// SPDX-License-Identifier: GPL-2.0-only/* * Stack tracing support * * Copyright (C) 2012 ARM Ltd. */#include <linux/kernel.h>#include <linux/efi.h>#include <linux/export.h>#include <linux/ftrace.h>#include <linux/sched.h>#include <linux/sched/debug.h>#include <linux/sched/task_stack.h>#include <linux/stacktrace.h> #include <asm/efi.h>#include <asm/irq.h>#include <asm/stack_pointer.h>#include <asm/stacktrace.h> /* * Start an unwind from a pt_regs. * * The unwind will begin at the PC within the regs. * * The regs must be on a stack currently owned by the calling task. */static __always_inline void unwind_init_from_regs(struct unwind_state *state,						  struct pt_regs *regs){	unwind_init_common(state, current); 	state->fp = regs->regs[29];	state->pc = regs->pc;} /* * Start an unwind from a caller. * * The unwind will begin at the caller of whichever function this is inlined * into. * * The function which invokes this must be noinline. */static __always_inline void unwind_init_from_caller(struct unwind_state *state){	unwind_init_common(state, current); 	state->fp = (unsigned long)__builtin_frame_address(1);	state->pc = (unsigned long)__builtin_return_address(0);} /* * Start an unwind from a blocked task. * * The unwind will begin at the blocked tasks saved PC (i.e. the caller of * cpu_switch_to()). * * The caller should ensure the task is blocked in cpu_switch_to() for the * duration of the unwind, or the unwind will be bogus. It is never valid to * call this for the current task. */static __always_inline void unwind_init_from_task(struct unwind_state *state,						  struct task_struct *task){	unwind_init_common(state, task); 	state->fp = thread_saved_fp(task);	state->pc = thread_saved_pc(task);} /* * Unwind from one frame record (A) to the next frame record (B). * * We terminate early if the location of B indicates a malformed chain of frame * records (e.g. a cycle), determined based on the location and fp value of A * and the location (but not the fp value) of B. */static int notrace unwind_next(struct unwind_state *state){	struct task_struct *tsk = state->task;	unsigned long fp = state->fp;	int err; 	/* Final frame; nothing to unwind */	if (fp == (unsigned long)task_pt_regs(tsk)->stackframe)		return -ENOENT; 	err = unwind_next_frame_record(state);	if (err)		return err; 	state->pc = ptrauth_strip_insn_pac(state->pc); #ifdef CONFIG_FUNCTION_GRAPH_TRACER	if (tsk->ret_stack &&		(state->pc == (unsigned long)return_to_handler)) {		unsigned long orig_pc;		/*		 * This is a case where function graph tracer has		 * modified a return address (LR) in a stack frame		 * to hook a function return.		 * So replace it to an original value.		 */		orig_pc = ftrace_graph_ret_addr(tsk, NULL, state->pc,						(void *)state->fp);		if (WARN_ON_ONCE(state->pc == orig_pc))			return -EINVAL;		state->pc = orig_pc;	}#endif /* CONFIG_FUNCTION_GRAPH_TRACER */#ifdef CONFIG_KRETPROBES	if (is_kretprobe_trampoline(state->pc))		state->pc = kretprobe_find_ret_addr(tsk, (void *)state->fp, &state->kr_cur);#endif 	return 0;}NOKPROBE_SYMBOL(unwind_next); static void notrace unwind(struct unwind_state *state,			   stack_trace_consume_fn consume_entry, void *cookie){	while (1) {		int ret; 		if (!consume_entry(cookie, state->pc))			break;		ret = unwind_next(state);		if (ret < 0)			break;	}}NOKPROBE_SYMBOL(unwind); static bool dump_backtrace_entry(void *arg, unsigned long where){	char *loglvl = arg;	printk("%s %pSb\n", loglvl, (void *)where);	return true;} void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,		    const char *loglvl){	pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk); 	if (regs && user_mode(regs))		return; 	if (!tsk)		tsk = current; 	if (!try_get_task_stack(tsk))		return; 	printk("%sCall trace:\n", loglvl);	arch_stack_walk(dump_backtrace_entry, (void *)loglvl, tsk, regs); 	put_task_stack(tsk);} void show_stack(struct task_struct *tsk, unsigned long *sp, const char *loglvl){	dump_backtrace(NULL, tsk, loglvl);	barrier();} /* * Per-cpu stacks are only accessible when unwinding the current task in a * non-preemptible context. */#define STACKINFO_CPU(name)					\	({							\		((task == current) && !preemptible())		\			? stackinfo_get_##name()		\			: stackinfo_get_unknown();		\	}) /* * SDEI stacks are only accessible when unwinding the current task in an NMI * context. */#define STACKINFO_SDEI(name)					\	({							\		((task == current) && in_nmi())			\			? stackinfo_get_sdei_##name()		\			: stackinfo_get_unknown();		\	}) #define STACKINFO_EFI						\	({							\		((task == current) && current_in_efi())		\			? stackinfo_get_efi()			\			: stackinfo_get_unknown();		\	}) noinline noinstr void arch_stack_walk(stack_trace_consume_fn consume_entry,			      void *cookie, struct task_struct *task,			      struct pt_regs *regs){	struct stack_info stacks[] = {		stackinfo_get_task(task),		STACKINFO_CPU(irq),#if defined(CONFIG_VMAP_STACK)		STACKINFO_CPU(overflow),#endif#if defined(CONFIG_VMAP_STACK) && defined(CONFIG_ARM_SDE_INTERFACE)		STACKINFO_SDEI(normal),		STACKINFO_SDEI(critical),#endif#ifdef CONFIG_EFI		STACKINFO_EFI,#endif	};	struct unwind_state state = {		.stacks = stacks,		.nr_stacks = ARRAY_SIZE(stacks),	}; 	if (regs) {		if (task != current)			return;		unwind_init_from_regs(&state, regs);	} else if (task == current) {		unwind_init_from_caller(&state);	} else {		unwind_init_from_task(&state, task);	} 	unwind(&state, consume_entry, cookie);}