Re: PING^5 [PATCH] rs6000: Adjust -fpatchable-function-entry* support for dual entry [PR112980]

2024-08-27 Thread Martin Jambor 
Hi,

On Fri, Aug 09 2024, Kewen.Lin wrote:
> Hi,
>
> Gentle ping this patch:
>
> https://gcc.gnu.org/pipermail/gcc-patches/2024-May/651025.html

I'd like to second this ping, please.

Thank you,

Martin


>
> BR,
> Kewen
>
>>> on 2024/7/12 00:15, Martin Jambor wrote:
 Hi,

 can I add myself to the bunch of people who are pinging this? 
 Having
 this in will make our life easier.

 Thanks a lot,

 Martin


 On Wed, May 08 2024, Kewen.Lin wrote:
> Hi,
>
> As the discussion in PR112980, although the current
> implementation for -fpatchable-function-entry* conforms
> with the documentation (making N NOPs be consecutive),
> it's inefficient for both kernel and userspace livepatching
> (see comments in PR for the details).
>
> So this patch is to change the current implementation by
> emitting the "before" NOPs before global entry point and
> the "after" NOPs after local entry point.  The new behavior
> would not keep NOPs to be consecutive, so the documentation
> is updated to emphasize this.
>
> Bootstrapped and regress-tested on powerpc64-linux-gnu
> P8/P9 and powerpc64le-linux-gnu P9 and P10.
>
> Is it ok for trunk?  And backporting to active branches
> after burn-in time?  I guess we should also mention this
> change in changes.html?
>
> BR,
> Kewen
> -
>   PR target/112980
>
> gcc/ChangeLog:
>
>   * config/rs6000/rs6000-logue.cc
> (rs6000_output_function_prologue):
>   Adjust the handling on patch area emitting with dual
> entry, remove
>   the restriction on "before" NOPs count, not emit
> "before" NOPs any
>   more but only emit "after" NOPs.
>   * config/rs6000/rs6000.cc
> (rs6000_print_patchable_function_entry):
>   Adjust by respecting cfun->machine-
>> stop_patch_area_print.
>   (rs6000_elf_declare_function_name): For ELFv2 with dual
> entry, set
>   cfun->machine->stop_patch_area_print as true.
>   * config/rs6000/rs6000.h (struct machine_function):
> Remove member
>   global_entry_emitted, add new member
> stop_patch_area_print.
>   * doc/invoke.texi (option -fpatchable-function-entry):
> Adjust the
>   documentation for PowerPC ELFv2 dual entry.
>
> gcc/testsuite/ChangeLog:
>
>   * c-c++-common/patchable_function_entry-default.c:
> Adjust.
>   * gcc.target/powerpc/pr99888-4.c: Likewise.
>   * gcc.target/powerpc/pr99888-5.c: Likewise.
>   * gcc.target/powerpc/pr99888-6.c: Likewise.
> ---
>  gcc/config/rs6000/rs6000-logue.cc | 40 +
> --
>  gcc/config/rs6000/rs6000.cc   | 15 +--
>  gcc/config/rs6000/rs6000.h    | 10 +++--
>  gcc/doc/invoke.texi   |  8 ++--
>  .../patchable_function_entry-default.c    |  3 --
>  gcc/testsuite/gcc.target/powerpc/pr99888-4.c  |  4 +-
>  gcc/testsuite/gcc.target/powerpc/pr99888-5.c  |  4 +-
>  gcc/testsuite/gcc.target/powerpc/pr99888-6.c  |  4 +-
>  8 files changed, 33 insertions(+), 55 deletions(-)
>
> diff --git a/gcc/config/rs6000/rs6000-logue.cc
> b/gcc/config/rs6000/rs6000-logue.cc
> index 60ba15a8bc3..0eb019b44b3 100644
> --- a/gcc/config/rs6000/rs6000-logue.cc
> +++ b/gcc/config/rs6000/rs6000-logue.cc
> @@ -4006,43 +4006,21 @@ rs6000_output_function_prologue (FILE
> *file)
>     fprintf (file, "\tadd 2,2,12\n");
>   }
>
> -  unsigned short patch_area_size = crtl->patch_area_size;
> -  unsigned short patch_area_entry = crtl->patch_area_entry;
> -  /* Need to emit the patching area.  */
> -  if (patch_area_size > 0)
> - {
> -   cfun->machine->global_entry_emitted = true;
> -   /* As ELFv2 ABI shows, the allowable bytes between the
> global
> -  and local entry points are 0, 4, 8, 16, 32 and 64
> when
> -  there is a local entry point.  Considering there
> are two
> -  non-prefixed instructions for global entry point
> prologue
> -  (8 bytes), the count for patchable nops before
> local entry
> -  point would be 2, 6 and 14.  It's possible to
> support those
> -  other counts of nops by not making a local entry
> point, but
> -  we don't have clear use cases for them, so leave
> them
> -  unsupported for now.  */
> -   if (patch_area_entry > 0)
> -     {
> -   if (patch_area_entry != 2
> -   && patch_area_entry != 6
> -   && patch_area_entry != 14)
> - error ("unsupported number of nops before
> function entry (%u)",
> -    patch_area_entry);
> -   rs6000_print_patchable_function_entry (file,
> patch_area_entry,
> -  true);
> -   patch_area_

PING^5 [PATCH] rs6000: Adjust -fpatchable-function-entry* support for dual entry [PR112980]

2024-08-09 Thread Kewen.Lin 
Hi,

Gentle ping this patch:

https://gcc.gnu.org/pipermail/gcc-patches/2024-May/651025.html

BR,
Kewen

>> on 2024/7/12 00:15, Martin Jambor wrote:
>>> Hi,
>>>
>>> can I add myself to the bunch of people who are pinging this? 
>>> Having
>>> this in will make our life easier.
>>>
>>> Thanks a lot,
>>>
>>> Martin
>>>
>>>
>>> On Wed, May 08 2024, Kewen.Lin wrote:
 Hi,

 As the discussion in PR112980, although the current
 implementation for -fpatchable-function-entry* conforms
 with the documentation (making N NOPs be consecutive),
 it's inefficient for both kernel and userspace livepatching
 (see comments in PR for the details).

 So this patch is to change the current implementation by
 emitting the "before" NOPs before global entry point and
 the "after" NOPs after local entry point.  The new behavior
 would not keep NOPs to be consecutive, so the documentation
 is updated to emphasize this.

 Bootstrapped and regress-tested on powerpc64-linux-gnu
 P8/P9 and powerpc64le-linux-gnu P9 and P10.

 Is it ok for trunk?  And backporting to active branches
 after burn-in time?  I guess we should also mention this
 change in changes.html?

