mbox series

[00/17] SME support for AArch64 gdb/gdbserver on Linux.

Message ID 20230411042658.1852730-1-luis.machado@arm.com
Headers
Series SME support for AArch64 gdb/gdbserver on Linux. |

Message

Luis Machado April 11, 2023, 4:26 a.m. UTC 
  The following series enables SME 1 (Scalable Matrix Extension) support for
AArch64 gdb and gdbserver.

SME expands on SVE by having a variable-sized matrix (ZA) of dimensions
SVL x SVL bytes.

The first few patches and some intermediate ones refactor the code and fix
issues prior to enabling SME support, and thus could go in independently.

I've kept them in the series as they are closely/logically related.

Ezra Sitorus (1):
  [binutils/aarch64] sme: Core file support

Luis Machado (16):
  [gdb/aarch64] Fix register fetch/store order for native AArch64 Linux
  [gdb/aarch64] refactor: Rename SVE-specific files
  [gdb/gdbserver] refactor: Simplify SVE interface to read/write
    registers
  [gdb/aarch64] sve: Fix return command when using V registers in a
    SVE-enabled target
  [gdb/aarch64] sme: Enable SME registers and pseudo-registers
  [gdbserver/aarch64] refactor: Adjust expedited registers dynamically
  [gdbserver/aarch64] sme: Add support for SME
  [gdb/aarch64] sve: Fix signal frame z/v register restore
  [gdb/aarch64] sme: Signal frame support
  [gdb/aarch64] sme: Fixup sigframe gdbarch when vg/svg changes
  [gdb/aarch64] sme: Support TPIDR2 signal frame context
  [gdb/generic] corefile/bug: Use thread-specific gdbarch when dumping
    register state to core files
  [gdb/generic] corefile/bug: Fixup (gcore) core file target description
    reading order
  [gdb/aarch64] sme: Core file support for Linux
  [gdb/testsuite] sme: Add SVE/SME testcases
  [gdb/docs] sme: Document SME registers and features

