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

Pull low-level x86 updates from Ingo Molnar:
 "In this cycle this topic tree has become one of those 'super topics'
  that accumulated a lot of changes:

   - Add CONFIG_VMAP_STACK=y support to the core kernel and enable it on
     x86 - preceded by an array of changes. v4.8 saw preparatory changes
     in this area already - this is the rest of the work. Includes the
     thread stack caching performance optimization. (Andy Lutomirski)

   - switch_to() cleanups and all around enhancements. (Brian Gerst)

   - A large number of dumpstack infrastructure enhancements and an
     unwinder abstraction. The secret long term plan is safe(r) live
     patching plus maybe another attempt at debuginfo based unwinding -
     but all these current bits are standalone enhancements in a frame
     pointer based debug environment as well. (Josh Poimboeuf)

   - More __ro_after_init and const annotations. (Kees Cook)

   - Enable KASLR for the vmemmap memory region. (Thomas Garnier)"

[ The virtually mapped stack changes are pretty fundamental, and not
  x86-specific per se, even if they are only used on x86 right now. ]

* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (70 commits)
  x86/asm: Get rid of __read_cr4_safe()
  thread_info: Use unsigned long for flags
  x86/alternatives: Add stack frame dependency to alternative_call_2()
  x86/dumpstack: Fix show_stack() task pointer regression
  x86/dumpstack: Remove dump_trace() and related callbacks
  x86/dumpstack: Convert show_trace_log_lvl() to use the new unwinder
  oprofile/x86: Convert x86_backtrace() to use the new unwinder
  x86/stacktrace: Convert save_stack_trace_*() to use the new unwinder
  perf/x86: Convert perf_callchain_kernel() to use the new unwinder
  x86/unwind: Add new unwind interface and implementations
  x86/dumpstack: Remove NULL task pointer convention
  fork: Optimize task creation by caching two thread stacks per CPU if CONFIG_VMAP_STACK=y
  sched/core: Free the stack early if CONFIG_THREAD_INFO_IN_TASK
  lib/syscall: Pin the task stack in collect_syscall()
  x86/process: Pin the target stack in get_wchan()
  x86/dumpstack: Pin the target stack when dumping it
  kthread: Pin the stack via try_get_task_stack()/put_task_stack() in to_live_kthread() function
  sched/core: Add try_get_task_stack() and put_task_stack()
  x86/entry/64: Fix a minor comment rebase error
  iommu/amd: Don't put completion-wait semaphore on stack
  ...

42 files changed, 664 insertions, 589 deletions

diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 0503f5bfb18d..45257cf84370 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -125,6 +125,12 @@ obj-$(CONFIG_EFI)			+= sysfb_efi.o
 obj-$(CONFIG_PERF_EVENTS)		+= perf_regs.o
 obj-$(CONFIG_TRACING)			+= tracepoint.o
 
+ifdef CONFIG_FRAME_POINTER
+obj-y					+= unwind_frame.o
+else
+obj-y					+= unwind_guess.o
+endif
+
 ###
 # 64 bit specific files
 ifeq ($(CONFIG_X86_64),y)
diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
index adb3eaf8fe2a..48587335ede8 100644
--- a/arch/x86/kernel/acpi/sleep.c
+++ b/arch/x86/kernel/acpi/sleep.c
@@ -99,7 +99,7 @@ int x86_acpi_suspend_lowlevel(void)
 	saved_magic = 0x12345678;
 #else /* CONFIG_64BIT */
 #ifdef CONFIG_SMP
-	stack_start = (unsigned long)temp_stack + sizeof(temp_stack);
+	initial_stack = (unsigned long)temp_stack + sizeof(temp_stack);
 	early_gdt_descr.address =
 			(unsigned long)get_cpu_gdt_table(smp_processor_id());
 	initial_gs = per_cpu_offset(smp_processor_id());
diff --git a/arch/x86/kernel/apic/apic_flat_64.c b/arch/x86/kernel/apic/apic_flat_64.c
index 5b2ae106bd4a..8862da76ef6f 100644
--- a/arch/x86/kernel/apic/apic_flat_64.c
+++ b/arch/x86/kernel/apic/apic_flat_64.c
@@ -25,7 +25,7 @@
 static struct apic apic_physflat;
 static struct apic apic_flat;
 
-struct apic __read_mostly *apic = &apic_flat;
+struct apic *apic __ro_after_init = &apic_flat;
 EXPORT_SYMBOL_GPL(apic);
 
 static int flat_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
@@ -154,7 +154,7 @@ static int flat_probe(void)
 	return 1;
 }
 
-static struct apic apic_flat =  {
+static struct apic apic_flat __ro_after_init = {
 	.name				= "flat",
 	.probe				= flat_probe,
 	.acpi_madt_oem_check		= flat_acpi_madt_oem_check,
@@ -248,7 +248,7 @@ static int physflat_probe(void)
 	return 0;
 }
 
-static struct apic apic_physflat =  {
+static struct apic apic_physflat __ro_after_init = {
 
 	.name				= "physical flat",
 	.probe				= physflat_probe,
diff --git a/arch/x86/kernel/apic/apic_noop.c b/arch/x86/kernel/apic/apic_noop.c
index c05688b2deff..b109e4389c92 100644
--- a/arch/x86/kernel/apic/apic_noop.c
+++ b/arch/x86/kernel/apic/apic_noop.c
@@ -108,7 +108,7 @@ static void noop_apic_write(u32 reg, u32 v)
 	WARN_ON_ONCE(boot_cpu_has(X86_FEATURE_APIC) && !disable_apic);
 }
 
-struct apic apic_noop = {
+struct apic apic_noop __ro_after_init = {
 	.name				= "noop",
 	.probe				= noop_probe,
 	.acpi_madt_oem_check		= NULL,
diff --git a/arch/x86/kernel/apic/bigsmp_32.c b/arch/x86/kernel/apic/bigsmp_32.c
index 06dbaa458bfe..56012010332c 100644
--- a/arch/x86/kernel/apic/bigsmp_32.c
+++ b/arch/x86/kernel/apic/bigsmp_32.c
@@ -142,7 +142,7 @@ static int probe_bigsmp(void)
 	return dmi_bigsmp;
 }
 
-static struct apic apic_bigsmp = {
+static struct apic apic_bigsmp __ro_after_init = {
 
 	.name				= "bigsmp",
 	.probe				= probe_bigsmp,
diff --git a/arch/x86/kernel/apic/msi.c b/arch/x86/kernel/apic/msi.c
index ade25320df96..015bbf30e3e3 100644
--- a/arch/x86/kernel/apic/msi.c
+++ b/arch/x86/kernel/apic/msi.c
@@ -269,7 +269,7 @@ static void hpet_msi_write_msg(struct irq_data *data, struct msi_msg *msg)
 	hpet_msi_write(irq_data_get_irq_handler_data(data), msg);
 }
 
-static struct irq_chip hpet_msi_controller = {
+static struct irq_chip hpet_msi_controller __ro_after_init = {
 	.name = "HPET-MSI",
 	.irq_unmask = hpet_msi_unmask,
 	.irq_mask = hpet_msi_mask,
diff --git a/arch/x86/kernel/apic/probe_32.c b/arch/x86/kernel/apic/probe_32.c
index 563096267ca2..c48264e202fd 100644
--- a/arch/x86/kernel/apic/probe_32.c
+++ b/arch/x86/kernel/apic/probe_32.c
@@ -72,7 +72,7 @@ static int probe_default(void)
 	return 1;
 }
 
-static struct apic apic_default = {
+static struct apic apic_default __ro_after_init = {
 
 	.name				= "default",
 	.probe				= probe_default,
@@ -126,7 +126,7 @@ static struct apic apic_default = {
 
 apic_driver(apic_default);
 
-struct apic *apic = &apic_default;
+struct apic *apic __ro_after_init = &apic_default;
 EXPORT_SYMBOL_GPL(apic);
 
 static int cmdline_apic __initdata;
diff --git a/arch/x86/kernel/apic/x2apic_cluster.c b/arch/x86/kernel/apic/x2apic_cluster.c
index 54f35d988025..200af5ae9662 100644
--- a/arch/x86/kernel/apic/x2apic_cluster.c
+++ b/arch/x86/kernel/apic/x2apic_cluster.c
@@ -227,7 +227,7 @@ static void cluster_vector_allocation_domain(int cpu, struct cpumask *retmask,
 		cpumask_and(retmask, mask, per_cpu(cpus_in_cluster, cpu));
 }
 
-static struct apic apic_x2apic_cluster = {
+static struct apic apic_x2apic_cluster __ro_after_init = {
 
 	.name				= "cluster x2apic",
 	.probe				= x2apic_cluster_probe,
diff --git a/arch/x86/kernel/apic/x2apic_phys.c b/arch/x86/kernel/apic/x2apic_phys.c
index 4f13f54f1b1f..ff111f05a314 100644
--- a/arch/x86/kernel/apic/x2apic_phys.c
+++ b/arch/x86/kernel/apic/x2apic_phys.c
@@ -98,7 +98,7 @@ static int x2apic_phys_probe(void)
 	return apic == &apic_x2apic_phys;
 }
 
-static struct apic apic_x2apic_phys = {
+static struct apic apic_x2apic_phys __ro_after_init = {
 
 	.name				= "physical x2apic",
 	.probe				= x2apic_phys_probe,
diff --git a/arch/x86/kernel/apic/x2apic_uv_x.c b/arch/x86/kernel/apic/x2apic_uv_x.c
index cb0673c1e940..b9f6157d4271 100644
--- a/arch/x86/kernel/apic/x2apic_uv_x.c
+++ b/arch/x86/kernel/apic/x2apic_uv_x.c
@@ -560,7 +560,7 @@ static int uv_probe(void)
 	return apic == &apic_x2apic_uv_x;
 }
 
-static struct apic __refdata apic_x2apic_uv_x = {
+static struct apic apic_x2apic_uv_x __ro_after_init = {
 
 	.name				= "UV large system",
 	.probe				= uv_probe,
diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c
index 2bd5c6ff7ee7..c62e015b126c 100644
--- a/arch/x86/kernel/asm-offsets.c
+++ b/arch/x86/kernel/asm-offsets.c
@@ -29,10 +29,13 @@
 
 void common(void) {
 	BLANK();
-	OFFSET(TI_flags, thread_info, flags);
-	OFFSET(TI_status, thread_info, status);
+	OFFSET(TASK_threadsp, task_struct, thread.sp);
+#ifdef CONFIG_CC_STACKPROTECTOR
+	OFFSET(TASK_stack_canary, task_struct, stack_canary);
+#endif
 
