Hi Catalin, David, all
> COMPAT_SYSCALL_WRAP2(creat, ...):
> mov w0, w0
> b
>
> > > Cost wise, this seems like it all cancels out in the end, but what
> > > do I know?
> >
> > I think you know something, and I also think Heiko and other s390 guys
> > know something as well
On Fri, May 27, 2016 at 07:58:06PM +0300, Yury Norov wrote:
> So, we have 3 options for now:
> 1. Clear top halves in entry.S which means we pass off_t as a pair.
>The cost is performance (didn't measure it yet and doubt about it
>makes serious impact). The advantage is simplicity and unifi
On Fri, May 27, 2016 at 02:04:47PM +0100, Catalin Marinas wrote:
> On Fri, May 27, 2016 at 12:49:11PM +0200, Arnd Bergmann wrote:
> > On Friday, May 27, 2016 10:30:52 AM CEST Catalin Marinas wrote:
> > > On Fri, May 27, 2016 at 10:42:59AM +0200, Arnd Bergmann wrote:
> > > > On Friday, May 27, 2016
On Fri, May 27, 2016 at 12:49:11PM +0200, Arnd Bergmann wrote:
> On Friday, May 27, 2016 10:30:52 AM CEST Catalin Marinas wrote:
> > On Fri, May 27, 2016 at 10:42:59AM +0200, Arnd Bergmann wrote:
> > > On Friday, May 27, 2016 8:03:57 AM CEST Heiko Carstens wrote:
> > > > > > > > Cost wise, this see
On Friday, May 27, 2016 10:30:52 AM CEST Catalin Marinas wrote:
> On Fri, May 27, 2016 at 10:42:59AM +0200, Arnd Bergmann wrote:
> > On Friday, May 27, 2016 8:03:57 AM CEST Heiko Carstens wrote:
> > > > > > > Cost wise, this seems like it all cancels out in the end, but what
> > > > > > > do I know
On Thu, May 26, 2016 at 12:43:44PM -0700, David Miller wrote:
> From: Catalin Marinas
> Date: Thu, 26 May 2016 15:20:58 +0100
>
> > We can solve (a) by adding more __SC_WRAP annotations in the generic
> > unistd.h.
> ...
>
> I really think it's much more robust to clear the tops of the register
On Fri, May 27, 2016 at 10:42:59AM +0200, Arnd Bergmann wrote:
> On Friday, May 27, 2016 8:03:57 AM CEST Heiko Carstens wrote:
> > > > > > Cost wise, this seems like it all cancels out in the end, but what
> > > > > > do I know?
> > > > >
> > > > > I think you know something, and I also think Heik
On Fri, May 27, 2016 at 08:03:57AM +0200, Heiko Carstens wrote:
> > > > The cost is pretty trivial though. See kernel/compat_wrapper.o:
> > > > COMPAT_SYSCALL_WRAP2(creat, const char __user *, pathname, umode_t,
> > > > mode);
> > > > 0: a9bf7bfdstp x29, x30, [sp,#-16]!
> > > > 4:
On Friday, May 27, 2016 8:03:57 AM CEST Heiko Carstens wrote:
> > > > > Cost wise, this seems like it all cancels out in the end, but what
> > > > > do I know?
> > > >
> > > > I think you know something, and I also think Heiko and other s390 guys
> > > > know something as well. So I'd like to list
> > > The cost is pretty trivial though. See kernel/compat_wrapper.o:
> > > COMPAT_SYSCALL_WRAP2(creat, const char __user *, pathname, umode_t, mode);
> > > 0: a9bf7bfdstp x29, x30, [sp,#-16]!
> > > 4: 910003fdmov x29, sp
> > > 8: 2a0003e0mov w0, w0
> > > c
On Wed, May 25, 2016 at 12:30:17PM -0700, David Miller wrote:
> From: Yury Norov
> Date: Tue, 24 May 2016 03:04:30 +0300
>
> > +To clear that top halves, automatic wrappers are introduced. They clear all
> > +required registers before passing control to regular syscall handler.
