From 12e9b4faf68a1a02ebf5ad69c03ac10f170f14cb Mon Sep 17 00:00:00 2001
From: Rich Felker <dalias@aerifal.cx>
Date: Thu, 11 Oct 2012 22:47:07 -0400
Subject: i386 vsyscall support (vdso-provided sysenter/syscall instruction
 based)

this doubles the performance of the fastest syscalls on the atom I
tested it on; improvement is reportedly much more dramatic on
worst-case cpus. cannot be used for cancellable syscalls.
---
 src/internal/i386/syscall.s | 74 +++++++++++++++++++++++++++++++++++----------
 1 file changed, 58 insertions(+), 16 deletions(-)

(limited to 'src/internal/i386/syscall.s')

diff --git a/src/internal/i386/syscall.s b/src/internal/i386/syscall.s
index 327d4cc0..79296ba0 100644
--- a/src/internal/i386/syscall.s
+++ b/src/internal/i386/syscall.s
@@ -1,20 +1,62 @@
+.hidden __sysinfo
+
+.global __vsyscall
+.type __vsyscall,@function
+__vsyscall:
+	push %edi
+	push %ebx
+	mov %edx,%ebx
+	mov %edi,%edx
+	mov 12(%esp),%edi
+	push %eax
+	call 1f
+2:	pop %ebx
+	pop %ebx
+	pop %edi
+	ret
+
+1:	mov (%esp),%eax
+	add $[__sysinfo-2b],%eax
+	mov (%eax),%eax
+	test %eax,%eax
+	jz 1f
+	push %eax
+	mov 8(%esp),%eax
+	ret
+1:	mov 4(%esp),%eax
+	int $128
+	ret
+
+.global __vsyscall6
+.type __vsyscall6,@function
+__vsyscall6:
+	push %ebp
+	push %eax
+	mov 12(%esp), %ebp
+	mov (%ebp), %eax
+	mov 4(%ebp), %ebp
+	push %eax
+	mov 4(%esp),%eax
+	call __vsyscall
+	pop %ebp
+	pop %ebp
+	pop %ebp
+	ret
+
 .global __syscall
 .type __syscall,@function
 __syscall:
-	pushl %ebx
-	pushl %esi
-	pushl %edi
-	pushl %ebp
-	movl 20(%esp),%eax
-	movl 24(%esp),%ebx
-	movl 28(%esp),%ecx
-	movl 32(%esp),%edx
-	movl 36(%esp),%esi
-	movl 40(%esp),%edi
-	movl 44(%esp),%ebp
-	int $128
-	popl %ebp
-	popl %edi
-	popl %esi
-	popl %ebx
+	lea 24(%esp),%eax
+	push %esi
+	push %edi
+	push %eax
+	mov 16(%esp),%eax
+	mov 20(%esp),%edx
+	mov 24(%esp),%ecx
+	mov 28(%esp),%edi
+	mov 32(%esp),%esi
+	call __vsyscall6
+	pop %edi
+	pop %edi
+	pop %esi
 	ret
-- 
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