 bfd/elf-bfd.h                                 |   4 +
 bfd/elf.c                                     |  58 +
 gdb/Makefile.in                               |   6 +-
 gdb/NEWS                                      |  11 +
 gdb/aarch64-linux-nat.c                       | 179 ++--
 gdb/aarch64-linux-tdep.c                      | 951 ++++++++++++++---
 gdb/aarch64-tdep.c                            | 724 ++++++++++++-
 gdb/aarch64-tdep.h                            |  47 +
 gdb/arch/aarch64-scalable-linux.c             |  55 +
 gdb/arch/aarch64-scalable-linux.h             |  53 +
 gdb/arch/aarch64.c                            |   5 +
 gdb/arch/aarch64.h                            |  57 +-
 gdb/configure.nat                             |   2 +-
 gdb/configure.tgt                             |   1 +
 gdb/corelow.c                                 |  24 +-
 gdb/doc/gdb.texinfo                           |  68 ++
 gdb/features/aarch64-sme.c                    |  63 ++
 gdb/linux-tdep.c                              |  18 +-
 gdb/nat/aarch64-scalable-linux-ptrace.c       | 993 ++++++++++++++++++
 gdb/nat/aarch64-scalable-linux-ptrace.h       | 156 +++
 ....h => aarch64-scalable-linux-sigcontext.h} |  73 +-
 gdb/nat/aarch64-sve-linux-ptrace.c            | 392 -------
 gdb/nat/aarch64-sve-linux-ptrace.h            |  72 --
 gdb/testsuite/gdb.arch/aarch64-sme-core-0.exp |  18 +
 gdb/testsuite/gdb.arch/aarch64-sme-core-1.exp |  18 +
 gdb/testsuite/gdb.arch/aarch64-sme-core-2.exp |  18 +
 gdb/testsuite/gdb.arch/aarch64-sme-core-3.exp |  18 +
 gdb/testsuite/gdb.arch/aarch64-sme-core-4.exp |  18 +
 gdb/testsuite/gdb.arch/aarch64-sme-core.c     | 361 +++++++
 .../gdb.arch/aarch64-sme-core.exp.tcl         | 167 +++
 .../gdb.arch/aarch64-sme-regs-available-0.exp |  18 +
 .../gdb.arch/aarch64-sme-regs-available-1.exp |  18 +
 .../gdb.arch/aarch64-sme-regs-available-2.exp |  18 +
 .../gdb.arch/aarch64-sme-regs-available-3.exp |  18 +
 .../gdb.arch/aarch64-sme-regs-available-4.exp |  18 +
 .../gdb.arch/aarch64-sme-regs-available.c     | 184 ++++
 .../aarch64-sme-regs-available.exp.tcl        | 194 ++++
 .../gdb.arch/aarch64-sme-regs-sigframe-0.exp  |  18 +
 .../gdb.arch/aarch64-sme-regs-sigframe-1.exp  |  18 +
 .../gdb.arch/aarch64-sme-regs-sigframe-2.exp  |  18 +
 .../gdb.arch/aarch64-sme-regs-sigframe-3.exp  |  18 +
 .../gdb.arch/aarch64-sme-regs-sigframe-4.exp  |  18 +
 .../gdb.arch/aarch64-sme-regs-sigframe.c      | 368 +++++++
 .../aarch64-sme-regs-sigframe.exp.tcl         | 156 +++
 .../aarch64-sme-regs-unavailable-0.exp        |  18 +
 .../aarch64-sme-regs-unavailable-1.exp        |  18 +
 .../aarch64-sme-regs-unavailable-2.exp        |  18 +
 .../aarch64-sme-regs-unavailable-3.exp        |  18 +
 .../aarch64-sme-regs-unavailable-4.exp        |  18 +
 .../gdb.arch/aarch64-sme-regs-unavailable.c   | 154 +++
 .../aarch64-sme-regs-unavailable.exp.tcl      | 162 +++
 gdb/testsuite/gdb.arch/aarch64-sme-sanity.c   | 249 +++++
 gdb/testsuite/gdb.arch/aarch64-sme-sanity.exp |  72 ++
 gdb/testsuite/lib/aarch64.exp                 | 372 +++++++
 gdb/testsuite/lib/gdb.exp                     |  63 ++
 gdb/tramp-frame.c                             |   1 +
 gdb/tramp-frame.h                             |  12 +
 gdbserver/Makefile.in                         |   2 +-
 gdbserver/configure.srv                       |   3 +-
 gdbserver/linux-aarch64-low.cc                | 100 +-
 gdbserver/linux-aarch64-tdesc.cc              |  28 +-
 gdbserver/server.h                            |   2 +-
 62 files changed, 6328 insertions(+), 694 deletions(-)
 create mode 100644 gdb/arch/aarch64-scalable-linux.c
 create mode 100644 gdb/arch/aarch64-scalable-linux.h
 create mode 100644 gdb/features/aarch64-sme.c
 create mode 100644 gdb/nat/aarch64-scalable-linux-ptrace.c
 create mode 100644 gdb/nat/aarch64-scalable-linux-ptrace.h
 rename gdb/nat/{aarch64-sve-linux-sigcontext.h => aarch64-scalable-linux-sigcontext.h} (78%)
 delete mode 100644 gdb/nat/aarch64-sve-linux-ptrace.c
 delete mode 100644 gdb/nat/aarch64-sve-linux-ptrace.h
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-core-0.exp
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-core-1.exp
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-core-2.exp
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-core-3.exp
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-core-4.exp
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-core.c
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-core.exp.tcl
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-available-0.exp
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-available-1.exp
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-available-2.exp
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-available-3.exp
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-available-4.exp
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-available.c
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-available.exp.tcl
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-sigframe-0.exp
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-sigframe-1.exp
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-sigframe-2.exp
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-sigframe-3.exp
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-sigframe-4.exp
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-sigframe.c
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-sigframe.exp.tcl
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-unavailable-0.exp
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-unavailable-1.exp
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-unavailable-2.exp
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-unavailable-3.exp
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-unavailable-4.exp
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-unavailable.c
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-unavailable.exp.tcl
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-sanity.c
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-sanity.exp
 create mode 100644 gdb/testsuite/lib/aarch64.exp

