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Commit 29934b0f authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Linus Torvalds
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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
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+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);
+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 */