Previously, `copyinmsg' was the same function as `copyin'. The former
is for messages, and the size of messages is a multiple of four.
Likewise for `copyoutmsg'.
Provide a specialized version of both functions. This shaves off a
couple of instructions and improves our IPC performance.
* i386/i386/locore.S (copyinmsg): New function.
(copyout): Do not needlessly copy length to %eax first.
(copyoutmsg): New function.
---
i386/i386/locore.S | 78 +++++++++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 71 insertions(+), 7 deletions(-)
diff --git a/i386/i386/locore.S b/i386/i386/locore.S
index 15715f6..ab17879 100644
--- a/i386/i386/locore.S
+++ b/i386/i386/locore.S
@@ -1232,13 +1232,12 @@ ENTRY(discover_x86_cpu_type)
*/
/*
- * Copy from user address space.
+ * Copy from user address space - generic version.
* arg0: user address
* arg1: kernel address
* arg2: byte count
*/
ENTRY(copyin)
-Entry(copyinmsg)
pushl %esi
pushl %edi /* save registers */
@@ -1275,13 +1274,43 @@ copyin_fail:
jmp copyin_ret /* pop frame and return */
/*
- * Copy to user address space.
+ * Copy from user address space - version for copying messages.
+ * arg0: user address
+ * arg1: kernel address
+ * arg2: byte count - must be a multiple of four
+ */
+ENTRY(copyinmsg)
+ pushl %esi
+ pushl %edi /* save registers */
+
+ movl 8+S_ARG0,%esi /* get user start address */
+ movl 8+S_ARG1,%edi /* get kernel destination address */
+ movl 8+S_ARG2,%ecx /* get count */
+
+ movl $USER_DS,%eax /* use user data segment for accesses */
+ mov %ax,%ds
+
+ /*cld*/ /* count up: default mode in all GCC
code */
+ shrl $2,%ecx
+ RECOVER(copyin_fail)
+ rep
+ movsl /* move longwords */
+ xorl %eax,%eax /* return 0 for success */
+
+ mov %ss,%di /* restore DS to kernel segment */
+ mov %di,%ds
+
+ popl %edi /* restore registers */
+ popl %esi
+ ret /* and return */
+
+/*
+ * Copy to user address space - generic version.
* arg0: kernel address
* arg1: user address
* arg2: byte count
*/
ENTRY(copyout)
-Entry(copyoutmsg)
pushl %esi
pushl %edi /* save registers */
@@ -1297,14 +1326,13 @@ Entry(copyoutmsg)
jbe copyout_retry /* Use slow version on i386 */
#endif /* !defined(MACH_HYP) && !PAE */
- movl %edx,%eax /* use count */
/*cld*/ /* count up: always this way in GCC
code */
- movl %eax,%ecx /* move by longwords first */
+ movl %edx,%ecx /* move by longwords first */
shrl $2,%ecx
RECOVER(copyout_fail)
rep
movsl
- movl %eax,%ecx /* now move remaining bytes */
+ movl %edx,%ecx /* now move remaining bytes */
andl $3,%ecx
RECOVER(copyout_fail)
rep
@@ -1323,6 +1351,42 @@ copyout_fail:
movl $1,%eax /* return 1 for failure */
jmp copyout_ret /* pop frame and return */
+/*
+ * Copy to user address space - version for copying messages.
+ * arg0: kernel address
+ * arg1: user address
+ * arg2: byte count - must be a multiple of four
+ */
+ENTRY(copyoutmsg)
+ pushl %esi
+ pushl %edi /* save registers */
+
+ movl 8+S_ARG0,%esi /* get kernel start address */
+ movl 8+S_ARG1,%edi /* get user start address */
+ movl 8+S_ARG2,%ecx /* get count */
+
+ movl $USER_DS,%eax /* use user data segment for accesses */
+ mov %ax,%es
+
+#if !defined(MACH_HYP) && !PAE
+ movl 8+S_ARG2,%edx /* copyout_retry expects count here */
+ cmpl $3,machine_slot+SUB_TYPE_CPU_TYPE
+ jbe copyout_retry /* Use slow version on i386 */
+#endif /* !defined(MACH_HYP) && !PAE */
+
+ shrl $2,%ecx /* move by longwords */
+ RECOVER(copyout_fail)
+ rep
+ movsl
+ xorl %eax,%eax /* return 0 for success */
+
+ mov %ss,%di /* restore ES to kernel segment */
+ mov %di,%es
+
+ popl %edi /* restore registers */
+ popl %esi
+ ret /* and return */
+
#if !defined(MACH_HYP) && !PAE
/*
* Check whether user address space is writable
--
2.1.3
