1 // SPDX-License-Identifier: GPL-2.0
4 * Stack trace utility functions etc.
6 * Copyright 2008 Christoph Hellwig, IBM Corp.
7 * Copyright 2018 SUSE Linux GmbH
8 * Copyright 2018 Nick Piggin, Michael Ellerman, IBM Corp.
11 #include <linux/delay.h>
12 #include <linux/export.h>
13 #include <linux/kallsyms.h>
14 #include <linux/module.h>
15 #include <linux/nmi.h>
16 #include <linux/sched.h>
17 #include <linux/sched/debug.h>
18 #include <linux/sched/task_stack.h>
19 #include <linux/stacktrace.h>
20 #include <asm/ptrace.h>
21 #include <asm/processor.h>
22 #include <linux/ftrace.h>
23 #include <asm/kprobes.h>
27 void __no_sanitize_address arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
28 struct task_struct *task, struct pt_regs *regs)
32 if (regs && !consume_entry(cookie, regs->nip))
37 else if (task == current)
38 sp = current_stack_frame();
40 sp = task->thread.ksp;
43 unsigned long *stack = (unsigned long *) sp;
44 unsigned long newsp, ip;
46 if (!validate_sp(sp, task))
50 ip = stack[STACK_FRAME_LR_SAVE];
52 if (!consume_entry(cookie, ip))
60 * This function returns an error if it detects any unreliable features of the
61 * stack. Otherwise it guarantees that the stack trace is reliable.
63 * If the task is not 'current', the caller *must* ensure the task is inactive.
65 int __no_sanitize_address arch_stack_walk_reliable(stack_trace_consume_fn consume_entry,
66 void *cookie, struct task_struct *task)
70 unsigned long stack_page = (unsigned long)task_stack_page(task);
71 unsigned long stack_end;
75 stack_end = stack_page + THREAD_SIZE;
77 // See copy_thread() for details.
78 if (task->flags & PF_KTHREAD)
79 stack_end -= STACK_FRAME_MIN_SIZE;
81 stack_end -= STACK_USER_INT_FRAME_SIZE;
84 sp = current_stack_frame();
86 sp = task->thread.ksp;
88 if (sp < stack_page + sizeof(struct thread_struct) ||
89 sp > stack_end - STACK_FRAME_MIN_SIZE) {
93 for (firstframe = true; sp != stack_end;
94 firstframe = false, sp = newsp) {
95 unsigned long *stack = (unsigned long *) sp;
98 /* sanity check: ABI requires SP to be aligned 16 bytes. */
103 /* Stack grows downwards; unwinder may only go up. */
107 if (newsp != stack_end &&
108 newsp > stack_end - STACK_FRAME_MIN_SIZE) {
109 return -EINVAL; /* invalid backlink, too far up. */
113 * We can only trust the bottom frame's backlink, the
114 * rest of the frame may be uninitialized, continue to
120 /* Mark stacktraces with exception frames as unreliable. */
121 if (sp <= stack_end - STACK_INT_FRAME_SIZE &&
122 stack[STACK_INT_FRAME_MARKER_LONGS] == STACK_FRAME_REGS_MARKER) {
126 /* Examine the saved LR: it must point into kernel code. */
127 ip = stack[STACK_FRAME_LR_SAVE];
128 if (!__kernel_text_address(ip))
132 * FIXME: IMHO these tests do not belong in
133 * arch-dependent code, they are generic.
135 ip = ftrace_graph_ret_addr(task, &graph_idx, ip, stack);
136 #ifdef CONFIG_KPROBES
138 * Mark stacktraces with kretprobed functions on them
141 if (ip == (unsigned long)__kretprobe_trampoline)
145 if (!consume_entry(cookie, ip))
151 #if defined(CONFIG_PPC_BOOK3S_64) && defined(CONFIG_NMI_IPI)
152 static void handle_backtrace_ipi(struct pt_regs *regs)
154 nmi_cpu_backtrace(regs);
157 static void raise_backtrace_ipi(cpumask_t *mask)
159 struct paca_struct *p;
163 for_each_cpu(cpu, mask) {
164 if (cpu == smp_processor_id()) {
165 handle_backtrace_ipi(NULL);
169 delay_us = 5 * USEC_PER_SEC;
171 if (smp_send_safe_nmi_ipi(cpu, handle_backtrace_ipi, delay_us)) {
172 // Now wait up to 5s for the other CPU to do its backtrace
173 while (cpumask_test_cpu(cpu, mask) && delay_us) {
178 // Other CPU cleared itself from the mask
185 cpumask_clear_cpu(cpu, mask);
187 pr_warn("CPU %d didn't respond to backtrace IPI, inspecting paca.\n", cpu);
188 if (!virt_addr_valid(p)) {
189 pr_warn("paca pointer appears corrupt? (%px)\n", p);
193 pr_warn("irq_soft_mask: 0x%02x in_mce: %d in_nmi: %d",
194 p->irq_soft_mask, p->in_mce, p->in_nmi);
196 if (virt_addr_valid(p->__current))
197 pr_cont(" current: %d (%s)\n", p->__current->pid,
200 pr_cont(" current pointer corrupt? (%px)\n", p->__current);
202 pr_warn("Back trace of paca->saved_r1 (0x%016llx) (possibly stale):\n", p->saved_r1);
203 show_stack(p->__current, (unsigned long *)p->saved_r1, KERN_WARNING);
207 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu)
209 nmi_trigger_cpumask_backtrace(mask, exclude_cpu, raise_backtrace_ipi);
211 #endif /* defined(CONFIG_PPC_BOOK3S_64) && defined(CONFIG_NMI_IPI) */