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![Dmitry Safonov](/assets/img/avatar_default.png)
Now the last users of show_stack() got converted to use an explicit log level, show_stack_loglvl() can drop it's redundant suffix and become once again well known show_stack(). Signed-off-by: Dmitry Safonov <dima@arista.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20200418201944.482088-51-dima@arista.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
271 lines
6.5 KiB
C
271 lines
6.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Stack trace utility functions etc.
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*
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* Copyright 2008 Christoph Hellwig, IBM Corp.
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* Copyright 2018 SUSE Linux GmbH
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* Copyright 2018 Nick Piggin, Michael Ellerman, IBM Corp.
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*/
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#include <linux/export.h>
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#include <linux/kallsyms.h>
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#include <linux/module.h>
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#include <linux/nmi.h>
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#include <linux/sched.h>
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#include <linux/sched/debug.h>
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#include <linux/sched/task_stack.h>
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#include <linux/stacktrace.h>
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#include <asm/ptrace.h>
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#include <asm/processor.h>
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#include <linux/ftrace.h>
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#include <asm/kprobes.h>
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#include <asm/paca.h>
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/*
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* Save stack-backtrace addresses into a stack_trace buffer.
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*/
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static void save_context_stack(struct stack_trace *trace, unsigned long sp,
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struct task_struct *tsk, int savesched)
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{
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for (;;) {
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unsigned long *stack = (unsigned long *) sp;
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unsigned long newsp, ip;
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if (!validate_sp(sp, tsk, STACK_FRAME_OVERHEAD))
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return;
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newsp = stack[0];
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ip = stack[STACK_FRAME_LR_SAVE];
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if (savesched || !in_sched_functions(ip)) {
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if (!trace->skip)
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trace->entries[trace->nr_entries++] = ip;
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else
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trace->skip--;
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}
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if (trace->nr_entries >= trace->max_entries)
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return;
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sp = newsp;
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}
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}
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void save_stack_trace(struct stack_trace *trace)
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{
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unsigned long sp;
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sp = current_stack_frame();
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save_context_stack(trace, sp, current, 1);
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}
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EXPORT_SYMBOL_GPL(save_stack_trace);
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void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
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{
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unsigned long sp;
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if (!try_get_task_stack(tsk))
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return;
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if (tsk == current)
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sp = current_stack_frame();
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else
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sp = tsk->thread.ksp;
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save_context_stack(trace, sp, tsk, 0);
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put_task_stack(tsk);
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}
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EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
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void
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save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
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{
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save_context_stack(trace, regs->gpr[1], current, 0);
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}
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EXPORT_SYMBOL_GPL(save_stack_trace_regs);
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#ifdef CONFIG_HAVE_RELIABLE_STACKTRACE
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/*
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* This function returns an error if it detects any unreliable features of the
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* stack. Otherwise it guarantees that the stack trace is reliable.
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*
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* If the task is not 'current', the caller *must* ensure the task is inactive.
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*/
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static int __save_stack_trace_tsk_reliable(struct task_struct *tsk,
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struct stack_trace *trace)
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{
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unsigned long sp;
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unsigned long newsp;
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unsigned long stack_page = (unsigned long)task_stack_page(tsk);
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unsigned long stack_end;
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int graph_idx = 0;
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bool firstframe;
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stack_end = stack_page + THREAD_SIZE;
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if (!is_idle_task(tsk)) {
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/*
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* For user tasks, this is the SP value loaded on
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* kernel entry, see "PACAKSAVE(r13)" in _switch() and
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* system_call_common()/EXCEPTION_PROLOG_COMMON().
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*
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* Likewise for non-swapper kernel threads,
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* this also happens to be the top of the stack
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* as setup by copy_thread().
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*
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* Note that stack backlinks are not properly setup by
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* copy_thread() and thus, a forked task() will have
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* an unreliable stack trace until it's been
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* _switch()'ed to for the first time.
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*/
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stack_end -= STACK_FRAME_OVERHEAD + sizeof(struct pt_regs);
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} else {
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/*
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* idle tasks have a custom stack layout,
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* c.f. cpu_idle_thread_init().
