// SPDX-License-Identifier: GPL-2.0 #include <linux/sched/debug.h> #include <linux/sched/task_stack.h> #include <linux/stacktrace.h> #include <linux/ftrace.h> #include <linux/ptrace.h> #ifdef CONFIG_FRAME_POINTER struct stackframe { unsigned long fp; unsigned long ra; }; void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg) { unsigned long fp, sp, pc; if (regs) { fp = frame_pointer(regs); sp = user_stack_pointer(regs); pc = instruction_pointer(regs); } else if (task == NULL || task == current) { const register unsigned long current_fp __asm__ ("r8"); fp = current_fp; sp = current_stack_pointer; pc = (unsigned long)walk_stackframe; } else { /* task blocked in __switch_to */ fp = thread_saved_fp(task); sp = thread_saved_sp(task); pc = thread_saved_lr(task); } for (;;) { unsigned long low, high; struct stackframe *frame; if (unlikely(!__kernel_text_address(pc) || fn(pc, arg))) break; /* Validate frame pointer */ low = sp; high = ALIGN(sp, THREAD_SIZE); if (unlikely(fp < low || fp > high || fp & 0x3)) break; /* Unwind stack frame */ frame = (struct stackframe *)fp; sp = fp; fp = frame->fp; pc = ftrace_graph_ret_addr(current, NULL, frame->ra, (unsigned long *)(fp - 8)); } } #else /* !CONFIG_FRAME_POINTER */ static void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg) { unsigned long sp, pc; unsigned long *ksp; if (regs) { sp = user_stack_pointer(regs); pc = instruction_pointer(regs); } else if (task == NULL || task == current) { sp = current_stack_pointer; pc = (unsigned long)walk_stackframe; } else { /* task blocked in __switch_to */ sp = thread_saved_sp(task); pc = thread_saved_lr(task); } if (unlikely(sp & 0x3)) return; ksp = (unsigned long *)sp; while (!kstack_end(ksp)) { if (__kernel_text_address(pc) && unlikely(fn(pc, arg))) break; pc = (*ksp++) - 0x4; } } #endif /* CONFIG_FRAME_POINTER */ static bool print_trace_address(unsigned long pc, void *arg) { print_ip_sym((const char *)arg, pc); return false; } void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl) { pr_cont("Call Trace:\n"); walk_stackframe(task, NULL, print_trace_address, (void *)loglvl); } static bool save_wchan(unsigned long pc, void *arg) { if (!in_sched_functions(pc)) { unsigned long *p = arg; *p = pc; return true; } return false; } unsigned long __get_wchan(struct task_struct *task) { unsigned long pc = 0; walk_stackframe(task, NULL, save_wchan, &pc); return pc; } #ifdef CONFIG_STACKTRACE static bool __save_trace(unsigned long pc, void *arg, bool nosched) { struct stack_trace *trace = arg; if (unlikely(nosched && in_sched_functions(pc))) return false; if (unlikely(trace->skip > 0)) { trace->skip--; return false; } trace->entries[trace->nr_entries++] = pc; return (trace->nr_entries >= trace->max_entries); } static bool save_trace(unsigned long pc, void *arg) { return __save_trace(pc, arg, false); } /* * Save stack-backtrace addresses into a stack_trace buffer. */ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) { walk_stackframe(tsk, NULL, save_trace, trace); } EXPORT_SYMBOL_GPL(save_stack_trace_tsk); void save_stack_trace(struct stack_trace *trace) { save_stack_trace_tsk(NULL, trace); } EXPORT_SYMBOL_GPL(save_stack_trace); #endif /* CONFIG_STACKTRACE */