 	BLANK();
+	OFFSET(TASK_TI_flags, task_struct, thread_info.flags);
 	OFFSET(TASK_addr_limit, task_struct, thread.addr_limit);
 
 	BLANK();
diff --git a/arch/x86/kernel/asm-offsets_32.c b/arch/x86/kernel/asm-offsets_32.c
index ecdc1d217dc0..880aa093268d 100644
--- a/arch/x86/kernel/asm-offsets_32.c
+++ b/arch/x86/kernel/asm-offsets_32.c
@@ -57,6 +57,11 @@ void foo(void)
 	/* Size of SYSENTER_stack */
 	DEFINE(SIZEOF_SYSENTER_stack, sizeof(((struct tss_struct *)0)->SYSENTER_stack));
 
+#ifdef CONFIG_CC_STACKPROTECTOR
+	BLANK();
+	OFFSET(stack_canary_offset, stack_canary, canary);
+#endif
+
 #if defined(CONFIG_LGUEST) || defined(CONFIG_LGUEST_GUEST) || defined(CONFIG_LGUEST_MODULE)
 	BLANK();
 	OFFSET(LGUEST_DATA_irq_enabled, lguest_data, irq_enabled);
diff --git a/arch/x86/kernel/asm-offsets_64.c b/arch/x86/kernel/asm-offsets_64.c
index d875f97d4e0b..210927ee2e74 100644
--- a/arch/x86/kernel/asm-offsets_64.c
+++ b/arch/x86/kernel/asm-offsets_64.c
@@ -56,6 +56,11 @@ int main(void)
 	OFFSET(TSS_sp0, tss_struct, x86_tss.sp0);
 	BLANK();
 
+#ifdef CONFIG_CC_STACKPROTECTOR
+	DEFINE(stack_canary_offset, offsetof(union irq_stack_union, stack_canary));
+	BLANK();
+#endif
+
 	DEFINE(__NR_syscall_max, sizeof(syscalls_64) - 1);
 	DEFINE(NR_syscalls, sizeof(syscalls_64));
 
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index bcc9ccc220c9..9bd910a7dd0a 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1264,9 +1264,14 @@ static __init int setup_disablecpuid(char *arg)
 __setup("clearcpuid=", setup_disablecpuid);
 
 #ifdef CONFIG_X86_64
-struct desc_ptr idt_descr = { NR_VECTORS * 16 - 1, (unsigned long) idt_table };
-struct desc_ptr debug_idt_descr = { NR_VECTORS * 16 - 1,
-				    (unsigned long) debug_idt_table };
+struct desc_ptr idt_descr __ro_after_init = {
+	.size = NR_VECTORS * 16 - 1,
+	.address = (unsigned long) idt_table,
+};
+const struct desc_ptr debug_idt_descr = {
+	.size = NR_VECTORS * 16 - 1,
+	.address = (unsigned long) debug_idt_table,
+};
 
 DEFINE_PER_CPU_FIRST(union irq_stack_union,
 		     irq_stack_union) __aligned(PAGE_SIZE) __visible;
@@ -1280,7 +1285,7 @@ DEFINE_PER_CPU(struct task_struct *, current_task) ____cacheline_aligned =
 EXPORT_PER_CPU_SYMBOL(current_task);
 
 DEFINE_PER_CPU(char *, irq_stack_ptr) =
-	init_per_cpu_var(irq_stack_union.irq_stack) + IRQ_STACK_SIZE - 64;
+	init_per_cpu_var(irq_stack_union.irq_stack) + IRQ_STACK_SIZE;
 
 DEFINE_PER_CPU(unsigned int, irq_count) __visible = -1;
 
@@ -1304,11 +1309,6 @@ static DEFINE_PER_CPU_PAGE_ALIGNED(char, exception_stacks
 /* May not be marked __init: used by software suspend */
 void syscall_init(void)
 {
-	/*
-	 * LSTAR and STAR live in a bit strange symbiosis.
-	 * They both write to the same internal register. STAR allows to
-	 * set CS/DS but only a 32bit target. LSTAR sets the 64bit rip.
-	 */
 	wrmsr(MSR_STAR, 0, (__USER32_CS << 16) | __KERNEL_CS);
 	wrmsrl(MSR_LSTAR, (unsigned long)entry_SYSCALL_64);
 
diff --git a/arch/x86/kernel/cpu/mtrr/main.c b/arch/x86/kernel/cpu/mtrr/main.c
index 28f1b54b7fad..24e87e74990d 100644
--- a/arch/x86/kernel/cpu/mtrr/main.c
+++ b/arch/x86/kernel/cpu/mtrr/main.c
@@ -72,14 +72,14 @@ static DEFINE_MUTEX(mtrr_mutex);
 u64 size_or_mask, size_and_mask;
 static bool mtrr_aps_delayed_init;
 
-static const struct mtrr_ops *mtrr_ops[X86_VENDOR_NUM];
+static const struct mtrr_ops *mtrr_ops[X86_VENDOR_NUM] __ro_after_init;
 
 const struct mtrr_ops *mtrr_if;
 
 static void set_mtrr(unsigned int reg, unsigned long base,
 		     unsigned long size, mtrr_type type);
 
-void set_mtrr_ops(const struct mtrr_ops *ops)
+void __init set_mtrr_ops(const struct mtrr_ops *ops)
 {
 	if (ops->vendor && ops->vendor < X86_VENDOR_NUM)
 		mtrr_ops[ops->vendor] = ops;
diff --git a/arch/x86/kernel/cpu/mtrr/mtrr.h b/arch/x86/kernel/cpu/mtrr/mtrr.h
index 6c7ced07d16d..ad8bd763efa5 100644
--- a/arch/x86/kernel/cpu/mtrr/mtrr.h
+++ b/arch/x86/kernel/cpu/mtrr/mtrr.h
@@ -54,7 +54,7 @@ void fill_mtrr_var_range(unsigned int index,
 bool get_mtrr_state(void);
 void mtrr_bp_pat_init(void);
 
-extern void set_mtrr_ops(const struct mtrr_ops *ops);
+extern void __init set_mtrr_ops(const struct mtrr_ops *ops);
 
 extern u64 size_or_mask, size_and_mask;
 extern const struct mtrr_ops *mtrr_if;
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 92e8f0a7159c..9b7cf5c28f5f 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -17,7 +17,7 @@
 #include <linux/sysfs.h>
 
 #include <asm/stacktrace.h>
-
+#include <asm/unwind.h>
 
 int panic_on_unrecovered_nmi;
 int panic_on_io_nmi;
@@ -25,11 +25,29 @@ unsigned int code_bytes = 64;
 int kstack_depth_to_print = 3 * STACKSLOTS_PER_LINE;
 static int die_counter;
 
+bool in_task_stack(unsigned long *stack, struct task_struct *task,
+		   struct stack_info *info)
+{
+	unsigned long *begin = task_stack_page(task);
+	unsigned long *end   = task_stack_page(task) + THREAD_SIZE;
+
+	if (stack < begin || stack >= end)
+		return false;
+
+	info->type	= STACK_TYPE_TASK;
+	info->begin	= begin;
+	info->end	= end;
+	info->next_sp	= NULL;
+
+	return true;
+}
+
 static void printk_stack_address(unsigned long address, int reliable,
-		void *data)
+				 char *log_lvl)
 {
+	touch_nmi_watchdog();
 	printk("%s [<%p>] %s%pB\n",
-		(char *)data, (void *)address, reliable ? "" : "? ",
+		log_lvl, (void *)address, reliable ? "" : "? ",
 		(void *)address);
 }
 
@@ -38,176 +56,120 @@ void printk_address(unsigned long address)
 	pr_cont(" [<%p>] %pS\n", (void *)address, (void *)address);
 }
 
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-static void
-print_ftrace_graph_addr(unsigned long addr, void *data,
-			const struct stacktrace_ops *ops,
-			struct task_struct *task, int *graph)
+void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
+			unsigned long *stack, char *log_lvl)
 {
-	unsigned long ret_addr;
-	int index;
-
-	if (addr != (unsigned long)return_to_handler)
-		return;
-
-	index = task->curr_ret_stack;
-
-	if (!task->ret_stack || index < *graph)
-		return;
-
-	index -= *graph;
-	ret_addr = task->ret_stack[index].ret;
-
-	ops->address(data, ret_addr, 1);
+	struct unwind_state state;
+	struct stack_info stack_info = {0};
+	unsigned long visit_mask = 0;
+	int graph_idx = 0;
 
-	(*graph)++;
-}
-#else
-static inline void
-print_ftrace_graph_addr(unsigned long addr, void *data,
-			const struct stacktrace_ops *ops,
-			struct task_struct *task, int *graph)
-{ }
-#endif
-
-/*
- * x86-64 can have up to three kernel stacks:
- * process stack
- * interrupt stack
- * severe exception (double fault, nmi, stack fault, debug, mce) hardware stack
- */
-
-static inline int valid_stack_ptr(struct task_struct *task,
-			void *p, unsigned int size, void *end)
-{
-	void *t = task_stack_page(task);
-	if (end) {
-		if (p < end && p >= (end-THREAD_SIZE))
-			return 1;
-		else
-			return 0;
-	}
-	return p >= t && p < t + THREAD_SIZE - size;
-}
+	printk("%sCall Trace:\n", log_lvl);
 
-unsigned long
-print_context_stack(struct task_struct *task,
-		unsigned long *stack, unsigned long bp,
-		const struct stacktrace_ops *ops, void *data,
-		unsigned long *end, int *graph)
-{
-	struct stack_frame *frame = (struct stack_frame *)bp;
+	unwind_start(&state, task, regs, stack);
 
 	/*
-	 * If we overflowed the stack into a guard page, jump back to the
-	 * bottom of the usable stack.
+	 * Iterate through the stacks, starting with the current stack pointer.
+	 * Each stack has a pointer to the next one.
+	 *
+	 * x86-64 can have several stacks:
+	 * - task stack
+	 * - interrupt stack
+	 * - HW exception stacks (double fault, nmi, debug, mce)
+	 *
+	 * x86-32 can have up to three stacks:
+	 * - task stack
+	 * - softirq stack
+	 * - hardirq stack
 	 */
-	if ((unsigned long)task_stack_page(task) - (unsigned long)stack <
-	    PAGE_SIZE)
-		stack = (unsigned long *)task_stack_page(task);
-
-	while (valid_stack_ptr(task, stack, sizeof(*stack), end)) {
-		unsigned long addr;
-
-		addr = *stack;
-		if (__kernel_text_address(addr)) {
-			if ((unsigned long) stack == bp + sizeof(long)) {
-				ops->address(data, addr, 1);
-				frame = frame->next_frame;
-				bp = (unsigned long) frame;
-			} else {
-				ops->address(data, addr, 0);
-			}
-			print_ftrace_graph_addr(addr, data, ops, task, graph);
-		}
-		stack++;
-	}
-	return bp;
-}
-EXPORT_SYMBOL_GPL(print_context_stack);
-
-unsigned long
-print_context_stack_bp(struct task_struct *task,
-		       unsigned long *stack, unsigned long bp,
-		       const struct stacktrace_ops *ops, void *data,
-		       unsigned long *end, int *graph)
-{
-	struct stack_frame *frame = (struct stack_frame *)bp;
-	unsigned long *ret_addr = &frame->return_address;
+	for (; stack; stack = stack_info.next_sp) {
+		const char *str_begin, *str_end;
 
