diff mbox

[RFC,v2,PR,remote/16896] Invalidate a register in cache when a remote target failed to write it.

Message ID 537E086A.9030803@embecosm.com
State New
Headers show

Commit Message

Pierre Langlois May 22, 2014, 2:23 p.m. UTC
Hello all,

This patch addresses the issue in patch [1] generically as pointed out by
a comment [2].

As opposed to invalidating a register in cache in the remote target before
throwing an error, we can do this using a cleanup in regcache_raw_write.  This
patch adds routines to add a regcache_invalidate cleanup to the current chain.
We can use this before target_store_registers and discard it after if an error
was not thrown.

[1] https://sourceware.org/ml/gdb-patches/2014-05/msg00083.html
[2] https://sourceware.org/ml/gdb-patches/2014-05/msg00357.html

2014-05-20  Pierre Langlois  <pierre.langlois@embecosm.com>

	PR remote/16896
	* regcache.c (register_to_invalidate): New structure. Combines a pointer
         to a struct regcache and a register number.
	(do_register_invalidate): New function. Call regcache_invalidate.
	(make_cleanup_regcache_invalidate): New function. Construct a cleanup
         for invalidating a register.
	(regcache_raw_write): Call make_cleanup_regcache_invalidate
	* regcache.h (make_cleanup_regcache_invalidate): New prototype.

---
  gdb/regcache.c | 41 ++++++++++++++++++++++++++++++++++++++---
  gdb/regcache.h |  2 ++
  2 files changed, 40 insertions(+), 3 deletions(-)

Comments

Pierre Langlois June 2, 2014, 9:12 a.m. UTC | #1
Ping.

On 22/05/14 15:23, Pierre Langlois wrote:
> Hello all,
> 
> This patch addresses the issue in patch [1] generically as pointed out by
> a comment [2].
> 
> As opposed to invalidating a register in cache in the remote target before
> throwing an error, we can do this using a cleanup in regcache_raw_write.  This
> patch adds routines to add a regcache_invalidate cleanup to the current chain.
> We can use this before target_store_registers and discard it after if an error
> was not thrown.
> 
> [1] https://sourceware.org/ml/gdb-patches/2014-05/msg00083.html
> [2] https://sourceware.org/ml/gdb-patches/2014-05/msg00357.html
> 
> 2014-05-20  Pierre Langlois  <pierre.langlois@embecosm.com>
> 
>     PR remote/16896
>     * regcache.c (register_to_invalidate): New structure. Combines a pointer
>         to a struct regcache and a register number.
>     (do_register_invalidate): New function. Call regcache_invalidate.
>     (make_cleanup_regcache_invalidate): New function. Construct a cleanup
>         for invalidating a register.
>     (regcache_raw_write): Call make_cleanup_regcache_invalidate
>     * regcache.h (make_cleanup_regcache_invalidate): New prototype.
> 
> ---
>  gdb/regcache.c | 41 ++++++++++++++++++++++++++++++++++++++---
>  gdb/regcache.h |  2 ++
>  2 files changed, 40 insertions(+), 3 deletions(-)
> 
> diff --git a/gdb/regcache.c b/gdb/regcache.c
> index 8b588c6..87a6b02 100644
> --- a/gdb/regcache.c
> +++ b/gdb/regcache.c
> @@ -267,6 +267,30 @@ make_cleanup_regcache_xfree (struct regcache *regcache)
>    return make_cleanup (do_regcache_xfree, regcache);
>  }
>  
> +/* Cleanup routines for invalidating a register.  */
> +
> +struct register_to_invalidate
> +{
> +  struct regcache *regcache;
> +  int regnum;
> +};
> +
> +static void
> +do_regcache_invalidate (void *data)
> +{
> +  struct register_to_invalidate *reg = data;
> +  regcache_invalidate (reg->regcache, reg->regnum);
> +}
> +
> +struct cleanup *
> +make_cleanup_regcache_invalidate (struct regcache *regcache, int regnum)
> +{
> +  struct register_to_invalidate* reg = XNEW (struct register_to_invalidate);
> +  reg->regcache = regcache;
> +  reg->regnum = regnum;
> +  return make_cleanup_dtor (do_regcache_invalidate, (void *) reg, xfree);
> +}
> +
>  /* Return REGCACHE's architecture.  */
>  
>  struct gdbarch *
> @@ -846,7 +870,8 @@ void
>  regcache_raw_write (struct regcache *regcache, int regnum,
>              const gdb_byte *buf)
>  {
> -  struct cleanup *old_chain;
> +  struct cleanup *chain_before_save_inferior;
> +  struct cleanup *chain_before_invalidate_register;
>  
>    gdb_assert (regcache != NULL && buf != NULL);
>    gdb_assert (regnum >= 0 && regnum < regcache->descr->nr_raw_registers);
> @@ -864,16 +889,26 @@ regcache_raw_write (struct regcache *regcache, int regnum,
>            regcache->descr->sizeof_register[regnum]) == 0))
>      return;
>  
> -  old_chain = save_inferior_ptid ();
> +  chain_before_save_inferior = save_inferior_ptid ();
>    inferior_ptid = regcache->ptid;
>  
>    target_prepare_to_store (regcache);
>    memcpy (register_buffer (regcache, regnum), buf,
>        regcache->descr->sizeof_register[regnum]);
>    regcache->register_status[regnum] = REG_VALID;
> +
> +  /* Register a cleanup function for invalidating the register after it is
> +     written, in case of a failure.  */
> +  chain_before_invalidate_register =
> +    make_cleanup_regcache_invalidate (regcache, regnum);
> +
>    target_store_registers (regcache, regnum);
>  
> -  do_cleanups (old_chain);
> +  /* The target did not throw an error so we can discard invalidating the
> +     register and restore the cleanup chain to what it was.  */
> +  discard_cleanups (chain_before_invalidate_register);
> +
> +  do_cleanups (chain_before_save_inferior);
>  }
>  
>  void
> diff --git a/gdb/regcache.h b/gdb/regcache.h
> index 8423f57..bb40b65 100644
> --- a/gdb/regcache.h
> +++ b/gdb/regcache.h
> @@ -33,6 +33,8 @@ extern struct regcache *get_thread_arch_aspace_regcache (ptid_t,
>  
>  void regcache_xfree (struct regcache *regcache);
>  struct cleanup *make_cleanup_regcache_xfree (struct regcache *regcache);
> +struct cleanup *make_cleanup_regcache_invalidate (struct regcache *regcache,
> +                          int regnum);
>  struct regcache *regcache_xmalloc (struct gdbarch *gdbarch,
>                     struct address_space *aspace);
>
Pierre Langlois June 11, 2014, 4:58 p.m. UTC | #2
Ping.

