1// SPDX-License-Identifier: GPL-2.0
 2/*
 3 * Stack trace management functions
 4 *
 5 * Copyright (C) 2022 Loongson Technology Corporation Limited
 6 */
 7#include <linux/sched.h>
 8#include <linux/stacktrace.h>
 9#include <linux/uaccess.h>
10
11#include <asm/stacktrace.h>
12#include <asm/unwind.h>
13
14void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
15		     struct task_struct *task, struct pt_regs *regs)
16{
17	unsigned long addr;
18	struct pt_regs dummyregs;
19	struct unwind_state state;
20
21	if (!regs) {
22		regs = &dummyregs;
23
24		if (task == current) {
25			regs->regs[3] = (unsigned long)__builtin_frame_address(0);
26			regs->csr_era = (unsigned long)__builtin_return_address(0);
27		} else {
28			regs->regs[3] = thread_saved_fp(task);
29			regs->csr_era = thread_saved_ra(task);
30		}
31		regs->regs[1] = 0;
32	}
33
34	for (unwind_start(&state, task, regs);
35	     !unwind_done(&state); unwind_next_frame(&state)) {
36		addr = unwind_get_return_address(&state);
37		if (!addr || !consume_entry(cookie, addr))
38			break;
39	}
40}
41
42static int
43copy_stack_frame(unsigned long fp, struct stack_frame *frame)
44{
45	int ret = 1;
46	unsigned long err;
47	unsigned long __user *user_frame_tail;
48
49	user_frame_tail = (unsigned long *)(fp - sizeof(struct stack_frame));
50	if (!access_ok(user_frame_tail, sizeof(*frame)))
51		return 0;
52
53	pagefault_disable();
54	err = (__copy_from_user_inatomic(frame, user_frame_tail, sizeof(*frame)));
55	if (err || (unsigned long)user_frame_tail >= frame->fp)
56		ret = 0;
57	pagefault_enable();
58
59	return ret;
60}
61
62void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
63			  const struct pt_regs *regs)
64{
65	unsigned long fp = regs->regs[22];
66
67	while (fp && !((unsigned long)fp & 0xf)) {
68		struct stack_frame frame;
69
70		frame.fp = 0;
71		frame.ra = 0;
72		if (!copy_stack_frame(fp, &frame))
73			break;
74		if (!frame.ra)
75			break;
76		if (!consume_entry(cookie, frame.ra))
77			break;
78		fp = frame.fp;
79	}
80}