On Sat, Apr 25, 2020 at 01:40:24PM +1000, Nicholas Piggin wrote:
> Excerpts from Rich Felker's message of April 24, 2020 3:42 am:
> > On Thu, Apr 23, 2020 at 02:15:58PM -0300, Adhemerval Zanella wrote:
> >>
> >>
> >> On 23/04/2020 13:43, Rich Felker wrote:
> >> > On Thu, Apr 23, 2020 at
Excerpts from Rich Felker's message of April 24, 2020 3:42 am:
> On Thu, Apr 23, 2020 at 02:15:58PM -0300, Adhemerval Zanella wrote:
>>
>>
>> On 23/04/2020 13:43, Rich Felker wrote:
>> > On Thu, Apr 23, 2020 at 01:35:01PM -0300, Adhemerval Zanella wrote:
>> >>
>> >>
>> >> On 23/04/2020 13:18,
Excerpts from Rich Felker's message of April 23, 2020 12:36 pm:
> On Wed, Apr 22, 2020 at 04:18:36PM +1000, Nicholas Piggin wrote:
>> Yeah I had a bit of a play around with musl (which is very nice code I
>> must say). The powerpc64 syscall asm is missing ctr clobber by the way.
>> Fortunately
On Thu, Apr 23, 2020 at 02:15:58PM -0300, Adhemerval Zanella wrote:
>
>
> On 23/04/2020 13:43, Rich Felker wrote:
> > On Thu, Apr 23, 2020 at 01:35:01PM -0300, Adhemerval Zanella wrote:
> >>
> >>
> >> On 23/04/2020 13:18, Rich Felker wrote:
> >>> On Thu, Apr 23, 2020 at 09:13:57AM -0300,
On 23/04/2020 13:43, Rich Felker wrote:
> On Thu, Apr 23, 2020 at 01:35:01PM -0300, Adhemerval Zanella wrote:
>>
>>
>> On 23/04/2020 13:18, Rich Felker wrote:
>>> On Thu, Apr 23, 2020 at 09:13:57AM -0300, Adhemerval Zanella wrote:
On 22/04/2020 23:36, Rich Felker wrote:
> On
On Thu, Apr 23, 2020 at 01:35:01PM -0300, Adhemerval Zanella wrote:
>
>
> On 23/04/2020 13:18, Rich Felker wrote:
> > On Thu, Apr 23, 2020 at 09:13:57AM -0300, Adhemerval Zanella wrote:
> >>
> >>
> >> On 22/04/2020 23:36, Rich Felker wrote:
> >>> On Wed, Apr 22, 2020 at 04:18:36PM +1000,
On 23/04/2020 13:18, Rich Felker wrote:
> On Thu, Apr 23, 2020 at 09:13:57AM -0300, Adhemerval Zanella wrote:
>>
>>
>> On 22/04/2020 23:36, Rich Felker wrote:
>>> On Wed, Apr 22, 2020 at 04:18:36PM +1000, Nicholas Piggin wrote:
Yeah I had a bit of a play around with musl (which is very
On Thu, Apr 23, 2020 at 09:13:57AM -0300, Adhemerval Zanella wrote:
>
>
> On 22/04/2020 23:36, Rich Felker wrote:
> > On Wed, Apr 22, 2020 at 04:18:36PM +1000, Nicholas Piggin wrote:
> >> Yeah I had a bit of a play around with musl (which is very nice code I
> >> must say). The powerpc64 syscall
On 22/04/2020 23:36, Rich Felker wrote:
> On Wed, Apr 22, 2020 at 04:18:36PM +1000, Nicholas Piggin wrote:
>> Yeah I had a bit of a play around with musl (which is very nice code I
>> must say). The powerpc64 syscall asm is missing ctr clobber by the way.
>> Fortunately adding it doesn't
On Wed, Apr 22, 2020 at 04:18:36PM +1000, Nicholas Piggin wrote:
> Yeah I had a bit of a play around with musl (which is very nice code I
> must say). The powerpc64 syscall asm is missing ctr clobber by the way.
