Index: uspace/lib/libc/arch/ia32/src/syscall.S
===================================================================
--- uspace/lib/libc/arch/ia32/src/syscall.S	(revision c98e6ee244a8e271a395a052069c23bca4f8b538)
+++ uspace/lib/libc/arch/ia32/src/syscall.S	(revision 05e69c59b06df4165bbd86304590e9d5f3964437)
@@ -29,5 +29,5 @@
 .text
 
-/** Syscall wrapper.
+/** Syscall wrapper - INT $0x30 version.
  *
  * Mind the order of arguments. First two arguments and the syscall number go to
@@ -35,6 +35,6 @@
  * could benefit from this and not save unused registers on the stack.
  */
-.global __syscall
-__syscall:
+.global __syscall_int
+__syscall_int:
 	pushl %ebx
 	pushl %esi
@@ -54,2 +54,37 @@
 	popl %ebx
 	ret
+
+
+/** Syscall wrapper - SYSENTER version.
+ *
+ * This is an optimized version of syscall for four or less arguments.  Note
+ * that EBP and EDI are used to remember user stack address and the return
+ * address. The kernel part doesn't save DS, ES and FS so the handler restores
+ * these to the selector immediately following CS (it must be the flat data
+ * segment, otherwise the SYSENTER wouldn't work in the first place).
+ */
+.global __syscall_sysenter
+__syscall_sysenter:
+	pushl %ebx
+	pushl %esi
+	pushl %edi
+	pushl %ebp
+	mov %esp, %ebp
+	lea ra, %edi
+	movl 20(%esp), %edx	# First argument.
+	movl 24(%esp), %ecx	# Second argument.
+	movl 28(%esp), %ebx	# Third argument.
+	movl 32(%esp), %esi	# Fourth argument.
+	movl 44(%esp), %eax	# Syscall number.
+	sysenter
+ra:
+	movw %cs, %cx
+	addw $8, %cx
+	movw %cx, %ds
+	movw %cx, %es
+	movw %cx, %fs
+	popl %ebp
+	popl %edi
+	popl %esi
+	popl %ebx
+	ret