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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
This commit is contained in:
christos 2014-11-24 15:33:18 +00:00
parent 4b574ec157
commit 625ac095d3
1 changed files with 11 additions and 2 deletions
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13
lib/libc/arch/x86_64/sys/ptrace.S
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@ -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