> Fortunately adding it doesn't change code generation for me, but it
> should be
Excerpts from Nicholas Piggin's message of April 22, 2020 4:18 pm:
> If we go further and try to preserve r3 as well by putting the return
> value in r9 or r0, we go backwards about 300 bytes. It's good for the
> lock loops and complex functions, but hurts a lot of simpler functions
> that have
Excerpts from Rich Felker's message of April 21, 2020 3:27 am:
> On Mon, Apr 20, 2020 at 02:31:58PM +1000, Nicholas Piggin wrote:
>> Excerpts from Rich Felker's message of April 20, 2020 2:09 pm:
>> > On Mon, Apr 20, 2020 at 12:32:21PM +1000, Nicholas Piggin wrote:
>> >> Excerpts from Rich
From: Nicholas Piggin
> Sent: 20 April 2020 02:10
...
> >> Yes, but does it really matter to optimize this specific usage case
> >> for size? glibc, for instance, tries to leverage the syscall mechanism
> >> by adding some complex pre-processor asm directives. It optimizes
> >> the syscall code
From: Adhemerval Zanella
> Sent: 21 April 2020 16:01
>
> On 21/04/2020 11:39, Rich Felker wrote:
> > On Tue, Apr 21, 2020 at 12:28:25PM +, David Laight wrote:
> >> From: Nicholas Piggin
> >>> Sent: 20 April 2020 02:10
> >> ...
> > Yes, but does it really matter to optimize this specific
On 21/04/2020 11:39, Rich Felker wrote:
> On Tue, Apr 21, 2020 at 12:28:25PM +, David Laight wrote:
>> From: Nicholas Piggin
>>> Sent: 20 April 2020 02:10
>> ...
> Yes, but does it really matter to optimize this specific usage case
> for size? glibc, for instance, tries to leverage
On Tue, Apr 21, 2020 at 12:28:25PM +, David Laight wrote:
> From: Nicholas Piggin
> > Sent: 20 April 2020 02:10
> ...
> > >> Yes, but does it really matter to optimize this specific usage case
> > >> for size? glibc, for instance, tries to leverage the syscall mechanism
> > >> by adding some
* Szabolcs Nagy:
> * Nicholas Piggin [2020-04-20 12:08:36 +1000]:
>> Excerpts from Rich Felker's message of April 20, 2020 11:29 am:
>> > Also, allowing patching of executable pages is generally frowned upon
>> > these days because W^X is a desirable hardening property.
>>
>> Right, it would
* Nicholas Piggin [2020-04-20 12:08:36 +1000]:
> Excerpts from Rich Felker's message of April 20, 2020 11:29 am:
> > Also, allowing patching of executable pages is generally frowned upon
> > these days because W^X is a desirable hardening property.
>
> Right, it would want be write-protected
On Mon, Apr 20, 2020 at 02:31:58PM +1000, Nicholas Piggin wrote:
> Excerpts from Rich Felker's message of April 20, 2020 2:09 pm:
> > On Mon, Apr 20, 2020 at 12:32:21PM +1000, Nicholas Piggin wrote:
> >> Excerpts from Rich Felker's message of April 20, 2020 11:34 am:
> >> > On Mon, Apr 20, 2020 at
Excerpts from Rich Felker's message of April 20, 2020 2:09 pm:
> On Mon, Apr 20, 2020 at 12:32:21PM +1000, Nicholas Piggin wrote:
>> Excerpts from Rich Felker's message of April 20, 2020 11:34 am:
>> > On Mon, Apr 20, 2020 at 11:10:25AM +1000, Nicholas Piggin wrote:
>> >> Excerpts from Rich
On Mon, Apr 20, 2020 at 12:32:21PM +1000, Nicholas Piggin wrote:
> Excerpts from Rich Felker's message of April 20, 2020 11:34 am:
> > On Mon, Apr 20, 2020 at 11:10:25AM +1000, Nicholas Piggin wrote:
> >> Excerpts from Rich Felker's message of April 17, 2020 4:31 am:
> >> > Note that because lr is
Excerpts from Rich Felker's message of April 20, 2020 11:34 am:
> On Mon, Apr 20, 2020 at 11:10:25AM +1000, Nicholas Piggin wrote:
>> Excerpts from Rich Felker's message of April 17, 2020 4:31 am:
>> > Note that because lr is clobbered we need at least once normally
>> > call-clobbered register
Excerpts from Rich Felker's message of April 20, 2020 11:29 am:
> On Mon, Apr 20, 2020 at 10:27:58AM +1000, Nicholas Piggin wrote:
>> Excerpts from Szabolcs Nagy's message of April 16, 2020 7:58 pm:
>> > * Nicholas Piggin via Libc-alpha [2020-04-16
>> > 10:16:54 +1000]:
>> >> Well it would have
On Mon, Apr 20, 2020 at 11:10:25AM +1000, Nicholas Piggin wrote:
> Excerpts from Rich Felker's message of April 17, 2020 4:31 am:
> > Note that because lr is clobbered we need at least once normally
> > call-clobbered register that's not syscall clobbered to save lr in.
