public inbox for gdb-patches@sourceware.org
 help / color / mirror / Atom feed
From: Luis Machado <luis.machado@arm.com>
To: Thiago Jung Bauermann <thiago.bauermann@linaro.org>,
	gdb-patches@sourceware.org
Subject: Re: [PATCH v3 4/8] gdbserver/linux-aarch64: When thread stops, update its target description
Date: Wed, 1 Feb 2023 09:05:06 +0000	[thread overview]
Message-ID: <c59e8543-5336-6232-82c1-6b60c1edf1bb@arm.com> (raw)
In-Reply-To: <20230130044518.3322695-5-thiago.bauermann@linaro.org>

On 1/30/23 04:45, Thiago Jung Bauermann wrote:
> This change prepares gdbserver to support remotely debugging programs in
> aarch64-linux where different threads have different SVE vector lengths.
> It allows gdbserver to support different inferior threads having different
> target descriptions.
> 
> To that end, a tdesc field is added to struct thread_info.  If it's
> nullptr (the default) it means that the thread uses the target description
> stored in struct process_info and thus gdbserver behaviour is unchanged.
> The get_thread_tdesc method is added to the linux_process_target class to
> allow aarch64-linux code to probe the inferior's vq register and provide a
> thread-specific target description reflecting the new vector length.
> 
> After this change, all targets except SVE-supporting aarch64-linux will
> still use per-process target descriptions.
> 
> Reviewed-by: Luis Machado <luis.machado@arm.com>
> ---
>   gdbserver/gdbthread.h          |  4 ++++
>   gdbserver/linux-aarch64-low.cc | 31 +++++++++++++++++++++++++++++++
>   gdbserver/linux-low.cc         | 17 +++++++++++++++++
>   gdbserver/linux-low.h          |  6 ++++++
>   gdbserver/regcache.cc          | 10 ++++++----
>   gdbserver/regcache.h           |  4 ++++
>   gdbserver/tdesc.cc             | 13 ++++++++++++-
>   gdbserver/tdesc.h              |  5 +++++
>   8 files changed, 85 insertions(+), 5 deletions(-)
> 
> diff --git a/gdbserver/gdbthread.h b/gdbserver/gdbthread.h
> index 493e1dbf6cb6..5b5ba6f8e521 100644
> --- a/gdbserver/gdbthread.h
> +++ b/gdbserver/gdbthread.h
> @@ -80,6 +80,10 @@ struct thread_info
>   
>     /* Branch trace target information for this thread.  */
>     struct btrace_target_info *btrace = nullptr;
> +
> +  /* Target description for this thread.  Only present if it's different
> +     from the one in process_info.  */
> +  const struct target_desc *tdesc = nullptr;
>   };
>   
>   extern std::list<thread_info *> all_threads;
> diff --git a/gdbserver/linux-aarch64-low.cc b/gdbserver/linux-aarch64-low.cc
> index 92c621e5548c..69765ee90db3 100644
> --- a/gdbserver/linux-aarch64-low.cc
> +++ b/gdbserver/linux-aarch64-low.cc
> @@ -99,6 +99,9 @@ protected:
>   
>     void low_arch_setup () override;
>   
> +  const struct target_desc *
> +    get_thread_tdesc (const thread_info *thread) override;
> +
>     bool low_cannot_fetch_register (int regno) override;
>   
>     bool low_cannot_store_register (int regno) override;
> @@ -184,6 +187,9 @@ struct arch_process_info
>        same for each thread, it is reasonable for the data to live here.
