[PATCH 2/2] gdb: new command 'maint flush dcache'

[Luis Machado]

On 11/23/20 7:39 AM, Andrew Burgess wrote:
> Add a new command to flush the dcache.
> 
> gdb/ChangeLog:
> 
> 	* NEWS: Mention new commands.
> 	* target-dcache.c: Add 'cli/cli-cmds.h' include.
> 	(maint_flush_dcache_command): New function.
> 	(_initialize_target_dcache): Create new 'maint flush dcache'
> 	command.
> 
> gdb/doc/ChangeLog:
> 
> 	* gdb.texinfo (Caching Target Data): Document 'maint flush
> 	dcache'.
> 
> gdb/testsuite/ChangeLog:
> 
> 	* gdb.base/dcache-flush.c: New file.
> 	* gdb.base/dcache-flush.exp: New file.
> ---
>   gdb/ChangeLog                           |  8 ++++
>   gdb/NEWS                                |  3 ++
>   gdb/doc/ChangeLog                       |  5 ++
>   gdb/doc/gdb.texinfo                     |  6 +++
>   gdb/target-dcache.c                     | 19 ++++++++
>   gdb/testsuite/ChangeLog                 |  5 ++
>   gdb/testsuite/gdb.base/dcache-flush.c   | 33 +++++++++++++
>   gdb/testsuite/gdb.base/dcache-flush.exp | 64 +++++++++++++++++++++++++
>   8 files changed, 143 insertions(+)
>   create mode 100644 gdb/testsuite/gdb.base/dcache-flush.c
>   create mode 100644 gdb/testsuite/gdb.base/dcache-flush.exp
> 
> diff --git a/gdb/NEWS b/gdb/NEWS
> index b07b054223f..ef59c7c1e69 100644
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -32,6 +32,9 @@ maintenance flush register-cache
>     These new commands are equivalent to the already existing commands
>     'maintenance flush-symbol-cache' and 'flushregs' respectively.
>   
> +maintenance flush dcache
> +  A new command to flush the dcache.
> +
>   * Changed commands
>   
>   break [PROBE_MODIFIER] [LOCATION] [thread THREADNUM]
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index 3745aa52973..7017823ef75 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -13494,6 +13494,12 @@
>   @kindex show dcache line-size
>   Show default size of dcache lines.
>   
> +@item maint flush dcache
> +@cindex dcache, flushing
> +@kindex maint flush dcache
> +Flush the contents (if any) of the dcache.  This maintainer command is
> +useful when debugging the dcache implementation.
> +
>   @end table
>   
>   @node Searching Memory
> diff --git a/gdb/target-dcache.c b/gdb/target-dcache.c
> index 0226d672780..90b60f62f2e 100644
> --- a/gdb/target-dcache.c
> +++ b/gdb/target-dcache.c
> @@ -19,6 +19,7 @@
>   #include "target-dcache.h"
>   #include "gdbcmd.h"
>   #include "progspace.h"
> +#include "cli/cli-cmds.h"
>   
>   /* The target dcache is kept per-address-space.  This key lets us
>      associate the cache with the address space.  */
> @@ -152,6 +153,16 @@ code_cache_enabled_p (void)
>     return code_cache_enabled;
>   }
>   
> +/* Implement the 'maint flush dcache' command.  */
> +
> +static void
> +maint_flush_dcache_command (const char *command, int from_tty)
> +{
> +  target_dcache_invalidate ();
> +  if (from_tty)
> +    printf_filtered (_("The dcache was flushed.\n"));
> +}
> + >   void _initialize_target_dcache ();
>   void
>   _initialize_target_dcache ()
> @@ -178,4 +189,12 @@ access is on."),
>   			   set_code_cache,
>   			   show_code_cache,
>   			   &setlist, &showlist);
> +
> +  add_cmd ("dcache", class_maintenance, maint_flush_dcache_command,
> +	   _("\
> +Force gdb to flush its target memory data cache.\n\
> +\n\
> +The dcache caches all target memory accesses where possible, this\n\
> +includes the stack-cache and the code-cache."),
> +	   &maintenanceflushlist);
>   }
> diff --git a/gdb/testsuite/gdb.base/dcache-flush.c b/gdb/testsuite/gdb.base/dcache-flush.c
> new file mode 100644
> index 00000000000..b512ea31760
> --- /dev/null
> +++ b/gdb/testsuite/gdb.base/dcache-flush.c
> @@ -0,0 +1,33 @@
> +/* This testcase is part of GDB, the GNU debugger.
> +
> +   Copyright 2020 Free Software Foundation, Inc.
> +
> +   This program is free software; you can redistribute it and/or modify
> +   it under the terms of the GNU General Public License as published by
> +   the Free Software Foundation; either version 3 of the License, or
> +   (at your option) any later version.
> +
> +   This program is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +   GNU General Public License for more details.
> +
> +   You should have received a copy of the GNU General Public License
> +   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
> +
> +int __attribute__((noinline))
> +func (int *v1, int *v2)
> +{
> +  return *v1 - *v2 - 1;
> +}
> +
> +int
> +main ()
> +{
> +  int var1 = 4;
> +  int var2 = 3;
> +  int res;
> +
> +  res = func (&var1, &var2);
> +  return res;
> +}
> diff --git a/gdb/testsuite/gdb.base/dcache-flush.exp b/gdb/testsuite/gdb.base/dcache-flush.exp
> new file mode 100644
> index 00000000000..6c7d2f4bef8
> --- /dev/null
> +++ b/gdb/testsuite/gdb.base/dcache-flush.exp
> @@ -0,0 +1,64 @@
> +# Copyright 2020 Free Software Foundation, Inc.
> +
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 3 of the License, or
> +# (at your option) any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program.  If not, see <http://www.gnu.org/licenses/>.
> +
> +# Test that the dcache can be flushed.
> +
> +standard_testfile
> +
> +if { [prepare_for_testing "failed to prepare" ${testfile}] } {
> +    return -1
> +}
> +
> +if ![runto func] {
> +    return -1
> +}
> +
> +gdb_test "up" ".* main .*"
> +gdb_test "p var1" " = 4"
> +gdb_test "p var2" " = 3"
> +
> +# By reading var1 and var2 we should have at least one line in the
> +# dcache.
> +gdb_test "info dcache" \
> +    [multi_line \
> +	 "Dcache $decimal lines of $decimal bytes each." \
> +	 "Contains data for process $decimal" \
> +	 "Line 0: address $hex \[$decimal hits\].*" \
> +	 "Cache state: $decimal active lines, $decimal hits" ] \
> +    "check dcache before flushing"
> +
> +# Flush the dcache.
> +gdb_test "maint flush dcache" "The dcache was flushed\."
> +
> +# Check the dcache is now empty.
> +gdb_test "info dcache" \
> +    [multi_line  "Dcache $decimal lines of $decimal bytes each." \
> +	 "No data cache available." ] \
> +    "check dcache after flushing"
> +
> +# Read the stack variables again, refilling the dcache.
> +with_test_prefix "refilling" {
> +    gdb_test "p var1" " = 4"
> +    gdb_test "p var2" " = 3"
> +}
> +
> +# And check we have some content back in the dcache.
> +gdb_test "info dcache" \
> +    [multi_line \
> +	 "Dcache $decimal lines of $decimal bytes each." \
> +	 "Contains data for process $decimal" \
> +	 "Line 0: address $hex \[$decimal hits\].*" \
> +	 "Cache state: $decimal active lines, $decimal hits" ] \
> +    "check dcache before refilling"
> 

LGTM