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ac61a75796
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>
70 lines
1.5 KiB
C
70 lines
1.5 KiB
C
#include <linux/kernel.h>
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#include "opcode.h"
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#include "selftest.h"
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struct selftest_opcode {
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unsigned int expected_size;
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const uint8_t *insn;
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const char *desc;
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};
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static const struct selftest_opcode selftest_opcodes[] = {
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/* REP MOVS */
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{1, "\xf3\xa4", "rep movsb <mem8>, <mem8>"},
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{4, "\xf3\xa5", "rep movsl <mem32>, <mem32>"},
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/* MOVZX / MOVZXD */
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{1, "\x66\x0f\xb6\x51\xf8", "movzwq <mem8>, <reg16>"},
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{1, "\x0f\xb6\x51\xf8", "movzwq <mem8>, <reg32>"},
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/* MOVSX / MOVSXD */
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{1, "\x66\x0f\xbe\x51\xf8", "movswq <mem8>, <reg16>"},
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{1, "\x0f\xbe\x51\xf8", "movswq <mem8>, <reg32>"},
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#ifdef CONFIG_X86_64
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/* MOVZX / MOVZXD */
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{1, "\x49\x0f\xb6\x51\xf8", "movzbq <mem8>, <reg64>"},
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{2, "\x49\x0f\xb7\x51\xf8", "movzbq <mem16>, <reg64>"},
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/* MOVSX / MOVSXD */
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{1, "\x49\x0f\xbe\x51\xf8", "movsbq <mem8>, <reg64>"},
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{2, "\x49\x0f\xbf\x51\xf8", "movsbq <mem16>, <reg64>"},
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{4, "\x49\x63\x51\xf8", "movslq <mem32>, <reg64>"},
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#endif
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};
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static bool selftest_opcode_one(const struct selftest_opcode *op)
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{
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unsigned size;
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kmemcheck_opcode_decode(op->insn, &size);
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if (size == op->expected_size)
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return true;
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printk(KERN_WARNING "kmemcheck: opcode %s: expected size %d, got %d\n",
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op->desc, op->expected_size, size);
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return false;
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}
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static bool selftest_opcodes_all(void)
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{
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bool pass = true;
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unsigned int i;
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for (i = 0; i < ARRAY_SIZE(selftest_opcodes); ++i)
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pass = pass && selftest_opcode_one(&selftest_opcodes[i]);
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return pass;
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}
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bool kmemcheck_selftest(void)
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{
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bool pass = true;
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pass = pass && selftest_opcodes_all();
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return pass;
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}
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