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x86/extable: use generic search and sort routines

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Replace the arch specific versions of search_extable() and
sort_extable() with calls to the generic ones, which now support
relative exception tables as well.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Ard Biesheuvel 2016-03-22 14:28:17 -07:00 committed by Linus Torvalds
parent c352e8b6de
commit 29934b0fb8
2 changed files with 2 additions and 111 deletions
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5
arch/x86/include/asm/uaccess.h
View File

@ -105,9 +105,8 @@ static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, un
struct exception_table_entry {
int insn, fixup, handler;
};
/* This is not the generic standard exception_table_entry format */
#define ARCH_HAS_SORT_EXTABLE
#define ARCH_HAS_SEARCH_EXTABLE
#define ARCH_HAS_RELATIVE_EXTABLE
extern int fixup_exception(struct pt_regs *regs, int trapnr);
extern bool ex_has_fault_handler(unsigned long ip);

108
arch/x86/mm/extable.c
View File

@ -1,16 +1,9 @@
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/sort.h>
#include <asm/uaccess.h>
typedef bool (*ex_handler_t)(const struct exception_table_entry *,
struct pt_regs *, int);
static inline unsigned long
ex_insn_addr(const struct exception_table_entry *x)
{
return (unsigned long)&x->insn + x->insn;
}
static inline unsigned long
ex_fixup_addr(const struct exception_table_entry *x)
{
@ -110,104 +103,3 @@ int __init early_fixup_exception(unsigned long *ip)
*ip = new_ip;
return 1;
}
/*
* Search one exception table for an entry corresponding to the
* given instruction address, and return the address of the entry,
* or NULL if none is found.
* We use a binary search, and thus we assume that the table is
* already sorted.
*/
const struct exception_table_entry *
search_extable(const struct exception_table_entry *first,
const struct exception_table_entry *last,
unsigned long value)
{
while (first <= last) {
const struct exception_table_entry *mid;
unsigned long addr;
mid = ((last - first) >> 1) + first;
addr = ex_insn_addr(mid);
if (addr < value)
first = mid + 1;
else if (addr > value)
last = mid - 1;
else
return mid;
}
return NULL;
}
/*
* The exception table needs to be sorted so that the binary
* search that we use to find entries in it works properly.
* This is used both for the kernel exception table and for
* the exception tables of modules that get loaded.
*
*/
static int cmp_ex(const void *a, const void *b)
{
const struct exception_table_entry *x = a, *y = b;
/*
* This value will always end up fittin in an int, because on
* both i386 and x86-64 the kernel symbol-reachable address
* space is < 2 GiB.
*
* This compare is only valid after normalization.
*/
return x->insn - y->insn;
}
void sort_extable(struct exception_table_entry *start,
struct exception_table_entry *finish)
{
struct exception_table_entry *p;
int i;
/* Convert all entries to being relative to the start of the section */
i = 0;
for (p = start; p < finish; p++) {
p->insn += i;
i += 4;
p->fixup += i;
i += 4;
p->handler += i;
i += 4;
}
sort(start, finish - start, sizeof(struct exception_table_entry),
cmp_ex, NULL);
/* Denormalize all entries */
i = 0;
for (p = start; p < finish; p++) {
p->insn -= i;
i += 4;
p->fixup -= i;
i += 4;
p->handler -= i;
i += 4;
}
}
#ifdef CONFIG_MODULES
/*
* If the exception table is sorted, any referring to the module init
* will be at the beginning or the end.
*/
void trim_init_extable(struct module *m)
{
/*trim the beginning*/
while (m->num_exentries &&
within_module_init(ex_insn_addr(&m->extable[0]), m)) {
m->extable++;
m->num_exentries--;
}
/*trim the end*/
while (m->num_exentries &&
within_module_init(ex_insn_addr(&m->extable[m->num_exentries-1]), m))
m->num_exentries--;
}
#endif /* CONFIG_MODULES */