Commit-ID: 5bdc48d1a90e3e34dd5c2756298190d3a48c3984 Gitweb: http://git.kernel.org/tip/5bdc48d1a90e3e34dd5c2756298190d3a48c3984 Author: Vegard Nossum <vegard.nossum@xxxxxxxxx> AuthorDate: Fri, 27 Feb 2009 11:35:55 +0100 Commit: Vegard Nossum <vegard.nossum@xxxxxxxxx> CommitDate: Sat, 28 Feb 2009 08:27:11 +0100 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! Signed-off-by: Vegard Nossum <vegard.nossum@xxxxxxxxx> --- arch/x86/mm/kmemcheck/Makefile | 2 +- arch/x86/mm/kmemcheck/kmemcheck.c | 38 ++++++++++++-------- arch/x86/mm/kmemcheck/selftest.c | 69 +++++++++++++++++++++++++++++++++++++ arch/x86/mm/kmemcheck/selftest.h | 6 +++ 4 files changed, 99 insertions(+), 16 deletions(-) diff --git a/arch/x86/mm/kmemcheck/Makefile b/arch/x86/mm/kmemcheck/Makefile index 4666b7a..520b3bc 100644 --- a/arch/x86/mm/kmemcheck/Makefile +++ b/arch/x86/mm/kmemcheck/Makefile @@ -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 diff --git a/arch/x86/mm/kmemcheck/kmemcheck.c b/arch/x86/mm/kmemcheck/kmemcheck.c index 9349565..2b5ca65 100644 --- a/arch/x86/mm/kmemcheck/kmemcheck.c +++ b/arch/x86/mm/kmemcheck/kmemcheck.c @@ -29,12 +29,26 @@ #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 + +#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; + void __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 @@ -46,21 +60,15 @@ void __init kmemcheck_init(void) setup_max_cpus = 1; } #endif -} -#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 + if (!kmemcheck_selftest()) { + printk(KERN_INFO "kmemcheck: self-tests failed; disabling\n"); + kmemcheck_enabled = 0; + return; + } -int kmemcheck_enabled = KMEMCHECK_ENABLED; + printk(KERN_INFO "kmemcheck: Initialized\n"); +} /* * We need to parse the kmemcheck= option before any memory is allocated. diff --git a/arch/x86/mm/kmemcheck/selftest.c b/arch/x86/mm/kmemcheck/selftest.c new file mode 100644 index 0000000..036efbe --- /dev/null +++ b/arch/x86/mm/kmemcheck/selftest.c @@ -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; +} diff --git a/arch/x86/mm/kmemcheck/selftest.h b/arch/x86/mm/kmemcheck/selftest.h new file mode 100644 index 0000000..8fed4fe --- /dev/null +++ b/arch/x86/mm/kmemcheck/selftest.h @@ -0,0 +1,6 @@ +#ifndef ARCH_X86_MM_KMEMCHECK_SELFTEST_H +#define ARCH_X86_MM_KMEMCHECK_SELFTEST_H + +bool kmemcheck_selftest(void); + +#endif -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html