efi/arm-stub: Round up FDT allocation to mapping size

The FDT is mapped via a fixmap entry that is at least 2 MB in size and
2 MB aligned on 4 KB page size kernels.

On UEFI systems, the FDT allocation may share this 2 MB mapping with a
reserved region (or another memory region that we should never map),
unless we account for this in the size of the allocation (the alignment
is already 2 MB)

So instead of taking guesses at the needed space, simply allocate 2 MB
immediately. The allocation will be recorded as EFI_LOADER_DATA, and the
kernel only memblock_reserve()'s the actual size of the FDT, so the
unused space will be released back to the kernel.

Reviewed-By: Jeffrey Hugo <jhugo@codeaurora.org>
Tested-by: Richard Ruigrok <rruigrok@codeaurora.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20170404160245.27812-6-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h
index 083a52d3b59fe251205259cd3d1c5af68ca59efa..8f3043aba87307c9ebc3435277e3f4f933fd3278 100644 (file)
--- a/arch/arm64/include/asm/efi.h
+++ b/arch/arm64/include/asm/efi.h
@@ -1,6 +1,7 @@
 #ifndef _ASM_EFI_H
 #define _ASM_EFI_H
 
+#include <asm/boot.h>
 #include <asm/cpufeature.h>
 #include <asm/io.h>
 #include <asm/mmu_context.h>

diff --git a/drivers/firmware/efi/libstub/fdt.c b/drivers/firmware/efi/libstub/fdt.c
index 260c4b4b492ec38735715859522068da40c21381..41f457be64e8dc01440c9d430f28e0590a67a9f7 100644 (file)
--- a/drivers/firmware/efi/libstub/fdt.c
+++ b/drivers/firmware/efi/libstub/fdt.c
@@ -206,6 +206,10 @@ static efi_status_t exit_boot_func(efi_system_table_t *sys_table_arg,
        return update_fdt_memmap(p->new_fdt_addr, map);
 }
 
+#ifndef MAX_FDT_SIZE
+#define MAX_FDT_SIZE   SZ_2M
+#endif
+
 /*
  * Allocate memory for a new FDT, then add EFI, commandline, and
  * initrd related fields to the FDT.  This routine increases the
@@ -233,7 +237,6 @@ efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table,
        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;
@@ -262,41 +265,29 @@ efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table,
               "Exiting boot services and installing virtual address map...\n");
 
        map.map = &memory_map;
+       status = efi_high_alloc(sys_table, MAX_FDT_SIZE, EFI_FDT_ALIGN,
+                               new_fdt_addr, max_addr);
+       if (status != EFI_SUCCESS) {
+               pr_efi_err(sys_table,
+                          "Unable to allocate memory for new device tree.\n");
+               goto fail;
+       }
+
        /*
-        * Estimate size of new FDT, and allocate memory for it. We
-        * will allocate a bigger buffer if this ends up being too
-        * small, so a rough guess is OK here.
+        * Now that we have done our final memory allocation (and free)
+        * we can get the memory map key needed for exit_boot_services().
         */
-       new_fdt_size = fdt_size + EFI_PAGE_SIZE;
-       while (1) {
-               status = efi_high_alloc(sys_table, new_fdt_size, EFI_FDT_ALIGN,
-                                       new_fdt_addr, max_addr);
-               if (status != EFI_SUCCESS) {
-                       pr_efi_err(sys_table, "Unable to allocate memory for new device tree.\n");
-                       goto fail;
-               }
-
-               status = update_fdt(sys_table,
-                                   (void *)fdt_addr, fdt_size,
-                                   (void *)*new_fdt_addr, new_fdt_size,
-                                   cmdline_ptr, initrd_addr, initrd_size);
+       status = efi_get_memory_map(sys_table, &map);
+       if (status != EFI_SUCCESS)
+               goto fail_free_new_fdt;
 
-               /* Succeeding the first time is the expected case. */
-               if (status == EFI_SUCCESS)
-                       break;
+       status = update_fdt(sys_table, (void *)fdt_addr, fdt_size,
+                           (void *)*new_fdt_addr, MAX_FDT_SIZE, cmdline_ptr,
+                           initrd_addr, initrd_size);
 
-               if (status == EFI_BUFFER_TOO_SMALL) {
-                       /*
-                        * We need to allocate more space for the new
-                        * device tree, so free existing buffer that is
-                        * too small.
-                        */
-                       efi_free(sys_table, new_fdt_size, *new_fdt_addr);
-                       new_fdt_size += EFI_PAGE_SIZE;
-               } else {
-                       pr_efi_err(sys_table, "Unable to construct new device tree.\n");
-                       goto fail_free_new_fdt;
-               }
+       if (status != EFI_SUCCESS) {
+               pr_efi_err(sys_table, "Unable to construct new device tree.\n");
+               goto fail_free_new_fdt;
        }
 
        priv.runtime_map = runtime_map;
@@ -340,7 +331,7 @@ efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table,
        pr_efi_err(sys_table, "Exit boot services failed.\n");
 
 fail_free_new_fdt:
-       efi_free(sys_table, new_fdt_size, *new_fdt_addr);
+       efi_free(sys_table, MAX_FDT_SIZE, *new_fdt_addr);
 
 fail:
        sys_table->boottime->free_pool(runtime_map);