[PATCH v4 0/2] efi: Free memory on exit

[PATCH v4 0/2] efi: Free memory on exit

[Alexander Graf]

When exiting grub, we currently leave the heap allocated. This means that if we
exit and rerun grub, after a few iterations we can run into memory shortage.

This patch set frees the heap on exit. That way we can rerun grub many times
without much problem.

v3 -> v4:

  - Move grub_reboot to kern/efi/efi.c
  - use dynamic list instead of static array at runtime
  - use allocate_pool for list, so we are not bound by heap or random numbers
  - remember all allocations, not just the heap

Alexander Graf (2):
  efi: Move grub_reboot() into kernel
  efi: Free malloc regions on exit

 grub-core/Makefile.core.def |  4 ---
 grub-core/kern/efi/efi.c    |  9 +++++++
 grub-core/kern/efi/init.c   |  1 +
 grub-core/kern/efi/mm.c     | 65 +++++++++++++++++++++++++++++++++++++++++++++
 grub-core/lib/efi/reboot.c  | 33 -----------------------
 include/grub/efi/efi.h      |  1 +
 include/grub/misc.h         |  3 ++-
 7 files changed, 78 insertions(+), 38 deletions(-)
 delete mode 100644 grub-core/lib/efi/reboot.c

-- 
2.12.3

[PATCH v4 1/2] efi: Move grub_reboot() into kernel

[Alexander Graf]

The reboot function calls machine_fini() and then reboots the system.
Currently it lives in lib/ which means it gets compiled into the
reboot module which lives on the heap.

In a following patch, I want to free the heap on machine_fini()
though, so we would free the memory that the code is running in. That
obviously breaks with smarter UEFI implementations.

So this patch moves it into the core. That way we ensure that all
code running after machine_fini() in the UEFI case is running from
memory that got allocated (and gets deallocated) by the UEFI core.

Signed-off-by: Alexander Graf <agraf@suse.de>

---

v3 -> v4:

  - Move grub_reboot to kern/efi/efi.c
---
 grub-core/Makefile.core.def |  4 ----
 grub-core/kern/efi/efi.c    |  9 +++++++++
 grub-core/lib/efi/reboot.c  | 33 ---------------------------------
 include/grub/misc.h         |  3 ++-
 4 files changed, 11 insertions(+), 38 deletions(-)
 delete mode 100644 grub-core/lib/efi/reboot.c

diff --git a/grub-core/Makefile.core.def b/grub-core/Makefile.core.def
index a65c27f7f..1cc4ce374 100644
--- a/grub-core/Makefile.core.def
+++ b/grub-core/Makefile.core.def
@@ -872,10 +872,6 @@ module = {
   name = reboot;
   i386 = lib/i386/reboot.c;
   i386 = lib/i386/reboot_trampoline.S;
-  ia64_efi = lib/efi/reboot.c;
-  x86_64_efi = lib/efi/reboot.c;
-  arm_efi = lib/efi/reboot.c;
-  arm64_efi = lib/efi/reboot.c;
   powerpc_ieee1275 = lib/ieee1275/reboot.c;
   sparc64_ieee1275 = lib/ieee1275/reboot.c;
   mips_arc = lib/mips/arc/reboot.c;
diff --git a/grub-core/kern/efi/efi.c b/grub-core/kern/efi/efi.c
index d467785fc..708581fcb 100644
--- a/grub-core/kern/efi/efi.c
+++ b/grub-core/kern/efi/efi.c
@@ -155,6 +155,15 @@ grub_efi_get_loaded_image (grub_efi_handle_t image_handle)
 }
 
 void
+grub_reboot (void)
+{
+  grub_machine_fini (GRUB_LOADER_FLAG_NORETURN);
+  efi_call_4 (grub_efi_system_table->runtime_services->reset_system,
+              GRUB_EFI_RESET_COLD, GRUB_EFI_SUCCESS, 0, NULL);
+  for (;;) ;
+}
+
+void
 grub_exit (void)
 {
   grub_machine_fini (GRUB_LOADER_FLAG_NORETURN);
diff --git a/grub-core/lib/efi/reboot.c b/grub-core/lib/efi/reboot.c
deleted file mode 100644
index 7de8bcb5d..000000000
--- a/grub-core/lib/efi/reboot.c
+++ /dev/null
@@ -1,33 +0,0 @@
-/*
- *  GRUB  --  GRand Unified Bootloader
- *  Copyright (C) 2011  Free Software Foundation, Inc.
- *
- *  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 <grub/efi/api.h>
-#include <grub/efi/efi.h>
-#include <grub/mm.h>
-#include <grub/misc.h>
-#include <grub/kernel.h>
-#include <grub/loader.h>
-
-void
-grub_reboot (void)
-{
-  grub_machine_fini (GRUB_LOADER_FLAG_NORETURN);
-  efi_call_4 (grub_efi_system_table->runtime_services->reset_system,
-              GRUB_EFI_RESET_COLD, GRUB_EFI_SUCCESS, 0, NULL);
-  for (;;) ;
-}
diff --git a/include/grub/misc.h b/include/grub/misc.h
index 2a9f87cc2..372f009e8 100644
--- a/include/grub/misc.h
+++ b/include/grub/misc.h
@@ -396,7 +396,8 @@ grub_abs (int x)
 }
 
 /* Reboot the machine.  */
-#if defined (GRUB_MACHINE_EMU) || defined (GRUB_MACHINE_QEMU_MIPS)
+#if defined (GRUB_MACHINE_EMU) || defined (GRUB_MACHINE_QEMU_MIPS) || \
+    defined (GRUB_MACHINE_EFI)
 void EXPORT_FUNC(grub_reboot) (void) __attribute__ ((noreturn));
 #else
 void grub_reboot (void) __attribute__ ((noreturn));
-- 
2.12.3

[PATCH v4 2/2] efi: Free malloc regions on exit

[Alexander Graf]

When we exit grub, we don't free all the memory that we allocated earlier
for our heap region. This can cause problems with setups where you try
to descend the boot order using "exit" entries, such as PXE -> HD boot
scenarios.