-	while (valid_stack_ptr(task, ret_addr, sizeof(*ret_addr), end)) {
-		unsigned long addr = *ret_addr;
+		/*
+		 * If we overflowed the task stack into a guard page, jump back
+		 * to the bottom of the usable stack.
+		 */
+		if (task_stack_page(task) - (void *)stack < PAGE_SIZE)
+			stack = task_stack_page(task);
 
-		if (!__kernel_text_address(addr))
+		if (get_stack_info(stack, task, &stack_info, &visit_mask))
 			break;
 
-		if (ops->address(data, addr, 1))
-			break;
-		frame = frame->next_frame;
-		ret_addr = &frame->return_address;
-		print_ftrace_graph_addr(addr, data, ops, task, graph);
-	}
-
-	return (unsigned long)frame;
-}
-EXPORT_SYMBOL_GPL(print_context_stack_bp);
-
-static int print_trace_stack(void *data, char *name)
-{
-	printk("%s <%s> ", (char *)data, name);
-	return 0;
-}
-
-/*
- * Print one address/symbol entries per line.
- */
-static int print_trace_address(void *data, unsigned long addr, int reliable)
-{
-	touch_nmi_watchdog();
-	printk_stack_address(addr, reliable, data);
-	return 0;
-}
-
-static const struct stacktrace_ops print_trace_ops = {
-	.stack			= print_trace_stack,
-	.address		= print_trace_address,
-	.walk_stack		= print_context_stack,
-};
-
-void
-show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
-		unsigned long *stack, unsigned long bp, char *log_lvl)
-{
-	printk("%sCall Trace:\n", log_lvl);
-	dump_trace(task, regs, stack, bp, &print_trace_ops, log_lvl);
-}
+		stack_type_str(stack_info.type, &str_begin, &str_end);
+		if (str_begin)
+			printk("%s <%s> ", log_lvl, str_begin);
+
+		/*
+		 * Scan the stack, printing any text addresses we find.  At the
+		 * same time, follow proper stack frames with the unwinder.
+		 *
+		 * Addresses found during the scan which are not reported by
+		 * the unwinder are considered to be additional clues which are
+		 * sometimes useful for debugging and are prefixed with '?'.
+		 * This also serves as a failsafe option in case the unwinder
+		 * goes off in the weeds.
+		 */
+		for (; stack < stack_info.end; stack++) {
+			unsigned long real_addr;
+			int reliable = 0;
+			unsigned long addr = *stack;
+			unsigned long *ret_addr_p =
+				unwind_get_return_address_ptr(&state);
+
+			if (!__kernel_text_address(addr))
+				continue;
+
+			if (stack == ret_addr_p)
+				reliable = 1;
+
+			/*
+			 * When function graph tracing is enabled for a
+			 * function, its return address on the stack is
+			 * replaced with the address of an ftrace handler
+			 * (return_to_handler).  In that case, before printing
+			 * the "real" address, we want to print the handler
+			 * address as an "unreliable" hint that function graph
+			 * tracing was involved.
+			 */
+			real_addr = ftrace_graph_ret_addr(task, &graph_idx,
+							  addr, stack);
+			if (real_addr != addr)
+				printk_stack_address(addr, 0, log_lvl);
+			printk_stack_address(real_addr, reliable, log_lvl);
+
+			if (!reliable)
+				continue;
+
+			/*
+			 * Get the next frame from the unwinder.  No need to
+			 * check for an error: if anything goes wrong, the rest
+			 * of the addresses will just be printed as unreliable.
+			 */
+			unwind_next_frame(&state);
+		}
 
-void show_trace(struct task_struct *task, struct pt_regs *regs,
-		unsigned long *stack, unsigned long bp)
-{
-	show_trace_log_lvl(task, regs, stack, bp, "");
+		if (str_end)
+			printk("%s <%s> ", log_lvl, str_end);
+	}
 }
 
 void show_stack(struct task_struct *task, unsigned long *sp)
 {
-	unsigned long bp = 0;
-	unsigned long stack;
+	task = task ? : current;
 
 	/*
 	 * Stack frames below this one aren't interesting.  Don't show them
 	 * if we're printing for %current.
 	 */
-	if (!sp && (!task || task == current)) {
-		sp = &stack;
-		bp = stack_frame(current, NULL);
-	}
+	if (!sp && task == current)
+		sp = get_stack_pointer(current, NULL);
 
-	show_stack_log_lvl(task, NULL, sp, bp, "");
+	show_stack_log_lvl(task, NULL, sp, "");
 }
 
 void show_stack_regs(struct pt_regs *regs)
 {
-	show_stack_log_lvl(current, regs, (unsigned long *)regs->sp, regs->bp, "");
+	show_stack_log_lvl(current, regs, NULL, "");
 }
 
 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c
index 09675712eba8..06eb322b5f9f 100644
--- a/arch/x86/kernel/dumpstack_32.c
+++ b/arch/x86/kernel/dumpstack_32.c
@@ -16,93 +16,121 @@
 
 #include <asm/stacktrace.h>
 
-static void *is_irq_stack(void *p, void *irq)
+void stack_type_str(enum stack_type type, const char **begin, const char **end)
 {
-	if (p < irq || p >= (irq + THREAD_SIZE))
-		return NULL;
-	return irq + THREAD_SIZE;
+	switch (type) {
+	case STACK_TYPE_IRQ:
+	case STACK_TYPE_SOFTIRQ:
+		*begin = "IRQ";
+		*end   = "EOI";
+		break;
+	default:
+		*begin = NULL;
+		*end   = NULL;
+	}
 }
 
-
-static void *is_hardirq_stack(unsigned long *stack, int cpu)
+static bool in_hardirq_stack(unsigned long *stack, struct stack_info *info)
 {
-	void *irq = per_cpu(hardirq_stack, cpu);
+	unsigned long *begin = (unsigned long *)this_cpu_read(hardirq_stack);
+	unsigned long *end   = begin + (THREAD_SIZE / sizeof(long));
 
-	return is_irq_stack(stack, irq);
-}
+	/*
+	 * This is a software stack, so 'end' can be a valid stack pointer.
+	 * It just means the stack is empty.
+	 */
+	if (stack < begin || stack > end)
+		return false;
 
-static void *is_softirq_stack(unsigned long *stack, int cpu)
-{
-	void *irq = per_cpu(softirq_stack, cpu);
+	info->type	= STACK_TYPE_IRQ;
+	info->begin	= begin;
+	info->end	= end;
 
-	return is_irq_stack(stack, irq);
+	/*
+	 * See irq_32.c -- the next stack pointer is stored at the beginning of
+	 * the stack.
+	 */
+	info->next_sp	= (unsigned long *)*begin;
+
+	return true;
 }
 
-void dump_trace(struct task_struct *task, struct pt_regs *regs,
-		unsigned long *stack, unsigned long bp,
-		const struct stacktrace_ops *ops, void *data)
+static bool in_softirq_stack(unsigned long *stack, struct stack_info *info)
 {
-	const unsigned cpu = get_cpu();
-	int graph = 0;
-	u32 *prev_esp;
+	unsigned long *begin = (unsigned long *)this_cpu_read(softirq_stack);
+	unsigned long *end   = begin + (THREAD_SIZE / sizeof(long));
 
-	if (!task)
-		task = current;
+	/*
+	 * This is a software stack, so 'end' can be a valid stack pointer.
+	 * It just means the stack is empty.
+	 */
+	if (stack < begin || stack > end)
+		return false;
 
-	if (!stack) {
-		unsigned long dummy;
+	info->type	= STACK_TYPE_SOFTIRQ;
+	info->begin	= begin;
+	info->end	= end;
 
-		stack = &dummy;
-		if (task != current)
-			stack = (unsigned long *)task->thread.sp;
-	}
+	/*
+	 * The next stack pointer is stored at the beginning of the stack.
+	 * See irq_32.c.
+	 */
+	info->next_sp	= (unsigned long *)*begin;
 
-	if (!bp)
-		bp = stack_frame(task, regs);
+	return true;
+}
 
-	for (;;) {
-		void *end_stack;
+int get_stack_info(unsigned long *stack, struct task_struct *task,
+		   struct stack_info *info, unsigned long *visit_mask)
+{
+	if (!stack)
+		goto unknown;
 
-		end_stack = is_hardirq_stack(stack, cpu);
-		if (!end_stack)
-			end_stack = is_softirq_stack(stack, cpu);
+	task = task ? : current;
 
-		bp = ops->walk_stack(task, stack, bp, ops, data,
-				     end_stack, &graph);
+	if (in_task_stack(stack, task, info))
+		goto recursion_check;
 
-		/* Stop if not on irq stack */
-		if (!end_stack)
-			break;
+	if (task != current)
+		goto unknown;
 
-		/* The previous esp is saved on the bottom of the stack */
-		prev_esp = (u32 *)(end_stack - THREAD_SIZE);
-		stack = (unsigned long *)*prev_esp;
-		if (!stack)
-			break;
+	if (in_hardirq_stack(stack, info))
+		goto recursion_check;
 
-		if (ops->stack(data, "IRQ") < 0)
-			break;
-		touch_nmi_watchdog();
+	if (in_softirq_stack(stack, info))
+		goto recursion_check;
+
+	goto unknown;
+
+recursion_check:
+	/*
+	 * Make sure we don't iterate through any given stack more than once.
+	 * If it comes up a second time then there's something wrong going on:
+	 * just break out and report an unknown stack type.
+	 */
+	if (visit_mask) {
+		if (*visit_mask & (1UL << info->type))
+			goto unknown;
+		*visit_mask |= 1UL << info->type;
 	}
-	put_cpu();
+
+	return 0;
+
+unknown:
+	info->type = STACK_TYPE_UNKNOWN;
+	return -EINVAL;
 }
-EXPORT_SYMBOL(dump_trace);
 