> > Otherwise stack frame
On Mon, Apr 20, 2020 at 10:27:58AM +1000, Nicholas Piggin wrote:
> Excerpts from Szabolcs Nagy's message of April 16, 2020 7:58 pm:
> > * Nicholas Piggin via Libc-alpha [2020-04-16
> > 10:16:54 +1000]:
> >> Well it would have to test HWCAP and patch in or branch to two
> >> completely different
Excerpts from Rich Felker's message of April 17, 2020 4:31 am:
> On Thu, Apr 16, 2020 at 03:18:42PM -0300, Adhemerval Zanella wrote:
>>
>>
>> On 16/04/2020 14:59, Rich Felker wrote:
>> > On Thu, Apr 16, 2020 at 02:50:18PM -0300, Adhemerval Zanella wrote:
>> >>
>> >>
>> >> On 16/04/2020 12:37,
Excerpts from Adhemerval Zanella's message of April 17, 2020 4:52 am:
>
>
> On 16/04/2020 15:31, Rich Felker wrote:
>> On Thu, Apr 16, 2020 at 03:18:42PM -0300, Adhemerval Zanella wrote:
>>>
>>>
>>> On 16/04/2020 14:59, Rich Felker wrote:
On Thu, Apr 16, 2020 at 02:50:18PM -0300, Adhemerval
Excerpts from Szabolcs Nagy's message of April 16, 2020 7:58 pm:
> * Nicholas Piggin via Libc-alpha [2020-04-16
> 10:16:54 +1000]:
>> Well it would have to test HWCAP and patch in or branch to two
>> completely different sequences including register save/restores yes.
>> You could have the same
* Segher Boessenkool:
> On Thu, Apr 16, 2020 at 08:34:42PM -0400, Rich Felker wrote:
>> On Thu, Apr 16, 2020 at 06:02:35PM -0500, Segher Boessenkool wrote:
>> > On Thu, Apr 16, 2020 at 08:12:19PM +0200, Florian Weimer wrote:
>> > > > I think my choice would be just making the inline syscall be a
On Thu, Apr 16, 2020 at 08:34:42PM -0400, Rich Felker wrote:
> On Thu, Apr 16, 2020 at 06:02:35PM -0500, Segher Boessenkool wrote:
> > On Thu, Apr 16, 2020 at 08:12:19PM +0200, Florian Weimer wrote:
> > > > I think my choice would be just making the inline syscall be a single
> > > > call insn to
On Thu, Apr 16, 2020 at 06:02:35PM -0500, Segher Boessenkool wrote:
> On Thu, Apr 16, 2020 at 08:12:19PM +0200, Florian Weimer wrote:
> > > I think my choice would be just making the inline syscall be a single
> > > call insn to an asm source file that out-of-lines the loading of TOC
> > > pointer
On Thu, Apr 16, 2020 at 08:12:19PM +0200, Florian Weimer wrote:
> > I think my choice would be just making the inline syscall be a single
> > call insn to an asm source file that out-of-lines the loading of TOC
> > pointer and call through it or branch based on hwcap so that it's not
> > repeated
* Nicholas Piggin via Libc-alpha:
> We may or may not be getting a new ABI that will use instructions not
> supported by old processors.
