v4.19.13 snapshot.
diff --git a/arch/powerpc/kernel/stacktrace.c b/arch/powerpc/kernel/stacktrace.c
new file mode 100644
index 0000000..e2c50b5
--- /dev/null
+++ b/arch/powerpc/kernel/stacktrace.c
@@ -0,0 +1,245 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Stack trace utility functions etc.
+ *
+ * Copyright 2008 Christoph Hellwig, IBM Corp.
+ * Copyright 2018 SUSE Linux GmbH
+ * Copyright 2018 Nick Piggin, Michael Ellerman, IBM Corp.
+ */
+
+#include <linux/export.h>
+#include <linux/kallsyms.h>
+#include <linux/module.h>
+#include <linux/nmi.h>
+#include <linux/sched.h>
+#include <linux/sched/debug.h>
+#include <linux/sched/task_stack.h>
+#include <linux/stacktrace.h>
+#include <asm/ptrace.h>
+#include <asm/processor.h>
+#include <linux/ftrace.h>
+#include <asm/kprobes.h>
+
+#include <asm/paca.h>
+
+/*
+ * Save stack-backtrace addresses into a stack_trace buffer.
+ */
+static void save_context_stack(struct stack_trace *trace, unsigned long sp,
+ struct task_struct *tsk, int savesched)
+{
+ for (;;) {
+ unsigned long *stack = (unsigned long *) sp;
+ unsigned long newsp, ip;
+
+ if (!validate_sp(sp, tsk, STACK_FRAME_OVERHEAD))
+ return;
+
+ newsp = stack[0];
+ ip = stack[STACK_FRAME_LR_SAVE];
+
+ if (savesched || !in_sched_functions(ip)) {
+ if (!trace->skip)
+ trace->entries[trace->nr_entries++] = ip;
+ else
+ trace->skip--;
+ }
+
+ if (trace->nr_entries >= trace->max_entries)
+ return;
+
+ sp = newsp;
+ }
+}
+
+void save_stack_trace(struct stack_trace *trace)
+{
+ unsigned long sp;
+
+ sp = current_stack_pointer();
+
+ save_context_stack(trace, sp, current, 1);
+}
+EXPORT_SYMBOL_GPL(save_stack_trace);
+
+void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
+{
+ unsigned long sp;
+
+ if (tsk == current)
+ sp = current_stack_pointer();
+ else
+ sp = tsk->thread.ksp;
+
+ save_context_stack(trace, sp, tsk, 0);
+}
+EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
+
+void
+save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
+{
+ save_context_stack(trace, regs->gpr[1], current, 0);
+}
+EXPORT_SYMBOL_GPL(save_stack_trace_regs);
+
+#ifdef CONFIG_HAVE_RELIABLE_STACKTRACE
+int
+save_stack_trace_tsk_reliable(struct task_struct *tsk,
+ struct stack_trace *trace)
+{
+ unsigned long sp;
+ unsigned long stack_page = (unsigned long)task_stack_page(tsk);
+ unsigned long stack_end;
+ int graph_idx = 0;
+
+ /*
+ * The last frame (unwinding first) may not yet have saved
+ * its LR onto the stack.
+ */
+ int firstframe = 1;
+
+ if (tsk == current)
+ sp = current_stack_pointer();
+ else
+ sp = tsk->thread.ksp;
+
+ stack_end = stack_page + THREAD_SIZE;
+ if (!is_idle_task(tsk)) {
+ /*
+ * For user tasks, this is the SP value loaded on
+ * kernel entry, see "PACAKSAVE(r13)" in _switch() and
+ * system_call_common()/EXCEPTION_PROLOG_COMMON().
+ *
+ * Likewise for non-swapper kernel threads,
+ * this also happens to be the top of the stack
+ * as setup by copy_thread().
+ *
+ * Note that stack backlinks are not properly setup by
+ * copy_thread() and thus, a forked task() will have
+ * an unreliable stack trace until it's been
+ * _switch()'ed to for the first time.
+ */
+ stack_end -= STACK_FRAME_OVERHEAD + sizeof(struct pt_regs);
+ } else {
+ /*
+ * idle tasks have a custom stack layout,
+ * c.f. cpu_idle_thread_init().