 BR,
 Kewen
 -
PR target/112980

 gcc/ChangeLog:

* config/rs6000/rs6000-logue.cc
 (rs6000_output_function_prologue):
Adjust the handling on patch area emitting with dual
 entry, remove
the restriction on "before" NOPs count, not emit
 "before" NOPs any
more but only emit "after" NOPs.
* config/rs6000/rs6000.cc
 (rs6000_print_patchable_function_entry):
Adjust by respecting cfun->machine-
> stop_patch_area_print.
(rs6000_elf_declare_function_name): For ELFv2 with dual
 entry, set
cfun->machine->stop_patch_area_print as true.
* config/rs6000/rs6000.h (struct machine_function):
 Remove member
global_entry_emitted, add new member
 stop_patch_area_print.
* doc/invoke.texi (option -fpatchable-function-entry):
 Adjust the
documentation for PowerPC ELFv2 dual entry.

 gcc/testsuite/ChangeLog:

* c-c++-common/patchable_function_entry-default.c:
 Adjust.
* gcc.target/powerpc/pr99888-4.c: Likewise.
* gcc.target/powerpc/pr99888-5.c: Likewise.
* gcc.target/powerpc/pr99888-6.c: Likewise.
 ---
  gcc/config/rs6000/rs6000-logue.cc | 40 +
 --
  gcc/config/rs6000/rs6000.cc   | 15 +--
  gcc/config/rs6000/rs6000.h    | 10 +++--
  gcc/doc/invoke.texi   |  8 ++--
  .../patchable_function_entry-default.c    |  3 --
  gcc/testsuite/gcc.target/powerpc/pr99888-4.c  |  4 +-
  gcc/testsuite/gcc.target/powerpc/pr99888-5.c  |  4 +-
  gcc/testsuite/gcc.target/powerpc/pr99888-6.c  |  4 +-
  8 files changed, 33 insertions(+), 55 deletions(-)

 diff --git a/gcc/config/rs6000/rs6000-logue.cc
 b/gcc/config/rs6000/rs6000-logue.cc
 index 60ba15a8bc3..0eb019b44b3 100644
 --- a/gcc/config/rs6000/rs6000-logue.cc
 +++ b/gcc/config/rs6000/rs6000-logue.cc
 @@ -4006,43 +4006,21 @@ rs6000_output_function_prologue (FILE
 *file)
      fprintf (file, "\tadd 2,2,12\n");
    }

 -  unsigned short patch_area_size = crtl->patch_area_size;
 -  unsigned short patch_area_entry = crtl->patch_area_entry;
 -  /* Need to emit the patching area.  */
 -  if (patch_area_size > 0)
 -  {
 -    cfun->machine->global_entry_emitted = true;
 -    /* As ELFv2 ABI shows, the allowable bytes between the
 global
 -   and local entry points are 0, 4, 8, 16, 32 and 64
 when
 -   there is a local entry point.  Considering there
 are two
 -   non-prefixed instructions for global entry point
 prologue
 -   (8 bytes), the count for patchable nops before
 local entry
 -   point would be 2, 6 and 14.  It's possible to
 support those
 -   other counts of nops by not making a local entry
 point, but
 -   we don't have clear use cases for them, so leave
 them
 -   unsupported for now.  */
 -    if (patch_area_entry > 0)
 -      {
 -    if (patch_area_entry != 2
 -    && patch_area_entry != 6
 -    && patch_area_entry != 14)
 -  error ("unsupported number of nops before
 function entry (%u)",
 -     patch_area_entry);
 -    rs6000_print_patchable_function_entry (file,
 patch_area_entry,
 -   true);
 -    patch_area_size -= patch_area_entry;
 -      }
 -  }
 -
    fputs ("\t.localentry\t", file);
    assemble_name (file, name);
    fputs (",.-", file);
    assemble_name (fil

Re: PING^3 [PATCH] rs6000: Adjust -fpatchable-function-entry* support for dual entry [PR112980]

2024-07-25 Thread Giuliano Belinassi 
Pinging this again.

Em seg, 2024-07-22 às 17:18 +0800, Kewen.Lin escreveu:
> Hi,
> 
> Gentle ping this patch:
> 
> https://gcc.gnu.org/pipermail/gcc-patches/2024-May/651025.html
> 
> BR,
> Kewen
> 
> on 2024/7/12 00:15, Martin Jambor wrote:
> > Hi,
> > 
> > can I add myself to the bunch of people who are pinging this? 
> > Having
> > this in will make our life easier.
> > 
> > Thanks a lot,
> > 
> > Martin
> > 
> > 
> > On Wed, May 08 2024, Kewen.Lin wrote:
> > > Hi,
> > > 
> > > As the discussion in PR112980, although the current
> > > implementation for -fpatchable-function-entry* conforms
> > > with the documentation (making N NOPs be consecutive),
> > > it's inefficient for both kernel and userspace livepatching
> > > (see comments in PR for the details).
> > > 
> > > So this patch is to change the current implementation by
> > > emitting the "before" NOPs before global entry point and
> > > the "after" NOPs after local entry point.  The new behavior
> > > would not keep NOPs to be consecutive, so the documentation
> > > is updated to emphasize this.
> > > 
> > > Bootstrapped and regress-tested on powerpc64-linux-gnu
> > > P8/P9 and powerpc64le-linux-gnu P9 and P10.
> > > 
> > > Is it ok for trunk?  And backporting to active branches
> > > after burn-in time?  I guess we should also mention this
> > > change in changes.html?
> > > 
> > > BR,
> > > Kewen
> > > -
> > >   PR target/112980
> > > 
> > > gcc/ChangeLog:
> > > 
> > >   * config/rs6000/rs6000-logue.cc
> > > (rs6000_output_function_prologue):
> > >   Adjust the handling on patch area emitting with dual
> > > entry, remove
> > >   the restriction on "before" NOPs count, not emit
> > > "before" NOPs any
> > >   more but only emit "after" NOPs.
> > >   * config/rs6000/rs6000.cc
> > > (rs6000_print_patchable_function_entry):
> > >   Adjust by respecting cfun->machine-
> > > >stop_patch_area_print.
> > >   (rs6000_elf_declare_function_name): For ELFv2 with dual
> > > entry, set
> > >   cfun->machine->stop_patch_area_print as true.
> > >   * config/rs6000/rs6000.h (struct machine_function):
> > > Remove member
> > >   global_entry_emitted, add new member
> > > stop_patch_area_print.
> > >   * doc/invoke.texi (option -fpatchable-function-entry):
> > > Adjust the
> > >   documentation for PowerPC ELFv2 dual entry.
> > > 
> > > gcc/testsuite/ChangeLog:
> > > 
> > >   * c-c++-common/patchable_function_entry-default.c:
> > > Adjust.
> > >   * gcc.target/powerpc/pr99888-4.c: Likewise.
> > >   * gcc.target/powerpc/pr99888-5.c: Likewise.
> > >   * gcc.target/powerpc/pr99888-6.c: Likewise.
> > > ---
> > >  gcc/config/rs6000/rs6000-logue.cc | 40 +
> > > --
> > >  gcc/config/rs6000/rs6000.cc   | 15 +--
> > >  gcc/config/rs6000/rs6000.h    | 10 +++--
> > >  gcc/doc/invoke.texi   |  8 ++--
> > >  .../patchable_function_entry-default.c    |  3 --
> > >  gcc/testsuite/gcc.target/powerpc/pr99888-4.c  |  4 +-
> > >  gcc/testsuite/gcc.target/powerpc/pr99888-5.c  |  4 +-
> > >  gcc/testsuite/gcc.target/powerpc/pr99888-6.c  |  4 +-
> > >  8 files changed, 33 insertions(+), 55 deletions(-)
> > > 
> > > diff --git a/gcc/config/rs6000/rs6000-logue.cc
> > > b/gcc/config/rs6000/rs6000-logue.cc
> > > index 60ba15a8bc3..0eb019b44b3 100644
> > > --- a/gcc/config/rs6000/rs6000-logue.cc
> > > +++ b/gcc/config/rs6000/rs6000-logue.cc
> > > @@ -4006,43 +4006,21 @@ rs6000_output_function_prologue (FILE
> > > *file)
> > >     fprintf (file, "\tadd 2,2,12\n");
> > >   }
> > > 
> > > -  unsigned short patch_area_size = crtl->patch_area_size;
> > > -  unsigned short patch_area_entry = crtl->patch_area_entry;
> > > -  /* Need to emit the patching area.  */
> > > -  if (patch_area_size > 0)
> > > - {
> > > -   cfun->machine->global_entry_emitted = true;
> > > -   /* As ELFv2 ABI shows, the allowable bytes between the
> > > global
> > > -  and local entry points are 0, 4, 8, 16, 32 and 64
> > > when
> > > -  there is a local entry point.  Considering there
> > > are two
> > > -  non-prefixed instructions for global entry point
> > > prologue
> > > -  (8 bytes), the count for patchable nops before
> > > local entry
> > > -  point would be 2, 6 and 14.  It's possible to
> > > support those
> > > -  other counts of nops by not making a local entry
> > > point, but
> > > -  we don't have clear use cases for them, so leave
> > > them
> > > -  unsupported for now.  */
> > > -   if (patch_area_entry > 0)
> > > -     {
> > > -   if (patch_area_entry != 2
> > > -   && patch_area_entry != 6
> > > -   && patch_area_entry != 14)
> > > - error ("unsupported number of nops before
> > > function entry (%u)",
> > > -    patch_area_entry);
> > > -   rs6000_print_patchable_function_entry (file,
> > > patch_area_entry,
> > > -  true);
> > > -   patch_area_size -= patch_area_ent