Comments

John Baldwin April 11, 2023, 3:50 p.m. UTC | #1 
On 4/10/23 9:26 PM, Luis Machado via Gdb-patches wrote:
> The following series enables SME 1 (Scalable Matrix Extension) support for
> AArch64 gdb and gdbserver.
> 
> SME expands on SVE by having a variable-sized matrix (ZA) of dimensions
> SVL x SVL bytes.
> 
> The first few patches and some intermediate ones refactor the code and fix
> issues prior to enabling SME support, and thus could go in independently.
> 
> I've kept them in the series as they are closely/logically related.

I briefly glanced at a few bits of the aarch64-specific parts I'm familiar
with and they all look fine to me.

One note is that I think the AMX patches from Intel (which deal with a
similar "tile area" split into variable-sized subregisters IIUC) ran into
some issues with wanting to update the tdesc to deal with the differing
subregisters since the layout of those can change at runtime.  I'm not
sure if that applies to SME in the same way and if any of the issues
Felix ran into might apply to SME as well (and thus if there are common
solutions?)  (I've cc'd Felix FYI)

> Ezra Sitorus (1):
>    [binutils/aarch64] sme: Core file support
> 
> Luis Machado (16):
>    [gdb/aarch64] Fix register fetch/store order for native AArch64 Linux
>    [gdb/aarch64] refactor: Rename SVE-specific files
>    [gdb/gdbserver] refactor: Simplify SVE interface to read/write
>      registers
>    [gdb/aarch64] sve: Fix return command when using V registers in a
>      SVE-enabled target
>    [gdb/aarch64] sme: Enable SME registers and pseudo-registers
>    [gdbserver/aarch64] refactor: Adjust expedited registers dynamically
>    [gdbserver/aarch64] sme: Add support for SME
>    [gdb/aarch64] sve: Fix signal frame z/v register restore
>    [gdb/aarch64] sme: Signal frame support
>    [gdb/aarch64] sme: Fixup sigframe gdbarch when vg/svg changes
>    [gdb/aarch64] sme: Support TPIDR2 signal frame context
>    [gdb/generic] corefile/bug: Use thread-specific gdbarch when dumping
>      register state to core files
>    [gdb/generic] corefile/bug: Fixup (gcore) core file target description
>      reading order
>    [gdb/aarch64] sme: Core file support for Linux
>    [gdb/testsuite] sme: Add SVE/SME testcases
>    [gdb/docs] sme: Document SME registers and features
> 
>   bfd/elf-bfd.h                                 |   4 +
>   bfd/elf.c                                     |  58 +
>   gdb/Makefile.in                               |   6 +-
>   gdb/NEWS                                      |  11 +
>   gdb/aarch64-linux-nat.c                       | 179 ++--
>   gdb/aarch64-linux-tdep.c                      | 951 ++++++++++++++---
>   gdb/aarch64-tdep.c                            | 724 ++++++++++++-
>   gdb/aarch64-tdep.h                            |  47 +
>   gdb/arch/aarch64-scalable-linux.c             |  55 +
>   gdb/arch/aarch64-scalable-linux.h             |  53 +
>   gdb/arch/aarch64.c                            |   5 +
>   gdb/arch/aarch64.h                            |  57 +-
>   gdb/configure.nat                             |   2 +-
>   gdb/configure.tgt                             |   1 +
>   gdb/corelow.c                                 |  24 +-
>   gdb/doc/gdb.texinfo                           |  68 ++
>   gdb/features/aarch64-sme.c                    |  63 ++
>   gdb/linux-tdep.c                              |  18 +-
