diff options
Diffstat (limited to 'arch/powerpc/kernel/stacktrace.c')
| -rw-r--r-- | arch/powerpc/kernel/stacktrace.c | 181 |
1 files changed, 174 insertions, 7 deletions
diff --git a/arch/powerpc/kernel/stacktrace.c b/arch/powerpc/kernel/stacktrace.c index d534ed9015384..07e97f289c520 100644 --- a/arch/powerpc/kernel/stacktrace.c +++ b/arch/powerpc/kernel/stacktrace.c @@ -1,21 +1,27 @@ +// SPDX-License-Identifier: GPL-2.0 + /* - * Stack trace utility + * Stack trace utility functions etc. * * Copyright 2008 Christoph Hellwig, IBM Corp. - * - * - * This program is free software; you can redistribute it and/or - * modify it under the terms of the GNU General Public License - * as published by the Free Software Foundation; either version - * 2 of the License, or (at your option) any later version. + * 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. @@ -76,3 +82,164 @@ 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 */ + +#ifdef CONFIG_PPC_BOOK3S_64 +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 /* CONFIG_PPC64 */ |