efi/libstub: arm32: Use low allocation for the uncompressed kernel

Before commit

  d0f9ca9be11f25ef ("ARM: decompressor: run decompressor in place if loaded via UEFI")

we were rather limited in the choice of base address for the uncompressed
kernel, as we were relying on the logic in the decompressor that blindly
rounds down the decompressor execution address to the next multiple of 128
MiB, and decompresses the kernel there. For this reason, we have a lot of
complicated memory region handling code, to ensure that this memory window
is available, even though it could be occupied by reserved regions or
other allocations that may or may not collide with the uncompressed image.

Today, we simply pass the target address for the decompressed image to the
decompressor directly, and so we can choose a suitable window just by
finding a 16 MiB aligned region, while taking TEXT_OFFSET and the region
for the swapper page tables into account.

So let's get rid of the complicated logic, and instead, use the existing
bottom up allocation routine to allocate a suitable window as low as
possible, and carve out a memory region that has the right properties.

Note that this removes any dependencies on the 'dram_base' argument to
handle_kernel_image(), and so this is removed as well. Given that this
was the only remaining use of dram_base, the code that produces it is
removed entirely as well.

Reviewed-by: Maxim Uvarov <maxim.uvarov@linaro.org>
Tested-by: Maxim Uvarov <maxim.uvarov@linaro.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

1 files changed, 1 insertions, 43 deletions

diff --git a/drivers/firmware/efi/libstub/efi-stub.c b/drivers/firmware/efi/libstub/efi-stub.c
index 65a0070010a1..311a16802dd6 100644
--- a/drivers/firmware/efi/libstub/efi-stub.c
+++ b/drivers/firmware/efi/libstub/efi-stub.c
@@ -87,40 +87,6 @@ static void install_memreserve_table(void)
 		efi_err("Failed to install memreserve config table!\n");
 }
 
-static unsigned long get_dram_base(void)
-{
-	efi_status_t status;
-	unsigned long map_size, buff_size;
-	unsigned long membase  = EFI_ERROR;
-	struct efi_memory_map map;
-	efi_memory_desc_t *md;
-	struct efi_boot_memmap boot_map;
-
-	boot_map.map		= (efi_memory_desc_t **)&map.map;
-	boot_map.map_size	= &map_size;
-	boot_map.desc_size	= &map.desc_size;
-	boot_map.desc_ver	= NULL;
-	boot_map.key_ptr	= NULL;
-	boot_map.buff_size	= &buff_size;
-
-	status = efi_get_memory_map(&boot_map);
-	if (status != EFI_SUCCESS)
-		return membase;
-
-	map.map_end = map.map + map_size;
-
-	for_each_efi_memory_desc_in_map(&map, md) {
-		if (md->attribute & EFI_MEMORY_WB) {
-			if (membase > md->phys_addr)
-				membase = md->phys_addr;
-		}
-	}
-
-	efi_bs_call(free_pool, map.map);
-
-	return membase;
-}
-
 /*
  * EFI entry point for the arm/arm64 EFI stubs.  This is the entrypoint
  * that is described in the PE/COFF header.  Most of the code is the same
@@ -134,7 +100,6 @@ efi_status_t __efiapi efi_pe_entry(efi_handle_t handle,
 	efi_status_t status;
 	unsigned long image_addr;
 	unsigned long image_size = 0;
-	unsigned long dram_base;
 	/* addr/point and size pairs for memory management*/
 	unsigned long initrd_addr = 0;
 	unsigned long initrd_size = 0;
@@ -174,13 +139,6 @@ efi_status_t __efiapi efi_pe_entry(efi_handle_t handle,
 		goto fail;
 	}
 
-	dram_base = get_dram_base();
-	if (dram_base == EFI_ERROR) {
-		efi_err("Failed to find DRAM base\n");
-		status = EFI_LOAD_ERROR;
-		goto fail;
-	}
-
 	/*
 	 * Get the command line from EFI, using the LOADED_IMAGE
 	 * protocol. We are going to copy the command line into the
@@ -218,7 +176,7 @@ efi_status_t __efiapi efi_pe_entry(efi_handle_t handle,
 	status = handle_kernel_image(&image_addr, &image_size,
 				     &reserve_addr,
 				     &reserve_size,
-				     dram_base, image);
+				     image);
 	if (status != EFI_SUCCESS) {
 		efi_err("Failed to relocate kernel\n");
 		goto fail_free_screeninfo;