^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 1) // SPDX-License-Identifier: GPL-2.0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 2) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 3) * Copyright (C) 2009 Matt Fleming
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 4) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 5) * Based, in part, on kernel/time/clocksource.c.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 6) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 7) * This file provides arbitration code for stack unwinders.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 8) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 9) * Multiple stack unwinders can be available on a system, usually with
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) * the most accurate unwinder being the currently active one.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) #include <linux/errno.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) #include <linux/list.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) #include <linux/spinlock.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) #include <linux/module.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) #include <asm/unwinder.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) #include <linux/atomic.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) * This is the most basic stack unwinder an architecture can
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) * provide. For architectures without reliable frame pointers, e.g.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) * RISC CPUs, it can be implemented by looking through the stack for
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) * addresses that lie within the kernel text section.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) * Other CPUs, e.g. x86, can use their frame pointer register to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) * construct more accurate stack traces.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) static struct list_head unwinder_list;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) static struct unwinder stack_reader = {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) .name = "stack-reader",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) .dump = stack_reader_dump,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) .rating = 50,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) .list = {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) .next = &unwinder_list,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) .prev = &unwinder_list,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) },
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) * "curr_unwinder" points to the stack unwinder currently in use. This
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) * is the unwinder with the highest rating.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) * "unwinder_list" is a linked-list of all available unwinders, sorted
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) * by rating.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) * All modifications of "curr_unwinder" and "unwinder_list" must be
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) * performed whilst holding "unwinder_lock".
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) static struct unwinder *curr_unwinder = &stack_reader;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) static struct list_head unwinder_list = {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) .next = &stack_reader.list,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) .prev = &stack_reader.list,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) static DEFINE_SPINLOCK(unwinder_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) * select_unwinder - Select the best registered stack unwinder.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) * Private function. Must hold unwinder_lock when called.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) * Select the stack unwinder with the best rating. This is useful for
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) * setting up curr_unwinder.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66) static struct unwinder *select_unwinder(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68) struct unwinder *best;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70) if (list_empty(&unwinder_list))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71) return NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 72)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 73) best = list_entry(unwinder_list.next, struct unwinder, list);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 74) if (best == curr_unwinder)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 75) return NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 76)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 77) return best;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 78) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 79)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 80) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 81) * Enqueue the stack unwinder sorted by rating.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 82) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 83) static int unwinder_enqueue(struct unwinder *ops)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 84) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 85) struct list_head *tmp, *entry = &unwinder_list;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 86)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 87) list_for_each(tmp, &unwinder_list) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 88) struct unwinder *o;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 89)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 90) o = list_entry(tmp, struct unwinder, list);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 91) if (o == ops)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 92) return -EBUSY;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 93) /* Keep track of the place, where to insert */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 94) if (o->rating >= ops->rating)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 95) entry = tmp;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 96) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 97) list_add(&ops->list, entry);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 98)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 99) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) * unwinder_register - Used to install new stack unwinder
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104) * @u: unwinder to be registered
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) * Install the new stack unwinder on the unwinder list, which is sorted
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) * by rating.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) * Returns -EBUSY if registration fails, zero otherwise.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) int unwinder_register(struct unwinder *u)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) unsigned long flags;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114) int ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116) spin_lock_irqsave(&unwinder_lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117) ret = unwinder_enqueue(u);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) if (!ret)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) curr_unwinder = select_unwinder();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120) spin_unlock_irqrestore(&unwinder_lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) return ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) int unwinder_faulted = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) * Unwind the call stack and pass information to the stacktrace_ops
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129) * functions. Also handle the case where we need to switch to a new
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130) * stack dumper because the current one faulted unexpectedly.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132) void unwind_stack(struct task_struct *task, struct pt_regs *regs,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) unsigned long *sp, const struct stacktrace_ops *ops,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134) void *data)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) unsigned long flags;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) * The problem with unwinders with high ratings is that they are
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) * inherently more complicated than the simple ones with lower
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) * ratings. We are therefore more likely to fault in the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) * complicated ones, e.g. hitting BUG()s. If we fault in the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) * code for the current stack unwinder we try to downgrade to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) * one with a lower rating.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) * Hopefully this will give us a semi-reliable stacktrace so we
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) * can diagnose why curr_unwinder->dump() faulted.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) if (unwinder_faulted) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) spin_lock_irqsave(&unwinder_lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152) /* Make sure no one beat us to changing the unwinder */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) if (unwinder_faulted && !list_is_singular(&unwinder_list)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154) list_del(&curr_unwinder->list);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) curr_unwinder = select_unwinder();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157) unwinder_faulted = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160) spin_unlock_irqrestore(&unwinder_lock, flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163) curr_unwinder->dump(task, regs, sp, ops, data);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165) EXPORT_SYMBOL_GPL(unwind_stack);
Orange Pi5 kernel
Deprecated Linux kernel 5.10.110 for OrangePi 5/5B/5+ boards
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