On 02/06/14 10:12, Pierre Langlois wrote:
> Ping.
> 
> On 22/05/14 15:23, Pierre Langlois wrote:
>> Hello all,
>>
>> This patch addresses the issue in patch [1] generically as pointed out by
>> a comment [2].
>>
>> As opposed to invalidating a register in cache in the remote target before
>> throwing an error, we can do this using a cleanup in regcache_raw_write.  This
>> patch adds routines to add a regcache_invalidate cleanup to the current chain.
>> We can use this before target_store_registers and discard it after if an error
>> was not thrown.
>>
>> [1] https://sourceware.org/ml/gdb-patches/2014-05/msg00083.html
>> [2] https://sourceware.org/ml/gdb-patches/2014-05/msg00357.html
>>
>> 2014-05-20  Pierre Langlois  <pierre.langlois@embecosm.com>
>>
>>     PR remote/16896
>>     * regcache.c (register_to_invalidate): New structure. Combines a pointer
>>         to a struct regcache and a register number.
>>     (do_register_invalidate): New function. Call regcache_invalidate.
>>     (make_cleanup_regcache_invalidate): New function. Construct a cleanup
>>         for invalidating a register.
>>     (regcache_raw_write): Call make_cleanup_regcache_invalidate
>>     * regcache.h (make_cleanup_regcache_invalidate): New prototype.
>>
>> ---
>>  gdb/regcache.c | 41 ++++++++++++++++++++++++++++++++++++++---
>>  gdb/regcache.h |  2 ++
>>  2 files changed, 40 insertions(+), 3 deletions(-)
>>
>> diff --git a/gdb/regcache.c b/gdb/regcache.c
>> index 8b588c6..87a6b02 100644
>> --- a/gdb/regcache.c
>> +++ b/gdb/regcache.c
>> @@ -267,6 +267,30 @@ make_cleanup_regcache_xfree (struct regcache *regcache)
>>    return make_cleanup (do_regcache_xfree, regcache);
>>  }
>>  
>> +/* Cleanup routines for invalidating a register.  */
>> +
>> +struct register_to_invalidate
>> +{
>> +  struct regcache *regcache;
>> +  int regnum;
>> +};
>> +
>> +static void
>> +do_regcache_invalidate (void *data)
>> +{
>> +  struct register_to_invalidate *reg = data;
>> +  regcache_invalidate (reg->regcache, reg->regnum);
>> +}
>> +
>> +struct cleanup *
>> +make_cleanup_regcache_invalidate (struct regcache *regcache, int regnum)
>> +{
>> +  struct register_to_invalidate* reg = XNEW (struct register_to_invalidate);
>> +  reg->regcache = regcache;
>> +  reg->regnum = regnum;
>> +  return make_cleanup_dtor (do_regcache_invalidate, (void *) reg, xfree);
>> +}
>> +
>>  /* Return REGCACHE's architecture.  */
>>  
>>  struct gdbarch *
>> @@ -846,7 +870,8 @@ void
>>  regcache_raw_write (struct regcache *regcache, int regnum,
>>              const gdb_byte *buf)
>>  {
>> -  struct cleanup *old_chain;
>> +  struct cleanup *chain_before_save_inferior;
>> +  struct cleanup *chain_before_invalidate_register;
>>  
>>    gdb_assert (regcache != NULL && buf != NULL);
>>    gdb_assert (regnum >= 0 && regnum < regcache->descr->nr_raw_registers);
>> @@ -864,16 +889,26 @@ regcache_raw_write (struct regcache *regcache, int regnum,
>>            regcache->descr->sizeof_register[regnum]) == 0))
>>      return;
>>  
>> -  old_chain = save_inferior_ptid ();
>> +  chain_before_save_inferior = save_inferior_ptid ();
>>    inferior_ptid = regcache->ptid;
>>  
>>    target_prepare_to_store (regcache);
>>    memcpy (register_buffer (regcache, regnum), buf,
>>        regcache->descr->sizeof_register[regnum]);
>>    regcache->register_status[regnum] = REG_VALID;
>> +
>> +  /* Register a cleanup function for invalidating the register after it is
>> +     written, in case of a failure.  */
>> +  chain_before_invalidate_register =
>> +    make_cleanup_regcache_invalidate (regcache, regnum);
>> +
>>    target_store_registers (regcache, regnum);
>>  
>> -  do_cleanups (old_chain);
>> +  /* The target did not throw an error so we can discard invalidating the
>> +     register and restore the cleanup chain to what it was.  */
>> +  discard_cleanups (chain_before_invalidate_register);
>> +
>> +  do_cleanups (chain_before_save_inferior);
>>  }
>>  
>>  void
>> diff --git a/gdb/regcache.h b/gdb/regcache.h
>> index 8423f57..bb40b65 100644
>> --- a/gdb/regcache.h
>> +++ b/gdb/regcache.h
>> @@ -33,6 +33,8 @@ extern struct regcache *get_thread_arch_aspace_regcache (ptid_t,
>>  
>>  void regcache_xfree (struct regcache *regcache);
>>  struct cleanup *make_cleanup_regcache_xfree (struct regcache *regcache);
>> +struct cleanup *make_cleanup_regcache_invalidate (struct regcache *regcache,
>> +                          int regnum);
>>  struct regcache *regcache_xmalloc (struct gdbarch *gdbarch,
>>                     struct address_space *aspace);
>>  
>
Pedro Alves June 12, 2014, 1:23 p.m. UTC | #3
Hi Pierre,

