Module Name: src
Committed By: christos
Date: Mon Nov 24 15:33:18 UTC 2014
Modified Files:
src/lib/libc/arch/x86_64/sys: ptrace.S
Log Message:
Fix ptrace %rcx corruption when pthread_errno() is used. Small example:
#include <sys/types.h>
#include <stdio.h>
#include <sys/ptrace.h>
int main(void) { ptrace(18, getpid(), NULL, 0xabcd); }
The -lpthread cases pases 0 instead of 0xabcd
To generate a diff of this commit:
cvs rdiff -u -r1.5 -r1.6 src/lib/libc/arch/x86_64/sys/ptrace.S
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/lib/libc/arch/x86_64/sys/ptrace.S
diff -u src/lib/libc/arch/x86_64/sys/ptrace.S:1.5 src/lib/libc/arch/x86_64/sys/ptrace.S:1.6
--- src/lib/libc/arch/x86_64/sys/ptrace.S:1.5 Thu May 22 11:01:57 2014
+++ src/lib/libc/arch/x86_64/sys/ptrace.S Mon Nov 24 10:33:18 2014
@@ -1,4 +1,4 @@
-/* $NetBSD: ptrace.S,v 1.5 2014/05/22 15:01:57 uebayasi Exp $ */
+/* $NetBSD: ptrace.S,v 1.6 2014/11/24 15:33:18 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 1.5 2014/05/22 15:01:57 uebayasi Exp $")
+ RCSID("$NetBSD: ptrace.S,v 1.6 2014/11/24 15:33:18 christos Exp $")
#endif /* SYSLIBC_SCCS and not lint */
#include "SYS.h"
@@ -44,12 +44,21 @@
.globl _C_LABEL(__errno)
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.
+ */
+ movq %rcx, %r10
#ifdef __PIC__
call PIC_PLT(_C_LABEL(__errno))
#else
call _C_LABEL(__errno)
#endif /* __PIC__ */
movl $0,(%rax)
+ movq %r10, %rcx
SYSTRAP(ptrace)
jc err
ret