>
> https://sourceware.org/legacy-ml/binutils/2019-05/msg00331.html
>
> Current ABI continues to work of course and be the default for some
> time, but
On 16/04/2020 15:31, Rich Felker wrote:
> On Thu, Apr 16, 2020 at 03:18:42PM -0300, Adhemerval Zanella wrote:
>>
>>
>> On 16/04/2020 14:59, Rich Felker wrote:
>>> On Thu, Apr 16, 2020 at 02:50:18PM -0300, Adhemerval Zanella wrote:
On 16/04/2020 12:37, Rich Felker wrote:
> On
On Thu, Apr 16, 2020 at 02:31:51PM -0400, Rich Felker wrote:
> > While on musl:
> >
> > :
> >0: 48 83 ec 08 sub$0x8,%rsp
> >4: 48 63 ffmovslq %edi,%rdi
> >7: 48 63 f6movslq %esi,%rsi
> >a: b8
On Thu, Apr 16, 2020 at 03:18:42PM -0300, Adhemerval Zanella wrote:
>
>
> On 16/04/2020 14:59, Rich Felker wrote:
> > On Thu, Apr 16, 2020 at 02:50:18PM -0300, Adhemerval Zanella wrote:
> >>
> >>
> >> On 16/04/2020 12:37, Rich Felker wrote:
> >>> On Thu, Apr 16, 2020 at 11:16:04AM -0300,
On 16/04/2020 14:59, Rich Felker wrote:
> On Thu, Apr 16, 2020 at 02:50:18PM -0300, Adhemerval Zanella wrote:
>>
>>
>> On 16/04/2020 12:37, Rich Felker wrote:
>>> On Thu, Apr 16, 2020 at 11:16:04AM -0300, Adhemerval Zanella wrote:
> My preference would be that it work just like the i386
* Rich Felker:
> On Thu, Apr 16, 2020 at 06:42:32PM +0200, Florian Weimer wrote:
>> * Rich Felker:
>>
>> > On Thu, Apr 16, 2020 at 06:48:44AM +0200, Florian Weimer wrote:
>> >> * Rich Felker:
>> >>
>> >> > My preference would be that it work just like the i386 AT_SYSINFO
>> >> > where you just
On Thu, Apr 16, 2020 at 02:50:18PM -0300, Adhemerval Zanella wrote:
>
>
> On 16/04/2020 12:37, Rich Felker wrote:
> > On Thu, Apr 16, 2020 at 11:16:04AM -0300, Adhemerval Zanella wrote:
> >>> My preference would be that it work just like the i386 AT_SYSINFO
> >>> where you just replace "int
On 16/04/2020 12:37, Rich Felker wrote:
> On Thu, Apr 16, 2020 at 11:16:04AM -0300, Adhemerval Zanella wrote:
>>> My preference would be that it work just like the i386 AT_SYSINFO
>>> where you just replace "int $128" with "call *%%gs:16" and the kernel
>>> provides a stub in the vdso that
On Thu, Apr 16, 2020 at 06:42:32PM +0200, Florian Weimer wrote:
> * Rich Felker:
>
> > On Thu, Apr 16, 2020 at 06:48:44AM +0200, Florian Weimer wrote:
> >> * Rich Felker:
> >>
> >> > My preference would be that it work just like the i386 AT_SYSINFO
> >> > where you just replace "int $128" with
* Rich Felker:
> On Thu, Apr 16, 2020 at 06:48:44AM +0200, Florian Weimer wrote:
>> * Rich Felker:
>>
>> > My preference would be that it work just like the i386 AT_SYSINFO
>> > where you just replace "int $128" with "call *%%gs:16" and the kernel
>> > provides a stub in the vdso that performs
On Thu, Apr 16, 2020 at 11:21:56AM -0400, Jeffrey Walton wrote:
> On Wed, Apr 15, 2020 at 8:17 PM Nicholas Piggin wrote:
> >
> > Excerpts from Rich Felker's message of April 16, 2020 8:55 am:
> > > On Thu, Apr 16, 2020 at 07:45:09AM +1000, Nicholas Piggin wrote:
> > >> I would like to enable
On Thu, Apr 16, 2020 at 11:16:04AM -0300, Adhemerval Zanella wrote:
> > My preference would be that it work just like the i386 AT_SYSINFO
> > where you just replace "int $128" with "call *%%gs:16" and the kernel
> > provides a stub in the vdso that performs either scv or the old
> > mechanism with
On Thu, Apr 16, 2020 at 06:48:44AM +0200, Florian Weimer wrote:
> * Rich Felker:
>
> > My preference would be that it work just like the i386 AT_SYSINFO
> > where you just replace "int $128" with "call *%%gs:16" and the kernel
> > provides a stub in the vdso that performs either scv or the old
>
On Wed, Apr 15, 2020 at 8:17 PM Nicholas Piggin wrote:
>
> Excerpts from Rich Felker's message of April 16, 2020 8:55 am:
> > On Thu, Apr 16, 2020 at 07:45:09AM +1000, Nicholas Piggin wrote:
> >> I would like to enable Linux support for the powerpc 'scv' instruction,
> >> as a faster system call
* Nicholas Piggin via Libc-alpha [2020-04-16
10:16:54 +1000]:
> Well it would have to test HWCAP and patch in or branch to two
> completely different sequences including register save/restores yes.