PING^3 [PATCH] rs6000: Adjust -fpatchable-function-entry* support for dual entry [PR112980]

2024-07-22 Thread Kewen.Lin 
Hi,

Gentle ping this patch:

https://gcc.gnu.org/pipermail/gcc-patches/2024-May/651025.html

BR,
Kewen

on 2024/7/12 00:15, Martin Jambor wrote:
> Hi,
> 
> can I add myself to the bunch of people who are pinging this?  Having
> this in will make our life easier.
> 
> Thanks a lot,
> 
> Martin
> 
> 
> On Wed, May 08 2024, Kewen.Lin wrote:
>> Hi,
>>
>> As the discussion in PR112980, although the current
>> implementation for -fpatchable-function-entry* conforms
>> with the documentation (making N NOPs be consecutive),
>> it's inefficient for both kernel and userspace livepatching
>> (see comments in PR for the details).
>>
>> So this patch is to change the current implementation by
>> emitting the "before" NOPs before global entry point and
>> the "after" NOPs after local entry point.  The new behavior
>> would not keep NOPs to be consecutive, so the documentation
>> is updated to emphasize this.
>>
>> Bootstrapped and regress-tested on powerpc64-linux-gnu
>> P8/P9 and powerpc64le-linux-gnu P9 and P10.
>>
>> Is it ok for trunk?  And backporting to active branches
>> after burn-in time?  I guess we should also mention this
>> change in changes.html?
>>
>> BR,
>> Kewen
>> -
>>  PR target/112980
>>
>> gcc/ChangeLog:
>>
>>  * config/rs6000/rs6000-logue.cc (rs6000_output_function_prologue):
>>  Adjust the handling on patch area emitting with dual entry, remove
>>  the restriction on "before" NOPs count, not emit "before" NOPs any
>>  more but only emit "after" NOPs.
>>  * config/rs6000/rs6000.cc (rs6000_print_patchable_function_entry):
>>  Adjust by respecting cfun->machine->stop_patch_area_print.
>>  (rs6000_elf_declare_function_name): For ELFv2 with dual entry, set
>>  cfun->machine->stop_patch_area_print as true.
>>  * config/rs6000/rs6000.h (struct machine_function): Remove member
>>  global_entry_emitted, add new member stop_patch_area_print.
>>  * doc/invoke.texi (option -fpatchable-function-entry): Adjust the
>>  documentation for PowerPC ELFv2 dual entry.
>>
>> gcc/testsuite/ChangeLog:
>>
>>  * c-c++-common/patchable_function_entry-default.c: Adjust.
>>  * gcc.target/powerpc/pr99888-4.c: Likewise.
>>  * gcc.target/powerpc/pr99888-5.c: Likewise.
>>  * gcc.target/powerpc/pr99888-6.c: Likewise.
>> ---
>>  gcc/config/rs6000/rs6000-logue.cc | 40 +--
>>  gcc/config/rs6000/rs6000.cc   | 15 +--
>>  gcc/config/rs6000/rs6000.h| 10 +++--
>>  gcc/doc/invoke.texi   |  8 ++--
>>  .../patchable_function_entry-default.c|  3 --
>>  gcc/testsuite/gcc.target/powerpc/pr99888-4.c  |  4 +-
>>  gcc/testsuite/gcc.target/powerpc/pr99888-5.c  |  4 +-
>>  gcc/testsuite/gcc.target/powerpc/pr99888-6.c  |  4 +-
>>  8 files changed, 33 insertions(+), 55 deletions(-)
>>
>> diff --git a/gcc/config/rs6000/rs6000-logue.cc 
>> b/gcc/config/rs6000/rs6000-logue.cc
>> index 60ba15a8bc3..0eb019b44b3 100644
>> --- a/gcc/config/rs6000/rs6000-logue.cc
>> +++ b/gcc/config/rs6000/rs6000-logue.cc
>> @@ -4006,43 +4006,21 @@ rs6000_output_function_prologue (FILE *file)
>>fprintf (file, "\tadd 2,2,12\n");
>>  }
>>
>> -  unsigned short patch_area_size = crtl->patch_area_size;
>> -  unsigned short patch_area_entry = crtl->patch_area_entry;
>> -  /* Need to emit the patching area.  */
>> -  if (patch_area_size > 0)
>> -{
>> -  cfun->machine->global_entry_emitted = true;
>> -  /* As ELFv2 ABI shows, the allowable bytes between the global
>> - and local entry points are 0, 4, 8, 16, 32 and 64 when
>> - there is a local entry point.  Considering there are two
>> - non-prefixed instructions for global entry point prologue
>> - (8 bytes), the count for patchable nops before local entry
>> - point would be 2, 6 and 14.  It's possible to support those
>> - other counts of nops by not making a local entry point, but
>> - we don't have clear use cases for them, so leave them
>> - unsupported for now.  */
>> -  if (patch_area_entry > 0)
>> -{
>> -  if (patch_area_entry != 2
>> -  && patch_area_entry != 6
>> -  && patch_area_entry != 14)
>> -error ("unsupported number of nops before function entry (%u)",
>> -   patch_area_entry);
>> -  rs6000_print_patchable_function_entry (file, patch_area_entry,
>> - true);
>> -  patch_area_size -= patch_area_entry;
>> -}
>> -}
>> -
>>fputs ("\t.localentry\t", file);
>>assemble_name (file, name);
>>fputs (",.-", file);
>>assemble_name (file, name);
>>fputs ("\n", file);
>>/* Emit the nops after local entry.  */
>> -  if (patch_area_size > 0)
>> -rs6000_print_patchable_function_entry (file, patch_area_size,
>> -   patch_a

