From: Joe Simmons-Talbott <josimmon@redhat.com>
To: Florian Weimer <fweimer@redhat.com>
Cc: Noah Goldstein via Libc-alpha <libc-alpha@sourceware.org>,
Noah Goldstein <goldstein.w.n@gmail.com>
Subject: Re: [PATCH v6 1/3] x86_64: Set the syscall register right before doing the syscall.
Date: Fri, 26 May 2023 08:59:47 -0400 [thread overview]
Message-ID: <20230526125947.GP176347@oak> (raw)
In-Reply-To: <877csvk1zt.fsf@oldenburg.str.redhat.com>
On Fri, May 26, 2023 at 09:04:06AM +0200, Florian Weimer wrote:
> * Noah Goldstein via Libc-alpha:
>
> > I'm minorly opposed to this patch. Even if GLIBC guarantees all
> > syscalls will set the number the instruction before, that's no guarantee
> > for the entire program. Furthermore in the event of:
> > `movl $VAL, %eax; syscall`
> > It's still not safe to *always* assume that `VAL` correspond to the
> > syscall number as a jump (direct or indirect) could still go between
> > the instructions (i.e there is no guarantee in the assembly that the
> > `mov` dominates the `syscall).
> > So at the end of the day, we are bloating the library without, AFAICT,
> > providing any real guarantee. Maybe I'm missing something?
>
> Joe, is there a size change to libc.so.6 as the result of this change?
No, the size is the same with and with out this patchset on x86_64.
Thanks,
Joe
next prev parent reply other threads:[~2023-05-26 12:59 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-24 15:03 [PATCH v6 0/3] x86_64: aarch64: Set call number just before syscall Joe Simmons-Talbott
2023-04-24 15:03 ` [PATCH v6 1/3] x86_64: Set the syscall register right before doing the syscall Joe Simmons-Talbott
2023-05-15 14:15 ` Joe Simmons-Talbott
2023-05-15 16:20 ` H.J. Lu
2023-05-25 18:07 ` Joe Simmons-Talbott
2023-05-25 18:40 ` Noah Goldstein
2023-05-26 7:04 ` Florian Weimer
2023-05-26 12:59 ` Joe Simmons-Talbott [this message]
2023-05-26 21:18 ` Noah Goldstein
2023-05-30 10:13 ` Florian Weimer
2023-05-31 18:23 ` Noah Goldstein
2023-06-28 19:17 ` Joe Simmons-Talbott
2023-04-24 15:03 ` [PATCH v6 2/3] aarch64: " Joe Simmons-Talbott
2023-05-09 7:47 ` Szabolcs Nagy
2023-04-24 15:03 ` [PATCH v6 3/3] nptl: Use direct syscall numbers in setxid Joe Simmons-Talbott
2023-04-24 15:17 ` Xi Ruoyao
2023-04-26 9:46 ` Szabolcs Nagy
2023-04-28 10:52 ` Florian Weimer
2023-04-26 12:39 ` Cristian Rodríguez
2023-04-26 13:24 ` Szabolcs Nagy
2023-05-25 18:07 ` Joe Simmons-Talbott
2023-05-08 14:13 ` [PATCH v6 0/3] x86_64: aarch64: Set call number just before syscall Joe Simmons-Talbott
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