-void
-show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
-		   unsigned long *sp, unsigned long bp, char *log_lvl)
+void show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
+			unsigned long *sp, char *log_lvl)
 {
 	unsigned long *stack;
 	int i;
 
-	if (sp == NULL) {
-		if (regs)
-			sp = (unsigned long *)regs->sp;
-		else if (task)
-			sp = (unsigned long *)task->thread.sp;
-		else
-			sp = (unsigned long *)&sp;
-	}
+	if (!try_get_task_stack(task))
+		return;
+
+	sp = sp ? : get_stack_pointer(task, regs);
 
 	stack = sp;
 	for (i = 0; i < kstack_depth_to_print; i++) {
@@ -117,7 +145,9 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
 		touch_nmi_watchdog();
 	}
 	pr_cont("\n");
-	show_trace_log_lvl(task, regs, sp, bp, log_lvl);
+	show_trace_log_lvl(task, regs, sp, log_lvl);
+
+	put_task_stack(task);
 }
 
 
@@ -139,7 +169,7 @@ void show_regs(struct pt_regs *regs)
 		u8 *ip;
 
 		pr_emerg("Stack:\n");
-		show_stack_log_lvl(NULL, regs, &regs->sp, 0, KERN_EMERG);
+		show_stack_log_lvl(current, regs, NULL, KERN_EMERG);
 
 		pr_emerg("Code:");
 
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index 9ee4520ce83c..36cf1a498227 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -16,261 +16,145 @@
 
 #include <asm/stacktrace.h>
 
+static char *exception_stack_names[N_EXCEPTION_STACKS] = {
+		[ DOUBLEFAULT_STACK-1	]	= "#DF",
+		[ NMI_STACK-1		]	= "NMI",
+		[ DEBUG_STACK-1		]	= "#DB",
+		[ MCE_STACK-1		]	= "#MC",
+};
 
-#define N_EXCEPTION_STACKS_END \
-		(N_EXCEPTION_STACKS + DEBUG_STKSZ/EXCEPTION_STKSZ - 2)
-
-static char x86_stack_ids[][8] = {
-		[ DEBUG_STACK-1			]	= "#DB",
-		[ NMI_STACK-1			]	= "NMI",
-		[ DOUBLEFAULT_STACK-1		]	= "#DF",
-		[ MCE_STACK-1			]	= "#MC",
-#if DEBUG_STKSZ > EXCEPTION_STKSZ
-		[ N_EXCEPTION_STACKS ...
-		  N_EXCEPTION_STACKS_END	]	= "#DB[?]"
-#endif
+static unsigned long exception_stack_sizes[N_EXCEPTION_STACKS] = {
+	[0 ... N_EXCEPTION_STACKS - 1]		= EXCEPTION_STKSZ,
+	[DEBUG_STACK - 1]			= DEBUG_STKSZ
 };
 
-static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
-					 unsigned *usedp, char **idp)
+void stack_type_str(enum stack_type type, const char **begin, const char **end)
 {
-	unsigned k;
-
-	/*
-	 * Iterate over all exception stacks, and figure out whether
-	 * 'stack' is in one of them:
-	 */
-	for (k = 0; k < N_EXCEPTION_STACKS; k++) {
-		unsigned long end = per_cpu(orig_ist, cpu).ist[k];
-		/*
-		 * Is 'stack' above this exception frame's end?
-		 * If yes then skip to the next frame.
-		 */
-		if (stack >= end)
-			continue;
-		/*
-		 * Is 'stack' above this exception frame's start address?
-		 * If yes then we found the right frame.
-		 */
-		if (stack >= end - EXCEPTION_STKSZ) {
-			/*
-			 * Make sure we only iterate through an exception
-			 * stack once. If it comes up for the second time
-			 * then there's something wrong going on - just
-			 * break out and return NULL:
-			 */
-			if (*usedp & (1U << k))
-				break;
-			*usedp |= 1U << k;
-			*idp = x86_stack_ids[k];
-			return (unsigned long *)end;
-		}
-		/*
-		 * If this is a debug stack, and if it has a larger size than
-		 * the usual exception stacks, then 'stack' might still
-		 * be within the lower portion of the debug stack:
-		 */
-#if DEBUG_STKSZ > EXCEPTION_STKSZ
-		if (k == DEBUG_STACK - 1 && stack >= end - DEBUG_STKSZ) {
-			unsigned j = N_EXCEPTION_STACKS - 1;
-
-			/*
-			 * Black magic. A large debug stack is composed of
-			 * multiple exception stack entries, which we
-			 * iterate through now. Dont look:
-			 */
-			do {
-				++j;
-				end -= EXCEPTION_STKSZ;
-				x86_stack_ids[j][4] = '1' +
-						(j - N_EXCEPTION_STACKS);
-			} while (stack < end - EXCEPTION_STKSZ);
-			if (*usedp & (1U << j))
-				break;
-			*usedp |= 1U << j;
-			*idp = x86_stack_ids[j];
-			return (unsigned long *)end;
-		}
-#endif
+	BUILD_BUG_ON(N_EXCEPTION_STACKS != 4);
+
+	switch (type) {
+	case STACK_TYPE_IRQ:
+		*begin = "IRQ";
+		*end   = "EOI";
+		break;
+	case STACK_TYPE_EXCEPTION ... STACK_TYPE_EXCEPTION_LAST:
+		*begin = exception_stack_names[type - STACK_TYPE_EXCEPTION];
+		*end   = "EOE";
+		break;
+	default:
+		*begin = NULL;
+		*end   = NULL;
 	}
-	return NULL;
 }
 
-static inline int
-in_irq_stack(unsigned long *stack, unsigned long *irq_stack,
-	     unsigned long *irq_stack_end)
+static bool in_exception_stack(unsigned long *stack, struct stack_info *info)
 {
-	return (stack >= irq_stack && stack < irq_stack_end);
-}
-
-static const unsigned long irq_stack_size =
-	(IRQ_STACK_SIZE - 64) / sizeof(unsigned long);
-
-enum stack_type {
-	STACK_IS_UNKNOWN,
-	STACK_IS_NORMAL,
-	STACK_IS_EXCEPTION,
-	STACK_IS_IRQ,
-};
-
-static enum stack_type
-analyze_stack(int cpu, struct task_struct *task, unsigned long *stack,
-	      unsigned long **stack_end, unsigned long *irq_stack,
-	      unsigned *used, char **id)
-{
-	unsigned long addr;
+	unsigned long *begin, *end;
+	struct pt_regs *regs;
+	unsigned k;
 
-	addr = ((unsigned long)stack & (~(THREAD_SIZE - 1)));
-	if ((unsigned long)task_stack_page(task) == addr)
-		return STACK_IS_NORMAL;
+	BUILD_BUG_ON(N_EXCEPTION_STACKS != 4);
 
-	*stack_end = in_exception_stack(cpu, (unsigned long)stack,
-					used, id);
-	if (*stack_end)
-		return STACK_IS_EXCEPTION;
+	for (k = 0; k < N_EXCEPTION_STACKS; k++) {
+		end   = (unsigned long *)raw_cpu_ptr(&orig_ist)->ist[k];
+		begin = end - (exception_stack_sizes[k] / sizeof(long));
+		regs  = (struct pt_regs *)end - 1;
 
-	if (!irq_stack)
-		return STACK_IS_NORMAL;
+		if (stack < begin || stack >= end)
+			continue;
 
-	*stack_end = irq_stack;
-	irq_stack = irq_stack - irq_stack_size;
+		info->type	= STACK_TYPE_EXCEPTION + k;
+		info->begin	= begin;
+		info->end	= end;
+		info->next_sp	= (unsigned long *)regs->sp;
 
-	if (in_irq_stack(stack, irq_stack, *stack_end))
-		return STACK_IS_IRQ;
+		return true;
+	}
 
-	return STACK_IS_UNKNOWN;
+	return false;
 }
 
-/*
- * x86-64 can have up to three kernel stacks:
- * process stack
- * interrupt stack
- * severe exception (double fault, nmi, stack fault, debug, mce) hardware stack
- */
-
-void dump_trace(struct task_struct *task, struct pt_regs *regs,
-		unsigned long *stack, unsigned long bp,
-		const struct stacktrace_ops *ops, void *data)
+static bool in_irq_stack(unsigned long *stack, struct stack_info *info)
 {
-	const unsigned cpu = get_cpu();
-	unsigned long *irq_stack = (unsigned long *)per_cpu(irq_stack_ptr, cpu);
-	unsigned long dummy;
-	unsigned used = 0;
-	int graph = 0;
-	int done = 0;
-
-	if (!task)
-		task = current;
-
-	if (!stack) {
-		if (regs)
-			stack = (unsigned long *)regs->sp;
-		else if (task != current)
-			stack = (unsigned long *)task->thread.sp;
-		else
-			stack = &dummy;
-	}
+	unsigned long *end   = (unsigned long *)this_cpu_read(irq_stack_ptr);
+	unsigned long *begin = end - (IRQ_STACK_SIZE / sizeof(long));
 
-	if (!bp)
-		bp = stack_frame(task, regs);
 	/*
-	 * Print function call entries in all stacks, starting at the
-	 * current stack address. If the stacks consist of nested
-	 * exceptions
+	 * This is a software stack, so 'end' can be a valid stack pointer.
+	 * It just means the stack is empty.
 	 */
-	while (!done) {
-		unsigned long *stack_end;
-		enum stack_type stype;
-		char *id;
+	if (stack < begin || stack > end)
+		return false;
 
-		stype = analyze_stack(cpu, task, stack, &stack_end,
-				      irq_stack, &used, &id);
+	info->type	= STACK_TYPE_IRQ;
+	info->begin	= begin;
+	info->end	= end;
 
-		/* Default finish unless specified to continue */
-		done = 1;
+	/*
+	 * The next stack pointer is the first thing pushed by the entry code
+	 * after switching to the irq stack.
+	 */
+	info->next_sp = (unsigned long *)*(end - 1);
 
-		switch (stype) {
+	return true;
+}
 
-		/* Break out early if we are on the thread stack */
-		case STACK_IS_NORMAL:
-			break;
+int get_stack_info(unsigned long *stack, struct task_struct *task,
+		   struct stack_info *info, unsigned long *visit_mask)
+{
+	if (!stack)
+		goto unknown;
 
-		case STACK_IS_EXCEPTION:
+	task = task ? : current;
 
-			if (ops->stack(data, id) < 0)
-				break;
+	if (in_task_stack(stack, task, info))
+		goto recursion_check;
 