Re: [PATCH] rs6000: Adjust -fpatchable-function-entry* support for dual entry [PR112980]

2024-07-11 Thread Martin Jambor 
Hi,

can I add myself to the bunch of people who are pinging this?  Having
this in will make our life easier.

Thanks a lot,

Martin


On Wed, May 08 2024, Kewen.Lin wrote:
> Hi,
>
> As the discussion in PR112980, although the current
> implementation for -fpatchable-function-entry* conforms
> with the documentation (making N NOPs be consecutive),
> it's inefficient for both kernel and userspace livepatching
> (see comments in PR for the details).
>
> So this patch is to change the current implementation by
> emitting the "before" NOPs before global entry point and
> the "after" NOPs after local entry point.  The new behavior
> would not keep NOPs to be consecutive, so the documentation
> is updated to emphasize this.
>
> Bootstrapped and regress-tested on powerpc64-linux-gnu
> P8/P9 and powerpc64le-linux-gnu P9 and P10.
>
> Is it ok for trunk?  And backporting to active branches
> after burn-in time?  I guess we should also mention this
> change in changes.html?
>
> BR,
> Kewen
> -
>   PR target/112980
>
> gcc/ChangeLog:
>
>   * config/rs6000/rs6000-logue.cc (rs6000_output_function_prologue):
>   Adjust the handling on patch area emitting with dual entry, remove
>   the restriction on "before" NOPs count, not emit "before" NOPs any
>   more but only emit "after" NOPs.
>   * config/rs6000/rs6000.cc (rs6000_print_patchable_function_entry):
>   Adjust by respecting cfun->machine->stop_patch_area_print.
>   (rs6000_elf_declare_function_name): For ELFv2 with dual entry, set
>   cfun->machine->stop_patch_area_print as true.
>   * config/rs6000/rs6000.h (struct machine_function): Remove member
>   global_entry_emitted, add new member stop_patch_area_print.
>   * doc/invoke.texi (option -fpatchable-function-entry): Adjust the
>   documentation for PowerPC ELFv2 dual entry.
>
> gcc/testsuite/ChangeLog:
>
>   * c-c++-common/patchable_function_entry-default.c: Adjust.
>   * gcc.target/powerpc/pr99888-4.c: Likewise.
>   * gcc.target/powerpc/pr99888-5.c: Likewise.
>   * gcc.target/powerpc/pr99888-6.c: Likewise.
> ---
>  gcc/config/rs6000/rs6000-logue.cc | 40 +--
>  gcc/config/rs6000/rs6000.cc   | 15 +--
>  gcc/config/rs6000/rs6000.h| 10 +++--
>  gcc/doc/invoke.texi   |  8 ++--
>  .../patchable_function_entry-default.c|  3 --
>  gcc/testsuite/gcc.target/powerpc/pr99888-4.c  |  4 +-
>  gcc/testsuite/gcc.target/powerpc/pr99888-5.c  |  4 +-
>  gcc/testsuite/gcc.target/powerpc/pr99888-6.c  |  4 +-
>  8 files changed, 33 insertions(+), 55 deletions(-)
>
> diff --git a/gcc/config/rs6000/rs6000-logue.cc 
> b/gcc/config/rs6000/rs6000-logue.cc
> index 60ba15a8bc3..0eb019b44b3 100644
> --- a/gcc/config/rs6000/rs6000-logue.cc
> +++ b/gcc/config/rs6000/rs6000-logue.cc
> @@ -4006,43 +4006,21 @@ rs6000_output_function_prologue (FILE *file)
> fprintf (file, "\tadd 2,2,12\n");
>   }
>
> -  unsigned short patch_area_size = crtl->patch_area_size;
> -  unsigned short patch_area_entry = crtl->patch_area_entry;
> -  /* Need to emit the patching area.  */
> -  if (patch_area_size > 0)
> - {
> -   cfun->machine->global_entry_emitted = true;
> -   /* As ELFv2 ABI shows, the allowable bytes between the global
> -  and local entry points are 0, 4, 8, 16, 32 and 64 when
> -  there is a local entry point.  Considering there are two
> -  non-prefixed instructions for global entry point prologue
> -  (8 bytes), the count for patchable nops before local entry
> -  point would be 2, 6 and 14.  It's possible to support those
> -  other counts of nops by not making a local entry point, but
> -  we don't have clear use cases for them, so leave them
> -  unsupported for now.  */
> -   if (patch_area_entry > 0)
> - {
> -   if (patch_area_entry != 2
> -   && patch_area_entry != 6
> -   && patch_area_entry != 14)
> - error ("unsupported number of nops before function entry (%u)",
> -patch_area_entry);
> -   rs6000_print_patchable_function_entry (file, patch_area_entry,
> -  true);
> -   patch_area_size -= patch_area_entry;
> - }
> - }
> -
>fputs ("\t.localentry\t", file);
>assemble_name (file, name);
>fputs (",.-", file);
>assemble_name (file, name);
>fputs ("\n", file);
>/* Emit the nops after local entry.  */
> -  if (patch_area_size > 0)
> - rs6000_print_patchable_function_entry (file, patch_area_size,
> -patch_area_entry == 0);
> +  unsigned short patch_area_size = crtl->patch_area_size;
> +  unsigned short patch_area_entry = crtl->patch_area_entry;
> +  if (patch_area_size > patch_area_entry)
> + {
> +   cfun->mach

Re: PING^1 [PATCH] rs6000: Adjust -fpatchable-function-entry* support for dual entry [PR112980]

2024-07-02 Thread Giuliano Belinassi 
Hello,

Em ter, 2024-07-02 às 16:46 +0800, Kewen.Lin escreveu:
> Hi,
> 
> Gentle ping this patch:
> 
> https://gcc.gnu.org/pipermail/gcc-patches/2024-May/651025.html
> 

I am testing this patch on our Userspace Livepatching product and we
found no issues so far.

