22  * AArch64 PCS assigns the frame pointer to x29.
36  * Unwind from one frame record (A) to the next frame record (B).
38  * We terminate early if the location of B indicates a malformed chain of frame
42 int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame)  in unwind_frame()  argument
44 	unsigned long fp = frame->fp;  in unwind_frame()
56 	if (test_bit(info.type, frame->stacks_done))  in unwind_frame()
72 	if (info.type == frame->prev_type) {  in unwind_frame()
73 		if (fp <= frame->prev_fp)  in unwind_frame()
76 		set_bit(frame->prev_type, frame->stacks_done);  in unwind_frame()
80 	 * Record this frame record's values and location. The prev_fp and  in unwind_frame()
83 	frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp));  in unwind_frame()
84 	frame->pc = READ_ONCE_NOCHECK(*(unsigned long *)(fp + 8));  in unwind_frame()
85 	frame->prev_fp = fp;  in unwind_frame()
86 	frame->prev_type = info.type;  in unwind_frame()
90 		(ptrauth_strip_insn_pac(frame->pc) == (unsigned long)return_to_handler)) {  in unwind_frame()
94 		 * modified a return address (LR) in a stack frame  in unwind_frame()
98 		ret_stack = ftrace_graph_get_ret_stack(tsk, frame->graph++);  in unwind_frame()
101 		frame->pc = ret_stack->ret;  in unwind_frame()
105 	frame->pc = ptrauth_strip_insn_pac(frame->pc);  in unwind_frame()
113 	if (!frame->fp && !frame->pc)  in unwind_frame()
120 void notrace walk_stackframe(struct task_struct *tsk, struct stackframe *frame,  in walk_stackframe()  argument
126 		if (!fn(data, frame->pc))  in walk_stackframe()
128 		ret = unwind_frame(tsk, frame);  in walk_stackframe()
143 	struct stackframe frame;  in dump_backtrace()  local
161 		start_backtrace(&frame,  in dump_backtrace()
168 		start_backtrace(&frame,  in dump_backtrace()
175 		/* skip until specified stack frame */  in dump_backtrace()
177 			dump_backtrace_entry(frame.pc, loglvl);  in dump_backtrace()
178 		} else if (frame.fp == regs->regs[29]) {  in dump_backtrace()
183 			 * stack frame does not contain the corresponding pc  in dump_backtrace()
189 	} while (!unwind_frame(tsk, &frame));  in dump_backtrace()
205 	struct stackframe frame;  in arch_stack_walk()  local
208 		start_backtrace(&frame, regs->regs[29], regs->pc);  in arch_stack_walk()
210 		start_backtrace(&frame,  in arch_stack_walk()
214 		start_backtrace(&frame, thread_saved_fp(task),  in arch_stack_walk()
217 	walk_stackframe(task, &frame, consume_entry, cookie);  in arch_stack_walk()