-			bp = ops->walk_stack(task, stack, bp, ops,
-					     data, stack_end, &graph);
-			ops->stack(data, "<EOE>");
-			/*
-			 * We link to the next stack via the
-			 * second-to-last pointer (index -2 to end) in the
-			 * exception stack:
-			 */
-			stack = (unsigned long *) stack_end[-2];
-			done = 0;
-			break;
+	if (task != current)
+		goto unknown;
 
-		case STACK_IS_IRQ:
+	if (in_exception_stack(stack, info))
+		goto recursion_check;
 
-			if (ops->stack(data, "IRQ") < 0)
-				break;
-			bp = ops->walk_stack(task, stack, bp,
-				     ops, data, stack_end, &graph);
-			/*
-			 * We link to the next stack (which would be
-			 * the process stack normally) the last
-			 * pointer (index -1 to end) in the IRQ stack:
-			 */
-			stack = (unsigned long *) (stack_end[-1]);
-			irq_stack = NULL;
-			ops->stack(data, "EOI");
-			done = 0;
-			break;
+	if (in_irq_stack(stack, info))
+		goto recursion_check;
 
-		case STACK_IS_UNKNOWN:
-			ops->stack(data, "UNK");
-			break;
-		}
-	}
+	goto unknown;
 
+recursion_check:
 	/*
-	 * This handles the process stack:
+	 * Make sure we don't iterate through any given stack more than once.
+	 * If it comes up a second time then there's something wrong going on:
+	 * just break out and report an unknown stack type.
 	 */
-	bp = ops->walk_stack(task, stack, bp, ops, data, NULL, &graph);
-	put_cpu();
+	if (visit_mask) {
+		if (*visit_mask & (1UL << info->type))
+			goto unknown;
+		*visit_mask |= 1UL << info->type;
+	}
+
+	return 0;
+
+unknown:
+	info->type = STACK_TYPE_UNKNOWN;
+	return -EINVAL;
 }
-EXPORT_SYMBOL(dump_trace);
 
-void
-show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
-		   unsigned long *sp, unsigned long bp, char *log_lvl)
+void show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
+			unsigned long *sp, char *log_lvl)
 {
 	unsigned long *irq_stack_end;
 	unsigned long *irq_stack;
 	unsigned long *stack;
-	int cpu;
 	int i;
 
-	preempt_disable();
-	cpu = smp_processor_id();
+	if (!try_get_task_stack(task))
+		return;
 
-	irq_stack_end	= (unsigned long *)(per_cpu(irq_stack_ptr, cpu));
-	irq_stack	= (unsigned long *)(per_cpu(irq_stack_ptr, cpu) - IRQ_STACK_SIZE);
+	irq_stack_end = (unsigned long *)this_cpu_read(irq_stack_ptr);
+	irq_stack     = irq_stack_end - (IRQ_STACK_SIZE / sizeof(long));
 
-	/*
-	 * Debugging aid: "show_stack(NULL, NULL);" prints the
-	 * back trace for this cpu:
-	 */
-	if (sp == NULL) {
-		if (regs)
-			sp = (unsigned long *)regs->sp;
-		else if (task)
-			sp = (unsigned long *)task->thread.sp;
-		else
-			sp = (unsigned long *)&sp;
-	}
+	sp = sp ? : get_stack_pointer(task, regs);
 
 	stack = sp;
 	for (i = 0; i < kstack_depth_to_print; i++) {
@@ -299,18 +183,17 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
 		stack++;
 		touch_nmi_watchdog();
 	}
-	preempt_enable();
 
 	pr_cont("\n");
-	show_trace_log_lvl(task, regs, sp, bp, log_lvl);
+	show_trace_log_lvl(task, regs, sp, log_lvl);
+
+	put_task_stack(task);
 }
 
 void show_regs(struct pt_regs *regs)
 {
 	int i;
-	unsigned long sp;
 
-	sp = regs->sp;
 	show_regs_print_info(KERN_DEFAULT);
 	__show_regs(regs, 1);
 
@@ -325,8 +208,7 @@ void show_regs(struct pt_regs *regs)
 		u8 *ip;
 
 		printk(KERN_DEFAULT "Stack:\n");
-		show_stack_log_lvl(NULL, regs, (unsigned long *)sp,
-				   0, KERN_DEFAULT);
+		show_stack_log_lvl(current, regs, NULL, KERN_DEFAULT);
 
 		printk(KERN_DEFAULT "Code: ");
 
diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
index 93982aebb398..2f2b8c7ccb85 100644
--- a/arch/x86/kernel/fpu/init.c
+++ b/arch/x86/kernel/fpu/init.c
@@ -317,7 +317,6 @@ static void __init fpu__init_system_ctx_switch(void)
 	on_boot_cpu = 0;
 
 	WARN_ON_FPU(current->thread.fpu.fpstate_active);
-	current_thread_info()->status = 0;
 
 	if (boot_cpu_has(X86_FEATURE_XSAVEOPT) && eagerfpu != DISABLE)
 		eagerfpu = ENABLE;
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index d036cfb4495d..8639bb2ae058 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -1029,7 +1029,7 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
 	}
 
 	if (ftrace_push_return_trace(old, self_addr, &trace.depth,
-		    frame_pointer) == -EBUSY) {
+				     frame_pointer, parent) == -EBUSY) {
 		*parent = old;
 		return;
 	}
diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index 6f8902b0d151..5f401262f12d 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -94,7 +94,7 @@ RESERVE_BRK(pagetables, INIT_MAP_SIZE)
  */
 __HEAD
 ENTRY(startup_32)
-	movl pa(stack_start),%ecx
+	movl pa(initial_stack),%ecx
 	
 	/* test KEEP_SEGMENTS flag to see if the bootloader is asking
 		us to not reload segments */
@@ -286,7 +286,7 @@ num_subarch_entries = (. - subarch_entries) / 4
  * start_secondary().
  */
 ENTRY(start_cpu0)
-	movl stack_start, %ecx
+	movl initial_stack, %ecx
 	movl %ecx, %esp
 	jmp  *(initial_code)
 ENDPROC(start_cpu0)
@@ -307,7 +307,7 @@ ENTRY(startup_32_smp)
 	movl %eax,%es
 	movl %eax,%fs
 	movl %eax,%gs
-	movl pa(stack_start),%ecx
+	movl pa(initial_stack),%ecx
 	movl %eax,%ss
 	leal -__PAGE_OFFSET(%ecx),%esp
 
@@ -703,7 +703,7 @@ ENTRY(initial_page_table)
 
 .data
 .balign 4
-ENTRY(stack_start)
+ENTRY(initial_stack)
 	.long init_thread_union+THREAD_SIZE
 
 __INITRODATA
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 9f8efc9f0075..c98a559c346e 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -66,7 +66,7 @@ startup_64:
 	 */
 
 	/*
-	 * Setup stack for verify_cpu(). "-8" because stack_start is defined
+	 * Setup stack for verify_cpu(). "-8" because initial_stack is defined
 	 * this way, see below. Our best guess is a NULL ptr for stack
 	 * termination heuristics and we don't want to break anything which
 	 * might depend on it (kgdb, ...).
@@ -226,7 +226,7 @@ ENTRY(secondary_startup_64)
 	movq	%rax, %cr0
 
 	/* Setup a boot time stack */
-	movq stack_start(%rip), %rsp
+	movq initial_stack(%rip), %rsp
 
 	/* zero EFLAGS after setting rsp */
 	pushq $0
@@ -310,7 +310,7 @@ ENDPROC(secondary_startup_64)
  * start_secondary().
  */
 ENTRY(start_cpu0)
-	movq stack_start(%rip),%rsp
+	movq initial_stack(%rip),%rsp
 	movq	initial_code(%rip),%rax
 	pushq	$0		# fake return address to stop unwinder
 	pushq	$__KERNEL_CS	# set correct cs
@@ -319,17 +319,15 @@ ENTRY(start_cpu0)
 ENDPROC(start_cpu0)
 #endif
 
-	/* SMP bootup changes these two */
+	/* Both SMP bootup and ACPI suspend change these variables */
 	__REFDATA
 	.balign	8
 	GLOBAL(initial_code)
 	.quad	x86_64_start_kernel
 	GLOBAL(initial_gs)
 	.quad	INIT_PER_CPU_VAR(irq_stack_union)
-
-	GLOBAL(stack_start)
+	GLOBAL(initial_stack)
 	.quad  init_thread_union+THREAD_SIZE-8
-	.word  0
 	__FINITDATA
 
 bad_address:
diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c
index 4a7903714065..9ebd0b0e73d9 100644
--- a/arch/x86/kernel/irq_64.c
+++ b/arch/x86/kernel/irq_64.c
@@ -40,8 +40,7 @@ static inline void stack_overflow_check(struct pt_regs *regs)
 	if (user_mode(regs))
 		return;
 
-	if (regs->sp >= curbase + sizeof(struct thread_info) +
-				  sizeof(struct pt_regs) + STACK_TOP_MARGIN &&
+	if (regs->sp >= curbase + sizeof(struct pt_regs) + STACK_TOP_MARGIN &&
 	    regs->sp <= curbase + THREAD_SIZE)
 		return;
 
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 04cde527d728..8e36f249646e 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -50,6 +50,7 @@
 #include <asm/apicdef.h>
 #include <asm/apic.h>
 #include <asm/nmi.h>
+#include <asm/switch_to.h>
 
 struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
 {
@@ -166,21 +167,19 @@ void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
 	gdb_regs[GDB_DX]	= 0;
 	gdb_regs[GDB_SI]	= 0;
 	gdb_regs[GDB_DI]	= 0;
-	gdb_regs[GDB_BP]	= *(unsigned long *)p->thread.sp;
+	gdb_regs[GDB_BP]	= ((struct inactive_task_frame *)p->thread.sp)->bp;
 #ifdef CONFIG_X86_32
 	gdb_regs[GDB_DS]	= __KERNEL_DS;
 	gdb_regs[GDB_ES]	= __KERNEL_DS;
 	gdb_regs[GDB_PS]	= 0;
 	gdb_regs[GDB_CS]	= __KERNEL_CS;
-	gdb_regs[GDB_PC]	= p->thread.ip;
 	gdb_regs[GDB_SS]	= __KERNEL_DS;
 	gdb_regs[GDB_FS]	= 0xFFFF;
 	gdb_regs[GDB_GS]	= 0xFFFF;
 #else
-	gdb_regs32[GDB_PS]	= *(unsigned long *)(p->thread.sp + 8);
+	gdb_regs32[GDB_PS]	= 0;
 	gdb_regs32[GDB_CS]	= __KERNEL_CS;
 	gdb_regs32[GDB_SS]	= __KERNEL_DS;
-	gdb_regs[GDB_PC]	= 0;
 	gdb_regs[GDB_R8]	= 0;
 	gdb_regs[GDB_R9]	= 0;
 	gdb_regs[GDB_R10]	= 0;
@@ -190,6 +189,7 @@ void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
 	gdb_regs[GDB_R14]	= 0;
 	gdb_regs[GDB_R15]	= 0;
 #endif
+	gdb_regs[GDB_PC]	= 0;
 	gdb_regs[GDB_SP]	= p->thread.sp;
 }
 
diff --git a/arch/x86/kernel/ksysfs.c b/arch/x86/kernel/ksysfs.c
index c2bedaea11f7..4afc67f5facc 100644
--- a/arch/x86/kernel/ksysfs.c
+++ b/arch/x86/kernel/ksysfs.c
@@ -184,7 +184,7 @@ out:
 
 static struct kobj_attribute type_attr = __ATTR_RO(type);
 