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*/
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stack_end -= STACK_FRAME_OVERHEAD;
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}
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if (tsk == current)
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sp = current_stack_frame();
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else
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sp = tsk->thread.ksp;
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if (sp < stack_page + sizeof(struct thread_struct) ||
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sp > stack_end - STACK_FRAME_MIN_SIZE) {
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return -EINVAL;
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}
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for (firstframe = true; sp != stack_end;
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firstframe = false, sp = newsp) {
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unsigned long *stack = (unsigned long *) sp;
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unsigned long ip;
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/* sanity check: ABI requires SP to be aligned 16 bytes. */
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if (sp & 0xF)
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return -EINVAL;
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newsp = stack[0];
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/* Stack grows downwards; unwinder may only go up. */
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if (newsp <= sp)
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return -EINVAL;
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if (newsp != stack_end &&
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newsp > stack_end - STACK_FRAME_MIN_SIZE) {
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return -EINVAL; /* invalid backlink, too far up. */
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}
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/*
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* We can only trust the bottom frame's backlink, the
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* rest of the frame may be uninitialized, continue to
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* the next.
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*/
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if (firstframe)
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continue;
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/* Mark stacktraces with exception frames as unreliable. */
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if (sp <= stack_end - STACK_INT_FRAME_SIZE &&
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stack[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) {
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return -EINVAL;
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}
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/* Examine the saved LR: it must point into kernel code. */
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ip = stack[STACK_FRAME_LR_SAVE];
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if (!__kernel_text_address(ip))
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return -EINVAL;
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/*
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* FIXME: IMHO these tests do not belong in
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* arch-dependent code, they are generic.
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*/
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ip = ftrace_graph_ret_addr(tsk, &graph_idx, ip, stack);
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#ifdef CONFIG_KPROBES
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/*
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* Mark stacktraces with kretprobed functions on them
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* as unreliable.
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*/
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if (ip == (unsigned long)kretprobe_trampoline)
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return -EINVAL;
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#endif
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if (trace->nr_entries >= trace->max_entries)
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return -E2BIG;
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if (!trace->skip)
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trace->entries[trace->nr_entries++] = ip;
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else
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trace->skip--;
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}
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return 0;
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}
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int save_stack_trace_tsk_reliable(struct task_struct *tsk,
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struct stack_trace *trace)
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{
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int ret;
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/*
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* If the task doesn't have a stack (e.g., a zombie), the stack is
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* "reliably" empty.
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*/
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if (!try_get_task_stack(tsk))
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return 0;
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ret = __save_stack_trace_tsk_reliable(tsk, trace);
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put_task_stack(tsk);
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return ret;
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}
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#endif /* CONFIG_HAVE_RELIABLE_STACKTRACE */
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#if defined(CONFIG_PPC_BOOK3S_64) && defined(CONFIG_NMI_IPI)
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static void handle_backtrace_ipi(struct pt_regs *regs)
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{
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nmi_cpu_backtrace(regs);
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}
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static void raise_backtrace_ipi(cpumask_t *mask)
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{
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unsigned int cpu;
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for_each_cpu(cpu, mask) {
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if (cpu == smp_processor_id())
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handle_backtrace_ipi(NULL);
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else
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smp_send_safe_nmi_ipi(cpu, handle_backtrace_ipi, 5 * USEC_PER_SEC);
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}
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for_each_cpu(cpu, mask) {
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struct paca_struct *p = paca_ptrs[cpu];
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cpumask_clear_cpu(cpu, mask);
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pr_warn("CPU %d didn't respond to backtrace IPI, inspecting paca.\n", cpu);
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if (!virt_addr_valid(p)) {
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pr_warn("paca pointer appears corrupt? (%px)\n", p);
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continue;
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}
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pr_warn("irq_soft_mask: 0x%02x in_mce: %d in_nmi: %d",
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p->irq_soft_mask, p->in_mce, p->in_nmi);
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if (virt_addr_valid(p->__current))
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pr_cont(" current: %d (%s)\n", p->__current->pid,
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p->__current->comm);
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else
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pr_cont(" current pointer corrupt? (%px)\n", p->__current);
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pr_warn("Back trace of paca->saved_r1 (0x%016llx) (possibly stale):\n", p->saved_r1);
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show_stack(p->__current, (unsigned long *)p->saved_r1, KERN_WARNING);
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}
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}
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void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
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{
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nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_backtrace_ipi);
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}
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#endif /* defined(CONFIG_PPC_BOOK3S_64) && defined(CONFIG_NMI_IPI) */
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