Thanks,
Giuliano.

> BR,
> Kewen
> 
> on 2024/5/8 13:49, Kewen.Lin wrote:
> > Hi,
> > 
> > As the discussion in PR112980, although the current
> > implementation for -fpatchable-function-entry* conforms
> > with the documentation (making N NOPs be consecutive),
> > it's inefficient for both kernel and userspace livepatching
> > (see comments in PR for the details).
> > 
> > So this patch is to change the current implementation by
> > emitting the "before" NOPs before global entry point and
> > the "after" NOPs after local entry point.  The new behavior
> > would not keep NOPs to be consecutive, so the documentation
> > is updated to emphasize this.
> > 
> > Bootstrapped and regress-tested on powerpc64-linux-gnu
> > P8/P9 and powerpc64le-linux-gnu P9 and P10.
> > 
> > Is it ok for trunk?  And backporting to active branches
> > after burn-in time?  I guess we should also mention this
> > change in changes.html?
> > 
> > BR,
> > Kewen
> > -
> > PR target/112980
> > 
> > gcc/ChangeLog:
> > 
> > * config/rs6000/rs6000-logue.cc
> > (rs6000_output_function_prologue):
> > Adjust the handling on patch area emitting with dual
> > entry, remove
> > the restriction on "before" NOPs count, not emit "before"
> > NOPs any
> > more but only emit "after" NOPs.
> > * config/rs6000/rs6000.cc
> > (rs6000_print_patchable_function_entry):
> > Adjust by respecting cfun->machine->stop_patch_area_print.
> > (rs6000_elf_declare_function_name): For ELFv2 with dual
> > entry, set
> > cfun->machine->stop_patch_area_print as true.
> > * config/rs6000/rs6000.h (struct machine_function): Remove
> > member
> > global_entry_emitted, add new member
> > stop_patch_area_print.
> > * doc/invoke.texi (option -fpatchable-function-entry):
> > Adjust the
> > documentation for PowerPC ELFv2 dual entry.
> > 
> > gcc/testsuite/ChangeLog:
> > 
> > * c-c++-common/patchable_function_entry-default.c: Adjust.
> > * gcc.target/powerpc/pr99888-4.c: Likewise.
> > * gcc.target/powerpc/pr99888-5.c: Likewise.
> > * gcc.target/powerpc/pr99888-6.c: Likewise.
> > ---
> >  gcc/config/rs6000/rs6000-logue.cc | 40 +--
> > 
> >  gcc/config/rs6000/rs6000.cc   | 15 +--
> >  gcc/config/rs6000/rs6000.h    | 10 +++--
> >  gcc/doc/invoke.texi   |  8 ++--
> >  .../patchable_function_entry-default.c    |  3 --
> >  gcc/testsuite/gcc.target/powerpc/pr99888-4.c  |  4 +-
> >  gcc/testsuite/gcc.target/powerpc/pr99888-5.c  |  4 +-
> >  gcc/testsuite/gcc.target/powerpc/pr99888-6.c  |  4 +-
> >  8 files changed, 33 insertions(+), 55 deletions(-)
> > 
> > diff --git a/gcc/config/rs6000/rs6000-logue.cc
> > b/gcc/config/rs6000/rs6000-logue.cc
> > index 60ba15a8bc3..0eb019b44b3 100644
> > --- a/gcc/config/rs6000/rs6000-logue.cc
> > +++ b/gcc/config/rs6000/rs6000-logue.cc
> > @@ -4006,43 +4006,21 @@ rs6000_output_function_prologue (FILE
> > *file)
> >       fprintf (file, "\tadd 2,2,12\n");
> >     }
> > 
> > -  unsigned short patch_area_size = crtl->patch_area_size;
> > -  unsigned short patch_area_entry = crtl->patch_area_entry;
> > -  /* Need to emit the patching area.  */
> > -  if (patch_area_size > 0)
> > -   {
> > -     cfun->machine->global_entry_emitted = true;
> > -     /* As ELFv2 ABI shows, the allowable bytes between the
> > global
> > -    and local entry points are 0, 4, 8, 16, 32 and 64
> > when
> > -    there is a local entry point.  Considering there are
> > two
> > -    non-prefixed instructions for global entry point
> > prologue
> > -    (8 bytes), the count for patchable nops before local
> > entry
> > -    point would be 2, 6 and 14.  It's possible to support
> > those
> > -    other counts of nops by not making a local entry
> > point, but
> > -    we don't have clear use cases for them, so leave them
> > -    unsupported for now.  */
> > -     if (patch_area_entry > 0)
> > -       {
> > -     if (patch_area_entry != 2
> > -     && patch_area_entry != 6
> > -     && patch_area_entry != 14)
> > -   error ("unsupported number of nops before function
> > entry (%u)",
> > -      patch_area_entry);
> > -     rs6000_print_patchable_function_entry (file,
> > patch_area_entry,
> > -    true);
> > -     patch_area_size -= patch_area_entry;
> > -       }
> > -   }
> > -
> >    fputs ("\t.localentry\t", file);
> >    assemble_name (file, name);
> >    fputs (",.-", file);
> >    assemble_name (file, name);
> >    fputs ("\n", file);
> >    /* Emit the nops after local entry.  */
> > -  if (p

PING^1 [PATCH] rs6000: Adjust -fpatchable-function-entry* support for dual entry [PR112980]

2024-07-02 Thread Kewen.Lin 
Hi,

Gentle ping this patch:

https://gcc.gnu.org/pipermail/gcc-patches/2024-May/651025.html

BR,
Kewen

on 2024/5/8 13:49, Kewen.Lin wrote:
> Hi,
> 
> As the discussion in PR112980, although the current
> implementation for -fpatchable-function-entry* conforms
> with the documentation (making N NOPs be consecutive),
> it's inefficient for both kernel and userspace livepatching
> (see comments in PR for the details).
> 
> So this patch is to change the current implementation by
> emitting the "before" NOPs before global entry point and
> the "after" NOPs after local entry point.  The new behavior
> would not keep NOPs to be consecutive, so the documentation
> is updated to emphasize this.
> 
> Bootstrapped and regress-tested on powerpc64-linux-gnu
> P8/P9 and powerpc64le-linux-gnu P9 and P10.
> 
> Is it ok for trunk?  And backporting to active branches
> after burn-in time?  I guess we should also mention this
> change in changes.html?
> 
> BR,
> Kewen
> -
>   PR target/112980
> 
> gcc/ChangeLog:
> 
>   * config/rs6000/rs6000-logue.cc (rs6000_output_function_prologue):
>   Adjust the handling on patch area emitting with dual entry, remove
>   the restriction on "before" NOPs count, not emit "before" NOPs any
>   more but only emit "after" NOPs.
>   * config/rs6000/rs6000.cc (rs6000_print_patchable_function_entry):
>   Adjust by respecting cfun->machine->stop_patch_area_print.
>   (rs6000_elf_declare_function_name): For ELFv2 with dual entry, set
>   cfun->machine->stop_patch_area_print as true.
>   * config/rs6000/rs6000.h (struct machine_function): Remove member
>   global_entry_emitted, add new member stop_patch_area_print.
>   * doc/invoke.texi (option -fpatchable-function-entry): Adjust the
>   documentation for PowerPC ELFv2 dual entry.
> 
> gcc/testsuite/ChangeLog:
> 
>   * c-c++-common/patchable_function_entry-default.c: Adjust.
>   * gcc.target/powerpc/pr99888-4.c: Likewise.
>   * gcc.target/powerpc/pr99888-5.c: Likewise.
>   * gcc.target/powerpc/pr99888-6.c: Likewise.
> ---
>  gcc/config/rs6000/rs6000-logue.cc | 40 +--
>  gcc/config/rs6000/rs6000.cc   | 15 +--
>  gcc/config/rs6000/rs6000.h| 10 +++--
>  gcc/doc/invoke.texi   |  8 ++--
>  .../patchable_function_entry-default.c|  3 --
>  gcc/testsuite/gcc.target/powerpc/pr99888-4.c  |  4 +-
>  gcc/testsuite/gcc.target/powerpc/pr99888-5.c  |  4 +-
>  gcc/testsuite/gcc.target/powerpc/pr99888-6.c  |  4 +-
>  8 files changed, 33 insertions(+), 55 deletions(-)
> 
> diff --git a/gcc/config/rs6000/rs6000-logue.cc 
> b/gcc/config/rs6000/rs6000-logue.cc
> index 60ba15a8bc3..0eb019b44b3 100644
> --- a/gcc/config/rs6000/rs6000-logue.cc
> +++ b/gcc/config/rs6000/rs6000-logue.cc
> @@ -4006,43 +4006,21 @@ rs6000_output_function_prologue (FILE *file)
> fprintf (file, "\tadd 2,2,12\n");
>   }
> 
> -  unsigned short patch_area_size = crtl->patch_area_size;
> -  unsigned short patch_area_entry = crtl->patch_area_entry;
> -  /* Need to emit the patching area.  */
> -  if (patch_area_size > 0)
> - {
> -   cfun->machine->global_entry_emitted = true;
> -   /* As ELFv2 ABI shows, the allowable bytes between the global
> -  and local entry points are 0, 4, 8, 16, 32 and 64 when
> -  there is a local entry point.  Considering there are two
> -  non-prefixed instructions for global entry point prologue
> -  (8 bytes), the count for patchable nops before local entry
> -  point would be 2, 6 and 14.  It's possible to support those
> -  other counts of nops by not making a local entry point, but
> -  we don't have clear use cases for them, so leave them
> -  unsupported for now.  */
> -   if (patch_area_entry > 0)
> - {
> -   if (patch_area_entry != 2
> -   && patch_area_entry != 6
> -   && patch_area_entry != 14)
> - error ("unsupported number of nops before function entry (%u)",
> -patch_area_entry);
> -   rs6000_print_patchable_function_entry (file, patch_area_entry,
> -  true);
> -   patch_area_size -= patch_area_entry;
> - }
> - }
> -
>fputs ("\t.localentry\t", file);
>assemble_name (file, name);
>fputs (",.-", file);
>assemble_name (file, name);
>fputs ("\n", file);
>/* Emit the nops after local entry.  */
> -  if (patch_area_size > 0)
> - rs6000_print_patchable_function_entry (file, patch_area_size,
> -patch_area_entry == 0);
> +  unsigned short patch_area_size = crtl->patch_area_size;
> +  unsigned short patch_area_entry = crtl->patch_area_entry;
> +  if (patch_area_size > patch_area_entry)
> + {
> +   cfun->machine->stop_patch_area_

Re: [PATCH] rs6000: Adjust -fpatchable-function-entry* support for dual entry [PR112980]

2024-05-23 Thread Fangrui Song 
On Wed, May 8, 2024 at 1:33 AM Kewen.Lin  wrote:
>
> Hi Richi,
>
> >> diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
> >> index c584664e168..58e48f7dc55 100644
> >> --- a/gcc/doc/invoke.texi
> >> +++ b/gcc/doc/invoke.texi
> >> @@ -18363,11 +18363,11 @@ If @code{N=0}, no pad location is recorded.
> >>  The NOP instructions are inserted at---and maybe before, depending on
> >>  @var{M}---the function entry address, even before the prologue.  On
> >>  PowerPC with the ELFv2 ABI, for a function with dual entry points,
> >> -the local entry point is this function entry address.
> >> +@var{M} NOP instructions are inserted before the global entry point and
> >> +@var{N} - @var{M} NOP instructions are inserted after the local entry
> >> +point, which means the NOP instructions may not be consecutive.
> >
> > Isn't it @var{M-1} NOP instructions before the global entry?  I suppose
>
> No, the existing documentation is a bit confusing, sigh ...
>
> > the existing
> >
> > "... with the function entry point before the @var{M}th NOP.
> > If @var{M} is omitted, it defaults to @code{0} so the
> > function entry points to the address just at the first NOP."
> >
> > wording is self-contradicting in a way since before the 0th NOP (default)
> > to me is the same as before the 1st NOP (M == 1).  So maybe that should
> > be _after_ the @var{M}th NOP instead which would be consistent with your
> > ELFv2 docs?  Maybe the sentence should be re-worded similar to your
> > ELVv2 one, specifying the number of NOPs before and after the entry point.
> >
>
> ... the current "with the function entry point before the Mth NOP."
> has the 0th NOP assumption, so the default (0th) NOP and 1st NOP (M == 1)
> are actually different, such as:
>
> -fpatchable-function-entry=3,0
>
> foo:
> nop
> nop
> nop
>
> -fpatchable-function-entry=3,1
>
> nop
> foo:
> nop
> nop
>
> Alan also had the similar concern on this wording before:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99888#c8
>
> " Alan Modra 2022-08-12 03:00:29 UTC
> "
> "(In reply to Segher Boessenkool from comment #7)
> "> '-fpatchable-function-entry=N[,M]'
> ">  Generate N NOPs right at the beginning of each function, with the
> ">  function entry point before the Mth NOP.
> "
> " Bad doco.  Should be "after the Mth NOP" I think.
> " Or better written to avoid the concept of a 0th nop.
> " Default for M is zero, placing all nops after the function entry and
> " before normal function prologue code.
>
> BR,
> Kewen
>
> >> -The maximum value of @var{N} and @var{M} is 65535.  On PowerPC with the
> >> -ELFv2 ABI, for a function with dual entry points, the supported values
> >> -for @var{M} are 0, 2, 6 and 14.
> >> +The maximum value of @var{N} and @var{M} is 65535.
> >>  @end table
> >>


