From 2f77465b05b1270c832b5e2ee27037672ad2a10a Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Tue, 30 Jan 2024 19:01:35 +0100 Subject: x86/efistub: Avoid placing the kernel below LOAD_PHYSICAL_ADDR The EFI stub's kernel placement logic randomizes the physical placement of the kernel by taking all available memory into account, and picking a region at random, based on a random seed. When KASLR is disabled, this seed is set to 0x0, and this results in the lowest available region of memory to be selected for loading the kernel, even if this is below LOAD_PHYSICAL_ADDR. Some of this memory is typically reserved for the GFP_DMA region, to accommodate masters that can only access the first 16 MiB of system memory. Even if such devices are rare these days, we may still end up with a warning in the kernel log, as reported by Tom: swapper/0: page allocation failure: order:10, mode:0xcc1(GFP_KERNEL|GFP_DMA), nodemask=(null),cpuset=/,mems_allowed=0 Fix this by tweaking the random allocation logic to accept a low bound on the placement, and set it to LOAD_PHYSICAL_ADDR. Fixes: a1b87d54f4e4 ("x86/efistub: Avoid legacy decompressor when doing EFI boot") Reported-by: Tom Englund Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218404 Signed-off-by: Ard Biesheuvel --- drivers/firmware/efi/libstub/kaslr.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/firmware/efi/libstub/kaslr.c') diff --git a/drivers/firmware/efi/libstub/kaslr.c b/drivers/firmware/efi/libstub/kaslr.c index 62d63f7a2645..1a9808012abd 100644 --- a/drivers/firmware/efi/libstub/kaslr.c +++ b/drivers/firmware/efi/libstub/kaslr.c @@ -119,7 +119,7 @@ efi_status_t efi_kaslr_relocate_kernel(unsigned long *image_addr, */ status = efi_random_alloc(*reserve_size, min_kimg_align, reserve_addr, phys_seed, - EFI_LOADER_CODE, EFI_ALLOC_LIMIT); + EFI_LOADER_CODE, 0, EFI_ALLOC_LIMIT); if (status != EFI_SUCCESS) efi_warn("efi_random_alloc() failed: 0x%lx\n", status); } else { -- cgit v1.2.3-70-g09d2