On 05/22/2014 03:23 PM, Pierre Langlois wrote:
> Hello all,
> 
> This patch addresses the issue in patch [1] generically as pointed out by
> a comment [2].
> 
> As opposed to invalidating a register in cache in the remote target before
> throwing an error, we can do this using a cleanup in regcache_raw_write.  This
> patch adds routines to add a regcache_invalidate cleanup to the current chain.
> We can use this before target_store_registers and discard it after if an error
> was not thrown.
> 
> [1] https://sourceware.org/ml/gdb-patches/2014-05/msg00083.html
> [2] https://sourceware.org/ml/gdb-patches/2014-05/msg00357.html

Based on the commit log / description of the change in v1, could
you propose a commit log for this version of the patch, please?

> 2014-05-20  Pierre Langlois  <pierre.langlois@embecosm.com>
> 
> 	PR remote/16896
> 	* regcache.c (register_to_invalidate): New structure. Combines a pointer

Double space after periods. "structure.  Combines".

But just "New structure" is enough.  The structure's description should be
in the code.  We usually spell out "struct" in the context part as well.  So:

	* regcache.c (struct register_to_invalidate): New structure.

>          to a struct regcache and a register number.
> 	(do_register_invalidate): New function. Call regcache_invalidate.
> 	(make_cleanup_regcache_invalidate): New function. Construct a cleanup
>          for invalidating a register.
> 	(regcache_raw_write): Call make_cleanup_regcache_invalidate

Missing period.

Also, please make sure ChangeLog entries are indented with a tab instead
of spaces.

I suggest:

	* regcache.c (struct register_to_invalidate): New structure.
	(do_register_invalidate, make_cleanup_regcache_invalidate): New
	functions.
	(regcache_raw_write): Call make_cleanup_regcache_invalidate.
	* regcache.h (make_cleanup_regcache_invalidate): New prototype.

