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213 lines
5.4 KiB
213 lines
5.4 KiB
// 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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void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie, |
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struct task_struct *task, struct pt_regs *regs) |
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{ |
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unsigned long sp; |
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if (regs && !consume_entry(cookie, regs->nip)) |
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return; |
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if (regs) |
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sp = regs->gpr[1]; |
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else if (task == current) |
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sp = current_stack_frame(); |
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else |
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sp = task->thread.ksp; |
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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, task, 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 (!consume_entry(cookie, ip)) |
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return; |
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sp = newsp; |
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} |
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} |
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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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int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry, |
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void *cookie, struct task_struct *task) |
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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(task); |
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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(task)) { |
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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 (task == current) |
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sp = current_stack_frame(); |
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else |
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sp = task->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(task, &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 (!consume_entry(cookie, ip)) |
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return -EINVAL; |
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} |
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return 0; |
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} |
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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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