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 regs = &dummyregs;
22
23 if (task == current) {
24 regs->regs[3] = (unsigned long)__builtin_frame_address(0);
25 regs->csr_era = (unsigned long)__builtin_return_address(0);
26 } else {
27 regs->regs[3] = thread_saved_fp(task);
28 regs->csr_era = thread_saved_ra(task);
29 }
30
31 regs->regs[1] = 0;
32 for (unwind_start(&state, task, regs);
33 !unwind_done(&state); unwind_next_frame(&state)) {
34 addr = unwind_get_return_address(&state);
35 if (!addr || !consume_entry(cookie, addr))
36 break;
37 }
38 }
39
40 static int
copy_stack_frame(unsigned long fp,struct stack_frame * frame)41 copy_stack_frame(unsigned long fp, struct stack_frame *frame)
42 {
43 int ret = 1;
44 unsigned long err;
45 unsigned long __user *user_frame_tail;
46
47 user_frame_tail = (unsigned long *)(fp - sizeof(struct stack_frame));
48 if (!access_ok(user_frame_tail, sizeof(*frame)))
49 return 0;
50
51 pagefault_disable();
52 err = (__copy_from_user_inatomic(frame, user_frame_tail, sizeof(*frame)));
53 if (err || (unsigned long)user_frame_tail >= frame->fp)
54 ret = 0;
55 pagefault_enable();
56
57 return ret;
58 }
59
arch_stack_walk_user(stack_trace_consume_fn consume_entry,void * cookie,const struct pt_regs * regs)60 void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
61 const struct pt_regs *regs)
62 {
63 unsigned long fp = regs->regs[22];
64
65 while (fp && !((unsigned long)fp & 0xf)) {
66 struct stack_frame frame;
67
68 frame.fp = 0;
69 frame.ra = 0;
70 if (!copy_stack_frame(fp, &frame))
71 break;
72 if (!frame.ra)
73 break;
74 if (!consume_entry(cookie, frame.ra))
75 break;
76 fp = frame.fp;
77 }
78 }
79