-static struct bin_attribute data_attr = {
+static struct bin_attribute data_attr __ro_after_init = {
 	.attr = {
 		.name = "data",
 		.mode = S_IRUGO,
diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
index 3692249a70f1..60b9949f1e65 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -29,7 +29,7 @@
 #include <asm/x86_init.h>
 #include <asm/reboot.h>
 
-static int kvmclock = 1;
+static int kvmclock __ro_after_init = 1;
 static int msr_kvm_system_time = MSR_KVM_SYSTEM_TIME;
 static int msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK;
 static cycle_t kvm_sched_clock_offset;
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index 1acfd76e3e26..bbf3d5933eaa 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -332,7 +332,6 @@ __visible struct pv_cpu_ops pv_cpu_ops = {
 	.read_cr0 = native_read_cr0,
 	.write_cr0 = native_write_cr0,
 	.read_cr4 = native_read_cr4,
-	.read_cr4_safe = native_read_cr4_safe,
 	.write_cr4 = native_write_cr4,
 #ifdef CONFIG_X86_64
 	.read_cr8 = native_read_cr8,
@@ -389,7 +388,7 @@ NOKPROBE_SYMBOL(native_load_idt);
 #define PTE_IDENT	__PV_IS_CALLEE_SAVE(_paravirt_ident_64)
 #endif
 
-struct pv_mmu_ops pv_mmu_ops = {
+struct pv_mmu_ops pv_mmu_ops __ro_after_init = {
 
 	.read_cr2 = native_read_cr2,
 	.write_cr2 = native_write_cr2,
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 62c0b0ea2ce4..4002b475171c 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -32,6 +32,7 @@
 #include <asm/tlbflush.h>
 #include <asm/mce.h>
 #include <asm/vm86.h>
+#include <asm/switch_to.h>
 
 /*
  * per-CPU TSS segments. Threads are completely 'soft' on Linux,
@@ -513,6 +514,17 @@ unsigned long arch_randomize_brk(struct mm_struct *mm)
 }
 
 /*
+ * Return saved PC of a blocked thread.
+ * What is this good for? it will be always the scheduler or ret_from_fork.
+ */
+unsigned long thread_saved_pc(struct task_struct *tsk)
+{
+	struct inactive_task_frame *frame =
+		(struct inactive_task_frame *) READ_ONCE(tsk->thread.sp);
+	return READ_ONCE_NOCHECK(frame->ret_addr);
+}
+
+/*
  * Called from fs/proc with a reference on @p to find the function
  * which called into schedule(). This needs to be done carefully
  * because the task might wake up and we might look at a stack
@@ -520,15 +532,18 @@ unsigned long arch_randomize_brk(struct mm_struct *mm)
  */
 unsigned long get_wchan(struct task_struct *p)
 {
-	unsigned long start, bottom, top, sp, fp, ip;
+	unsigned long start, bottom, top, sp, fp, ip, ret = 0;
 	int count = 0;
 
 	if (!p || p == current || p->state == TASK_RUNNING)
 		return 0;
 
+	if (!try_get_task_stack(p))
+		return 0;
+
 	start = (unsigned long)task_stack_page(p);
 	if (!start)
-		return 0;
+		goto out;
 
 	/*
 	 * Layout of the stack page:
@@ -537,9 +552,7 @@ unsigned long get_wchan(struct task_struct *p)
 	 * PADDING
 	 * ----------- top = topmax - TOP_OF_KERNEL_STACK_PADDING
 	 * stack
-	 * ----------- bottom = start + sizeof(thread_info)
-	 * thread_info
-	 * ----------- start
+	 * ----------- bottom = start
 	 *
 	 * The tasks stack pointer points at the location where the
 	 * framepointer is stored. The data on the stack is:
@@ -550,20 +563,25 @@ unsigned long get_wchan(struct task_struct *p)
 	 */
 	top = start + THREAD_SIZE - TOP_OF_KERNEL_STACK_PADDING;
 	top -= 2 * sizeof(unsigned long);
-	bottom = start + sizeof(struct thread_info);
+	bottom = start;
 
 	sp = READ_ONCE(p->thread.sp);
 	if (sp < bottom || sp > top)
-		return 0;
+		goto out;
 
-	fp = READ_ONCE_NOCHECK(*(unsigned long *)sp);
+	fp = READ_ONCE_NOCHECK(((struct inactive_task_frame *)sp)->bp);
 	do {
 		if (fp < bottom || fp > top)
-			return 0;
+			goto out;
 		ip = READ_ONCE_NOCHECK(*(unsigned long *)(fp + sizeof(unsigned long)));
-		if (!in_sched_functions(ip))
-			return ip;
+		if (!in_sched_functions(ip)) {
+			ret = ip;
+			goto out;
+		}
 		fp = READ_ONCE_NOCHECK(*(unsigned long *)fp);
 	} while (count++ < 16 && p->state != TASK_RUNNING);
-	return 0;
+
+out:
+	put_task_stack(p);
+	return ret;
 }
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index d86be29c38c7..bd7be8efdc4c 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -55,17 +55,6 @@
 #include <asm/switch_to.h>
 #include <asm/vm86.h>
 
-asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
-asmlinkage void ret_from_kernel_thread(void) __asm__("ret_from_kernel_thread");
-
-/*
- * Return saved PC of a blocked thread.
- */
-unsigned long thread_saved_pc(struct task_struct *tsk)
-{
-	return ((unsigned long *)tsk->thread.sp)[3];
-}
-
 void __show_regs(struct pt_regs *regs, int all)
 {
 	unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L;
@@ -101,7 +90,7 @@ void __show_regs(struct pt_regs *regs, int all)
 	cr0 = read_cr0();
 	cr2 = read_cr2();
 	cr3 = read_cr3();
-	cr4 = __read_cr4_safe();
+	cr4 = __read_cr4();
 	printk(KERN_DEFAULT "CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n",
 			cr0, cr2, cr3, cr4);
 
@@ -133,35 +122,31 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long sp,
 	unsigned long arg, struct task_struct *p, unsigned long tls)
 {
 	struct pt_regs *childregs = task_pt_regs(p);
+	struct fork_frame *fork_frame = container_of(childregs, struct fork_frame, regs);
+	struct inactive_task_frame *frame = &fork_frame->frame;
 	struct task_struct *tsk;
 	int err;
 
-	p->thread.sp = (unsigned long) childregs;
+	frame->bp = 0;
+	frame->ret_addr = (unsigned long) ret_from_fork;
+	p->thread.sp = (unsigned long) fork_frame;
 	p->thread.sp0 = (unsigned long) (childregs+1);
 	memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
 
 	if (unlikely(p->flags & PF_KTHREAD)) {
 		/* kernel thread */
 		memset(childregs, 0, sizeof(struct pt_regs));
-		p->thread.ip = (unsigned long) ret_from_kernel_thread;
-		task_user_gs(p) = __KERNEL_STACK_CANARY;
-		childregs->ds = __USER_DS;
-		childregs->es = __USER_DS;
-		childregs->fs = __KERNEL_PERCPU;
-		childregs->bx = sp;	/* function */
-		childregs->bp = arg;
-		childregs->orig_ax = -1;
-		childregs->cs = __KERNEL_CS | get_kernel_rpl();
-		childregs->flags = X86_EFLAGS_IF | X86_EFLAGS_FIXED;
+		frame->bx = sp;		/* function */
+		frame->di = arg;
 		p->thread.io_bitmap_ptr = NULL;
 		return 0;
 	}
+	frame->bx = 0;
 	*childregs = *current_pt_regs();
 	childregs->ax = 0;
 	if (sp)
 		childregs->sp = sp;
 
-	p->thread.ip = (unsigned long) ret_from_fork;
 	task_user_gs(p) = get_user_gs(current_pt_regs());
 
 	p->thread.io_bitmap_ptr = NULL;
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 63236d8f84bf..de9acaf2d371 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -50,8 +50,6 @@
 #include <asm/switch_to.h>
 #include <asm/xen/hypervisor.h>
 
-asmlinkage extern void ret_from_fork(void);
-
 __visible DEFINE_PER_CPU(unsigned long, rsp_scratch);
 
 /* Prints also some state that isn't saved in the pt_regs */
@@ -141,12 +139,17 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long sp,
 {
 	int err;
 	struct pt_regs *childregs;
+	struct fork_frame *fork_frame;
+	struct inactive_task_frame *frame;
 	struct task_struct *me = current;
 
 	p->thread.sp0 = (unsigned long)task_stack_page(p) + THREAD_SIZE;
 	childregs = task_pt_regs(p);
-	p->thread.sp = (unsigned long) childregs;
-	set_tsk_thread_flag(p, TIF_FORK);
+	fork_frame = container_of(childregs, struct fork_frame, regs);
+	frame = &fork_frame->frame;
+	frame->bp = 0;
+	frame->ret_addr = (unsigned long) ret_from_fork;
+	p->thread.sp = (unsigned long) fork_frame;
 	p->thread.io_bitmap_ptr = NULL;
 
 	savesegment(gs, p->thread.gsindex);
@@ -160,15 +163,11 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long sp,
 	if (unlikely(p->flags & PF_KTHREAD)) {
 		/* kernel thread */
 		memset(childregs, 0, sizeof(struct pt_regs));
-		childregs->sp = (unsigned long)childregs;
-		childregs->ss = __KERNEL_DS;
-		childregs->bx = sp; /* function */
-		childregs->bp = arg;
-		childregs->orig_ax = -1;
-		childregs->cs = __KERNEL_CS | get_kernel_rpl();
-		childregs->flags = X86_EFLAGS_IF | X86_EFLAGS_FIXED;
+		frame->bx = sp;		/* function */
+		frame->r12 = arg;
 		return 0;
 	}
+	frame->bx = 0;
 	*childregs = *current_pt_regs();
 