> So this patch is to change the current implementation by
> emitting the "before" NOPs before global entry point and
> the "after" NOPs after local entry point.  The new behavior

Thanks.  This looks good to me :)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99888#c5


-- 
宋方睿

Re: [PATCH] rs6000: Adjust -fpatchable-function-entry* support for dual entry [PR112980]

2024-05-08 Thread Kewen.Lin 
Hi Richi,

>> diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
>> index c584664e168..58e48f7dc55 100644
>> --- a/gcc/doc/invoke.texi
>> +++ b/gcc/doc/invoke.texi
>> @@ -18363,11 +18363,11 @@ If @code{N=0}, no pad location is recorded.
>>  The NOP instructions are inserted at---and maybe before, depending on
>>  @var{M}---the function entry address, even before the prologue.  On
>>  PowerPC with the ELFv2 ABI, for a function with dual entry points,
>> -the local entry point is this function entry address.
>> +@var{M} NOP instructions are inserted before the global entry point and
>> +@var{N} - @var{M} NOP instructions are inserted after the local entry
>> +point, which means the NOP instructions may not be consecutive.
> 
> Isn't it @var{M-1} NOP instructions before the global entry?  I suppose

No, the existing documentation is a bit confusing, sigh ...

> the existing
> 
> "... with the function entry point before the @var{M}th NOP.
> If @var{M} is omitted, it defaults to @code{0} so the
> function entry points to the address just at the first NOP."
> 
> wording is self-contradicting in a way since before the 0th NOP (default)
> to me is the same as before the 1st NOP (M == 1).  So maybe that should
> be _after_ the @var{M}th NOP instead which would be consistent with your
> ELFv2 docs?  Maybe the sentence should be re-worded similar to your
> ELVv2 one, specifying the number of NOPs before and after the entry point.
> 

... the current "with the function entry point before the Mth NOP."
has the 0th NOP assumption, so the default (0th) NOP and 1st NOP (M == 1)
are actually different, such as:

-fpatchable-function-entry=3,0

foo:
nop
nop
nop

-fpatchable-function-entry=3,1

nop
foo:
nop
nop

Alan also had the similar concern on this wording before:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99888#c8

" Alan Modra 2022-08-12 03:00:29 UTC
"
"(In reply to Segher Boessenkool from comment #7)
"> '-fpatchable-function-entry=N[,M]'
">  Generate N NOPs right at the beginning of each function, with the
">  function entry point before the Mth NOP.
"
" Bad doco.  Should be "after the Mth NOP" I think.
" Or better written to avoid the concept of a 0th nop.
" Default for M is zero, placing all nops after the function entry and
" before normal function prologue code.

BR,
Kewen

>> -The maximum value of @var{N} and @var{M} is 65535.  On PowerPC with the
>> -ELFv2 ABI, for a function with dual entry points, the supported values
>> -for @var{M} are 0, 2, 6 and 14.
>> +The maximum value of @var{N} and @var{M} is 65535.
>>  @end table
>>

Re: [PATCH] rs6000: Adjust -fpatchable-function-entry* support for dual entry [PR112980]

2024-05-08 Thread Richard Biener 
On Wed, May 8, 2024 at 7:50 AM Kewen.Lin  wrote:
>
> Hi,
>
> As the discussion in PR112980, although the current
> implementation for -fpatchable-function-entry* conforms
> with the documentation (making N NOPs be consecutive),
> it's inefficient for both kernel and userspace livepatching
> (see comments in PR for the details).
>
> So this patch is to change the current implementation by
> emitting the "before" NOPs before global entry point and
> the "after" NOPs after local entry point.  The new behavior
> would not keep NOPs to be consecutive, so the documentation
> is updated to emphasize this.
>
> Bootstrapped and regress-tested on powerpc64-linux-gnu
> P8/P9 and powerpc64le-linux-gnu P9 and P10.
>
> Is it ok for trunk?  And backporting to active branches
> after burn-in time?  I guess we should also mention this
> change in changes.html?
>
> BR,
> Kewen
> -
> PR target/112980
>
> gcc/ChangeLog:
>
> * config/rs6000/rs6000-logue.cc (rs6000_output_function_prologue):
> Adjust the handling on patch area emitting with dual entry, remove
> the restriction on "before" NOPs count, not emit "before" NOPs any
> more but only emit "after" NOPs.
> * config/rs6000/rs6000.cc (rs6000_print_patchable_function_entry):
> Adjust by respecting cfun->machine->stop_patch_area_print.
> (rs6000_elf_declare_function_name): For ELFv2 with dual entry, set
> cfun->machine->stop_patch_area_print as true.
> * config/rs6000/rs6000.h (struct machine_function): Remove member
> global_entry_emitted, add new member stop_patch_area_print.
> * doc/invoke.texi (option -fpatchable-function-entry): Adjust the
> documentation for PowerPC ELFv2 dual entry.
>
> gcc/testsuite/ChangeLog:
>
> * c-c++-common/patchable_function_entry-default.c: Adjust.
> * gcc.target/powerpc/pr99888-4.c: Likewise.
> * gcc.target/powerpc/pr99888-5.c: Likewise.
> * gcc.target/powerpc/pr99888-6.c: Likewise.
> ---
>  gcc/config/rs6000/rs6000-logue.cc | 40 +--
>  gcc/config/rs6000/rs6000.cc   | 15 +--
>  gcc/config/rs6000/rs6000.h| 10 +++--
>  gcc/doc/invoke.texi   |  8 ++--
>  .../patchable_function_entry-default.c|  3 --
>  gcc/testsuite/gcc.target/powerpc/pr99888-4.c  |  4 +-
>  gcc/testsuite/gcc.target/powerpc/pr99888-5.c  |  4 +-
>  gcc/testsuite/gcc.target/powerpc/pr99888-6.c  |  4 +-
>  8 files changed, 33 insertions(+), 55 deletions(-)
>
> diff --git a/gcc/config/rs6000/rs6000-logue.cc 
> b/gcc/config/rs6000/rs6000-logue.cc
> index 60ba15a8bc3..0eb019b44b3 100644
> --- a/gcc/config/rs6000/rs6000-logue.cc
> +++ b/gcc/config/rs6000/rs6000-logue.cc
> @@ -4006,43 +4006,21 @@ rs6000_output_function_prologue (FILE *file)
>   fprintf (file, "\tadd 2,2,12\n");
> }
>
> -  unsigned short patch_area_size = crtl->patch_area_size;
> -  unsigned short patch_area_entry = crtl->patch_area_entry;
> -  /* Need to emit the patching area.  */
> -  if (patch_area_size > 0)
> -   {
> - cfun->machine->global_entry_emitted = true;
> - /* As ELFv2 ABI shows, the allowable bytes between the global
> -and local entry points are 0, 4, 8, 16, 32 and 64 when
> -there is a local entry point.  Considering there are two
> -non-prefixed instructions for global entry point prologue
> -(8 bytes), the count for patchable nops before local entry
> -point would be 2, 6 and 14.  It's possible to support those
> -other counts of nops by not making a local entry point, but
> -we don't have clear use cases for them, so leave them
> -unsupported for now.  */
> - if (patch_area_entry > 0)
> -   {
> - if (patch_area_entry != 2
> - && patch_area_entry != 6
> - && patch_area_entry != 14)
> -   error ("unsupported number of nops before function entry 
> (%u)",
> -  patch_area_entry);
> - rs6000_print_patchable_function_entry (file, patch_area_entry,
> -true);
> - patch_area_size -= patch_area_entry;
> -   }
> -   }
> -
>fputs ("\t.localentry\t", file);
>assemble_name (file, name);
>fputs (",.-", file);
>assemble_name (file, name);
>fputs ("\n", file);
>/* Emit the nops after local entry.  */
> -  if (patch_area_size > 0)
> -   rs6000_print_patchable_function_entry (file, patch_area_size,
> -  patch_area_entry == 0);
> +  unsigned short patch_area_size = crtl->patch_area_size;
> +  unsigned short patch_area_entry = crtl->patch_area_entry;
> +  if (patch_area_size > patch_area_entry)
> +   {
> + cfun->machine->stop_patch_area_print

