extable.c

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/*
 * linux/arch/sparc/mm/extable.c
 */

#include <linux/module.h>
#include <asm/uaccess.h>

void sort_extable(struct exception_table_entry *start,
          struct exception_table_entry *finish)
{
}

/* Caller knows they are in a range if ret->fixup == 0 */
const struct exception_table_entry *
search_extable(const struct exception_table_entry *start,
           const struct exception_table_entry *last,
           unsigned long value)
{
    const struct exception_table_entry *walk;

    /* Single insn entries are encoded as:
     *  word 1: insn address
     *  word 2: fixup code address
     *
     * Range entries are encoded as:
     *  word 1: first insn address
     *  word 2: 0
     *  word 3: last insn address + 4 bytes
     *  word 4: fixup code address
     *
     * Deleted entries are encoded as:
     *  word 1: unused
     *  word 2: -1
     *
     * See asm/uaccess.h for more details.
     */

    /* 1. Try to find an exact match. */
    for (walk = start; walk <= last; walk++) {
        if (walk->fixup == 0) {
            /* A range entry, skip both parts. */
            walk++;
            continue;
        }

        /* A deleted entry; see trim_init_extable */
        if (walk->fixup == -1)
            continue;

        if (walk->insn == value)
            return walk;
    }

    /* 2. Try to find a range match. */
    for (walk = start; walk <= (last - 1); walk++) {
        if (walk->fixup)
            continue;

        if (walk[0].insn <= value && walk[1].insn > value)
            return walk;

        walk++;
    }

        return NULL;
}

#ifdef CONFIG_MODULES
/* We could memmove them around; easier to mark the trimmed ones. */
void trim_init_extable(struct module *m)
{
    unsigned int i;
    bool range;

    for (i = 0; i < m->num_exentries; i += range ? 2 : 1) {
        range = m->extable[i].fixup == 0;

        if (within_module_init(m->extable[i].insn, m)) {
            m->extable[i].fixup = -1;
            if (range)
                m->extable[i+1].fixup = -1;
        }
        if (range)
            i++;
    }
}
#endif /* CONFIG_MODULES */

/* Special extable search, which handles ranges.  Returns fixup */
unsigned long search_extables_range(unsigned long addr, unsigned long *g2)
{
    const struct exception_table_entry *entry;

    entry = search_exception_tables(addr);
    if (!entry)
        return 0;

    /* Inside range?  Fix g2 and return correct fixup */
    if (!entry->fixup) {
        *g2 = (addr - entry->insn) / 4;
        return (entry + 1)->fixup;
    }

    return entry->fixup;
}