>        */
>     struct aarch64_debug_reg_state debug_reg_state;
> +
> +  /* Whether this process has the Scalable Vector Extension available.  */
> +  bool has_sve;
>   };
>   
>   /* Return true if the size of register 0 is 8 byte.  */
> @@ -869,6 +875,9 @@ aarch64_target::low_arch_setup ()
>   
>         current_process ()->tdesc = aarch64_linux_read_description (features);
>   
> +      if (features.vq > 0)
> +	current_process ()->priv->arch_private->has_sve = true;
> +
>         /* Adjust the register sets we should use for this particular set of
>   	 features.  */
>         aarch64_adjust_register_sets (features);
> @@ -879,6 +888,28 @@ aarch64_target::low_arch_setup ()
>     aarch64_linux_get_debug_reg_capacity (lwpid_of (current_thread));
>   }
>   
> +/* Implementation of linux target ops method "get_thread_tdesc".  */
> +
> +const struct target_desc *
> +aarch64_target::get_thread_tdesc (const thread_info *thread)
> +{
> +  const struct process_info *process = get_thread_process (thread);
> +
> +  /* Only inferiors with SVE need a thread-specific target description.  */
> +  if (!process->priv->arch_private->has_sve)
> +    return nullptr;
> +
> +  const struct aarch64_features features = aarch64_get_arch_features (thread);
> +  const struct target_desc *tdesc = aarch64_linux_read_description (features);
> +
> +  /* If the target description we just found is the same as the process-wide
> +     one, there's no need to set a thread-specific one.  */
> +  if (tdesc == process->tdesc)
> +    return nullptr;
> +
> +  return tdesc;
> +}
> +
>   /* Implementation of linux target ops method "get_regs_info".  */
>   
>   const regs_info *
> diff --git a/gdbserver/linux-low.cc b/gdbserver/linux-low.cc
> index 5cd22824e470..47916009ebaf 100644
> --- a/gdbserver/linux-low.cc
> +++ b/gdbserver/linux-low.cc
> @@ -483,6 +483,12 @@ linux_process_target::arch_setup_thread (thread_info *thread)
>     low_arch_setup ();
>   }
>   
> +const struct target_desc *
> +linux_process_target::get_thread_tdesc (const thread_info *thread)
> +{
> +  return nullptr;
> +}
> +
>   int
>   linux_process_target::handle_extended_wait (lwp_info **orig_event_lwp,
>   					    int wstat)
> @@ -2348,6 +2354,17 @@ linux_process_target::filter_event (int lwpid, int wstat)
>   	      return;
>   	    }
>   	}
> +      else
> +	{
> +	  /* Give the arch code an opportunity to set the thread's target
> +	     description.  */
> +	  const struct target_desc *new_tdesc = get_thread_tdesc (thread);
> +	  if (new_tdesc != thread->tdesc)
> +	    {
> +	      free_register_cache_thread (thread);
> +	      thread->tdesc = new_tdesc;
> +	    }
> +	}
>       }
>   
>     if (WIFSTOPPED (wstat) && child->must_set_ptrace_flags)
> diff --git a/gdbserver/linux-low.h b/gdbserver/linux-low.h
> index 221de85aa2ee..b52eb23cc444 100644
> --- a/gdbserver/linux-low.h
> +++ b/gdbserver/linux-low.h
> @@ -604,6 +604,12 @@ class linux_process_target : public process_stratum_target
>     /* Architecture-specific setup for the current thread.  */
>     virtual void low_arch_setup () = 0;
>   
> +  /* Allows arch-specific code to set the thread's target description when the
> +     inferior stops.  Returns nullptr if no thread-specific target description
> +     is necessary.  */
> +  virtual const struct target_desc *
> +    get_thread_tdesc (const thread_info *thread);
> +
>     /* Return false if we can fetch/store the register, true if we cannot
>        fetch/store the register.  */
>     virtual bool low_cannot_fetch_register (int regno) = 0;
> diff --git a/gdbserver/regcache.cc b/gdbserver/regcache.cc
> index 7b896a19767d..fb60e2c9c399 100644
> --- a/gdbserver/regcache.cc
> +++ b/gdbserver/regcache.cc
> @@ -39,11 +39,11 @@ get_thread_regcache (struct thread_info *thread, int fetch)
>        have.  */
>     if (regcache == NULL)
>       {
> -      struct process_info *proc = get_thread_process (thread);