 	childregs->ax = 0;
@@ -511,7 +510,7 @@ void set_personality_ia32(bool x32)
 		current->personality &= ~READ_IMPLIES_EXEC;
 		/* in_compat_syscall() uses the presence of the x32
 		   syscall bit flag to determine compat status */
-		current_thread_info()->status &= ~TS_COMPAT;
+		current->thread.status &= ~TS_COMPAT;
 	} else {
 		set_thread_flag(TIF_IA32);
 		clear_thread_flag(TIF_X32);
@@ -519,7 +518,7 @@ void set_personality_ia32(bool x32)
 			current->mm->context.ia32_compat = TIF_IA32;
 		current->personality |= force_personality32;
 		/* Prepare the first "return" to user space */
-		current_thread_info()->status |= TS_COMPAT;
+		current->thread.status |= TS_COMPAT;
 	}
 }
 EXPORT_SYMBOL_GPL(set_personality_ia32);
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index f79576a541ff..ce94c38cf4d6 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -173,8 +173,8 @@ unsigned long kernel_stack_pointer(struct pt_regs *regs)
 		return sp;
 
 	prev_esp = (u32 *)(context);
-	if (prev_esp)
-		return (unsigned long)prev_esp;
+	if (*prev_esp)
+		return (unsigned long)*prev_esp;
 
 	return (unsigned long)regs;
 }
@@ -934,7 +934,7 @@ static int putreg32(struct task_struct *child, unsigned regno, u32 value)
 		 */
 		regs->orig_ax = value;
 		if (syscall_get_nr(child, regs) >= 0)
-			task_thread_info(child)->status |= TS_I386_REGS_POKED;
+			child->thread.status |= TS_I386_REGS_POKED;
 		break;
 
 	case offsetof(struct user32, regs.eflags):
@@ -1250,7 +1250,7 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
 
 #ifdef CONFIG_X86_64
 
-static struct user_regset x86_64_regsets[] __read_mostly = {
+static struct user_regset x86_64_regsets[] __ro_after_init = {
 	[REGSET_GENERAL] = {
 		.core_note_type = NT_PRSTATUS,
 		.n = sizeof(struct user_regs_struct) / sizeof(long),
@@ -1291,7 +1291,7 @@ static const struct user_regset_view user_x86_64_view = {
 #endif	/* CONFIG_X86_64 */
 
 #if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
-static struct user_regset x86_32_regsets[] __read_mostly = {
+static struct user_regset x86_32_regsets[] __ro_after_init = {
 	[REGSET_GENERAL] = {
 		.core_note_type = NT_PRSTATUS,
 		.n = sizeof(struct user_regs_struct32) / sizeof(u32),
@@ -1344,7 +1344,7 @@ static const struct user_regset_view user_x86_32_view = {
  */
 u64 xstate_fx_sw_bytes[USER_XSTATE_FX_SW_WORDS];
 
-void update_regset_xstate_info(unsigned int size, u64 xstate_mask)
+void __init update_regset_xstate_info(unsigned int size, u64 xstate_mask)
 {
 #ifdef CONFIG_X86_64
 	x86_64_regsets[REGSET_XSTATE].n = size / sizeof(u64);
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 63bf27d972b7..e244c19a2451 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -705,7 +705,7 @@ static void native_machine_power_off(void)
 	tboot_shutdown(TB_SHUTDOWN_HALT);
 }
 
-struct machine_ops machine_ops = {
+struct machine_ops machine_ops __ro_after_init = {
 	.power_off = native_machine_power_off,
 	.shutdown = native_machine_shutdown,
 	.emergency_restart = native_machine_emergency_restart,
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 2c4bc85dfe90..eeb094ea794a 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -210,9 +210,9 @@ EXPORT_SYMBOL(boot_cpu_data);
 
 
 #if !defined(CONFIG_X86_PAE) || defined(CONFIG_X86_64)
-__visible unsigned long mmu_cr4_features;
+__visible unsigned long mmu_cr4_features __ro_after_init;
 #else
-__visible unsigned long mmu_cr4_features = X86_CR4_PAE;
+__visible unsigned long mmu_cr4_features __ro_after_init = X86_CR4_PAE;
 #endif
 
 /* Boot loader ID and version as integers, for the benefit of proc_dointvec */
@@ -1137,7 +1137,7 @@ void __init setup_arch(char **cmdline_p)
 	 * auditing all the early-boot CR4 manipulation would be needed to
 	 * rule it out.
 	 */
-	mmu_cr4_features = __read_cr4_safe();
+	mmu_cr4_features = __read_cr4();
 
 	memblock_set_current_limit(get_max_mapped());
 
diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index 7a40e068302d..2bbd27f89802 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -33,7 +33,7 @@ EXPORT_PER_CPU_SYMBOL(cpu_number);
 DEFINE_PER_CPU_READ_MOSTLY(unsigned long, this_cpu_off) = BOOT_PERCPU_OFFSET;
 EXPORT_PER_CPU_SYMBOL(this_cpu_off);
 
-unsigned long __per_cpu_offset[NR_CPUS] __read_mostly = {
+unsigned long __per_cpu_offset[NR_CPUS] __ro_after_init = {
 	[0 ... NR_CPUS-1] = BOOT_PERCPU_OFFSET,
 };
 EXPORT_SYMBOL(__per_cpu_offset);
@@ -246,7 +246,7 @@ void __init setup_per_cpu_areas(void)
 #ifdef CONFIG_X86_64
 		per_cpu(irq_stack_ptr, cpu) =
 			per_cpu(irq_stack_union.irq_stack, cpu) +
-			IRQ_STACK_SIZE - 64;
+			IRQ_STACK_SIZE;
 #endif
 #ifdef CONFIG_NUMA
 		per_cpu(x86_cpu_to_node_map, cpu) =
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 04cb3212db2d..da20ecb5397a 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -783,7 +783,7 @@ static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
 	 * than the tracee.
 	 */
 #ifdef CONFIG_IA32_EMULATION
-	if (current_thread_info()->status & (TS_COMPAT|TS_I386_REGS_POKED))
+	if (current->thread.status & (TS_COMPAT|TS_I386_REGS_POKED))
 		return __NR_ia32_restart_syscall;
 #endif
 #ifdef CONFIG_X86_X32_ABI
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 54e2f1a968a4..7249dcf2cbcb 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -943,7 +943,6 @@ void common_cpu_up(unsigned int cpu, struct task_struct *idle)
 	per_cpu(cpu_current_top_of_stack, cpu) =
 		(unsigned long)task_stack_page(idle) + THREAD_SIZE;
 #else
-	clear_tsk_thread_flag(idle, TIF_FORK);
 	initial_gs = per_cpu_offset(cpu);
 #endif
 }
@@ -970,7 +969,7 @@ static int do_boot_cpu(int apicid, int cpu, struct task_struct *idle)
 
 	early_gdt_descr.address = (unsigned long)get_cpu_gdt_table(cpu);
 	initial_code = (unsigned long)start_secondary;
-	stack_start  = idle->thread.sp;
+	initial_stack  = idle->thread.sp;
 
 	/*
 	 * Enable the espfix hack for this CPU
diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c
index 4738f5e0f2ab..0653788026e2 100644
--- a/arch/x86/kernel/stacktrace.c
+++ b/arch/x86/kernel/stacktrace.c
@@ -8,80 +8,69 @@
 #include <linux/export.h>
 #include <linux/uaccess.h>
 #include <asm/stacktrace.h>
+#include <asm/unwind.h>
 
-static int save_stack_stack(void *data, char *name)
+static int save_stack_address(struct stack_trace *trace, unsigned long addr,
+			      bool nosched)
 {
-	return 0;
-}
-
-static int
-__save_stack_address(void *data, unsigned long addr, bool reliable, bool nosched)
-{
-	struct stack_trace *trace = data;
-#ifdef CONFIG_FRAME_POINTER
-	if (!reliable)
-		return 0;
-#endif
 	if (nosched && in_sched_functions(addr))
 		return 0;
+
 	if (trace->skip > 0) {
 		trace->skip--;
 		return 0;
 	}
-	if (trace->nr_entries < trace->max_entries) {
-		trace->entries[trace->nr_entries++] = addr;
-		return 0;
-	} else {
-		return -1; /* no more room, stop walking the stack */
-	}
-}
 
-static int save_stack_address(void *data, unsigned long addr, int reliable)
-{
-	return __save_stack_address(data, addr, reliable, false);
+	if (trace->nr_entries >= trace->max_entries)
+		return -1;
+
+	trace->entries[trace->nr_entries++] = addr;
+	return 0;
 }
 
-static int
-save_stack_address_nosched(void *data, unsigned long addr, int reliable)
+static void __save_stack_trace(struct stack_trace *trace,
+			       struct task_struct *task, struct pt_regs *regs,
+			       bool nosched)
 {
-	return __save_stack_address(data, addr, reliable, true);
-}
+	struct unwind_state state;
+	unsigned long addr;
 
-static const struct stacktrace_ops save_stack_ops = {
-	.stack		= save_stack_stack,
-	.address	= save_stack_address,
-	.walk_stack	= print_context_stack,
-};
+	if (regs)
+		save_stack_address(trace, regs->ip, nosched);
 
-static const struct stacktrace_ops save_stack_ops_nosched = {
-	.stack		= save_stack_stack,
-	.address	= save_stack_address_nosched,
-	.walk_stack	= print_context_stack,
-};
+	for (unwind_start(&state, task, regs, NULL); !unwind_done(&state);
+	     unwind_next_frame(&state)) {
+		addr = unwind_get_return_address(&state);
+		if (!addr || save_stack_address(trace, addr, nosched))
+			break;
+	}
+
+	if (trace->nr_entries < trace->max_entries)
+		trace->entries[trace->nr_entries++] = ULONG_MAX;
+}
 
 /*
  * Save stack-backtrace addresses into a stack_trace buffer.
  */
 void save_stack_trace(struct stack_trace *trace)
 {
-	dump_trace(current, NULL, NULL, 0, &save_stack_ops, trace);
-	if (trace->nr_entries < trace->max_entries)
-		trace->entries[trace->nr_entries++] = ULONG_MAX;
+	__save_stack_trace(trace, current, NULL, false);
 }
 EXPORT_SYMBOL_GPL(save_stack_trace);
 
 void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
 {
-	dump_trace(current, regs, NULL, 0, &save_stack_ops, trace);
-	if (trace->nr_entries < trace->max_entries)
-		trace->entries[trace->nr_entries++] = ULONG_MAX;
+	__save_stack_trace(trace, current, regs, false);
 }
 
