From: Jakub Jelinek <jakub@redhat.com>
To: davidm@hpl.hp.com
Cc: Andreas Schwab <schwab@suse.de>,
Ulrich Drepper <drepper@redhat.com>,
Glibc hackers <libc-hacker@sources.redhat.com>
Subject: Re: [PATCH] getpid/vfork/raise fix
Date: Wed, 10 Mar 2004 18:19:00 -0000 [thread overview]
Message-ID: <20040310160758.GZ3822@sunsite.ms.mff.cuni.cz> (raw)
In-Reply-To: <16463.21532.841079.452596@napali.hpl.hp.com>
On Wed, Mar 10, 2004 at 09:45:00AM -0800, David Mosberger wrote:
> >>>>> On Wed, 10 Mar 2004 15:50:52 +0100, Jakub Jelinek <jakub@redhat.com> said:
>
> >> Most scratch registers are _not_ preserved across system calls.
> >> You could spill the register onto the memory stack though. If it
> >> uses at most 16 bytes, you won't have to adjust the stack pointer
> >> even.
>
> Jakub> But as soon as you spill something into memory the vfork
> Jakub> child can clobber it and you restore in the parent something
> Jakub> different from what you saved.
>
> How many registers need to be preserved? Just one? (Sorry, I could
> read the code but I'm a bit preoccupied with other stuff at the
> moment.) If it's just one, I think you could use r11 because that one
> is required to be preserved for the light-weight syscall convention.
One (plus b0) is needed.
But first of all I'd like to understand the differences between
NPTL pt-vfork.S and libc vfork.S on IA-64. Why does one use
DO_CALL_VIA_BREAK and the other one DO_CALL, one has gas workarounds and one
does not?
Jakub
next prev parent reply other threads:[~2004-03-10 18:19 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-03-07 23:18 getpid/vfork broken Andreas Schwab
2004-03-07 23:30 ` Ulrich Drepper
2004-03-08 2:22 ` Roland McGrath
2004-03-08 2:28 ` Ulrich Drepper
2004-03-08 2:37 ` Roland McGrath
2004-03-08 13:10 ` Jakub Jelinek
2004-03-09 1:28 ` Roland McGrath
2004-03-09 2:04 ` Ulrich Drepper
2004-03-09 3:50 ` Richard Henderson
2004-03-09 7:48 ` Ulrich Drepper
2004-03-09 13:01 ` Andreas Schwab
2004-03-09 13:59 ` [PATCH] getpid/vfork/raise fix Jakub Jelinek
2004-03-09 16:44 ` Andreas Schwab
2004-03-09 19:38 ` Jakub Jelinek
2004-03-10 5:53 ` Ulrich Drepper
2004-03-10 10:37 ` Andreas Schwab
2004-03-10 12:24 ` Jakub Jelinek
2004-03-10 14:33 ` Andreas Schwab
2004-03-10 15:01 ` Jakub Jelinek
2004-03-10 15:06 ` Andreas Schwab
2004-03-10 16:56 ` David Mosberger
2004-03-10 17:02 ` Jakub Jelinek
2004-03-10 17:45 ` David Mosberger
2004-03-10 18:19 ` Jakub Jelinek [this message]
2004-03-10 19:24 ` David Mosberger
2004-03-10 18:44 ` Ulrich Drepper
2004-03-10 19:18 ` [PATCH] IA-64 pt-vfork fix Jakub Jelinek
2004-03-10 23:10 ` Ulrich Drepper
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