> +      const target_desc *tdesc = get_thread_target_desc (thread);
>   
> -      gdb_assert (proc->tdesc != NULL);
> +      gdb_assert (tdesc != nullptr);
>   
> -      regcache = new_register_cache (proc->tdesc);
> +      regcache = new_register_cache (tdesc);
>         set_thread_regcache_data (thread, regcache);
>       }
>   
> @@ -270,7 +270,9 @@ find_regno (const struct target_desc *tdesc, const char *name)
>     internal_error ("Unknown register %s requested", name);
>   }
>   
> -static void
> +/* See regcache.h.  */
> +
> +void
>   free_register_cache_thread (struct thread_info *thread)
>   {
>     struct regcache *regcache = thread_regcache_data (thread);
> diff --git a/gdbserver/regcache.h b/gdbserver/regcache.h
> index 7248bcf5808a..4beea0139cd6 100644
> --- a/gdbserver/regcache.h
> +++ b/gdbserver/regcache.h
> @@ -79,6 +79,10 @@ void free_register_cache (struct regcache *regcache);
>   
>   void regcache_invalidate_thread (struct thread_info *);
>   
> +/* Invalidate and release the register cache of the given THREAD.  */
> +
> +void free_register_cache_thread (struct thread_info *thread);
> +
>   /* Invalidate cached registers for all threads of the given process.  */
>   
>   void regcache_invalidate_pid (int pid);
> diff --git a/gdbserver/tdesc.cc b/gdbserver/tdesc.cc
> index 2c7257c458f4..e3339dde4d6c 100644
> --- a/gdbserver/tdesc.cc
> +++ b/gdbserver/tdesc.cc
> @@ -123,13 +123,24 @@ copy_target_description (struct target_desc *dest,
>     dest->xmltarget = src->xmltarget;
>   }
>   
> +/* See tdesc.h.  */
> +
> +const struct target_desc *
> +get_thread_target_desc (const struct thread_info *thread)
> +{
> +  if (thread->tdesc != nullptr)
> +    return thread->tdesc;
> +
> +  return get_thread_process (thread)->tdesc;
> +}
> +
>   const struct target_desc *
>   current_target_desc (void)
>   {
>     if (current_thread == NULL)
>       return &default_description;
>   
> -  return current_process ()->tdesc;
> +  return get_thread_target_desc (current_thread);
>   }
>   
>   /* An empty structure.  */
> diff --git a/gdbserver/tdesc.h b/gdbserver/tdesc.h
> index 7fe7d0d8eb30..71cc5b51c84e 100644
> --- a/gdbserver/tdesc.h
> +++ b/gdbserver/tdesc.h
> @@ -88,6 +88,11 @@ void copy_target_description (struct target_desc *dest,
>   void init_target_desc (struct target_desc *tdesc,
>   		       const char **expedite_regs);
>   
> +/* Return the target description corresponding to the given THREAD.  */
> +
> +const struct target_desc *
> +  get_thread_target_desc (const struct thread_info *thread);
> +
>   /* Return the current inferior's target description.  Never returns
>      NULL.  */
>   

I don't have any comments on this code. It looks good to me.

  reply	other threads:[~2023-02-01  9:05 UTC|newest]

Thread overview: 94+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-30  4:45 [PATCH v3 0/8] gdbserver improvements for AArch64 SVE support Thiago Jung Bauermann
2023-01-30  4:45 ` [PATCH v3 1/8] gdbserver: Add assert in find_register_by_number Thiago Jung Bauermann
2023-01-31 17:05   ` Simon Marchi
2023-01-31 19:49     ` Thiago Jung Bauermann
2023-02-01 15:43       ` Simon Marchi
2023-01-30  4:45 ` [PATCH v3 2/8] gdbserver: Add PID parameter to linux_get_auxv and linux_get_hwcap Thiago Jung Bauermann
2023-02-01  9:07   ` Luis Machado
2023-02-01 10:54   ` Andrew Burgess
2023-02-01 16:01     ` Simon Marchi
2023-02-01 19:33       ` Thiago Jung Bauermann
2023-02-01 19:53         ` Simon Marchi
2023-02-01 21:55           ` Thiago Jung Bauermann
2023-02-06 19:54   ` Pedro Alves
2023-02-06 20:16     ` Simon Marchi
2023-02-07 15:19       ` Pedro Alves
2023-02-07 21:47         ` Thiago Jung Bauermann
2023-02-09  1:31           ` Simon Marchi
2023-02-10  3:54             ` Thiago Jung Bauermann
2023-02-07 22:28     ` Thiago Jung Bauermann
2023-01-30  4:45 ` [PATCH v3 3/8] gdbserver/linux-aarch64: Factor out function to get aarch64_features Thiago Jung Bauermann