[PATCH] rs6000: Adjust -fpatchable-function-entry* support for dual entry [PR112980]

2024-05-07 Thread Kewen.Lin 
Hi,

As the discussion in PR112980, although the current
implementation for -fpatchable-function-entry* conforms
with the documentation (making N NOPs be consecutive),
it's inefficient for both kernel and userspace livepatching
(see comments in PR for the details).

So this patch is to change the current implementation by
emitting the "before" NOPs before global entry point and
the "after" NOPs after local entry point.  The new behavior
would not keep NOPs to be consecutive, so the documentation
is updated to emphasize this.

Bootstrapped and regress-tested on powerpc64-linux-gnu
P8/P9 and powerpc64le-linux-gnu P9 and P10.

Is it ok for trunk?  And backporting to active branches
after burn-in time?  I guess we should also mention this
change in changes.html?

BR,
Kewen
-
PR target/112980

gcc/ChangeLog:

* config/rs6000/rs6000-logue.cc (rs6000_output_function_prologue):
Adjust the handling on patch area emitting with dual entry, remove
the restriction on "before" NOPs count, not emit "before" NOPs any
more but only emit "after" NOPs.
* config/rs6000/rs6000.cc (rs6000_print_patchable_function_entry):
Adjust by respecting cfun->machine->stop_patch_area_print.
(rs6000_elf_declare_function_name): For ELFv2 with dual entry, set
cfun->machine->stop_patch_area_print as true.
* config/rs6000/rs6000.h (struct machine_function): Remove member
global_entry_emitted, add new member stop_patch_area_print.
* doc/invoke.texi (option -fpatchable-function-entry): Adjust the
documentation for PowerPC ELFv2 dual entry.

gcc/testsuite/ChangeLog:

* c-c++-common/patchable_function_entry-default.c: Adjust.
* gcc.target/powerpc/pr99888-4.c: Likewise.
* gcc.target/powerpc/pr99888-5.c: Likewise.
* gcc.target/powerpc/pr99888-6.c: Likewise.
---
 gcc/config/rs6000/rs6000-logue.cc | 40 +--
 gcc/config/rs6000/rs6000.cc   | 15 +--
 gcc/config/rs6000/rs6000.h| 10 +++--
 gcc/doc/invoke.texi   |  8 ++--
 .../patchable_function_entry-default.c|  3 --
 gcc/testsuite/gcc.target/powerpc/pr99888-4.c  |  4 +-
 gcc/testsuite/gcc.target/powerpc/pr99888-5.c  |  4 +-
 gcc/testsuite/gcc.target/powerpc/pr99888-6.c  |  4 +-
 8 files changed, 33 insertions(+), 55 deletions(-)

diff --git a/gcc/config/rs6000/rs6000-logue.cc 
b/gcc/config/rs6000/rs6000-logue.cc
index 60ba15a8bc3..0eb019b44b3 100644
--- a/gcc/config/rs6000/rs6000-logue.cc
+++ b/gcc/config/rs6000/rs6000-logue.cc
@@ -4006,43 +4006,21 @@ rs6000_output_function_prologue (FILE *file)
  fprintf (file, "\tadd 2,2,12\n");
}

-  unsigned short patch_area_size = crtl->patch_area_size;
-  unsigned short patch_area_entry = crtl->patch_area_entry;
-  /* Need to emit the patching area.  */
-  if (patch_area_size > 0)
-   {
- cfun->machine->global_entry_emitted = true;
- /* As ELFv2 ABI shows, the allowable bytes between the global
-and local entry points are 0, 4, 8, 16, 32 and 64 when
-there is a local entry point.  Considering there are two
-non-prefixed instructions for global entry point prologue
-(8 bytes), the count for patchable nops before local entry
-point would be 2, 6 and 14.  It's possible to support those
-other counts of nops by not making a local entry point, but
-we don't have clear use cases for them, so leave them
-unsupported for now.  */
- if (patch_area_entry > 0)
-   {
- if (patch_area_entry != 2
- && patch_area_entry != 6
- && patch_area_entry != 14)
-   error ("unsupported number of nops before function entry (%u)",
-  patch_area_entry);
- rs6000_print_patchable_function_entry (file, patch_area_entry,
-true);
- patch_area_size -= patch_area_entry;
-   }
-   }
-
   fputs ("\t.localentry\t", file);
   assemble_name (file, name);
   fputs (",.-", file);
   assemble_name (file, name);
   fputs ("\n", file);
   /* Emit the nops after local entry.  */
-  if (patch_area_size > 0)
-   rs6000_print_patchable_function_entry (file, patch_area_size,
-  patch_area_entry == 0);
+  unsigned short patch_area_size = crtl->patch_area_size;
+  unsigned short patch_area_entry = crtl->patch_area_entry;
+  if (patch_area_size > patch_area_entry)
+   {
+ cfun->machine->stop_patch_area_print = false;
+ patch_area_size -= patch_area_entry;
+ rs6000_print_patchable_function_entry (file, patch_area_size,
+patch_area_entry == 0);
+   }
 }

   else if (rs6000_pcrel_p ())
diff --git