Date: Tue, 06 May 2003 16:12:15 -0400 (EDT) From: John Baldwin <jhb@FreeBSD.org> To: Igor Sysoev <is@rambler-co.ru> Cc: freebsd-arch@freebsd.org Subject: Re: rfork(RFPROC|RFMEM) Message-ID: <XFMail.20030506161215.jhb@FreeBSD.org> In-Reply-To: <Pine.BSF.4.21.0305061751340.64470-100000@is>
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On 06-May-2003 Igor Sysoev wrote:
> On Mon, 5 May 2003, Terry Lambert wrote:
>
>> Igor Sysoev wrote:
>> > On Mon, 5 May 2003, Terry Lambert wrote:
>> > What is stack glue ?
>>
>> See the code in fork1() in /sys/kern/kern_fork.c.
>
> I do not see any stack manipulation in kern_fork.c except the creating
> alternate kstack for KSE thread in 5.0. And rfork(2) can not create
> such stack - it passes 0 to fork1().
> In 4.x there's no stack code at all.
>
>> > I use rfork_thread(3) wrapper that allows to setup another stack for
>> > rfork()ed process.
>
> By the way I found the bug in x86 rfork_thread(3)'s error handling:
>
> --- /usr/src/lib/libc/i386/gen/rfork_thread.S Wed Feb 7 03:12:45 2001
> +++ /usr/src/lib/libc/i386/gen/rfork_thread.S Tue May 6 17:45:14 2003
> @@ -108,5 +108,8 @@
> * Branch here if the thread creation fails:
> */
> 2:
> + popl %esi
> + movl %ebp, %esp
> + popl %ebp
> PIC_PROLOGUE
> jmp PIC_PLT(HIDENAME(cerror))
Shouldn't this be:
2:
+ addl $8, %esp
+ popl %esi
+ movl %ebp, %esp
+ popl %ebp
PIC_PROLOGUE
jmp PIC_PLT(HIDENAME(cerror))
To match the parent return case above the 1: label?
--
John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve!" - http://www.FreeBSD.org/
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