2023-02-01  8:59   ` Luis Machado
2023-02-01 16:04     ` Simon Marchi
2023-02-01 22:13       ` Thiago Jung Bauermann
2023-01-30  4:45 ` [PATCH v3 4/8] gdbserver/linux-aarch64: When thread stops, update its target description Thiago Jung Bauermann
2023-02-01  9:05   ` Luis Machado [this message]
2023-02-01 11:06   ` Andrew Burgess
2023-02-01 16:21     ` Simon Marchi
2023-02-01 16:32       ` Luis Machado
2023-02-02  2:54         ` Thiago Jung Bauermann
2023-02-02  3:47           ` Simon Marchi
2023-02-03  3:47             ` Thiago Jung Bauermann
2023-02-03 11:13               ` Luis Machado
2023-02-04 15:26                 ` Thiago Jung Bauermann
2023-02-03 11:11             ` Luis Machado
2023-02-04 15:21               ` Thiago Jung Bauermann
2023-02-06  9:07                 ` Luis Machado
2023-02-06 12:15                   ` Thiago Jung Bauermann
2023-02-06 20:29                 ` Pedro Alves
2023-02-07  8:11                   ` Luis Machado
2023-02-07 14:39                     ` Thiago Jung Bauermann
2023-02-03 10:57           ` Luis Machado
2023-02-04  6:18             ` Thiago Jung Bauermann
2023-02-06 20:26           ` Pedro Alves
2023-02-07 21:06             ` Thiago Jung Bauermann
2023-02-09  2:46               ` Simon Marchi
2023-02-10  3:29                 ` Thiago Jung Bauermann
2023-02-10 14:56                   ` Luis Machado
2023-02-10 15:04                     ` Tom Tromey
2023-02-10 15:28                       ` Luis Machado
2023-02-10 17:26                       ` Thiago Jung Bauermann
2023-02-10 21:01                         ` Simon Marchi
2023-01-30  4:45 ` [PATCH v3 5/8] gdbserver: Transmit target description ID in thread list and stop reply Thiago Jung Bauermann
2023-01-30 12:52   ` Eli Zaretskii
2023-01-30 14:05     ` Thiago Jung Bauermann
2023-02-01  9:39   ` Luis Machado
2023-02-01 12:07   ` Andrew Burgess
2023-02-01 13:03     ` Eli Zaretskii
2023-02-01 17:37     ` Simon Marchi
2023-02-02 20:36       ` Thiago Jung Bauermann
2023-02-02 20:56         ` Simon Marchi
2023-02-01 20:46     ` Simon Marchi
2023-02-02 21:43       ` Thiago Jung Bauermann
2023-02-01 14:51   ` Andrew Burgess
2023-02-01 17:03     ` Simon Marchi
2023-02-02 19:52       ` Thiago Jung Bauermann
2023-02-02 20:51         ` Simon Marchi
2023-02-03  2:44           ` Thiago Jung Bauermann
2023-02-03 16:29             ` Andrew Burgess
2023-02-04  6:08               ` Thiago Jung Bauermann
2023-02-03 11:22       ` Luis Machado
2023-02-03 12:50         ` Simon Marchi
2023-01-30  4:45 ` [PATCH v3 6/8] gdb/remote: Parse tdesc field in stop reply and threads list XML Thiago Jung Bauermann
2023-02-01  9:52   ` Luis Machado
2023-02-05  0:06     ` Thiago Jung Bauermann
2023-02-06  9:10       ` Luis Machado
2023-02-01 14:32   ` Andrew Burgess
2023-02-01 19:50     ` Simon Marchi
2023-02-01 20:16       ` Simon Marchi
2023-02-03 11:27         ` Luis Machado
2023-02-03 13:19           ` Simon Marchi
2023-02-03 16:33             ` Andrew Burgess
2023-01-30  4:45 ` [PATCH v3 7/8] gdb/aarch64: Detect vector length changes when debugging remotely Thiago Jung Bauermann
2023-02-01  9:58   ` Luis Machado
2023-02-01 15:26   ` Andrew Burgess
2023-02-01 20:20     ` Simon Marchi
2023-02-03 11:31       ` Luis Machado
2023-02-03 16:38       ` Andrew Burgess
2023-02-03 19:07         ` Simon Marchi
2023-01-30  4:45 ` [PATCH v3 8/8] gdb/testsuite: Add test to exercise multi-threaded AArch64 SVE inferiors Thiago Jung Bauermann
2023-02-01 10:10   ` Luis Machado
2023-02-06 19:11 ` [PATCH v3 0/8] gdbserver improvements for AArch64 SVE support Pedro Alves
2023-02-06 20:05   ` Simon Marchi
2023-02-06 21:06     ` Pedro Alves
2023-02-07 13:49       ` Simon Marchi

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=c59e8543-5336-6232-82c1-6b60c1edf1bb@arm.com \
    --to=luis.machado@arm.com \
    --cc=gdb-patches@sourceware.org \
    --cc=thiago.bauermann@linaro.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).