+ */
+ stack_end -= STACK_FRAME_OVERHEAD;
+ }
+
+ if (sp < stack_page + sizeof(struct thread_struct) ||
+ sp > stack_end - STACK_FRAME_MIN_SIZE) {
+ return 1;
+ }
+
+ for (;;) {
+ unsigned long *stack = (unsigned long *) sp;
+ unsigned long newsp, ip;
+
+ /* sanity check: ABI requires SP to be aligned 16 bytes. */
+ if (sp & 0xF)
+ return 1;
+
+ /* Mark stacktraces with exception frames as unreliable. */
+ if (sp <= stack_end - STACK_INT_FRAME_SIZE &&
+ stack[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) {
+ return 1;
+ }
+
+ newsp = stack[0];
+ /* Stack grows downwards; unwinder may only go up. */
+ if (newsp <= sp)
+ return 1;
+
+ if (newsp != stack_end &&
+ newsp > stack_end - STACK_FRAME_MIN_SIZE) {
+ return 1; /* invalid backlink, too far up. */
+ }
+
+ /* Examine the saved LR: it must point into kernel code. */
+ ip = stack[STACK_FRAME_LR_SAVE];
+ if (!firstframe && !__kernel_text_address(ip))
+ return 1;
+ firstframe = 0;
+
+ /*
+ * FIXME: IMHO these tests do not belong in
+ * arch-dependent code, they are generic.
+ */
+ ip = ftrace_graph_ret_addr(tsk, &graph_idx, ip, NULL);
+#ifdef CONFIG_KPROBES
+ /*
+ * Mark stacktraces with kretprobed functions on them
+ * as unreliable.
+ */
+ if (ip == (unsigned long)kretprobe_trampoline)
+ return 1;
+#endif
+
+ if (!trace->skip)
+ trace->entries[trace->nr_entries++] = ip;
+ else
+ trace->skip--;
+
+ if (newsp == stack_end)
+ break;
+
+ if (trace->nr_entries >= trace->max_entries)
+ return -E2BIG;
+
+ sp = newsp;
+ }
+ return 0;
+}
+EXPORT_SYMBOL_GPL(save_stack_trace_tsk_reliable);
+#endif /* CONFIG_HAVE_RELIABLE_STACKTRACE */
+
+#if defined(CONFIG_PPC_BOOK3S_64) && defined(CONFIG_NMI_IPI)
+static void handle_backtrace_ipi(struct pt_regs *regs)
+{
+ nmi_cpu_backtrace(regs);
+}
+
+static void raise_backtrace_ipi(cpumask_t *mask)
+{
+ unsigned int cpu;
+
+ for_each_cpu(cpu, mask) {
+ if (cpu == smp_processor_id())
+ handle_backtrace_ipi(NULL);
+ else
+ smp_send_safe_nmi_ipi(cpu, handle_backtrace_ipi, 5 * USEC_PER_SEC);
+ }
+
+ for_each_cpu(cpu, mask) {
+ struct paca_struct *p = paca_ptrs[cpu];
+
+ cpumask_clear_cpu(cpu, mask);
+
+ pr_warn("CPU %d didn't respond to backtrace IPI, inspecting paca.\n", cpu);
+ if (!virt_addr_valid(p)) {
+ pr_warn("paca pointer appears corrupt? (%px)\n", p);
+ continue;
+ }
+
+ pr_warn("irq_soft_mask: 0x%02x in_mce: %d in_nmi: %d",
+ p->irq_soft_mask, p->in_mce, p->in_nmi);
+
+ if (virt_addr_valid(p->__current))
+ pr_cont(" current: %d (%s)\n", p->__current->pid,
+ p->__current->comm);
+ else
+ pr_cont(" current pointer corrupt? (%px)\n", p->__current);
+
+ pr_warn("Back trace of paca->saved_r1 (0x%016llx) (possibly stale):\n", p->saved_r1);
+ show_stack(p->__current, (unsigned long *)p->saved_r1);
+ }
+}
+
+void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
+{
+ nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_backtrace_ipi);
+}
+#endif /* defined(CONFIG_PPC_BOOK3S_64) && defined(CONFIG_NMI_IPI) */