[PATCH v2 14/15] [RFC] Add memtool module with memory allocation stress-test

[Daniel Axtens]

When working on memory, it's nice to be able to test your work.

Add a memtest module. When compiled with --enable-mm-debug, it exposes
3 commands:

 * lsmem - print all allocations and free space in all regions
 * lsfreemem - print free space in all regions

 * stress_big_allocs - stress test large allocations:
  - how much memory can we allocate in one chunk?
  - how many 1MB chunks can we allocate?
  - check that gap-filling works with a 1MB aligned 900kB alloc + a
     100kB alloc.

Signed-off-by: Daniel Axtens <dja@axtens.net>

---

I haven't addressed most of the change requests yet. This will need lots
of work to get to a mergable state, especially the ability to check
MM_DEBUG in template files so that it can only be built if
--enable-mm-debug is set, ('enable = mm_debug' or something) and that
involves a lot of slow and painful build system hacking. Perhaps later
on. But I have sorted out the copyright assignment so at least that
is clear if anyone else wants to hack on it.
---
 grub-core/Makefile.core.def   |   5 ++
 grub-core/commands/memtools.c | 155 ++++++++++++++++++++++++++++++++++
 grub-core/kern/mm.c           |   4 +
 3 files changed, 164 insertions(+)
 create mode 100644 grub-core/commands/memtools.c

