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Commit 29934b0f authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Linus Torvalds
Browse files

x86/extable: use generic search and sort routines 



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: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c352e8b6

arch/x86/include/asm/uaccess.h

+2 −3
Original line number Diff line number Diff line
@@ -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);

arch/x86/mm/extable.c

+0 −108
Original line number Diff line number Diff line 
#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 */