| 1 | |
| 2 | * Stack trace management functions
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| 3 | *
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| 4 | * Copyright (C) 2006-2009 Red Hat, Inc., Ingo Molnar <[email protected]>
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| 5 |
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| 6 | #include <linux/sched.h>
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| 7 | #include <linux/sched/debug.h>
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| 8 | #include <linux/sched/task_stack.h>
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| 9 | #include <linux/stacktrace.h>
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| 10 | #include <linux/export.h>
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| 11 | #include <linux/uaccess.h>
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| 12 | #include <asm/stacktrace.h>
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| 13 | #include <asm/unwind.h>
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| 14 |
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| 15 | void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
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| 16 | struct task_struct *task, struct pt_regs *regs)
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| 17 | {
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| 18 | struct unwind_state state;
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| 19 | unsigned long addr;
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| 20 |
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| 21 | if (regs && !consume_entry(cookie, regs->ip))
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| 22 | return;
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| 23 |
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| 24 | for (unwind_start(&state, task, regs, NULL); !unwind_done(&state);
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| 25 | unwind_next_frame(&state)) {
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| 26 | addr = unwind_get_return_address(&state);
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| 27 | if (!addr || !consume_entry(cookie, addr))
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| 28 | break;
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| 29 | }
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| 30 | }
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| 31 |
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| 32 | int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry,
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| 33 | void *cookie, struct task_struct *task)
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| 34 | {
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| 35 | struct unwind_state state;
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| 36 | struct pt_regs *regs;
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| 37 | unsigned long addr;
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| 38 |
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| 39 | for (unwind_start(&state, task, NULL, NULL);
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| 40 | !unwind_done(&state) && !unwind_error(&state);
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| 41 | unwind_next_frame(&state)) {
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| 42 |
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| 43 | regs = unwind_get_entry_regs(&state, NULL);
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| 44 | if (regs) {
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| 45 |
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| 46 | if (user_mode(regs))
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| 47 | return 0;
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| 48 |
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| 49 | |
| 50 | * Kernel mode registers on the stack indicate an
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| 51 | * in-kernel interrupt or exception (e.g., preemption
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| 52 | * or a page fault), which can make frame pointers
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| 53 | * unreliable.
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| 54 |
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| 55 | if (IS_ENABLED(CONFIG_FRAME_POINTER))
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| 56 | return -EINVAL;
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| 57 | }
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| 58 |
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| 59 | addr = unwind_get_return_address(&state);
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| 60 |
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| 61 | |
| 62 | * A NULL or invalid return address probably means there's some
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| 63 | * generated code which __kernel_text_address() doesn't know
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| 64 | * about.
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| 65 |
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| 66 | if (!addr)
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| 67 | return -EINVAL;
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| 68 |
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| 69 | if (!consume_entry(cookie, addr))
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| 70 | return -EINVAL;
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| 71 | }
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| 72 |
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| 73 |
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| 74 | if (unwind_error(&state))
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| 75 | return -EINVAL;
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| 76 |
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| 77 | return 0;
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| 78 | }
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| 79 |
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| 80 |
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| 81 |
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| 82 | struct stack_frame_user {
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| 83 | const void __user *next_fp;
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| 84 | unsigned long ret_addr;
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| 85 | };
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| 86 |
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| 87 | static int
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| 88 | copy_stack_frame(const struct stack_frame_user __user *fp,
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| 89 | struct stack_frame_user *frame)
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| 90 | {
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| 91 | int ret;
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| 92 |
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| 93 | if (!__access_ok(fp, sizeof(*frame)))
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| 94 | return 0;
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| 95 |
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| 96 | ret = 1;
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| 97 | pagefault_disable();
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| 98 | if (__get_user(frame->next_fp, &fp->next_fp) ||
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| 99 | __get_user(frame->ret_addr, &fp->ret_addr))
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| 100 | ret = 0;
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| 101 | pagefault_enable();
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| 102 |
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| 103 | return ret;
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| 104 | }
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| 105 |
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| 106 | void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
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| 107 | const struct pt_regs *regs)
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| 108 | {
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| 109 | const void __user *fp = (const void __user *)regs->bp;
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| 110 |
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| 111 | if (!consume_entry(cookie, regs->ip))
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| 112 | return;
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| 113 |
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| 114 | while (1) {
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| 115 | struct stack_frame_user frame;
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| 116 |
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| 117 | frame.next_fp = NULL;
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| 118 | frame.ret_addr = 0;
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| 119 | if (!copy_stack_frame(fp, &frame))
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| 120 | break;
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| 121 | if ((unsigned long)fp < regs->sp)
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| 122 | break;
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| 123 | if (!frame.ret_addr)
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| 124 | break;
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| 125 | if (!consume_entry(cookie, frame.ret_addr))
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| 126 | break;
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| 127 | fp = frame.next_fp;
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| 128 | }
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| 129 | }
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| 130 |
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