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Commit 08a42e86 authored by Ivan Kokshaysky's avatar Ivan Kokshaysky Committed by Linus Torvalds
Browse files

alpha: exception table sorting 



Exception fixups for sections other than .text (like one in futex_init())
break the natural ordering of fixup entries, so sorting is required.

Without that the result of the exception table search depends on phase of
the moon.

Signed-off-by: default avatarIvan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Richard Henderson <rth@twiddle.net
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1ffb1c0c

arch/alpha/include/asm/uaccess.h

+2 −0
Original line number Diff line number Diff line
@@ -507,5 +507,7 @@ struct exception_table_entry 
	(pc) + (_fixup)->fixup.bits.nextinsn;			\

})



#define ARCH_HAS_SORT_EXTABLE

#define ARCH_HAS_SEARCH_EXTABLE



#endif /* __ALPHA_UACCESS_H */

arch/alpha/mm/extable.c

+39 −1
Original line number Diff line number Diff line
@@ -3,11 +3,49 @@ 
 */



#include <linux/module.h>

#include <linux/sort.h>

#include <asm/uaccess.h>



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

{

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

}



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

{

	struct exception_table_entry *ex_a = a, *ex_b = b;

	unsigned long addr_a = ex_to_addr(ex_a), addr_b = ex_to_addr(ex_b);

	unsigned int t = ex_a->fixup.unit;



	ex_a->fixup.unit = ex_b->fixup.unit;

	ex_b->fixup.unit = t;

	ex_a->insn = (int)(addr_b - (unsigned long)&ex_a->insn);

	ex_b->insn = (int)(addr_a - (unsigned long)&ex_b->insn);

}



/*

 * 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;



	/* avoid overflow */

	if (ex_to_addr(x) > ex_to_addr(y))

		return 1;

	if (ex_to_addr(x) < ex_to_addr(y))

		return -1;

	return 0;

}



void sort_extable(struct exception_table_entry *start,

		  struct exception_table_entry *finish)

{

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

	     cmp_ex, swap_ex);

}



const struct exception_table_entry *
@@ -20,7 +58,7 @@ search_extable(const struct exception_table_entry *first, 
		unsigned long mid_value;



		mid = (last - first) / 2 + first;

		mid_value = (unsigned long)&mid->insn + mid->insn;

		mid_value = ex_to_addr(mid);

                if (mid_value == value)

                        return mid;

                else if (mid_value < value)