| 1 | |
| 2 | |
| 3 | * Stack trace management functions
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| 4 | *
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| 5 | * Copyright (C) 2022 Loongson Technology Corporation Limited
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| 6 |
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| 7 | #include <linux/sched.h>
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| 8 | #include <linux/stacktrace.h>
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| 9 | #include <linux/uaccess.h>
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| 10 |
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| 11 | #include <asm/stacktrace.h>
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| 12 | #include <asm/unwind.h>
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| 13 |
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| 14 | void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
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| 15 | struct task_struct *task, struct pt_regs *regs)
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| 16 | {
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| 17 | unsigned long addr;
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| 18 | struct pt_regs dummyregs;
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| 19 | struct unwind_state state;
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| 20 |
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| 21 | if (!regs) {
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| 22 | regs = &dummyregs;
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| 23 |
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| 24 | if (task == current) {
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| 25 | regs->regs[3] = (unsigned long)__builtin_frame_address(0);
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| 26 | regs->csr_era = (unsigned long)__builtin_return_address(0);
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| 27 | } else {
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| 28 | regs->regs[3] = thread_saved_fp(task);
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| 29 | regs->csr_era = thread_saved_ra(task);
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| 30 | }
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| 31 | regs->regs[1] = 0;
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| 32 | regs->regs[22] = 0;
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| 33 | }
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| 34 |
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| 35 | for (unwind_start(&state, task, regs);
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| 36 | !unwind_done(&state); unwind_next_frame(&state)) {
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| 37 | addr = unwind_get_return_address(&state);
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| 38 | if (!addr || !consume_entry(cookie, addr))
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| 39 | break;
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| 40 | }
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| 41 | }
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| 42 |
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| 43 | int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry,
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| 44 | void *cookie, struct task_struct *task)
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| 45 | {
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| 46 | unsigned long addr;
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| 47 | struct pt_regs dummyregs;
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| 48 | struct pt_regs *regs = &dummyregs;
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| 49 | struct unwind_state state;
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| 50 |
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| 51 | if (task == current) {
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| 52 | regs->regs[3] = (unsigned long)__builtin_frame_address(0);
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| 53 | regs->csr_era = (unsigned long)__builtin_return_address(0);
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| 54 | regs->regs[22] = 0;
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| 55 | } else {
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| 56 | regs->regs[3] = thread_saved_fp(task);
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| 57 | regs->csr_era = thread_saved_ra(task);
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| 58 | regs->regs[22] = task->thread.reg22;
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| 59 | }
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| 60 | regs->regs[1] = 0;
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| 61 |
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| 62 | for (unwind_start(&state, task, regs);
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| 63 | !unwind_done(&state) && !unwind_error(&state); unwind_next_frame(&state)) {
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| 64 | addr = unwind_get_return_address(&state);
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| 65 |
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| 66 | |
| 67 | * A NULL or invalid return address probably means there's some
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| 68 | * generated code which __kernel_text_address() doesn't know about.
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| 69 |
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| 70 | if (!addr)
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| 71 | return -EINVAL;
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| 72 |
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| 73 | if (!consume_entry(cookie, addr))
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| 74 | return -EINVAL;
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| 75 | }
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| 76 |
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| 77 |
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| 78 | if (unwind_error(&state))
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| 79 | return -EINVAL;
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| 80 |
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| 81 | return 0;
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| 82 | }
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| 83 |
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| 84 | static int
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| 85 | copy_stack_frame(unsigned long fp, struct stack_frame *frame)
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| 86 | {
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| 87 | int ret = 1;
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| 88 | unsigned long err;
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| 89 | unsigned long __user *user_frame_tail;
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| 90 |
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| 91 | user_frame_tail = (unsigned long *)(fp - sizeof(struct stack_frame));
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| 92 | if (!access_ok(user_frame_tail, sizeof(*frame)))
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| 93 | return 0;
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| 94 |
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| 95 | pagefault_disable();
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| 96 | err = (__copy_from_user_inatomic(frame, user_frame_tail, sizeof(*frame)));
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| 97 | if (err || (unsigned long)user_frame_tail >= frame->fp)
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| 98 | ret = 0;
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| 99 | pagefault_enable();
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| 100 |
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| 101 | return ret;
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| 102 | }
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| 103 |
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| 104 | void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
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| 105 | const struct pt_regs *regs)
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| 106 | {
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| 107 | unsigned long fp = regs->regs[22];
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| 108 |
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| 109 | while (fp && !((unsigned long)fp & 0xf)) {
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| 110 | struct stack_frame frame;
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| 111 |
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| 112 | frame.fp = 0;
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| 113 | frame.ra = 0;
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| 114 | if (!copy_stack_frame(fp, &frame))
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| 115 | break;
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| 116 | if (!frame.ra)
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| 117 | break;
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| 118 | if (!consume_entry(cookie, frame.ra))
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| 119 | break;
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| 120 | fp = frame.fp;
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| 121 | }
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| 122 | }
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