Commit-ID: 3d11709f5c12b86b039efc16b86cf11873a8ab4f
Gitweb: http://git.kernel.org/tip/3d11709f5c12b86b039efc16b86cf11873a8ab4f
Author: Vegard Nossum <vegard.nossum@xxxxxxxxx>
AuthorDate: Fri, 27 Feb 2009 11:39:31 +0100
Commit: Vegard Nossum <vegard.nossum@xxxxxxxxx>
CommitDate: Sat, 28 Feb 2009 08:27:24 +0100
kmemcheck: decode sign/zero-extension move instructions correctly
There were quite a few errors in this area. For 32-bit, we didn't
handle sign-extension (only zero-extension), and for 64-bit we
didn't do anything right. This patch hopefully fixes that.
Signed-off-by: Vegard Nossum <vegard.nossum@xxxxxxxxx>
---
arch/x86/mm/kmemcheck/opcode.c | 46 +++++++++++++++++++++++++++++----------
1 files changed, 34 insertions(+), 12 deletions(-)
diff --git a/arch/x86/mm/kmemcheck/opcode.c b/arch/x86/mm/kmemcheck/opcode.c
index 5283f0b..63c19e2 100644
--- a/arch/x86/mm/kmemcheck/opcode.c
+++ b/arch/x86/mm/kmemcheck/opcode.c
@@ -28,6 +28,8 @@ static bool opcode_is_rex_prefix(uint8_t b)
}
#endif
+#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
@@ -47,27 +49,47 @@ void kmemcheck_opcode_decode(const uint8_t *op, unsigned int *size)
/* REX prefix */
if (opcode_is_rex_prefix(*op)) {
- if (*op & 0x08) {
+ 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;
}
-
- ++op;
}
/* escape opcode */
if (*op == 0x0f) {
++op;
- if (*op == 0xb6) {
- *size = 1;
- return;
- }
-
- if (*op == 0xb7) {
- *size = 2;
- return;
- }
+ /*
+ * 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;
--
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
|