// 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 <linux/rethook.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); 		/*		 * Mark stacktraces with kretprobed functions on them		 * as unreliable.		 */#ifdef CONFIG_RETHOOK		if (ip == (unsigned long)arch_rethook_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) */