kmemcheck: add opcode self-testing at boot
We've had some troubles in the past with weird instructions. This patch adds a self-test framework which can be used to verify that a certain set of opcodes are decoded correctly. Of course, the opcodes which are not tested can still give the wrong results. In short, this is just a safeguard to catch unintentional changes in the opcode decoder. It does not mean that errors can't still occur! [rebased for mainline inclusion] Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
This commit is contained in:
parent
eb63657e13
commit
ac61a75796
|
@ -1 +1 @@
|
|||
obj-y := error.o kmemcheck.o opcode.o pte.o shadow.o
|
||||
obj-y := error.o kmemcheck.o opcode.o pte.o selftest.o shadow.o
|
||||
|
|
|
@ -29,8 +29,10 @@
|
|||
#include "error.h"
|
||||
#include "opcode.h"
|
||||
#include "pte.h"
|
||||
#include "selftest.h"
|
||||
#include "shadow.h"
|
||||
|
||||
|
||||
#ifdef CONFIG_KMEMCHECK_DISABLED_BY_DEFAULT
|
||||
# define KMEMCHECK_ENABLED 0
|
||||
#endif
|
||||
|
@ -47,8 +49,6 @@ int kmemcheck_enabled = KMEMCHECK_ENABLED;
|
|||
|
||||
int __init kmemcheck_init(void)
|
||||
{
|
||||
printk(KERN_INFO "kmemcheck: Initialized\n");
|
||||
|
||||
#ifdef CONFIG_SMP
|
||||
/*
|
||||
* Limit SMP to use a single CPU. We rely on the fact that this code
|
||||
|
@ -61,25 +61,18 @@ int __init kmemcheck_init(void)
|
|||
}
|
||||
#endif
|
||||
|
||||
if (!kmemcheck_selftest()) {
|
||||
printk(KERN_INFO "kmemcheck: self-tests failed; disabling\n");
|
||||
kmemcheck_enabled = 0;
|
||||
return -EINVAL;
|
||||
}
|
||||
|
||||
printk(KERN_INFO "kmemcheck: Initialized\n");
|
||||
return 0;
|
||||
}
|
||||
|
||||
early_initcall(kmemcheck_init);
|
||||
|
||||
#ifdef CONFIG_KMEMCHECK_DISABLED_BY_DEFAULT
|
||||
# define KMEMCHECK_ENABLED 0
|
||||
#endif
|
||||
|
||||
#ifdef CONFIG_KMEMCHECK_ENABLED_BY_DEFAULT
|
||||
# define KMEMCHECK_ENABLED 1
|
||||
#endif
|
||||
|
||||
#ifdef CONFIG_KMEMCHECK_ONESHOT_BY_DEFAULT
|
||||
# define KMEMCHECK_ENABLED 2
|
||||
#endif
|
||||
|
||||
int kmemcheck_enabled = KMEMCHECK_ENABLED;
|
||||
|
||||
/*
|
||||
* We need to parse the kmemcheck= option before any memory is allocated.
|
||||
*/
|
||||
|
|
69
arch/x86/mm/kmemcheck/selftest.c
Normal file
69
arch/x86/mm/kmemcheck/selftest.c
Normal file
|
@ -0,0 +1,69 @@
|
|||
#include <linux/kernel.h>
|
||||
|
||||
#include "opcode.h"
|
||||
#include "selftest.h"
|
||||
|
||||
struct selftest_opcode {
|
||||
unsigned int expected_size;
|
||||
const uint8_t *insn;
|
||||
const char *desc;
|
||||
};
|
||||
|
||||
static const struct selftest_opcode selftest_opcodes[] = {
|
||||
/* REP MOVS */
|
||||
{1, "\xf3\xa4", "rep movsb <mem8>, <mem8>"},
|
||||
{4, "\xf3\xa5", "rep movsl <mem32>, <mem32>"},
|
||||
|
||||
/* MOVZX / MOVZXD */
|
||||
{1, "\x66\x0f\xb6\x51\xf8", "movzwq <mem8>, <reg16>"},
|
||||
{1, "\x0f\xb6\x51\xf8", "movzwq <mem8>, <reg32>"},
|
||||
|
||||
/* MOVSX / MOVSXD */
|
||||
{1, "\x66\x0f\xbe\x51\xf8", "movswq <mem8>, <reg16>"},
|
||||
{1, "\x0f\xbe\x51\xf8", "movswq <mem8>, <reg32>"},
|
||||
|
||||
#ifdef CONFIG_X86_64
|
||||
/* MOVZX / MOVZXD */
|
||||
{1, "\x49\x0f\xb6\x51\xf8", "movzbq <mem8>, <reg64>"},
|
||||
{2, "\x49\x0f\xb7\x51\xf8", "movzbq <mem16>, <reg64>"},
|
||||
|
||||
/* MOVSX / MOVSXD */
|
||||
{1, "\x49\x0f\xbe\x51\xf8", "movsbq <mem8>, <reg64>"},
|
||||
{2, "\x49\x0f\xbf\x51\xf8", "movsbq <mem16>, <reg64>"},
|
||||
{4, "\x49\x63\x51\xf8", "movslq <mem32>, <reg64>"},
|
||||
#endif
|
||||
};
|
||||
|
||||
static bool selftest_opcode_one(const struct selftest_opcode *op)
|
||||
{
|
||||
unsigned size;
|
||||
|
||||
kmemcheck_opcode_decode(op->insn, &size);
|
||||
|
||||
if (size == op->expected_size)
|
||||
return true;
|
||||
|
||||
printk(KERN_WARNING "kmemcheck: opcode %s: expected size %d, got %d\n",
|
||||
op->desc, op->expected_size, size);
|
||||
return false;
|
||||
}
|
||||
|
||||
static bool selftest_opcodes_all(void)
|
||||
{
|
||||
bool pass = true;
|
||||
unsigned int i;
|
||||
|
||||
for (i = 0; i < ARRAY_SIZE(selftest_opcodes); ++i)
|
||||
pass = pass && selftest_opcode_one(&selftest_opcodes[i]);
|
||||
|
||||
return pass;
|
||||
}
|
||||
|
||||
bool kmemcheck_selftest(void)
|
||||
{
|
||||
bool pass = true;
|
||||
|
||||
pass = pass && selftest_opcodes_all();
|
||||
|
||||
return pass;
|
||||
}
|
6
arch/x86/mm/kmemcheck/selftest.h
Normal file
6
arch/x86/mm/kmemcheck/selftest.h
Normal file
|
@ -0,0 +1,6 @@
|
|||
#ifndef ARCH_X86_MM_KMEMCHECK_SELFTEST_H
|
||||
#define ARCH_X86_MM_KMEMCHECK_SELFTEST_H
|
||||
|
||||
bool kmemcheck_selftest(void);
|
||||
|
||||
#endif
|
Loading…
Reference in a new issue