Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 18df7577 authored by Ard Biesheuvel's avatar Ard Biesheuvel
Browse files

efi/memreserve: deal with memreserve entries in unmapped memory 



Ensure that the EFI memreserve entries can be accessed, even if they
are located in memory that the kernel (e.g., a crashkernel) omits from
the linear map.

Fixes: 80424b02 ("efi: Reduce the amount of memblock reservations ...")
Cc: <stable@vger.kernel.org> # 5.0+
Reported-by: default avatarJonathan Richardson <jonathan.richardson@broadcom.com>
Reviewed-by: default avatarJonathan Richardson <jonathan.richardson@broadcom.com>
Tested-by: default avatarJonathan Richardson <jonathan.richardson@broadcom.com>
Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
parent d1fdb6d8

drivers/firmware/efi/efi.c

+10 −2
Original line number Diff line number Diff line
@@ -1009,14 +1009,16 @@ int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size) 


	/* first try to find a slot in an existing linked list entry */

	for (prsv = efi_memreserve_root->next; prsv; prsv = rsv->next) {

		rsv = __va(prsv);

		rsv = memremap(prsv, sizeof(*rsv), MEMREMAP_WB);

		index = atomic_fetch_add_unless(&rsv->count, 1, rsv->size);

		if (index < rsv->size) {

			rsv->entry[index].base = addr;

			rsv->entry[index].size = size;



			memunmap(rsv);

			return 0;

		}

		memunmap(rsv);

	}



	/* no slot found - allocate a new linked list entry */
@@ -1024,7 +1026,13 @@ int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size) 
	if (!rsv)

		return -ENOMEM;



	rsv->size = EFI_MEMRESERVE_COUNT(PAGE_SIZE);

	/*

	 * The memremap() call above assumes that a linux_efi_memreserve entry

	 * never crosses a page boundary, so let's ensure that this remains true

	 * even when kexec'ing a 4k pages kernel from a >4k pages kernel, by

	 * using SZ_4K explicitly in the size calculation below.

	 */

	rsv->size = EFI_MEMRESERVE_COUNT(SZ_4K);

	atomic_set(&rsv->count, 1);

	rsv->entry[0].base = addr;

	rsv->entry[0].size = size;