>   gdb/nat/aarch64-scalable-linux-ptrace.c       | 993 ++++++++++++++++++
>   gdb/nat/aarch64-scalable-linux-ptrace.h       | 156 +++
>   ....h => aarch64-scalable-linux-sigcontext.h} |  73 +-
>   gdb/nat/aarch64-sve-linux-ptrace.c            | 392 -------
>   gdb/nat/aarch64-sve-linux-ptrace.h            |  72 --
>   gdb/testsuite/gdb.arch/aarch64-sme-core-0.exp |  18 +
>   gdb/testsuite/gdb.arch/aarch64-sme-core-1.exp |  18 +
>   gdb/testsuite/gdb.arch/aarch64-sme-core-2.exp |  18 +
>   gdb/testsuite/gdb.arch/aarch64-sme-core-3.exp |  18 +
>   gdb/testsuite/gdb.arch/aarch64-sme-core-4.exp |  18 +
>   gdb/testsuite/gdb.arch/aarch64-sme-core.c     | 361 +++++++
>   .../gdb.arch/aarch64-sme-core.exp.tcl         | 167 +++
>   .../gdb.arch/aarch64-sme-regs-available-0.exp |  18 +
>   .../gdb.arch/aarch64-sme-regs-available-1.exp |  18 +
>   .../gdb.arch/aarch64-sme-regs-available-2.exp |  18 +
>   .../gdb.arch/aarch64-sme-regs-available-3.exp |  18 +
>   .../gdb.arch/aarch64-sme-regs-available-4.exp |  18 +
>   .../gdb.arch/aarch64-sme-regs-available.c     | 184 ++++
>   .../aarch64-sme-regs-available.exp.tcl        | 194 ++++
>   .../gdb.arch/aarch64-sme-regs-sigframe-0.exp  |  18 +
>   .../gdb.arch/aarch64-sme-regs-sigframe-1.exp  |  18 +
>   .../gdb.arch/aarch64-sme-regs-sigframe-2.exp  |  18 +
>   .../gdb.arch/aarch64-sme-regs-sigframe-3.exp  |  18 +
>   .../gdb.arch/aarch64-sme-regs-sigframe-4.exp  |  18 +
>   .../gdb.arch/aarch64-sme-regs-sigframe.c      | 368 +++++++
>   .../aarch64-sme-regs-sigframe.exp.tcl         | 156 +++
>   .../aarch64-sme-regs-unavailable-0.exp        |  18 +
>   .../aarch64-sme-regs-unavailable-1.exp        |  18 +
>   .../aarch64-sme-regs-unavailable-2.exp        |  18 +
>   .../aarch64-sme-regs-unavailable-3.exp        |  18 +
>   .../aarch64-sme-regs-unavailable-4.exp        |  18 +
>   .../gdb.arch/aarch64-sme-regs-unavailable.c   | 154 +++
>   .../aarch64-sme-regs-unavailable.exp.tcl      | 162 +++
>   gdb/testsuite/gdb.arch/aarch64-sme-sanity.c   | 249 +++++
>   gdb/testsuite/gdb.arch/aarch64-sme-sanity.exp |  72 ++
>   gdb/testsuite/lib/aarch64.exp                 | 372 +++++++
>   gdb/testsuite/lib/gdb.exp                     |  63 ++
>   gdb/tramp-frame.c                             |   1 +
>   gdb/tramp-frame.h                             |  12 +
>   gdbserver/Makefile.in                         |   2 +-
>   gdbserver/configure.srv                       |   3 +-
>   gdbserver/linux-aarch64-low.cc                | 100 +-
>   gdbserver/linux-aarch64-tdesc.cc              |  28 +-
>   gdbserver/server.h                            |   2 +-
>   62 files changed, 6328 insertions(+), 694 deletions(-)
>   create mode 100644 gdb/arch/aarch64-scalable-linux.c
>   create mode 100644 gdb/arch/aarch64-scalable-linux.h
>   create mode 100644 gdb/features/aarch64-sme.c
>   create mode 100644 gdb/nat/aarch64-scalable-linux-ptrace.c
>   create mode 100644 gdb/nat/aarch64-scalable-linux-ptrace.h
>   rename gdb/nat/{aarch64-sve-linux-sigcontext.h => aarch64-scalable-linux-sigcontext.h} (78%)
>   delete mode 100644 gdb/nat/aarch64-sve-linux-ptrace.c
>   delete mode 100644 gdb/nat/aarch64-sve-linux-ptrace.h
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-core-0.exp
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-core-1.exp
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-core-2.exp
