[Xen-devel] [PATCH for-4.5] EFI: Fix efi_arch_allocate_mmap_buffer() to return new size

[Roy Franz <roy.franz@xxxxxxxxxx>]

efi_arch_allocate_mmap_buffer() allocates a buffer for the EFI memory map, and
for ARM it allocates a larger buffer than requested. This is done to account
for the increase in the map size that may occur when the allocation is made.
The previous code allocated a larger buffer, but did not adjust the size to
match.  This caused the later call to GetMemoryMap() to fail with a
BUFFER_TOO_SMALL error, since the original, smaller size was used.  This patch
changes the argument to efi_arch_allocate_mmap_buffer() to be a pointer to
UINTN, and the ARM version updates the size on a successful allocation.
The x86 version uses a different allocation method, so only the function
argument type is changed.
Also add decode of the BUFFER_TOO_SMALL error code to PrintErrMesg().

Signed-off-by: Roy Franz <roy.franz@xxxxxxxxxx>
---
 xen/arch/arm/efi/efi-boot.h | 6 ++++--
 xen/arch/x86/efi/efi-boot.h | 4 ++--
 xen/common/efi/boot.c       | 5 ++++-
 3 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/xen/arch/arm/efi/efi-boot.h b/xen/arch/arm/efi/efi-boot.h
index d40d8b2..639942d 100644
--- a/xen/arch/arm/efi/efi-boot.h
+++ b/xen/arch/arm/efi/efi-boot.h
@@ -370,14 +370,16 @@ static void __init efi_arch_cfg_file_late(EFI_FILE_HANDLE 
dir_handle, char *sect
 {
 }
 
-static void *__init efi_arch_allocate_mmap_buffer(UINTN map_size)
+static void *__init efi_arch_allocate_mmap_buffer(UINTN *map_size)
 {
     void *ptr;
     EFI_STATUS status;
+    UINTN map_size_alloc = *map_size + EFI_PAGE_SIZE;
 
-    status = efi_bs->AllocatePool(EfiLoaderData, map_size + EFI_PAGE_SIZE, 
&ptr);
+    status = efi_bs->AllocatePool(EfiLoaderData, map_size_alloc, &ptr);
     if ( status != EFI_SUCCESS )
         return NULL;
+    *map_size = map_size_alloc;
     return ptr;
 }
 
diff --git a/xen/arch/x86/efi/efi-boot.h b/xen/arch/x86/efi/efi-boot.h
index 4348cfe..454ffb6 100644
--- a/xen/arch/x86/efi/efi-boot.h
+++ b/xen/arch/x86/efi/efi-boot.h
@@ -190,10 +190,10 @@ static void __init 
efi_arch_process_memory_map(EFI_SYSTEM_TABLE *SystemTable,
 
 }
 
-static void *__init efi_arch_allocate_mmap_buffer(UINTN map_size)
+static void *__init efi_arch_allocate_mmap_buffer(UINTN *map_size)
 {
     place_string(&mbi.mem_upper, NULL);
-    mbi.mem_upper -= map_size;
+    mbi.mem_upper -= *map_size;
     mbi.mem_upper &= -__alignof__(EFI_MEMORY_DESCRIPTOR);
     if ( mbi.mem_upper < xen_phys_start )
         return NULL;
diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
index f272171..4257341 100644
--- a/xen/common/efi/boot.c
+++ b/xen/common/efi/boot.c
@@ -271,6 +271,9 @@ static void __init PrintErrMesg(const CHAR16 *mesg, 
EFI_STATUS ErrCode)
     case EFI_COMPROMISED_DATA:
         mesg = L"Compromised data";
         break;
+    case EFI_BUFFER_TOO_SMALL:
+        mesg = L"Buffer too small";
+        break;
     default:
         PrintErr(L"ErrCode: ");
         DisplayUint(ErrCode, 0);
@@ -1038,7 +1041,7 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE 
*SystemTable)
 
     efi_bs->GetMemoryMap(&efi_memmap_size, NULL, &map_key,
                          &efi_mdesc_size, &mdesc_ver);
-    efi_memmap = efi_arch_allocate_mmap_buffer(efi_memmap_size);
+    efi_memmap = efi_arch_allocate_mmap_buffer(&efi_memmap_size);
     if ( !efi_memmap )
         blexit(L"Unable to allocate memory for EFI memory map");
 
-- 
1.9.1


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