Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=4cd20952d74323df06e438c0c3273b5be89d6bfd
Commit: 4cd20952d74323df06e438c0c3273b5be89d6bfd
Parent: 959b3be64cab9160cd74532a49b89cdd918d38e9
Author: H. Peter Anvin <[EMAIL PROTECTED]>
AuthorDate: Mon Feb 18 23:24:33 2008 -0800
Committer: Ingo Molnar <[EMAIL PROTECTED]>
CommitDate: Tue Feb 26 12:55:51 2008 +0100
x86: add comments for NOPs
Add comments describing the various NOP sequences.
Signed-off-by: H. Peter Anvin <[EMAIL PROTECTED]>
Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]>
Signed-off-by: Thomas Gleixner <[EMAIL PROTECTED]>
---
include/asm-x86/nops.h | 62 ++++++++++++++++++++++++++++++++++-------------
1 files changed, 45 insertions(+), 17 deletions(-)
diff --git a/include/asm-x86/nops.h b/include/asm-x86/nops.h
index c52b334..e3b2bce 100644
--- a/include/asm-x86/nops.h
+++ b/include/asm-x86/nops.h
@@ -3,17 +3,29 @@
/* Define nops for use with alternative() */
-/* generic versions from gas */
-#define GENERIC_NOP1 ".byte 0x90\n"
-#define GENERIC_NOP2 ".byte 0x89,0xf6\n"
-#define GENERIC_NOP3 ".byte 0x8d,0x76,0x00\n"
-#define GENERIC_NOP4 ".byte 0x8d,0x74,0x26,0x00\n"
-#define GENERIC_NOP5 GENERIC_NOP1 GENERIC_NOP4
-#define GENERIC_NOP6 ".byte 0x8d,0xb6,0x00,0x00,0x00,0x00\n"
-#define GENERIC_NOP7 ".byte 0x8d,0xb4,0x26,0x00,0x00,0x00,0x00\n"
-#define GENERIC_NOP8 GENERIC_NOP1 GENERIC_NOP7
+/* generic versions from gas
+ 1: nop
+ 2: movl %esi,%esi
+ 3: leal 0x00(%esi),%esi
+ 4: leal 0x00(,%esi,1),%esi
+ 6: leal 0x00000000(%esi),%esi
+ 7: leal 0x00000000(,%esi,1),%esi
+*/
+#define GENERIC_NOP1 ".byte 0x90\n"
+#define GENERIC_NOP2 ".byte 0x89,0xf6\n"
+#define GENERIC_NOP3 ".byte 0x8d,0x76,0x00\n"
+#define GENERIC_NOP4 ".byte 0x8d,0x74,0x26,0x00\n"
+#define GENERIC_NOP5 GENERIC_NOP1 GENERIC_NOP4
+#define GENERIC_NOP6 ".byte 0x8d,0xb6,0x00,0x00,0x00,0x00\n"
+#define GENERIC_NOP7 ".byte 0x8d,0xb4,0x26,0x00,0x00,0x00,0x00\n"
+#define GENERIC_NOP8 GENERIC_NOP1 GENERIC_NOP7
-/* Opteron 64bit nops */
+/* Opteron 64bit nops
+ 1: nop
+ 2: osp nop
+ 3: osp osp nop
+ 4: osp osp osp nop
+*/
#define K8_NOP1 GENERIC_NOP1
#define K8_NOP2 ".byte 0x66,0x90\n"
#define K8_NOP3 ".byte 0x66,0x66,0x90\n"
@@ -23,19 +35,35 @@
#define K8_NOP7 K8_NOP4 K8_NOP3
#define K8_NOP8 K8_NOP4 K8_NOP4
-/* K7 nops */
-/* uses eax dependencies (arbitary choice) */
-#define K7_NOP1 GENERIC_NOP1
+/* K7 nops
+ uses eax dependencies (arbitary choice)
+ 1: nop
+ 2: movl %eax,%eax
+ 3: leal (,%eax,1),%eax
+ 4: leal 0x00(,%eax,1),%eax
+ 6: leal 0x00000000(%eax),%eax
+ 7: leal 0x00000000(,%eax,1),%eax
+*/
+#define K7_NOP1 GENERIC_NOP1
#define K7_NOP2 ".byte 0x8b,0xc0\n"
#define K7_NOP3 ".byte 0x8d,0x04,0x20\n"
#define K7_NOP4 ".byte 0x8d,0x44,0x20,0x00\n"
#define K7_NOP5 K7_NOP4 ASM_NOP1
#define K7_NOP6 ".byte 0x8d,0x80,0,0,0,0\n"
-#define K7_NOP7 ".byte 0x8D,0x04,0x05,0,0,0,0\n"
-#define K7_NOP8 K7_NOP7 ASM_NOP1
+#define K7_NOP7 ".byte 0x8D,0x04,0x05,0,0,0,0\n"
+#define K7_NOP8 K7_NOP7 ASM_NOP1
-/* P6 nops */
-/* uses eax dependencies (Intel-recommended choice) */
+/* P6 nops
+ uses eax dependencies (Intel-recommended choice)
+ 1: nop
+ 2: osp nop
+ 3: nopl (%eax)
+ 4: nopl 0x00(%eax)
+ 5: nopl 0x00(%eax,%eax,1)
+ 6: osp nopl 0x00(%eax,%eax,1)
+ 7: nopl 0x00000000(%eax)
+ 8: nopl 0x00000000(%eax,%eax,1)
+*/
#define P6_NOP1 GENERIC_NOP1
#define P6_NOP2 ".byte 0x66,0x90\n"
#define P6_NOP3 ".byte 0x0f,0x1f,0x00\n"
-
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