long base, unsigned long size, int replace_reg)
 	case 7:
 		if (size < 0x40)
 			break;
-		/* Else, fall through */
+		fallthrough;
 	case 6:
 	case 5:
 	case 4:
diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c
index 8cdf29ffd95f..b98ff620ba77 100644
--- a/arch/x86/kernel/hw_breakpoint.c
+++ b/arch/x86/kernel/hw_breakpoint.c
@@ -349,7 +349,7 @@ static int arch_build_bp_info(struct perf_event *bp,
 			hw->len = X86_BREAKPOINT_LEN_X;
 			return 0;
 		}
-		/* fall through */
+		fallthrough;
 	default:
 		return -EINVAL;
 	}
diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
index 181060247e3c..c5dd50369e2f 100644
--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -227,7 +227,7 @@ static __always_inline void handle_irq(struct irq_desc *desc,
 				       struct pt_regs *regs)
 {
 	if (IS_ENABLED(CONFIG_X86_64))
-		run_on_irqstack_cond(desc->handle_irq, desc, regs);
+		run_irq_on_irqstack_cond(desc->handle_irq, desc, regs);
 	else
 		__handle_irq(desc, regs);
 }
diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c
index 1b4fe93a86c5..440eed558558 100644
--- a/arch/x86/kernel/irq_64.c
+++ b/arch/x86/kernel/irq_64.c
@@ -74,5 +74,5 @@ int irq_init_percpu_irqstack(unsigned int cpu)
 
 void do_softirq_own_stack(void)
 {
-	run_on_irqstack_cond(__do_softirq, NULL, NULL);
+	run_on_irqstack_cond(__do_softirq, NULL);
 }
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 68acd30c6b87..c2f02f308ecf 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -450,7 +450,7 @@ int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
 		ptr = &remcomInBuffer[1];
 		if (kgdb_hex2long(&ptr, &addr))
 			linux_regs->ip = addr;
-		/* fall through */
+		fallthrough;
 	case 'D':
 	case 'k':
 		/* clear the trace bit */
@@ -539,7 +539,7 @@ static int __kgdb_notify(struct die_args *args, unsigned long cmd)
 			 * a system call which should be ignored
 			 */
 			return NOTIFY_DONE;
-		/* fall through */
+		fallthrough;
 	default:
 		if (user_mode(regs))
 			return NOTIFY_DONE;
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 08320b0b2b27..9663ba31347c 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -270,9 +270,8 @@ DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_asyncpf_interrupt)
 {
 	struct pt_regs *old_regs = set_irq_regs(regs);
 	u32 token;
-	irqentry_state_t state;
 
-	state = irqentry_enter(regs);
+	ack_APIC_irq();
 
 	inc_irq_stat(irq_hv_callback_count);
 
@@ -283,7 +282,6 @@ DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_asyncpf_interrupt)
 		wrmsrl(MSR_KVM_ASYNC_PF_ACK, 1);
 	}
 
-	irqentry_exit(regs, state);
 	set_irq_regs(old_regs);
 }
 
diff --git a/arch/x86/kernel/mpparse.c b/arch/x86/kernel/mpparse.c
index 411af4aa7b51..baa21090c9be 100644
--- a/arch/x86/kernel/mpparse.c
+++ b/arch/x86/kernel/mpparse.c
@@ -312,7 +312,7 @@ static void __init construct_default_ioirq_mptable(int mpc_default_type)
 		case 2:
 			if (i == 0 || i == 13)
 				continue;	/* IRQ0 & IRQ13 not connected */
-			/* fall through */
+			fallthrough;
 		default:
 			if (i == 2)
 				continue;	/* IRQ2 is never connected */
@@ -356,7 +356,7 @@ static void __init construct_ioapic_table(int mpc_default_type)
 	default:
 		pr_err("???\nUnknown standard configuration %d\n",
 		       mpc_default_type);
-		/* fall through */
+		fallthrough;
 	case 1:
 	case 5:
 		memcpy(bus.bustype, "ISA   ", 6);
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 13ce616cc7af..ba4593a913fa 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -42,6 +42,7 @@
 #include <asm/spec-ctrl.h>
 #include <asm/io_bitmap.h>
 #include <asm/proto.h>
+#include <asm/frame.h>
 
