Re: [PING 4] [PATCH 0/5] Improve support for regcache_map_entry with variable register base

[John Baldwin <jhb@FreeBSD.org>]

On 9/20/22 10:50 AM, John Baldwin wrote:
> On 8/22/22 7:11 PM, John Baldwin wrote:
>> On 7/21/22 7:53 AM, John Baldwin wrote:
>>> On 7/7/22 5:58 PM, John Baldwin wrote:
>>>> When I added support for TLS to the ARM and AArch64 architectures on
>>>> FreeBSD, I had to construct register maps and associated register sets
>>>> on the fly in both the callback for processing register core dump
>>>> notes and in the native target routines to fetch and store registers.
>>>>
>>>> The reason I had to create these on the fly is that the register
>>>> number was not known at compile time, so the register map and register
>>>> set could not be constant structures shared among the -tdep and -nat
>>>> code the way other register sets were.
>>>>
>>>> This series aims to rectify that.  The first patch adds new variants
>>>> of regcache::collect_regset and regcache::supply_regset that accept an
>>>> additional 'regbase' argument.  When these functions iterate over
>>>> regcache map entries, the effective register number for the entry is
>>>> computed by adding the value in the entry to 'regbase' permittting the
>>>> regcache map entries to hold relative register numbers for a block of
>>>> registers.
>>>>
>>>> The rest of the series then makes use of this to use a single, shared
>>>> register map and register set for TLS on FreeBSD/ARM and
>>>> FreeBSD/AArch64.  Using this requires custom supply and collect regset
>>>> routines for the TLS regsets that extract the base register number
>>>> from the gdbarch's tdep and invoke the new regcache class methods, so
>>>> patch 2 updates the wrappers for dealing with regsets in fbsd-nat to
>>>> always invoke the regset routines from the regset instead of directly
>>>> calling the default functions.  Patch 3 is another change to fbsd-nat
>>>> to cope with the fact that regcache_map_supplies() needs to pass in
>>>> the relative register number in the wrapper routines rather than the
>>>> absolute register number.
>>>>
>>>> Patches 4 and 5 are the updates to the ARM and AArch64 FreeBSD
>>>> architectures and targets.
>>>>
>>>> I have not done the work to make use of this in the Linux AArch64
>>>> architecture, though I think it would apply to at least the TLS and
>>>> MTE register sets there in a similar fashion.  SVE is harder because
>>>> the register sizes change (though SVE might be able to make use of
>>>> this if register_size() returns the right value by using a register
>>>> size of 0 in the relevant register cache map entries).
>>>>
>>>> John Baldwin (5):
>>>>       regcache: Add collect/supply_regset variants that accept a register
>>>>         base.
>>>>       fbsd-nat: Use regset supply/collect methods.
>>>>       fbsd-nat: Pass an optional register base to the register set helpers.
>>>>       arm-fbsd: Use a static regset for the TLS register set.
>>>>       aarch64-fbsd: Use a static regset for the TLS register set.
>>>>
>>>>      gdb/aarch64-fbsd-nat.c  | 36 +++------------------------
>>>>      gdb/aarch64-fbsd-tdep.c | 54 ++++++++++++++++++++++++++++-------------
>>>>      gdb/aarch64-fbsd-tdep.h |  1 +
>>>>      gdb/arm-fbsd-nat.c      | 34 +++-----------------------
>>>>      gdb/arm-fbsd-tdep.c     | 52 +++++++++++++++++++++++++++------------
>>>>      gdb/arm-fbsd-tdep.h     |  1 +
>>>>      gdb/fbsd-nat.c          | 42 +++++++++++++++++---------------
>>>>      gdb/fbsd-nat.h          | 49 +++++++++++++++++++++----------------
>>>>      gdb/regcache.c          | 28 ++++++++++++++++++---
>>>>      gdb/regcache.h          | 24 ++++++++++++++++--
>>>>      10 files changed, 181 insertions(+), 140 deletions(-)
>>>
>>> Ping.
>>>
>>
>>
> 
> Pinging again.  Only patch 1 needs approval by another maintainer, the rest
> are FreeBSD specific.
> 


-- 
John Baldwin