[src/trunk]: src/lib/libc/arch/x86_64/sys Save and restore all the registers ...

[christos <christos%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/e467533f7dc3
branches:  trunk
changeset: 344284:e467533f7dc3
user:      christos <christos%NetBSD.org@localhost>
date:      Sat Mar 19 21:27:38 2016 +0000

description:
Save and restore all the registers we need instead of playing tricks and
"knowing" which registers the compiler clobbers. gcc-5.3 clobbers both
rcx and rdx...

diffstat:

 lib/libc/arch/x86_64/sys/ptrace.S |  20 +++++++++++---------
 1 files changed, 11 insertions(+), 9 deletions(-)

diffs (47 lines):

diff -r e4da54733326 -r e467533f7dc3 lib/libc/arch/x86_64/sys/ptrace.S
--- a/lib/libc/arch/x86_64/sys/ptrace.S Sat Mar 19 20:57:48 2016 +0000
+++ b/lib/libc/arch/x86_64/sys/ptrace.S Sat Mar 19 21:27:38 2016 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ptrace.S,v 1.6 2014/11/24 15:33:18 christos Exp $      */
+/*     $NetBSD: ptrace.S,v 1.7 2016/03/19 21:27:38 christos Exp $      */
 
 /*-
  * Copyright (c) 1990 The Regents of the University of California.
@@ -36,7 +36,7 @@
 
 #include <machine/asm.h>
 #if defined(SYSLIBC_SCCS) && !defined(lint)
-       RCSID("$NetBSD: ptrace.S,v 1.6 2014/11/24 15:33:18 christos Exp $")
+       RCSID("$NetBSD: ptrace.S,v 1.7 2016/03/19 21:27:38 christos Exp $")
 #endif /* SYSLIBC_SCCS and not lint */
 
 #include "SYS.h"
@@ -46,19 +46,21 @@
 ENTRY(ptrace)
        /*
         * The following code calls __errno() to set it to 0 before
-        * calling ptrace(2). The libc version of __errno() does not use
-        * any registers, but the libpthread version clobbers %rcx
-        * before we get a chance to store it in %r10. So we save it
-        * in %r10 and restore it.
+        * calling ptrace(2). Preserve and restore all the parameters
         */
-       movq    %rcx, %r10
+       pushq   %rdi
+       pushq   %rsi
+       pushq   %rdx
+       pushq   %rcx
 #ifdef __PIC__
        call    PIC_PLT(_C_LABEL(__errno))
 #else
        call    _C_LABEL(__errno)
 #endif /* __PIC__ */
-       movl    $0,(%rax)
-       movq    %r10, %rcx
+       popq    %rcx
+       popq    %rdx
+       popq    %rsi
+       popq    %rdi
        SYSTRAP(ptrace)
        jc      err
        ret