 #include "process.h"
 
@@ -133,7 +134,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp, unsigned long arg,
 	fork_frame = container_of(childregs, struct fork_frame, regs);
 	frame = &fork_frame->frame;
 
-	frame->bp = 0;
+	frame->bp = encode_frame_pointer(childregs);
 	frame->ret_addr = (unsigned long) ret_from_fork;
 	p->thread.sp = (unsigned long) fork_frame;
 	p->thread.io_bitmap = NULL;
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 5679aa3fdcb8..e7537c5440bb 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -204,7 +204,7 @@ static int set_segment_reg(struct task_struct *task,
 	case offsetof(struct user_regs_struct, ss):
 		if (unlikely(value == 0))
 			return -EIO;
-		/* Else, fall through */
+		fallthrough;
 
 	default:
 		*pt_regs_access(task_pt_regs(task), offset) = value;
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 0ec7ced727fe..a515e2d230b7 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -654,7 +654,7 @@ static void native_machine_emergency_restart(void)
 
 		case BOOT_CF9_FORCE:
 			port_cf9_safe = true;
-			/* Fall through */
+			fallthrough;
 
 		case BOOT_CF9_SAFE:
 			if (port_cf9_safe) {
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index d5fa494c2304..be0d7d4152ec 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -726,7 +726,7 @@ handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 				regs->ax = -EINTR;
 				break;
 			}
-		/* fallthrough */
+			fallthrough;
 		case -ERESTARTNOINTR:
 			regs->ax = regs->orig_ax;
 			regs->ip -= 2;
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 27aa04a95702..f5ef689dd62a 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1594,14 +1594,28 @@ int native_cpu_disable(void)
 	if (ret)
 		return ret;
 
-	/*
-	 * Disable the local APIC. Otherwise IPI broadcasts will reach
-	 * it. It still responds normally to INIT, NMI, SMI, and SIPI
-	 * messages.
-	 */
-	apic_soft_disable();
 	cpu_disable_common();
 
+        /*
+         * Disable the local APIC. Otherwise IPI broadcasts will reach
+         * it. It still responds normally to INIT, NMI, SMI, and SIPI
+         * messages.
+         *
+         * Disabling the APIC must happen after cpu_disable_common()
+         * which invokes fixup_irqs().
+         *
+         * Disabling the APIC preserves already set bits in IRR, but
+         * an interrupt arriving after disabling the local APIC does not
+         * set the corresponding IRR bit.
+         *
+         * fixup_irqs() scans IRR for set bits so it can raise a not
+         * yet handled interrupt on the new destination CPU via an IPI
+         * but obviously it can't do so for IRR bits which are not set.
+         * IOW, interrupts arriving after disabling the local APIC will
+         * be lost.
+         */
+	apic_soft_disable();
+
 	return 0;
 }
 
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 1f66d2d1e998..81a2fb711091 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -729,20 +729,9 @@ static bool is_sysenter_singlestep(struct pt_regs *regs)
 #endif
 }
 
-static __always_inline void debug_enter(unsigned long *dr6, unsigned long *dr7)
+static __always_inline unsigned long debug_read_clear_dr6(void)
 {
-	/*
-	 * Disable breakpoints during exception handling; recursive exceptions
-	 * are exceedingly 'fun'.
-	 *
-	 * Since this function is NOKPROBE, and that also applies to
-	 * HW_BREAKPOINT_X, we can't hit a breakpoint before this (XXX except a
-	 * HW_BREAKPOINT_W on our stack)
-	 *
-	 * Entry text is excluded for HW_BP_X and cpu_entry_area, which
-	 * includes the entry stack is excluded for everything.
-	 */
-	*dr7 = local_db_save();
+	unsigned long dr6;
 
 	/*
 	 * The Intel SDM says:
@@ -755,15 +744,12 @@ static __always_inline void debug_enter(unsigned long *dr6, unsigned long *dr7)
 	 *
 	 * Keep it simple: clear DR6 immediately.
 	 */
-	get_debugreg(*dr6, 6);
+	get_debugreg(dr6, 6);
 	set_debugreg(0, 6);
 	/* Filter out all the reserved bits which are preset to 1 */
-	*dr6 &= ~DR6_RESERVED;
-}
+	dr6 &= ~DR6_RESERVED;
 