>
> Why have one
On Thu, May 26, 2016 at 11:29:45PM +0100, Catalin Marinas wrote:
> On Thu, May 26, 2016 at 11:48:19PM +0300, Yury Norov wrote:
> > On Wed, May 25, 2016 at 02:28:21PM -0700, David Miller wrote:
> > > From: Arnd Bergmann
> > > Date: Wed, 25 May 2016 23:01:06 +0200
> > >
> > > > On Wednesday, May 25
On Thu, May 26, 2016 at 11:48:19PM +0300, Yury Norov wrote:
> On Wed, May 25, 2016 at 02:28:21PM -0700, David Miller wrote:
> > From: Arnd Bergmann
> > Date: Wed, 25 May 2016 23:01:06 +0200
> >
> > > On Wednesday, May 25, 2016 1:50:39 PM CEST David Miller wrote:
> > >> From: Arnd Bergmann
> > >>
On Wed, May 25, 2016 at 02:28:21PM -0700, David Miller wrote:
> From: Arnd Bergmann
> Date: Wed, 25 May 2016 23:01:06 +0200
>
> > On Wednesday, May 25, 2016 1:50:39 PM CEST David Miller wrote:
> >> From: Arnd Bergmann
> >> Date: Wed, 25 May 2016 22:47:33 +0200
> >>
> >> > If we use the normal c
From: Catalin Marinas
Date: Thu, 26 May 2016 15:20:58 +0100
> We can solve (a) by adding more __SC_WRAP annotations in the generic
> unistd.h.
...
I really think it's much more robust to clear the tops of the registers
by default. Then you won't be auditing constantly and adding more and
more
On Thu, May 26, 2016 at 03:50:01PM +0100, Szabolcs Nagy wrote:
> On 26/05/16 15:20, Catalin Marinas wrote:
> > While writing the above, I realised the current ILP32 patches still miss
> > on converting pointers passed from user space (unless I got myself
> > confused in macros). The new __SC_WRAP()
On 26/05/16 15:20, Catalin Marinas wrote:
> While writing the above, I realised the current ILP32 patches still miss
> on converting pointers passed from user space (unless I got myself
> confused in macros). The new __SC_WRAP() and COMPAT_SYSCALL_WRAPx()
> macros take care of zero or sign extensio
On Wed, May 25, 2016 at 02:28:21PM -0700, David Miller wrote:
> From: Arnd Bergmann
> Date: Wed, 25 May 2016 23:01:06 +0200
>
> > On Wednesday, May 25, 2016 1:50:39 PM CEST David Miller wrote:
> >> From: Arnd Bergmann
> >> Date: Wed, 25 May 2016 22:47:33 +0200
> >>
> >> > If we use the normal c
From: Arnd Bergmann
Date: Wed, 25 May 2016 23:01:06 +0200
> On Wednesday, May 25, 2016 1:50:39 PM CEST David Miller wrote:
>> From: Arnd Bergmann
>> Date: Wed, 25 May 2016 22:47:33 +0200
>>
>> > If we use the normal calling conventions, we could remove these overrides
>> > along with the respec
On Wednesday, May 25, 2016 1:50:39 PM CEST David Miller wrote:
> From: Arnd Bergmann
> Date: Wed, 25 May 2016 22:47:33 +0200
>
> > If we use the normal calling conventions, we could remove these overrides
> > along with the respective special-case handling in glibc. None of them
> > look particul
From: Arnd Bergmann
Date: Wed, 25 May 2016 22:47:33 +0200
> If we use the normal calling conventions, we could remove these overrides
> along with the respective special-case handling in glibc. None of them
> look particularly performance-sensitive, but I could be wrong there.
You could set the
On Wednesday, May 25, 2016 1:21:45 PM CEST David Miller wrote:
> From: Yury Norov
> Date: Wed, 25 May 2016 23:03:27 +0300
>
> > On Wed, May 25, 2016 at 12:30:17PM -0700, David Miller wrote:
> >> From: Yury Norov
> >> Date: Tue, 24 May 2016 03:04:30 +0300
> >>
> >> > +To clear that top halves, a
From: Yury Norov
Date: Wed, 25 May 2016 23:03:27 +0300
> On Wed, May 25, 2016 at 12:30:17PM -0700, David Miller wrote:
>> From: Yury Norov
>> Date: Tue, 24 May 2016 03:04:30 +0300
>>
>> > +To clear that top halves, automatic wrappers are introduced. They clear
>> > all
>> > +required registers
On Wed, May 25, 2016 at 12:30:17PM -0700, David Miller wrote:
> From: Yury Norov
> Date: Tue, 24 May 2016 03:04:30 +0300
>
> > +To clear that top halves, automatic wrappers are introduced. They clear all
> > +required registers before passing control to regular syscall handler.
>
> Why have one
From: Yury Norov
Date: Tue, 24 May 2016 03:04:30 +0300
> +To clear that top halves, automatic wrappers are introduced. They clear all
> +required registers before passing control to regular syscall handler.
Why have one of these for every single compat system call, rather than
simply clearing th
Signed-off-by: Yury Norov
---
Documentation/adding-syscalls.txt | 32
1 file changed, 32 insertions(+)
diff --git a/Documentation/adding-syscalls.txt
b/Documentation/adding-syscalls.txt
index cc2d4ac..d02a6bd 100644
--- a/Documentation/adding-syscalls.txt
+++ b/
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