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-core-3.exp
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-core-4.exp
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-core.c
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-core.exp.tcl
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-available-0.exp
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-available-1.exp
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-available-2.exp
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-available-3.exp
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-available-4.exp
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-available.c
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-available.exp.tcl
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-sigframe-0.exp
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-sigframe-1.exp
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-sigframe-2.exp
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-sigframe-3.exp
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-sigframe-4.exp
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-sigframe.c
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-sigframe.exp.tcl
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-unavailable-0.exp
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-unavailable-1.exp
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-unavailable-2.exp
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-unavailable-3.exp
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-unavailable-4.exp
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-unavailable.c
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-unavailable.exp.tcl
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-sanity.c
>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-sanity.exp
>   create mode 100644 gdb/testsuite/lib/aarch64.exp
>
Terekhov, Mikhail via Gdb-patches April 12, 2023, 8:47 a.m. UTC | #2 
> -----Original Message-----
> From: John Baldwin <jhb@FreeBSD.org>
> Sent: Dienstag, 11. April 2023 17:51
> To: Luis Machado <luis.machado@arm.com>; gdb-patches@sourceware.org
> Cc: Willgerodt, Felix <felix.willgerodt@intel.com>
> Subject: Re: [PATCH 00/17] SME support for AArch64 gdb/gdbserver on
> Linux.
> 
> On 4/10/23 9:26 PM, Luis Machado via Gdb-patches wrote:
> > The following series enables SME 1 (Scalable Matrix Extension) support for
> > AArch64 gdb and gdbserver.
> >
> > SME expands on SVE by having a variable-sized matrix (ZA) of dimensions
> > SVL x SVL bytes.
> >
> > The first few patches and some intermediate ones refactor the code and
> fix
> > issues prior to enabling SME support, and thus could go in independently.
> >
> > I've kept them in the series as they are closely/logically related.
> 
> I briefly glanced at a few bits of the aarch64-specific parts I'm familiar
> with and they all look fine to me.
> 
> One note is that I think the AMX patches from Intel (which deal with a
> similar "tile area" split into variable-sized subregisters IIUC) ran into
> some issues with wanting to update the tdesc to deal with the differing
> subregisters since the layout of those can change at runtime.  I'm not
> sure if that applies to SME in the same way and if any of the issues
> Felix ran into might apply to SME as well (and thus if there are common
> solutions?)  (I've cc'd Felix FYI)

