linux-kernel - Re: [PATCH v2] Add preadv and pwritev system calls.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sun, 14 Dec 2008 12:49:31 +0100
From:	Heiko Carstens <heiko.carstens@...ibm.com>
To:	Matthew Wilcox <matthew@....cx>
Cc:	Gerd Hoffmann <kraxel@...hat.com>, linux-kernel@...r.kernel.org,
	linux-arch@...r.kernel.org
Subject: Re: [PATCH v2] Add preadv and pwritev system calls.

On Fri, Dec 12, 2008 at 08:29:29AM -0700, Matthew Wilcox wrote:
> On Fri, Dec 12, 2008 at 03:00:40PM +0100, Gerd Hoffmann wrote:
> > The patch sports the actual system call implementation and the windup in
> > the x86 system call tables.  Other archs are TBD.
> 
> > +asmlinkage ssize_t sys_preadv(unsigned long fd, const struct iovec __user *vec,
> > +                              unsigned long vlen, loff_t pos)
> > +asmlinkage ssize_t sys_pwritev(unsigned long fd, const struct iovec __user *vec,
> > +                               unsigned long vlen, loff_t pos)
> 
> Are these prototypes required?  MIPS and PARISC will need wrappers to
> fix them if they are.  These two architectures have an ABI which
> requires 64-bit arguments to be passed in aligned pairs of registers,
> but glibc doesn't know that (and given the existence of syscall(3),
> can't do much about it even if it knew), so some of the arguments end up
> in the wrong registers.
> 
> Things will go much better if we can prototype these as:
> 
> asmlinkage ssize_t sys_preadv(unsigned int fd, const struct iovec __user *vec,
> 				loff_t pos, unsigned long vlen);
> asmlinkage ssize_t sys_pwritev(unsigned int fd, const struct iovec __user *vec,
> 				loff_t pos, unsigned long vlen);
> 
> That way 'pos' ends up split between arg2 and arg3 and vlen ends up in
> arg4 instead of having vlen in arg2 and pos in arg3 and arg4 which then
> have to be munged to be in arg4 and arg5 by a compat wrapper.
> 
> I seem to recall the s390 folks having some concerns with this kind of
> thing too, but I forget what they are, so I'll let them weigh in on
> this.

I think a lot of stuff that needs to be known for new system calls was
written up with these two postings:

http://marc.info/?l=linux-arch&m=118277150812137&w=2
http://lkml.org/lkml/2007/8/1/354
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/