 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
 {
-	dump_trace(tsk, NULL, NULL, 0, &save_stack_ops_nosched, trace);
-	if (trace->nr_entries < trace->max_entries)
-		trace->entries[trace->nr_entries++] = ULONG_MAX;
+	if (!try_get_task_stack(tsk))
+		return;
+
+	__save_stack_trace(trace, tsk, NULL, true);
+
+	put_task_stack(tsk);
 }
 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
 
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index b70ca12dd389..bd4e3d4d3625 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -292,12 +292,30 @@ DO_ERROR(X86_TRAP_NP,     SIGBUS,  "segment not present",	segment_not_present)
 DO_ERROR(X86_TRAP_SS,     SIGBUS,  "stack segment",		stack_segment)
 DO_ERROR(X86_TRAP_AC,     SIGBUS,  "alignment check",		alignment_check)
 
+#ifdef CONFIG_VMAP_STACK
+__visible void __noreturn handle_stack_overflow(const char *message,
+						struct pt_regs *regs,
+						unsigned long fault_address)
+{
+	printk(KERN_EMERG "BUG: stack guard page was hit at %p (stack is %p..%p)\n",
+		 (void *)fault_address, current->stack,
+		 (char *)current->stack + THREAD_SIZE - 1);
+	die(message, regs, 0);
+
+	/* Be absolutely certain we don't return. */
+	panic(message);
+}
+#endif
+
 #ifdef CONFIG_X86_64
 /* Runs on IST stack */
 dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
 {
 	static const char str[] = "double fault";
 	struct task_struct *tsk = current;
+#ifdef CONFIG_VMAP_STACK
+	unsigned long cr2;
+#endif
 
 #ifdef CONFIG_X86_ESPFIX64
 	extern unsigned char native_irq_return_iret[];
@@ -332,6 +350,49 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
 	tsk->thread.error_code = error_code;
 	tsk->thread.trap_nr = X86_TRAP_DF;
 
+#ifdef CONFIG_VMAP_STACK
+	/*
+	 * If we overflow the stack into a guard page, the CPU will fail
+	 * to deliver #PF and will send #DF instead.  Similarly, if we
+	 * take any non-IST exception while too close to the bottom of
+	 * the stack, the processor will get a page fault while
+	 * delivering the exception and will generate a double fault.
+	 *
+	 * According to the SDM (footnote in 6.15 under "Interrupt 14 -
+	 * Page-Fault Exception (#PF):
+	 *
+	 *   Processors update CR2 whenever a page fault is detected. If a
+	 *   second page fault occurs while an earlier page fault is being
+	 *   deliv- ered, the faulting linear address of the second fault will
+	 *   overwrite the contents of CR2 (replacing the previous
+	 *   address). These updates to CR2 occur even if the page fault
+	 *   results in a double fault or occurs during the delivery of a
+	 *   double fault.
+	 *
+	 * The logic below has a small possibility of incorrectly diagnosing
+	 * some errors as stack overflows.  For example, if the IDT or GDT
+	 * gets corrupted such that #GP delivery fails due to a bad descriptor
+	 * causing #GP and we hit this condition while CR2 coincidentally
+	 * points to the stack guard page, we'll think we overflowed the
+	 * stack.  Given that we're going to panic one way or another
+	 * if this happens, this isn't necessarily worth fixing.
+	 *
+	 * If necessary, we could improve the test by only diagnosing
+	 * a stack overflow if the saved RSP points within 47 bytes of
+	 * the bottom of the stack: if RSP == tsk_stack + 48 and we
+	 * take an exception, the stack is already aligned and there
+	 * will be enough room SS, RSP, RFLAGS, CS, RIP, and a
+	 * possible error code, so a stack overflow would *not* double
+	 * fault.  With any less space left, exception delivery could
+	 * fail, and, as a practical matter, we've overflowed the
+	 * stack even if the actual trigger for the double fault was
+	 * something else.
+	 */
+	cr2 = read_cr2();
+	if ((unsigned long)task_stack_page(tsk) - 1 - cr2 < PAGE_SIZE)
+		handle_stack_overflow("kernel stack overflow (double-fault)", regs, cr2);
+#endif
+
 #ifdef CONFIG_DOUBLEFAULT
 	df_debug(regs, error_code);
 #endif
diff --git a/arch/x86/kernel/unwind_frame.c b/arch/x86/kernel/unwind_frame.c
new file mode 100644
index 000000000000..a2456d4d286a
--- /dev/null
+++ b/arch/x86/kernel/unwind_frame.c
@@ -0,0 +1,93 @@
+#include <linux/sched.h>
+#include <asm/ptrace.h>
+#include <asm/bitops.h>
+#include <asm/stacktrace.h>
+#include <asm/unwind.h>
+
+#define FRAME_HEADER_SIZE (sizeof(long) * 2)
+
+unsigned long unwind_get_return_address(struct unwind_state *state)
+{
+	unsigned long addr;
+	unsigned long *addr_p = unwind_get_return_address_ptr(state);
+
+	if (unwind_done(state))
+		return 0;
+
+	addr = ftrace_graph_ret_addr(state->task, &state->graph_idx, *addr_p,
+				     addr_p);
+
+	return __kernel_text_address(addr) ? addr : 0;
+}
+EXPORT_SYMBOL_GPL(unwind_get_return_address);
+
+static bool update_stack_state(struct unwind_state *state, void *addr,
+			       size_t len)
+{
+	struct stack_info *info = &state->stack_info;
+
+	/*
+	 * If addr isn't on the current stack, switch to the next one.
+	 *
+	 * We may have to traverse multiple stacks to deal with the possibility
+	 * that 'info->next_sp' could point to an empty stack and 'addr' could
+	 * be on a subsequent stack.
+	 */
+	while (!on_stack(info, addr, len))
+		if (get_stack_info(info->next_sp, state->task, info,
+				   &state->stack_mask))
+			return false;
+
+	return true;
+}
+
+bool unwind_next_frame(struct unwind_state *state)
+{
+	unsigned long *next_bp;
+
+	if (unwind_done(state))
+		return false;
+
+	next_bp = (unsigned long *)*state->bp;
+
+	/* make sure the next frame's data is accessible */
+	if (!update_stack_state(state, next_bp, FRAME_HEADER_SIZE))
+		return false;
+
+	/* move to the next frame */
+	state->bp = next_bp;
+	return true;
+}
+EXPORT_SYMBOL_GPL(unwind_next_frame);
+
+void __unwind_start(struct unwind_state *state, struct task_struct *task,
+		    struct pt_regs *regs, unsigned long *first_frame)
+{
+	memset(state, 0, sizeof(*state));
+	state->task = task;
+
+	/* don't even attempt to start from user mode regs */
+	if (regs && user_mode(regs)) {
+		state->stack_info.type = STACK_TYPE_UNKNOWN;
+		return;
+	}
+
+	/* set up the starting stack frame */
+	state->bp = get_frame_pointer(task, regs);
+
+	/* initialize stack info and make sure the frame data is accessible */
+	get_stack_info(state->bp, state->task, &state->stack_info,
+		       &state->stack_mask);
+	update_stack_state(state, state->bp, FRAME_HEADER_SIZE);
+
+	/*
+	 * The caller can provide the address of the first frame directly
+	 * (first_frame) or indirectly (regs->sp) to indicate which stack frame
+	 * to start unwinding at.  Skip ahead until we reach it.
+	 */
+	while (!unwind_done(state) &&
+	       (!on_stack(&state->stack_info, first_frame, sizeof(long)) ||
+			state->bp < first_frame))
+		unwind_next_frame(state);
+}
+EXPORT_SYMBOL_GPL(__unwind_start);
diff --git a/arch/x86/kernel/unwind_guess.c b/arch/x86/kernel/unwind_guess.c
new file mode 100644
index 000000000000..b5a834c93065
--- /dev/null
+++ b/arch/x86/kernel/unwind_guess.c
@@ -0,0 +1,43 @@
+#include <linux/sched.h>
+#include <linux/ftrace.h>
+#include <asm/ptrace.h>
+#include <asm/bitops.h>
+#include <asm/stacktrace.h>
+#include <asm/unwind.h>
+
+bool unwind_next_frame(struct unwind_state *state)
+{
+	struct stack_info *info = &state->stack_info;
+
+	if (unwind_done(state))
+		return false;
+
+	do {
+		for (state->sp++; state->sp < info->end; state->sp++)
+			if (__kernel_text_address(*state->sp))
+				return true;
+
+		state->sp = info->next_sp;
+
+	} while (!get_stack_info(state->sp, state->task, info,
+				 &state->stack_mask));
+
+	return false;
+}
+EXPORT_SYMBOL_GPL(unwind_next_frame);
+
+void __unwind_start(struct unwind_state *state, struct task_struct *task,
+		    struct pt_regs *regs, unsigned long *first_frame)
+{
+	memset(state, 0, sizeof(*state));
+
+	state->task = task;
+	state->sp   = first_frame;
+
+	get_stack_info(first_frame, state->task, &state->stack_info,
+		       &state->stack_mask);
+
+	if (!__kernel_text_address(*first_frame))
+		unwind_next_frame(state);
+}
+EXPORT_SYMBOL_GPL(__unwind_start);
diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c
index 76c5e52436c4..0bd9f1287f39 100644
--- a/arch/x86/kernel/x86_init.c
+++ b/arch/x86/kernel/x86_init.c
@@ -91,7 +91,7 @@ struct x86_cpuinit_ops x86_cpuinit = {
 static void default_nmi_init(void) { };
 static int default_i8042_detect(void) { return 1; };
 
-struct x86_platform_ops x86_platform = {
+struct x86_platform_ops x86_platform __ro_after_init = {
 	.calibrate_cpu			= native_calibrate_cpu,
 	.calibrate_tsc			= native_calibrate_tsc,
 	.get_wallclock			= mach_get_cmos_time,
@@ -108,7 +108,7 @@ struct x86_platform_ops x86_platform = {
 EXPORT_SYMBOL_GPL(x86_platform);
 
 #if defined(CONFIG_PCI_MSI)
-struct x86_msi_ops x86_msi = {
+struct x86_msi_ops x86_msi __ro_after_init = {
 	.setup_msi_irqs		= native_setup_msi_irqs,
 	.teardown_msi_irq	= native_teardown_msi_irq,
 	.teardown_msi_irqs	= default_teardown_msi_irqs,
@@ -137,7 +137,7 @@ void arch_restore_msi_irqs(struct pci_dev *dev)
 }
 #endif
 
-struct x86_io_apic_ops x86_io_apic_ops = {
+struct x86_io_apic_ops x86_io_apic_ops __ro_after_init = {
 	.read			= native_io_apic_read,
 	.disable		= native_disable_io_apic,
 };