> You could have the same asm and matching clobbers to put the sequence
> inline and then you
On 15/04/2020 19:55, Rich Felker wrote:
> On Thu, Apr 16, 2020 at 07:45:09AM +1000, Nicholas Piggin wrote:
>> I would like to enable Linux support for the powerpc 'scv' instruction,
>> as a faster system call instruction.
>>
>> This requires two things to be defined: Firstly a way to advertise
* Rich Felker:
> My preference would be that it work just like the i386 AT_SYSINFO
> where you just replace "int $128" with "call *%%gs:16" and the kernel
> provides a stub in the vdso that performs either scv or the old
> mechanism with the same calling convention.
The i386 mechanism has
Excerpts from Rich Felker's message of April 16, 2020 1:03 pm:
> On Thu, Apr 16, 2020 at 12:53:31PM +1000, Nicholas Piggin wrote:
>> > Not to mention the dcache line to access
>> > __hwcap or whatever, and the icache lines to setup access TOC-relative
>> > access to it. (Of course you could put a
On Thu, Apr 16, 2020 at 12:53:31PM +1000, Nicholas Piggin wrote:
> > Not to mention the dcache line to access
> > __hwcap or whatever, and the icache lines to setup access TOC-relative
> > access to it. (Of course you could put a copy of its value in TLS at a
> > fixed offset, which would somewhat
Excerpts from Rich Felker's message of April 16, 2020 12:35 pm:
> On Thu, Apr 16, 2020 at 12:24:16PM +1000, Nicholas Piggin wrote:
>> >> > Likewise, it's not useful to have different error return mechanisms
>> >> > because the caller just has to branch to support both (or the
>> >> >
On Thu, Apr 16, 2020 at 12:24:16PM +1000, Nicholas Piggin wrote:
> >> > Likewise, it's not useful to have different error return mechanisms
> >> > because the caller just has to branch to support both (or the
> >> > kernel-provided stub just has to emulate one for it; that could work
> >> > if you
Excerpts from Rich Felker's message of April 16, 2020 10:48 am:
> On Thu, Apr 16, 2020 at 10:16:54AM +1000, Nicholas Piggin wrote:
>> Excerpts from Rich Felker's message of April 16, 2020 8:55 am:
>> > On Thu, Apr 16, 2020 at 07:45:09AM +1000, Nicholas Piggin wrote:
>> >> I would like to enable
On Thu, Apr 16, 2020 at 10:16:54AM +1000, Nicholas Piggin wrote:
> Excerpts from Rich Felker's message of April 16, 2020 8:55 am:
> > On Thu, Apr 16, 2020 at 07:45:09AM +1000, Nicholas Piggin wrote:
> >> I would like to enable Linux support for the powerpc 'scv' instruction,
> >> as a faster
Excerpts from Rich Felker's message of April 16, 2020 8:55 am:
> On Thu, Apr 16, 2020 at 07:45:09AM +1000, Nicholas Piggin wrote:
>> I would like to enable Linux support for the powerpc 'scv' instruction,
>> as a faster system call instruction.
>>
>> This requires two things to be defined:
On Thu, Apr 16, 2020 at 07:45:09AM +1000, Nicholas Piggin wrote:
> I would like to enable Linux support for the powerpc 'scv' instruction,
> as a faster system call instruction.
>
> This requires two things to be defined: Firstly a way to advertise to
> userspace that kernel supports scv, and a
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