Hi John, Luis,

I didn't read the SME series in full detail and probably won't have the time to
do that for a while, sorry. I can only repeat my AMX problems.
My problem was related to the fact that I tried to make the AMX register
pseudo registers to do the dynamic resizing.
This doesn't work well with the regcache.

I am currently waiting on this series to land to continue:
https://sourceware.org/pipermail/gdb-patches/2023-January/196353.html
I am planning to do the tdesc update dynamically instead, forgoing
pseudo registers all together. But I haven't started implementing that.
We had an internal version that tried this, but in the end we scrapped that
because gdbserver doesn't support it (yet).

I think my main problem with pseudo registers is that regcache is initialized
with a certain size and types of registers. Even the pseudo registers.
For AMX we have 8 kB of register state. That is currently divided into 8 registers
of the same dimensions.
But that is actually configurable, and it could be that future platforms add a
configuration ("palette") that divides it into 4 registers of dimension "x * x". Or
another palette that divides this into 4 registers of dimension "y * z". Or another
palette that divides it into 16 registers. Switching configurations can be done
at runtime.
I was initially planning to just take the biggest dimension and the
biggest amount of names, and keep that up-to-date.

The actual problem I had in the end was discussed here:
https://sourceware.org/pipermail/gdb-patches/2022-August/191259.html
But the solution I proposed there isn't a good one.
It works by accident for now. It only touches the type, but not the actual
memory that is already reserved for the reg, which can become a problem.

I am not familiar with SME. I see that the SME series also added pseudo
registers and doesn't touch regcache.c. But I didn't look at the code in
detail. I am not familiar with the aarch64 target code. I don't know if Luis
found a way around the same problem or if it just doesn’t exist for SME.
Or if my AMX code just wasn't smart enough or done the right way.

Regards,
Felix
Intel Deutschland GmbH
Registered Address: Am Campeon 10, 85579 Neubiberg, Germany
Tel: +49 89 99 8853-0, www.intel.de <http://www.intel.de>
Managing Directors: Christin Eisenschmid, Sharon Heck, Tiffany Doon Silva  
Chairperson of the Supervisory Board: Nicole Lau
Registered Office: Munich
Commercial Register: Amtsgericht Muenchen HRB 186928
Luis Machado April 12, 2023, 9:12 a.m. UTC | #3 
Hi John,

On 4/11/23 16:50, John Baldwin wrote:
> On 4/10/23 9:26 PM, Luis Machado via Gdb-patches wrote:
>> The following series enables SME 1 (Scalable Matrix Extension) support for
>> AArch64 gdb and gdbserver.
>>
>> SME expands on SVE by having a variable-sized matrix (ZA) of dimensions
>> SVL x SVL bytes.
>>
>> The first few patches and some intermediate ones refactor the code and fix
>> issues prior to enabling SME support, and thus could go in independently.
>>
>> I've kept them in the series as they are closely/logically related.
> 
> I briefly glanced at a few bits of the aarch64-specific parts I'm familiar
> with and they all look fine to me.

Thanks for checking it.

> 
> One note is that I think the AMX patches from Intel (which deal with a
> similar "tile area" split into variable-sized subregisters IIUC) ran into
> some issues with wanting to update the tdesc to deal with the differing
> subregisters since the layout of those can change at runtime.  I'm not
> sure if that applies to SME in the same way and if any of the issues
> Felix ran into might apply to SME as well (and thus if there are common
> solutions?)  (I've cc'd Felix FYI)

I did read Felix's reply, but I'm replying to this thread instead.

I'm not entirely familiar with the AMX spec, though from Felix's descriptions it sounds like there are similarities.

The limitation of gdbserver not being able to properly communicate changes to the vector length to GDB is a known one
for AArch64, as that has been the case since SVE support was put together. I know Thiago is working on it, and SME support
should be fairly simple to adjust to match that design. So I don't see that as a blocker.

For SME we have a new independent vector length (streaming vector length, SVL), so we handle that in the same way as
we handle SVE's vector length (VL). The added complexity comes from the fact we have a new mode called streaming mode.

Whenever that streaming mode is active, then the SVE vectors will use SVL rather than VL for their sizes.

With that said, the new matrix register (ZA) has quite a few subregisters (tiles and tile slices), which I modelled
as pseudo-registers. And yes, they change sizes based on SVL changes.

I addressed that situation by having a separate gdbarch for each VL/SVL set. That means each pseudo-register has its
type cached in the proper gdbarch, so we need to be careful to use the right gdbarch.

I can see there are a few areas of gdb where the code is not totally aware that we can have multiple tdesc's and
gdbarches.

One such example is the gdb core file target XML dump note. That only dumps the process-wide tdesc, but for AArch64
we really need to dump a tdesc for each tdesc.

There might be some corner cases here and there. While implementing SME support I did find some issues that I attempted
to address. For example, the aarch64-linux-specific signal return code having to find out the proper gdbarch as opposed
to just reusing the next frame's gdbarch, which is potentially wrong for SVE/SME.