Signed-off-by: Alexander Graf <agraf@suse.de>

---

v1 -> v2:

  - add comment explaining the number of regions
  - move nr of regions into a define
  - add warning if we exceed the number of freeable regions
  - reset region counter to 0 on fini

v2 -> v3:

  - use dynamic list instead of static array at runtime
  - use allocate_pool for list, so we are not bound by heap or random numbers
  - remember all allocations, not just the heap
---
 grub-core/kern/efi/init.c |  1 +
 grub-core/kern/efi/mm.c   | 65 +++++++++++++++++++++++++++++++++++++++++++++++
 include/grub/efi/efi.h    |  1 +
 3 files changed, 67 insertions(+)

diff --git a/grub-core/kern/efi/init.c b/grub-core/kern/efi/init.c
index 2c31847bf..3dfdf2d22 100644
--- a/grub-core/kern/efi/init.c
+++ b/grub-core/kern/efi/init.c
@@ -80,4 +80,5 @@ grub_efi_fini (void)
 {
   grub_efidisk_fini ();
   grub_console_fini ();
+  grub_efi_memory_fini ();
 }
diff --git a/grub-core/kern/efi/mm.c b/grub-core/kern/efi/mm.c
index ac2a4c556..63c660eba 100644
--- a/grub-core/kern/efi/mm.c
+++ b/grub-core/kern/efi/mm.c
@@ -49,6 +49,41 @@ static grub_efi_uintn_t finish_desc_size;
 static grub_efi_uint32_t finish_desc_version;
 int grub_efi_is_finished = 0;
 
+/*
+ * We need to roll back EFI allocations on exit. Remember allocations that
+ * we'll free on exit. In most cases only one will be used.
+ */
+struct efi_allocation;
+struct efi_allocation {
+	struct efi_allocation *next;
+	grub_efi_physical_address_t start_addr;
+	grub_efi_uint64_t pages;
+};
+static struct efi_allocation *efi_allocated_memory;
+
+static void
+grub_efi_remember_pages (grub_efi_physical_address_t address,
+                         grub_efi_uintn_t pages)
+{
+  grub_efi_boot_services_t *b;
+  struct efi_allocation *alloc;
+  grub_efi_status_t status;
+
+  b = grub_efi_system_table->boot_services;
+  status = efi_call_3 (b->allocate_pool, GRUB_EFI_LOADER_DATA,
+                           sizeof(*alloc), (void**)&alloc);
+  if (status == GRUB_EFI_SUCCESS)
+    {
+      alloc->next = efi_allocated_memory;
+      alloc->start_addr = address;
+      alloc->pages = pages;
+      efi_allocated_memory = alloc;
+    }
+  else
+      grub_printf ("Could not malloc memory to remember EFI allocation. "
+                   "Exiting grub2 won't free all memory.\n");
+}
+
 /* Allocate pages. Return the pointer to the first of allocated pages.  */
 void *
 grub_efi_allocate_pages_real (grub_efi_physical_address_t address,
@@ -79,6 +114,7 @@ grub_efi_allocate_pages_real (grub_efi_physical_address_t address,
 	return 0;
     }
 
+  grub_efi_remember_pages (address, pages);
   return (void *) ((grub_addr_t) address);
 }
 
@@ -422,6 +458,35 @@ add_memory_regions (grub_efi_memory_descriptor_t *memory_map,
     grub_fatal ("too little memory");
 }
 
+void
+grub_efi_memory_fini (void)
+{
+  struct efi_allocation *alloc;
+  grub_efi_boot_services_t *b;
+
+  b = grub_efi_system_table->boot_services;
+
+  for (alloc = efi_allocated_memory; alloc;)
+    {
+      struct efi_allocation *next;
+
+      /* Free the allocation */
+      grub_efi_free_pages (alloc->start_addr,
+                           alloc->pages);
+
+      /* Remember the next entry */
+      next = alloc->next;
+
+      /* Free the current list entry */
+      efi_call_1 (b->free_pool, alloc);
+
+      /* And move on to the next */
+      alloc = next;
+    }
+
+  efi_allocated_memory = NULL;
+}
+
 #if 0
 /* Print the memory map.  */
 static void
diff --git a/include/grub/efi/efi.h b/include/grub/efi/efi.h
index 3fa082816..c996913e5 100644
--- a/include/grub/efi/efi.h
+++ b/include/grub/efi/efi.h
@@ -55,6 +55,7 @@ EXPORT_FUNC(grub_efi_get_memory_map) (grub_efi_uintn_t *memory_map_size,
 				      grub_efi_uintn_t *map_key,
 				      grub_efi_uintn_t *descriptor_size,
 				      grub_efi_uint32_t *descriptor_version);
+void grub_efi_memory_fini (void);
 grub_efi_loaded_image_t *EXPORT_FUNC(grub_efi_get_loaded_image) (grub_efi_handle_t image_handle);
 void EXPORT_FUNC(grub_efi_print_device_path) (grub_efi_device_path_t *dp);
 char *EXPORT_FUNC(grub_efi_get_filename) (grub_efi_device_path_t *dp);
-- 
2.12.3