v4.19.13 snapshot.
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
new file mode 100644
index 0000000..5cdb9e8
--- /dev/null
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -0,0 +1,151 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ * Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
+ */
+#include <linux/sched/debug.h>
+#include <linux/kallsyms.h>
+#include <linux/kprobes.h>
+#include <linux/uaccess.h>
+#include <linux/hardirq.h>
+#include <linux/kdebug.h>
+#include <linux/export.h>
+#include <linux/ptrace.h>
+#include <linux/kexec.h>
+#include <linux/sysfs.h>
+#include <linux/bug.h>
+#include <linux/nmi.h>
+
+#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",
+};
+
+static unsigned long exception_stack_sizes[N_EXCEPTION_STACKS] = {
+ [0 ... N_EXCEPTION_STACKS - 1] = EXCEPTION_STKSZ,
+ [DEBUG_STACK - 1] = DEBUG_STKSZ
+};
+
+const char *stack_type_name(enum stack_type type)
+{
+ BUILD_BUG_ON(N_EXCEPTION_STACKS != 4);
+
+ if (type == STACK_TYPE_IRQ)
+ return "IRQ";
+
+ if (type == STACK_TYPE_ENTRY) {
+ /*
+ * On 64-bit, we have a generic entry stack that we
+ * use for all the kernel entry points, including
+ * SYSENTER.
+ */
+ return "ENTRY_TRAMPOLINE";
+ }
+
+ if (type >= STACK_TYPE_EXCEPTION && type <= STACK_TYPE_EXCEPTION_LAST)
+ return exception_stack_names[type - STACK_TYPE_EXCEPTION];
+
+ return NULL;
+}
+
+static bool in_exception_stack(unsigned long *stack, struct stack_info *info)
+{
+ unsigned long *begin, *end;
+ struct pt_regs *regs;
+ unsigned k;
+
+ BUILD_BUG_ON(N_EXCEPTION_STACKS != 4);
+
+ 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 (stack <= begin || stack >= end)
+ continue;
+
+ info->type = STACK_TYPE_EXCEPTION + k;
+ info->begin = begin;
+ info->end = end;
+ info->next_sp = (unsigned long *)regs->sp;
+
+ return true;
+ }
+
+ return false;
+}
+
+static bool in_irq_stack(unsigned long *stack, struct stack_info *info)
+{
+ unsigned long *end = (unsigned long *)this_cpu_read(irq_stack_ptr);
+ unsigned long *begin = end - (IRQ_STACK_SIZE / sizeof(long));
+
+ /*
+ * 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;
+
+ info->type = STACK_TYPE_IRQ;
+ info->begin = begin;
+ info->end = end;
+
+ /*
+ * 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);
+
+ return true;
+}
+
+int get_stack_info(unsigned long *stack, struct task_struct *task,
+ struct stack_info *info, unsigned long *visit_mask)
+{
+ if (!stack)
+ goto unknown;
+
+ task = task ? : current;
+
+ if (in_task_stack(stack, task, info))
+ goto recursion_check;
+
+ if (task != current)
+ goto unknown;
+
+ if (in_exception_stack(stack, info))
+ goto recursion_check;
+
+ if (in_irq_stack(stack, info))
+ goto recursion_check;
+
+ if (in_entry_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)) {
+ printk_deferred_once(KERN_WARNING "WARNING: stack recursion on stack type %d\n", info->type);
+ goto unknown;
+ }
+ *visit_mask |= 1UL << info->type;
+ }
+
+ return 0;
+
+unknown:
+ info->type = STACK_TYPE_UNKNOWN;
+ return -EINVAL;
+}