kmemcheck: add the kmemcheck core
General description: kmemcheck is a patch to the linux kernel that
detects use of uninitialized memory. It does this by trapping every
read and write to memory that was allocated dynamically (e.g. using
kmalloc()). If a memory address is read that has not previously been
written to, a message is printed to the kernel log.
Thanks to Andi Kleen for the set_memory_4k() solution.
Andrew Morton suggested documenting the shadow member of struct page.
Signed-off-by: Vegard Nossum <vegardno@ifi.uio.no>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
[export kmemcheck_mark_initialized]
[build fix for setup_max_cpus]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
[rebased for mainline inclusion]
Signed-off-by: Vegard Nossum <vegardno@ifi.uio.no>
diff --git a/arch/x86/mm/kmemcheck/opcode.c b/arch/x86/mm/kmemcheck/opcode.c
new file mode 100644
index 0000000..a4100b6
--- /dev/null
+++ b/arch/x86/mm/kmemcheck/opcode.c
@@ -0,0 +1,101 @@
+#include <linux/types.h>
+
+#include "opcode.h"
+
+static bool opcode_is_prefix(uint8_t b)
+{
+ return
+ /* Group 1 */
+ b == 0xf0 || b == 0xf2 || b == 0xf3
+ /* Group 2 */
+ || b == 0x2e || b == 0x36 || b == 0x3e || b == 0x26
+ || b == 0x64 || b == 0x65 || b == 0x2e || b == 0x3e
+ /* Group 3 */
+ || b == 0x66
+ /* Group 4 */
+ || b == 0x67;
+}
+
+static bool opcode_is_rex_prefix(uint8_t b)
+{
+ return (b & 0xf0) == 0x40;
+}
+
+#define REX_W (1 << 3)
+
+/*
+ * This is a VERY crude opcode decoder. We only need to find the size of the
+ * load/store that caused our #PF and this should work for all the opcodes
+ * that we care about. Moreover, the ones who invented this instruction set
+ * should be shot.
+ */
+void kmemcheck_opcode_decode(const uint8_t *op, unsigned int *size)
+{
+ /* Default operand size */
+ int operand_size_override = 4;
+
+ /* prefixes */
+ for (; opcode_is_prefix(*op); ++op) {
+ if (*op == 0x66)
+ operand_size_override = 2;
+ }
+
+#ifdef CONFIG_X86_64
+ /* REX prefix */
+ if (opcode_is_rex_prefix(*op)) {
+ uint8_t rex = *op;
+
+ ++op;
+ if (rex & REX_W) {
+ switch (*op) {
+ case 0x63:
+ *size = 4;
+ return;
+ case 0x0f:
+ ++op;
+
+ switch (*op) {
+ case 0xb6:
+ case 0xbe:
+ *size = 1;
+ return;
+ case 0xb7:
+ case 0xbf:
+ *size = 2;
+ return;
+ }
+
+ break;
+ }
+
+ *size = 8;
+ return;
+ }
+ }
+#endif
+
+ /* escape opcode */
+ if (*op == 0x0f) {
+ ++op;
+
+ /*
+ * This is move with zero-extend and sign-extend, respectively;
+ * we don't have to think about 0xb6/0xbe, because this is
+ * already handled in the conditional below.
+ */
+ if (*op == 0xb7 || *op == 0xbf)
+ operand_size_override = 2;
+ }
+
+ *size = (*op & 1) ? operand_size_override : 1;
+}
+
+const uint8_t *kmemcheck_opcode_get_primary(const uint8_t *op)
+{
+ /* skip prefixes */
+ while (opcode_is_prefix(*op))
+ ++op;
+ if (opcode_is_rex_prefix(*op))
+ ++op;
+ return op;
+}