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Diffstat (limited to '')
| -rw-r--r-- | arch/powerpc/kernel/stacktrace.c | 211 |
1 files changed, 211 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/stacktrace.c b/arch/powerpc/kernel/stacktrace.c new file mode 100644 index 0000000000..e6a958a5da --- /dev/null +++ b/arch/powerpc/kernel/stacktrace.c @@ -0,0 +1,211 @@ +// 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/delay.h> +#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> + +void __no_sanitize_address arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie, + struct task_struct *task, struct pt_regs *regs) +{ + unsigned long sp; + + if (regs && !consume_entry(cookie, regs->nip)) + return; + + if (regs) + sp = regs->gpr[1]; + else if (task == current) + sp = current_stack_frame(); + else + sp = task->thread.ksp; + + for (;;) { + unsigned long *stack = (unsigned long *) sp; + unsigned long newsp, ip; + + if (!validate_sp(sp, task)) + return; + + newsp = stack[0]; + ip = stack[STACK_FRAME_LR_SAVE]; + + if (!consume_entry(cookie, ip)) + return; + + sp = newsp; + } +} + +/* + * This function returns an error if it detects any unreliable features of the + * stack. Otherwise it guarantees that the stack trace is reliable. + * + * If the task is not 'current', the caller *must* ensure the task is inactive. + */ +int __no_sanitize_address arch_stack_walk_reliable(stack_trace_consume_fn consume_entry, + void *cookie, struct task_struct *task) +{ + unsigned long sp; + unsigned long newsp; + unsigned long stack_page = (unsigned long)task_stack_page(task); + unsigned long stack_end; + int graph_idx = 0; + bool firstframe; + + stack_end = stack_page + THREAD_SIZE; + + // See copy_thread() for details. + if (task->flags & PF_KTHREAD) + stack_end -= STACK_FRAME_MIN_SIZE; + else + stack_end -= STACK_USER_INT_FRAME_SIZE; + + if (task == current) + sp = current_stack_frame(); + else + sp = task->thread.ksp; + + if (sp < stack_page + sizeof(struct thread_struct) || + sp > stack_end - STACK_FRAME_MIN_SIZE) { + return -EINVAL; + } + + for (firstframe = true; sp != stack_end; + firstframe = false, sp = newsp) { + unsigned long *stack = (unsigned long *) sp; + unsigned long ip; + + /* sanity check: ABI requires SP to be aligned 16 bytes. */ + if (sp & 0xF) + return -EINVAL; + + newsp = stack[0]; + /* Stack grows downwards; unwinder may only go up. */ + if (newsp <= sp) + return -EINVAL; + + if (newsp != stack_end && + newsp > stack_end - STACK_FRAME_MIN_SIZE) { + return -EINVAL; /* invalid backlink, too far up. */ + } + + /* + * We can only trust the bottom frame's backlink, the + * rest of the frame may be uninitialized, continue to + * the next. + */ + if (firstframe) + continue; + + /* Mark stacktraces with exception frames as unreliable. */ + if (sp <= stack_end - STACK_INT_FRAME_SIZE && + stack[STACK_INT_FRAME_MARKER_LONGS] == STACK_FRAME_REGS_MARKER) { + return -EINVAL; + } + + /* Examine the saved LR: it must point into kernel code. */ + ip = stack[STACK_FRAME_LR_SAVE]; + if (!__kernel_text_address(ip)) + return -EINVAL; + + /* + * FIXME: IMHO these tests do not belong in + * arch-dependent code, they are generic. + */ + ip = ftrace_graph_ret_addr(task, &graph_idx, ip, stack); +#ifdef CONFIG_KPROBES + /* + * Mark stacktraces with kretprobed functions on them + * as unreliable. + */ + if (ip == (unsigned long)__kretprobe_trampoline) + return -EINVAL; +#endif + + if (!consume_entry(cookie, ip)) + return -EINVAL; + } + return 0; +} + +#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) +{ + struct paca_struct *p; + unsigned int cpu; + u64 delay_us; + + for_each_cpu(cpu, mask) { + if (cpu == smp_processor_id()) { + handle_backtrace_ipi(NULL); + continue; + } + + delay_us = 5 * USEC_PER_SEC; + + if (smp_send_safe_nmi_ipi(cpu, handle_backtrace_ipi, delay_us)) { + // Now wait up to 5s for the other CPU to do its backtrace + while (cpumask_test_cpu(cpu, mask) && delay_us) { + udelay(1); + delay_us--; + } + + // Other CPU cleared itself from the mask + if (delay_us) + continue; + } + + 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, KERN_WARNING); + } +} + +void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu) +{ + nmi_trigger_cpumask_backtrace(mask, exclude_cpu, raise_backtrace_ipi); +} +#endif /* defined(CONFIG_PPC_BOOK3S_64) && defined(CONFIG_NMI_IPI) */ |