> 
>> Ezra Sitorus (1):
>>    [binutils/aarch64] sme: Core file support
>>
>> Luis Machado (16):
>>    [gdb/aarch64] Fix register fetch/store order for native AArch64 Linux
>>    [gdb/aarch64] refactor: Rename SVE-specific files
>>    [gdb/gdbserver] refactor: Simplify SVE interface to read/write
>>      registers
>>    [gdb/aarch64] sve: Fix return command when using V registers in a
>>      SVE-enabled target
>>    [gdb/aarch64] sme: Enable SME registers and pseudo-registers
>>    [gdbserver/aarch64] refactor: Adjust expedited registers dynamically
>>    [gdbserver/aarch64] sme: Add support for SME
>>    [gdb/aarch64] sve: Fix signal frame z/v register restore
>>    [gdb/aarch64] sme: Signal frame support
>>    [gdb/aarch64] sme: Fixup sigframe gdbarch when vg/svg changes
>>    [gdb/aarch64] sme: Support TPIDR2 signal frame context
>>    [gdb/generic] corefile/bug: Use thread-specific gdbarch when dumping
>>      register state to core files
>>    [gdb/generic] corefile/bug: Fixup (gcore) core file target description
>>      reading order
>>    [gdb/aarch64] sme: Core file support for Linux
>>    [gdb/testsuite] sme: Add SVE/SME testcases
>>    [gdb/docs] sme: Document SME registers and features
>>
>>   bfd/elf-bfd.h                                 |   4 +
>>   bfd/elf.c                                     |  58 +
>>   gdb/Makefile.in                               |   6 +-
>>   gdb/NEWS                                      |  11 +
>>   gdb/aarch64-linux-nat.c                       | 179 ++--
>>   gdb/aarch64-linux-tdep.c                      | 951 ++++++++++++++---
>>   gdb/aarch64-tdep.c                            | 724 ++++++++++++-
>>   gdb/aarch64-tdep.h                            |  47 +
>>   gdb/arch/aarch64-scalable-linux.c             |  55 +
>>   gdb/arch/aarch64-scalable-linux.h             |  53 +
>>   gdb/arch/aarch64.c                            |   5 +
>>   gdb/arch/aarch64.h                            |  57 +-
>>   gdb/configure.nat                             |   2 +-
>>   gdb/configure.tgt                             |   1 +
>>   gdb/corelow.c                                 |  24 +-
>>   gdb/doc/gdb.texinfo                           |  68 ++
>>   gdb/features/aarch64-sme.c                    |  63 ++
>>   gdb/linux-tdep.c                              |  18 +-
>>   gdb/nat/aarch64-scalable-linux-ptrace.c       | 993 ++++++++++++++++++
>>   gdb/nat/aarch64-scalable-linux-ptrace.h       | 156 +++
>>   ....h => aarch64-scalable-linux-sigcontext.h} |  73 +-
>>   gdb/nat/aarch64-sve-linux-ptrace.c            | 392 -------
>>   gdb/nat/aarch64-sve-linux-ptrace.h            |  72 --
>>   gdb/testsuite/gdb.arch/aarch64-sme-core-0.exp |  18 +
>>   gdb/testsuite/gdb.arch/aarch64-sme-core-1.exp |  18 +
>>   gdb/testsuite/gdb.arch/aarch64-sme-core-2.exp |  18 +
>>   gdb/testsuite/gdb.arch/aarch64-sme-core-3.exp |  18 +
>>   gdb/testsuite/gdb.arch/aarch64-sme-core-4.exp |  18 +
>>   gdb/testsuite/gdb.arch/aarch64-sme-core.c     | 361 +++++++
>>   .../gdb.arch/aarch64-sme-core.exp.tcl         | 167 +++
>>   .../gdb.arch/aarch64-sme-regs-available-0.exp |  18 +
>>   .../gdb.arch/aarch64-sme-regs-available-1.exp |  18 +
>>   .../gdb.arch/aarch64-sme-regs-available-2.exp |  18 +
>>   .../gdb.arch/aarch64-sme-regs-available-3.exp |  18 +
>>   .../gdb.arch/aarch64-sme-regs-available-4.exp |  18 +
>>   .../gdb.arch/aarch64-sme-regs-available.c     | 184 ++++
>>   .../aarch64-sme-regs-available.exp.tcl        | 194 ++++
>>   .../gdb.arch/aarch64-sme-regs-sigframe-0.exp  |  18 +
>>   .../gdb.arch/aarch64-sme-regs-sigframe-1.exp  |  18 +
>>   .../gdb.arch/aarch64-sme-regs-sigframe-2.exp  |  18 +
>>   .../gdb.arch/aarch64-sme-regs-sigframe-3.exp  |  18 +
>>   .../gdb.arch/aarch64-sme-regs-sigframe-4.exp  |  18 +
>>   .../gdb.arch/aarch64-sme-regs-sigframe.c      | 368 +++++++