-static __always_inline void debug_exit(unsigned long dr7)
-{
-	local_db_restore(dr7);
+	return dr6;
 }
 
 /*
@@ -863,6 +849,18 @@ out:
 static __always_inline void exc_debug_kernel(struct pt_regs *regs,
 					     unsigned long dr6)
 {
+	/*
+	 * Disable breakpoints during exception handling; recursive exceptions
+	 * are exceedingly 'fun'.
+	 *
+	 * Since this function is NOKPROBE, and that also applies to
+	 * HW_BREAKPOINT_X, we can't hit a breakpoint before this (XXX except a
+	 * HW_BREAKPOINT_W on our stack)
+	 *
+	 * Entry text is excluded for HW_BP_X and cpu_entry_area, which
+	 * includes the entry stack is excluded for everything.
+	 */
+	unsigned long dr7 = local_db_save();
 	bool irq_state = idtentry_enter_nmi(regs);
 	instrumentation_begin();
 
@@ -883,6 +881,8 @@ static __always_inline void exc_debug_kernel(struct pt_regs *regs,
 
 	instrumentation_end();
 	idtentry_exit_nmi(regs, irq_state);
+
+	local_db_restore(dr7);
 }
 
 static __always_inline void exc_debug_user(struct pt_regs *regs,
@@ -894,6 +894,15 @@ static __always_inline void exc_debug_user(struct pt_regs *regs,
 	 */
 	WARN_ON_ONCE(!user_mode(regs));
 
+	/*
+	 * NB: We can't easily clear DR7 here because
+	 * idtentry_exit_to_usermode() can invoke ptrace, schedule, access
+	 * user memory, etc.  This means that a recursive #DB is possible.  If
+	 * this happens, that #DB will hit exc_debug_kernel() and clear DR7.
+	 * Since we're not on the IST stack right now, everything will be
+	 * fine.
+	 */
+
 	irqentry_enter_from_user_mode(regs);
 	instrumentation_begin();
 
@@ -907,36 +916,24 @@ static __always_inline void exc_debug_user(struct pt_regs *regs,
 /* IST stack entry */
 DEFINE_IDTENTRY_DEBUG(exc_debug)
 {
-	unsigned long dr6, dr7;
-
-	debug_enter(&dr6, &dr7);
-	exc_debug_kernel(regs, dr6);
-	debug_exit(dr7);
+	exc_debug_kernel(regs, debug_read_clear_dr6());
 }
 
 /* User entry, runs on regular task stack */
 DEFINE_IDTENTRY_DEBUG_USER(exc_debug)
 {
-	unsigned long dr6, dr7;
-
-	debug_enter(&dr6, &dr7);
-	exc_debug_user(regs, dr6);
-	debug_exit(dr7);
+	exc_debug_user(regs, debug_read_clear_dr6());
 }
 #else
 /* 32 bit does not have separate entry points. */
 DEFINE_IDTENTRY_RAW(exc_debug)
 {
-	unsigned long dr6, dr7;
-
-	debug_enter(&dr6, &dr7);
+	unsigned long dr6 = debug_read_clear_dr6();
 
 	if (user_mode(regs))
 		exc_debug_user(regs, dr6);
 	else
 		exc_debug_kernel(regs, dr6);
-
-	debug_exit(dr7);
 }
 #endif
 
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index 15e5aad8ac2c..3fdaa042823d 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -735,7 +735,7 @@ static int branch_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn)
 		 * OPCODE1() of the "short" jmp which checks the same condition.
 		 */
 		opc1 = OPCODE2(insn) - 0x10;
-		/* fall through */
+		fallthrough;
 	default:
 		if (!is_cond_jmp_opcode(opc1))
 			return -ENOSYS;
@@ -892,7 +892,7 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
 			fix_ip_or_call = 0;
 			break;
 		}
-		/* fall through */
+		fallthrough;
 	default:
 		riprel_analyze(auprobe, &insn);
 	}