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
arch_stack_walk(stack_trace_consume_fn consume_entry,void * cookie,struct task_struct * task,struct pt_regs * regs)14 void 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
42 static int
copy_stack_frame(unsigned long fp,struct stack_frame * frame)43 copy_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
arch_stack_walk_user(stack_trace_consume_fn consume_entry,void * cookie,const struct pt_regs * regs)62 void 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 }
81