>>   .../aarch64-sme-regs-sigframe.exp.tcl         | 156 +++
>>   .../aarch64-sme-regs-unavailable-0.exp        |  18 +
>>   .../aarch64-sme-regs-unavailable-1.exp        |  18 +
>>   .../aarch64-sme-regs-unavailable-2.exp        |  18 +
>>   .../aarch64-sme-regs-unavailable-3.exp        |  18 +
>>   .../aarch64-sme-regs-unavailable-4.exp        |  18 +
>>   .../gdb.arch/aarch64-sme-regs-unavailable.c   | 154 +++
>>   .../aarch64-sme-regs-unavailable.exp.tcl      | 162 +++
>>   gdb/testsuite/gdb.arch/aarch64-sme-sanity.c   | 249 +++++
>>   gdb/testsuite/gdb.arch/aarch64-sme-sanity.exp |  72 ++
>>   gdb/testsuite/lib/aarch64.exp                 | 372 +++++++
>>   gdb/testsuite/lib/gdb.exp                     |  63 ++
>>   gdb/tramp-frame.c                             |   1 +
>>   gdb/tramp-frame.h                             |  12 +
>>   gdbserver/Makefile.in                         |   2 +-
>>   gdbserver/configure.srv                       |   3 +-
>>   gdbserver/linux-aarch64-low.cc                | 100 +-
>>   gdbserver/linux-aarch64-tdesc.cc              |  28 +-
>>   gdbserver/server.h                            |   2 +-
>>   62 files changed, 6328 insertions(+), 694 deletions(-)
>>   create mode 100644 gdb/arch/aarch64-scalable-linux.c
>>   create mode 100644 gdb/arch/aarch64-scalable-linux.h
>>   create mode 100644 gdb/features/aarch64-sme.c
>>   create mode 100644 gdb/nat/aarch64-scalable-linux-ptrace.c
>>   create mode 100644 gdb/nat/aarch64-scalable-linux-ptrace.h
>>   rename gdb/nat/{aarch64-sve-linux-sigcontext.h => aarch64-scalable-linux-sigcontext.h} (78%)
>>   delete mode 100644 gdb/nat/aarch64-sve-linux-ptrace.c
>>   delete mode 100644 gdb/nat/aarch64-sve-linux-ptrace.h
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-core-0.exp
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-core-1.exp
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-core-2.exp
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-core-3.exp
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-core-4.exp
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-core.c
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-core.exp.tcl
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-available-0.exp
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-available-1.exp
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-available-2.exp
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-available-3.exp
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-available-4.exp
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-available.c
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-available.exp.tcl
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-sigframe-0.exp
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-sigframe-1.exp
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-sigframe-2.exp
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-sigframe-3.exp
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-sigframe-4.exp
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-sigframe.c
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-sigframe.exp.tcl
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-unavailable-0.exp
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-unavailable-1.exp
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-unavailable-2.exp
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-unavailable-3.exp
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-unavailable-4.exp
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-unavailable.c
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-regs-unavailable.exp.tcl
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-sanity.c
>>   create mode 100644 gdb/testsuite/gdb.arch/aarch64-sme-sanity.exp
>>   create mode 100644 gdb/testsuite/lib/aarch64.exp
>>
>