Re: [PATCH v3 00/13] Handle variable XSAVE layouts

[John Baldwin <jhb@FreeBSD.org>]

On 5/19/22 8:42 AM, Willgerodt, Felix wrote:
> Hi John,
> 
> I saw them but I only skimmed over them a bit so far, sorry.
> I didn't have any direct comments apart from what I already
> stated for earlier versions, so I didn't answer.
> 
> I couldn't apply the patches unfortunately. For some reason git
> tells me formatting is off. Not sure if the fault is on my end or on
> yours. But I tried a bit on my side to no avail.
> So I couldn't test them on some of our internal targets.

Ok, if it helps you can pull the branch directly
from https://github.com/bsdjhb/gdb/tree/xsave_layout
  
> Yes you can remove the Intel changelogs.

Ok, I will trim those.  Should I keep or drop the SOB trailers
given that at least the log messages are now a bit different?

> Regards,
> Felix
> 
>> -----Original Message-----
>> From: John Baldwin <jhb@FreeBSD.org>
>> Sent: Mittwoch, 18. Mai 2022 23:53
>> To: gdb-patches@sourceware.org
>> Cc: Willgerodt, Felix <felix.willgerodt@intel.com>
>> Subject: Re: [PATCH v3 00/13] Handle variable XSAVE layouts
>>
>> Felix,
>>
>> Did you have any thoughts on this series?  I had tried to cc you on it,
>> but that didn't succeed it seems.  This does have some conflicts with
>> your AMX series, but those should be minor to resolve.
>>
>> On 5/3/22 2:05 PM, John Baldwin wrote:
>>> Changes since V2:
>>>
>>> - Pulled in some of the changes from Intel's branch Felix pointed me
>>>     at, in particular gdbserver support.  However, relative to that
>>>     branch these patches make the following changes:
>>>
>>>     - The i387_* structs and class remain in gdbserver/i387-fp.cc
>>>       rather than moving to gdbsupport/.
>>>
>>>     - Rather than invoking cpuid each time an XSAVE area is parsed,
>>>       the x86_xsave_layout structure is used to hold offsets and
>>>       CPUID is only invoked the first time NT_X86_XSTATE is probed
>>>       with the offsets cached for later use.
>>>
>>>     - I did not update the ChangeLog bits of these log messages, but
>>>       probably they can be dropped for the Intel commits as GDB
>>>       commits generally do not include these now?
>>>
>>> - Added Linux support both for gdbarches and the x86 native targets.
>>>     I wasn't sure if PT_GETREGSET on Linux provides a way to query the
>>>     size of the XSAVE register set (on FreeBSD PT_GETREGSET returns
>>>     the register set's size in iov_len of the passed-in iovec if the
>>>     original iovec has a NULL pointer and zero length), so I used
>>>     cpuid leaf 0xd subleaf 0x0 to query the size of the register set
>>>     for the native targets as well as for the Linux gdbserver support.
>>>
>>> Note that this still depends on the size and xcr0 mask heuristic for
>>> Linux and FreeBSD core dumps to determine the layout (and I have not
>>> added any additional layouts as I wasn't sure if Jini was intending to
>>> add additional AMD-specific layouts).  I'd kind of like to land this
>>> series before doing a followup to flesh out a new core dump note.
>>>
>>> I think for the new core dump note what I would propose is a simple
>>> array of CPUID results for sub-leaves of the 0xd leaf (as a
>>> NT_X86_XSTATE_CPUID or the like) where each entry in the array
>>> contained the subleaf as well as eax, ebx, ecx, and edx results.  This
>>> note might even eventually permit handling "compact" XSTATE in future
>>> core dumps rather than only "standard".
>>>
>>> I have tested this on both an AMD Ryzen 9 5900X and Intel Core
>>> i7-8650U on FreeBSD/amd64 as well as on a Linux/x86-64 VM on the Intel
>>> system.  I also tested FreeBSD/i386 in a VM on the AMD system.
>>>
>>> Aleksandar Paunovic (2):
>>>     gdbserver: Refactor the legacy region within the xsave struct
>>>     gdbserver: Read offsets of the XSAVE extended region via CPUID
>>>
>>> John Baldwin (11):
>>>     x86: Add an x86_xsave_layout structure to handle variable XSAVE
>>>       layouts.
>>>     core: Support fetching TARGET_OBJECT_X86_XSAVE_LAYOUT from
>>>       architectures.
>>>     nat/x86-cpuid.h: Add x86_cpuid_count wrapper around __get_cpuid_count.
>>>     x86 nat: Add helper functions to save the XSAVE layout for the host.
>>>     gdb: Update x86 FreeBSD architectures to support XSAVE layouts.
>>>     gdb: Support XSAVE layouts for the current host in the FreeBSD x86
>>>       targets.
>>>     gdb: Update x86 Linux architectures to support XSAVE layouts.
>>>     gdb: Support XSAVE layouts for the current host in the Linux x86
>>>       targets.
>>>     gdb: Use x86_xstate_layout to parse the XSAVE extended state area.
>>>     gdbserver: Add a function to set the XSAVE mask and size.
>>>     x86: Remove X86_XSTATE_SIZE and related constants.
>>>
>>>    gdb/amd64-fbsd-nat.c       |  40 +--
>>>    gdb/amd64-fbsd-tdep.c      |   8 +-
>>>    gdb/amd64-linux-nat.c      |   6 +-
>>>    gdb/amd64-linux-tdep.c     |   8 +-
>>>    gdb/configure.nat          |   8 +-
>>>    gdb/corelow.c              |  22 ++
>>>    gdb/gdbarch-components.py  |  13 +
>>>    gdb/gdbarch-gen.h          |  10 +
>>>    gdb/gdbarch.c              |  32 +++
>>>    gdb/i386-fbsd-nat.c        |  39 +--
>>>    gdb/i386-fbsd-tdep.c       |  37 ++-
>>>    gdb/i386-fbsd-tdep.h       |   6 +
>>>    gdb/i386-linux-nat.c       |   8 +-
>>>    gdb/i386-linux-tdep.c      |  34 ++-
>>>    gdb/i386-linux-tdep.h      |   6 +
>>>    gdb/i386-tdep.c            |  36 ++-
>>>    gdb/i386-tdep.h            |   3 +
>>>    gdb/i387-tdep.c            | 493 ++++++++++++++++++++++++-------------
>>>    gdb/i387-tdep.h            |   8 +
>>>    gdb/nat/x86-cpuid.h        |  27 ++
>>>    gdb/nat/x86-xstate.c       |  65 +++++
>>>    gdb/nat/x86-xstate.h       |  35 +++
>>>    gdb/target.h               |   2 +
>>>    gdb/x86-fbsd-nat.c         |  51 ++++
>>>    gdb/x86-fbsd-nat.h         |  29 ++-
>>>    gdb/x86-linux-nat.c        |  33 +++
>>>    gdb/x86-linux-nat.h        |  11 +
>>>    gdbserver/configure.srv    |  12 +-
>>>    gdbserver/i387-fp.cc       | 312 ++++++++++++++---------
>>>    gdbserver/i387-fp.h        |   2 +-
>>>    gdbserver/linux-x86-low.cc |  10 +-
>>>    gdbsupport/x86-xstate.h    |  69 ++++--
>>>    32 files changed, 1067 insertions(+), 408 deletions(-)
>>>    create mode 100644 gdb/nat/x86-xstate.c
>>>    create mode 100644 gdb/nat/x86-xstate.h
>>>
>>
>>
>> --
>> John Baldwin
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-- 
John Baldwin