diff --git a/grub-core/Makefile.core.def b/grub-core/Makefile.core.def
index cada67b667ff..ce7d79d38e5b 100644
--- a/grub-core/Makefile.core.def
+++ b/grub-core/Makefile.core.def
@@ -2530,3 +2530,8 @@ module = {
   common = commands/i386/wrmsr.c;
   enable = x86;
 };
+
+module = {
+  name = memtools;
+  common = commands/memtools.c;
+};
diff --git a/grub-core/commands/memtools.c b/grub-core/commands/memtools.c
new file mode 100644
index 000000000000..bb4ad359e013
--- /dev/null
+++ b/grub-core/commands/memtools.c
@@ -0,0 +1,155 @@
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2021 Free Software Foundation, Inc.
+ *  Copyright (C) 2021 IBM Corporation
+ *
+ *  GRUB 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.
+ *
+ *  GRUB 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 GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+#include <grub/dl.h>
+#include <grub/misc.h>
+#include <grub/command.h>
+#include <grub/i18n.h>
+#include <grub/memory.h>
+#include <grub/mm.h>
+
+GRUB_MOD_LICENSE ("GPLv3+");
+
+#ifdef MM_DEBUG
+
+static grub_err_t
+grub_cmd_lsmem (grub_command_t cmd __attribute__ ((unused)),
+                int argc __attribute__ ((unused)),
+                char **args __attribute__ ((unused)))
+
+{
+#ifndef GRUB_MACHINE_EMU
+  grub_mm_dump(0);
+#endif
+
+  return 0;
+}
+
+static grub_err_t
+grub_cmd_lsfreemem (grub_command_t cmd __attribute__ ((unused)),
+                   int argc __attribute__ ((unused)),
+                   char **args __attribute__ ((unused)))
+
+{
+#ifndef GRUB_MACHINE_EMU
+  grub_mm_dump_free();
+#endif
+
+  return 0;
+}
+
+
+static grub_err_t
+grub_cmd_stress_big_allocs (grub_command_t cmd __attribute__ ((unused)),
+                           int argc __attribute__ ((unused)),
+                           char **args __attribute__ ((unused)))
+{
+  int i, max_mb, blocks_alloced;
+  void *mem;
+  void **blocklist;
+
+  grub_printf ("Test 1: increasingly sized allocs to 1GB block\n");
+  for (i = 1; i < 1024; i++) {
+    grub_printf ("%d MB . ", i);
+    mem = grub_malloc (i * 1024 * 1024);
+    if (mem == NULL)
+      {
+       grub_printf ("failed\n");
+       break;
+      }
+    else
+      grub_free (mem);
+
+    if (i % 10 == 0)
+      grub_printf ("\n");
+  }
+
+  max_mb = i - 1;
+  grub_printf ("Max sized allocation we did was %d MB\n", max_mb);
+  
+  grub_printf ("Test 2: 1MB at a time, max 4GB\n");
+  blocklist = grub_calloc (4096, sizeof (void *));
+  for (i = 0; i < 4096; i++)
+    {
+      blocklist[i] = grub_malloc (1024 * 1024);
+      if (!blocklist[i])
+       {
+         grub_printf ("Ran out of memory at iteration %d\n", i);
+         break;
+       }
+    }
+  blocks_alloced = i;
+  for (i = 0; i < blocks_alloced; i++)
+    grub_free (blocklist[i]);
+
+  grub_printf ("\nTest 3: 1MB aligned 900kB + 100kB\n");
+  //grub_mm_debug=1;
+  for (i = 0; i < 4096; i += 2)
+    {
+      blocklist[i] = grub_memalign (1024 * 1024, 900 * 1024);
+      if (!blocklist[i])
+       {
+         grub_printf ("Failed big allocation, iteration %d\n", i);
+         blocks_alloced = i;
+         break;
+       }
+
+      blocklist[i + 1] = grub_malloc (100 * 1024);
+      if (!blocklist[i + 1])
+       {
+         grub_printf ("Failed small allocation, iteration %d\n", i);
+         blocks_alloced = i + 1;
+         break;
+       }
+      grub_printf (".");
+    }
+  for (i = 0; i < blocks_alloced; i++)
+    grub_free (blocklist[i]);
+
+  grub_free (blocklist);
+
+  grub_errno = GRUB_ERR_NONE;
+  return GRUB_ERR_NONE;
+}
+
+static grub_command_t cmd_lsmem, cmd_lsfreemem, cmd_sba;
+
+#endif /* MM_DEBUG */
+
+GRUB_MOD_INIT(memtools)
+{
+#ifdef MM_DEBUG
+  cmd_lsmem = grub_register_command ("lsmem", grub_cmd_lsmem,
+                                    0, N_("List free and allocated memory 
blocks."));
+  cmd_lsfreemem = grub_register_command ("lsfreemem", grub_cmd_lsfreemem,
+                                        0, N_("List free memory blocks."));
+  cmd_sba = grub_register_command ("stress_big_allocs", 
grub_cmd_stress_big_allocs,
+                                  0, N_("Stress test large allocations."));
+#endif
+}
+
+GRUB_MOD_FINI(memtools)
+{
+#ifdef MM_DEBUG
+  grub_unregister_command (cmd_lsmem);
+  grub_unregister_command (cmd_lsfreemem);
+  grub_unregister_command (cmd_sba);
+#endif
+}
diff --git a/grub-core/kern/mm.c b/grub-core/kern/mm.c
index c3bf4646f55e..1e93d0d6cdb4 100644
--- a/grub-core/kern/mm.c
+++ b/grub-core/kern/mm.c
@@ -657,6 +657,8 @@ grub_mm_dump_free (void)
     {
       grub_mm_header_t p;
 
+      grub_printf ("Region %p (size %" PRIuGRUB_SIZE ")\n\n", r, r->size);
+
       /* Follow the free list.  */
       p = r->first;
       do
@@ -684,6 +686,8 @@ grub_mm_dump (unsigned lineno)
     {
       grub_mm_header_t p;
 
+      grub_printf ("Region %p (size %" PRIuGRUB_SIZE ")\n\n", r, r->size);
+
       for (p = (grub_mm_header_t) ALIGN_UP ((grub_addr_t) (r + 1),
                                            GRUB_MM_ALIGN);
           (grub_addr_t) p < (grub_addr_t) (r+1) + r->size;
-- 
2.32.0