From: Ard Biesheuvel ardb@kernel.org
[ Upstream commit 3a262423755b83a5f85009ace415d6e7f572dfe8 ]
Commit 82046702e288 ("efi/libstub/arm64: Replace 'preferred' offset with alignment check") simplified the way the stub moves the kernel image around in memory before booting it, given that a relocatable image does not need to be copied to a 2M aligned offset if it was loaded on a 64k boundary by EFI.
Commit d32de9130f6c ("efi/arm64: libstub: Deal gracefully with EFI_RNG_PROTOCOL failure") inadvertently defeated this logic by overriding the value of efi_nokaslr if EFI_RNG_PROTOCOL is not available, which was mistaken by the loader logic as an explicit request on the part of the user to disable KASLR and any associated relocation of an Image not loaded on a 2M boundary.
So let's reinstate this functionality, by capturing the value of efi_nokaslr at function entry to choose the minimum alignment.
Fixes: d32de9130f6c ("efi/arm64: libstub: Deal gracefully with EFI_RNG_PROTOCOL failure") Signed-off-by: Ard Biesheuvel ardb@kernel.org Tested-by: Benjamin Herrenschmidt benh@kernel.crashing.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/firmware/efi/libstub/arm64-stub.c | 28 +++++++++++------------ 1 file changed, 13 insertions(+), 15 deletions(-)
diff --git a/drivers/firmware/efi/libstub/arm64-stub.c b/drivers/firmware/efi/libstub/arm64-stub.c index 3698c1ce2940..6f214c9c303e 100644 --- a/drivers/firmware/efi/libstub/arm64-stub.c +++ b/drivers/firmware/efi/libstub/arm64-stub.c @@ -79,18 +79,6 @@ static bool check_image_region(u64 base, u64 size) return ret; }
-/* - * Although relocatable kernels can fix up the misalignment with respect to - * MIN_KIMG_ALIGN, the resulting virtual text addresses are subtly out of - * sync with those recorded in the vmlinux when kaslr is disabled but the - * image required relocation anyway. Therefore retain 2M alignment unless - * KASLR is in use. - */ -static u64 min_kimg_align(void) -{ - return efi_nokaslr ? MIN_KIMG_ALIGN : EFI_KIMG_ALIGN; -} - efi_status_t handle_kernel_image(unsigned long *image_addr, unsigned long *image_size, unsigned long *reserve_addr, @@ -101,6 +89,16 @@ efi_status_t handle_kernel_image(unsigned long *image_addr, unsigned long kernel_size, kernel_memsize = 0; u32 phys_seed = 0;
+ /* + * Although relocatable kernels can fix up the misalignment with + * respect to MIN_KIMG_ALIGN, the resulting virtual text addresses are + * subtly out of sync with those recorded in the vmlinux when kaslr is + * disabled but the image required relocation anyway. Therefore retain + * 2M alignment if KASLR was explicitly disabled, even if it was not + * going to be activated to begin with. + */ + u64 min_kimg_align = efi_nokaslr ? MIN_KIMG_ALIGN : EFI_KIMG_ALIGN; + if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { if (!efi_nokaslr) { status = efi_get_random_bytes(sizeof(phys_seed), @@ -130,7 +128,7 @@ efi_status_t handle_kernel_image(unsigned long *image_addr, * If KASLR is enabled, and we have some randomness available, * locate the kernel at a randomized offset in physical memory. */ - status = efi_random_alloc(*reserve_size, min_kimg_align(), + status = efi_random_alloc(*reserve_size, min_kimg_align, reserve_addr, phys_seed); } else { status = EFI_OUT_OF_RESOURCES; @@ -139,7 +137,7 @@ efi_status_t handle_kernel_image(unsigned long *image_addr, if (status != EFI_SUCCESS) { if (!check_image_region((u64)_text, kernel_memsize)) { efi_err("FIRMWARE BUG: Image BSS overlaps adjacent EFI memory region\n"); - } else if (IS_ALIGNED((u64)_text, min_kimg_align())) { + } else if (IS_ALIGNED((u64)_text, min_kimg_align)) { /* * Just execute from wherever we were loaded by the * UEFI PE/COFF loader if the alignment is suitable. @@ -150,7 +148,7 @@ efi_status_t handle_kernel_image(unsigned long *image_addr, }
status = efi_allocate_pages_aligned(*reserve_size, reserve_addr, - ULONG_MAX, min_kimg_align()); + ULONG_MAX, min_kimg_align);
if (status != EFI_SUCCESS) { efi_err("Failed to relocate kernel\n");