efi/libstub: Allocate headspace in efi_get_memory_map()

efi_get_memory_map() allocates a buffer to store the memory map that it
retrieves.  This buffer may need to be reused by the client after
ExitBootServices() is called, at which point allocations are not longer
permitted.  To support this usecase, provide the allocated buffer size back
to the client, and allocate some additional headroom to account for any
reasonable growth in the map that is likely to happen between the call to
efi_get_memory_map() and the client reusing the buffer.

Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>

1 files changed, 12 insertions, 5 deletions

diff --git a/drivers/firmware/efi/libstub/fdt.c b/drivers/firmware/efi/libstub/fdt.c
index e58abfa953cc..bec0fa8d8746 100644
--- a/drivers/firmware/efi/libstub/fdt.c
+++ b/drivers/firmware/efi/libstub/fdt.c
@@ -175,13 +175,21 @@ efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table,
                                             unsigned long fdt_addr,
                                             unsigned long fdt_size)
 {
-        unsigned long map_size, desc_size;
+        unsigned long map_size, desc_size, buff_size;
         u32 desc_ver;
         unsigned long mmap_key;
         efi_memory_desc_t *memory_map, *runtime_map;
         unsigned long new_fdt_size;
         efi_status_t status;
         int runtime_entry_count = 0;
+        struct efi_boot_memmap map;
+
+        map.map =       &runtime_map;
+        map.map_size =  &map_size;
+        map.desc_size = &desc_size;
+        map.desc_ver =  &desc_ver;
+        map.key_ptr =   &mmap_key;
+        map.buff_size = &buff_size;
 
         /*
          * Get a copy of the current memory map that we will use to prepare
@@ -189,8 +197,7 @@ efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table,
          * subsequent allocations adding entries, since they could not affect
          * the number of EFI_MEMORY_RUNTIME regions.
          */
-        status = efi_get_memory_map(sys_table, &runtime_map, &map_size,
-                                    &desc_size, &desc_ver, &mmap_key);
+        status = efi_get_memory_map(sys_table, &map);
         if (status != EFI_SUCCESS) {
                 pr_efi_err(sys_table, "Unable to retrieve UEFI memory map.\n");
                 return status;
@@ -199,6 +206,7 @@ efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table,
         pr_efi(sys_table,
                "Exiting boot services and installing virtual address map...\n");
 
+        map.map = &memory_map;
         /*
          * Estimate size of new FDT, and allocate memory for it. We
          * will allocate a bigger buffer if this ends up being too
@@ -218,8 +226,7 @@ efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table,
                  * we can get the memory map key  needed for
                  * exit_boot_services().
                  */
-                status = efi_get_memory_map(sys_table, &memory_map, &map_size,
-                                            &desc_size, &desc_ver, &mmap_key);
+                status = efi_get_memory_map(sys_table, &map);
                 if (status != EFI_SUCCESS)
                         goto fail_free_new_fdt;