linux-imx

// SPDX-License-Identifier: GPL-2.0

/*

 * Kernel unwinding support

 *

 * (c) 2002-2004 Randolph Chung <tausq@debian.org>

 *

 * Derived partially from the IA64 implementation. The PA-RISC

 * Runtime Architecture Document is also a useful reference to

 * understand what is happening here

 */

​

#include <linux/kernel.h>

#include <linux/init.h>

#include <linux/sched.h>

#include <linux/slab.h>

#include <linux/sort.h>

​

#include <linux/uaccess.h>

#include <asm/assembly.h>

#include <asm/asm-offsets.h>

#include <asm/ptrace.h>

​

#include <asm/unwind.h>

​

/* #define DEBUG 1 */

#ifdef DEBUG

#define dbg(x...) pr_debug(x)

#else

#define dbg(x...)

#endif

​

#define KERNEL_START (KERNEL_BINARY_TEXT_START)

​

extern struct unwind_table_entry __start___unwind[];

extern struct unwind_table_entry __stop___unwind[];

​

static DEFINE_SPINLOCK(unwind_lock);

/*

 * the kernel unwind block is not dynamically allocated so that

 * we can call unwind_init as early in the bootup process as 

 * possible (before the slab allocator is initialized)

 */

static struct unwind_table kernel_unwind_table __read_mostly;

static LIST_HEAD(unwind_tables);

​

static inline const struct unwind_table_entry *

find_unwind_entry_in_table(const struct unwind_table *table, unsigned long addr)

{

    const struct unwind_table_entry *e = NULL;

    unsigned long lo, hi, mid;

​

    lo = 0; 

    hi = table->length - 1; 

    while (lo <= hi) {

        mid = (hi - lo) / 2 + lo;

        e = &table->table[mid];

        if (addr < e->region_start)

            hi = mid - 1;

        else if (addr > e->region_end)

            lo = mid + 1;

        else

            return e;

    }

​

    return NULL;

}

​

static const struct unwind_table_entry *

find_unwind_entry(unsigned long addr)

{

    struct unwind_table *table;

    const struct unwind_table_entry *e = NULL;

​

    if (addr >= kernel_unwind_table.start && 

        addr <= kernel_unwind_table.end)

        e = find_unwind_entry_in_table(&kernel_unwind_table, addr);

    else {

        unsigned long flags;

​

        spin_lock_irqsave(&unwind_lock, flags);

        list_for_each_entry(table, &unwind_tables, list) {

            if (addr >= table->start && 

                addr <= table->end)

                e = find_unwind_entry_in_table(table, addr);

            if (e) {

                /* Move-to-front to exploit common traces */

                list_move(&table->list, &unwind_tables);

                break;

            }

        }

        spin_unlock_irqrestore(&unwind_lock, flags);