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Commit a272858a authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Catalin Marinas
Browse files

extable: add support for relative extables to search and sort routines 



This adds support to the generic search_extable() and sort_extable()
implementations for dealing with exception table entries whose fields
contain relative offsets rather than absolute addresses.

Acked-by: default avatarHelge Deller <deller@gmx.de>
Acked-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
Acked-by: default avatarTony Luck <tony.luck@intel.com>
Acked-by: default avatarWill Deacon <will.deacon@arm.com>
Acked-by: default avatarRichard Henderson <rth@twiddle.net>
Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 7b957b6e

lib/extable.c

+41 −9
Original line number Diff line number Diff line
@@ -14,7 +14,37 @@ 
#include <linux/sort.h>

#include <asm/uaccess.h>



#ifndef ARCH_HAS_RELATIVE_EXTABLE

#define ex_to_insn(x)	((x)->insn)

#else

static inline unsigned long ex_to_insn(const struct exception_table_entry *x)

{

	return (unsigned long)&x->insn + x->insn;

}

#endif



#ifndef ARCH_HAS_SORT_EXTABLE

#ifndef ARCH_HAS_RELATIVE_EXTABLE

#define swap_ex		NULL

#else

static void swap_ex(void *a, void *b, int size)

{

	struct exception_table_entry *x = a, *y = b, tmp;

	int delta = b - a;



	tmp = *x;

	x->insn = y->insn + delta;

	y->insn = tmp.insn - delta;



#ifdef swap_ex_entry_fixup

	swap_ex_entry_fixup(x, y, tmp, delta);

#else

	x->fixup = y->fixup + delta;

	y->fixup = tmp.fixup - delta;

#endif

}

#endif /* ARCH_HAS_RELATIVE_EXTABLE */



/*

 * The exception table needs to be sorted so that the binary

 * search that we use to find entries in it works properly.
@@ -26,9 +56,9 @@ static int cmp_ex(const void *a, const void *b) 
	const struct exception_table_entry *x = a, *y = b;



	/* avoid overflow */

	if (x->insn > y->insn)

	if (ex_to_insn(x) > ex_to_insn(y))

		return 1;

	if (x->insn < y->insn)

	if (ex_to_insn(x) < ex_to_insn(y))

		return -1;

	return 0;

}
@@ -37,7 +67,7 @@ void sort_extable(struct exception_table_entry *start, 
		  struct exception_table_entry *finish)

{

	sort(start, finish - start, sizeof(struct exception_table_entry),

	     cmp_ex, NULL);

	     cmp_ex, swap_ex);

}



#ifdef CONFIG_MODULES
@@ -48,13 +78,15 @@ void sort_extable(struct exception_table_entry *start, 
void trim_init_extable(struct module *m)

{

	/*trim the beginning*/

	while (m->num_exentries && within_module_init(m->extable[0].insn, m)) {

	while (m->num_exentries &&

	       within_module_init(ex_to_insn(&m->extable[0]), m)) {

		m->extable++;

		m->num_exentries--;

	}

	/*trim the end*/

	while (m->num_exentries &&

		within_module_init(m->extable[m->num_exentries-1].insn, m))

	       within_module_init(ex_to_insn(&m->extable[m->num_exentries - 1]),

				  m))

		m->num_exentries--;

}

#endif /* CONFIG_MODULES */
@@ -81,9 +113,9 @@ search_extable(const struct exception_table_entry *first, 
		 * careful, the distance between value and insn

		 * can be larger than MAX_LONG:

		 */

		if (mid->insn < value)

		if (ex_to_insn(mid) < value)

			first = mid + 1;

		else if (mid->insn > value)

		else if (ex_to_insn(mid) > value)

			last = mid - 1;

		else

			return mid;