> +
> +static void
> +do_regcache_invalidate (void *data)
> +{
> +  struct register_to_invalidate *reg = data;
> +  regcache_invalidate (reg->regcache, reg->regnum);

Empty line after declaration.

> +}
> +
> +struct cleanup *
> +make_cleanup_regcache_invalidate (struct regcache *regcache, int regnum)

As nothing is calling this outside regcache.c, please make it static.

> +{
> +  struct register_to_invalidate* reg = XNEW (struct register_to_invalidate);
> +  reg->regcache = regcache;

Empty line after declaration.

Thanks!
Pierre Langlois June 12, 2014, 4:03 p.m. UTC | #4
Hi Pedro,

>> +}
>> +
>> +struct cleanup *
>> +make_cleanup_regcache_invalidate (struct regcache *regcache, int regnum)
> 
> As nothing is calling this outside regcache.c, please make it static.
> 

Should I exclude make_cleanup_regcache_invalidate from regcache.h as well in
this case?

Thank you for the review! And sorry for the formatting errors.

Best,

Pierre
Pedro Alves June 12, 2014, 4:30 p.m. UTC | #5
On 06/12/2014 05:03 PM, Pierre Langlois wrote:
> Should I exclude make_cleanup_regcache_invalidate from regcache.h as well in
> this case?

Yes.  You'll get a compilation error if you don't, even.
diff mbox

Patch

diff --git a/gdb/regcache.c b/gdb/regcache.c
index 8b588c6..87a6b02 100644
--- a/gdb/regcache.c
+++ b/gdb/regcache.c
@@ -267,6 +267,30 @@  make_cleanup_regcache_xfree (struct regcache *regcache)
    return make_cleanup (do_regcache_xfree, regcache);
  }
  
+/* Cleanup routines for invalidating a register.  */
+
+struct register_to_invalidate
+{
+  struct regcache *regcache;
+  int regnum;
+};
+
+static void
+do_regcache_invalidate (void *data)
+{
+  struct register_to_invalidate *reg = data;
+  regcache_invalidate (reg->regcache, reg->regnum);
+}
+
+struct cleanup *
+make_cleanup_regcache_invalidate (struct regcache *regcache, int regnum)
+{
+  struct register_to_invalidate* reg = XNEW (struct register_to_invalidate);
+  reg->regcache = regcache;
+  reg->regnum = regnum;
+  return make_cleanup_dtor (do_regcache_invalidate, (void *) reg, xfree);
+}
+
  /* Return REGCACHE's architecture.  */
  
  struct gdbarch *
@@ -846,7 +870,8 @@  void
  regcache_raw_write (struct regcache *regcache, int regnum,
  		    const gdb_byte *buf)
  {
-  struct cleanup *old_chain;
+  struct cleanup *chain_before_save_inferior;
+  struct cleanup *chain_before_invalidate_register;
  
    gdb_assert (regcache != NULL && buf != NULL);
    gdb_assert (regnum >= 0 && regnum < regcache->descr->nr_raw_registers);
@@ -864,16 +889,26 @@  regcache_raw_write (struct regcache *regcache, int regnum,
  		  regcache->descr->sizeof_register[regnum]) == 0))
      return;
  
-  old_chain = save_inferior_ptid ();
+  chain_before_save_inferior = save_inferior_ptid ();
    inferior_ptid = regcache->ptid;
  
    target_prepare_to_store (regcache);
    memcpy (register_buffer (regcache, regnum), buf,
  	  regcache->descr->sizeof_register[regnum]);
    regcache->register_status[regnum] = REG_VALID;
+
+  /* Register a cleanup function for invalidating the register after it is
+     written, in case of a failure.  */
+  chain_before_invalidate_register =
+    make_cleanup_regcache_invalidate (regcache, regnum);
+
    target_store_registers (regcache, regnum);
  
-  do_cleanups (old_chain);
+  /* The target did not throw an error so we can discard invalidating the
+     register and restore the cleanup chain to what it was.  */
+  discard_cleanups (chain_before_invalidate_register);
+
+  do_cleanups (chain_before_save_inferior);
  }
  
  void
diff --git a/gdb/regcache.h b/gdb/regcache.h
index 8423f57..bb40b65 100644
--- a/gdb/regcache.h
+++ b/gdb/regcache.h
@@ -33,6 +33,8 @@  extern struct regcache *get_thread_arch_aspace_regcache (ptid_t,
  
  void regcache_xfree (struct regcache *regcache);
  struct cleanup *make_cleanup_regcache_xfree (struct regcache *regcache);
+struct cleanup *make_cleanup_regcache_invalidate (struct regcache *regcache,
+						  int regnum);
  struct regcache *regcache_xmalloc (struct gdbarch *gdbarch,
  				   struct address_space *aspace);