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eb608fb366
This is the s390 port of 70627654 "x86, extable: Switch to relative
exception table entries".
Reduces the size of our exception tables by 50% on 64 bit builds.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
82 lines
2.1 KiB
C
82 lines
2.1 KiB
C
#include <linux/module.h>
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#include <linux/sort.h>
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#include <asm/uaccess.h>
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/*
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* Search one exception table for an entry corresponding to the
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* given instruction address, and return the address of the entry,
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* or NULL if none is found.
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* We use a binary search, and thus we assume that the table is
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* already sorted.
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*/
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const struct exception_table_entry *
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search_extable(const struct exception_table_entry *first,
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const struct exception_table_entry *last,
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unsigned long value)
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{
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const struct exception_table_entry *mid;
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unsigned long addr;
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while (first <= last) {
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mid = ((last - first) >> 1) + first;
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addr = extable_insn(mid);
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if (addr < value)
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first = mid + 1;
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else if (addr > value)
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last = mid - 1;
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else
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return mid;
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}
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return NULL;
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}
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/*
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* The exception table needs to be sorted so that the binary
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* search that we use to find entries in it works properly.
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* This is used both for the kernel exception table and for
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* the exception tables of modules that get loaded.
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*
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*/
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static int cmp_ex(const void *a, const void *b)
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{
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const struct exception_table_entry *x = a, *y = b;
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/* This compare is only valid after normalization. */
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return x->insn - y->insn;
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}
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void sort_extable(struct exception_table_entry *start,
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struct exception_table_entry *finish)
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{
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struct exception_table_entry *p;
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int i;
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/* Normalize entries to being relative to the start of the section */
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for (p = start, i = 0; p < finish; p++, i += 8)
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p->insn += i;
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sort(start, finish - start, sizeof(*start), cmp_ex, NULL);
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/* Denormalize all entries */
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for (p = start, i = 0; p < finish; p++, i += 8)
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p->insn -= i;
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}
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#ifdef CONFIG_MODULES
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/*
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* If the exception table is sorted, any referring to the module init
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* will be at the beginning or the end.
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*/
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void trim_init_extable(struct module *m)
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{
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/* Trim the beginning */
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while (m->num_exentries &&
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within_module_init(extable_insn(&m->extable[0]), m)) {
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m->extable++;
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m->num_exentries--;
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}
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/* Trim the end */
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while (m->num_exentries &&
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within_module_init(extable_insn(&m->extable[m->num_exentries-1]), m))
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m->num_exentries--;
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}
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#endif /* CONFIG_MODULES */
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