From mboxrd@z Thu Jan 1 00:00:00 1970 From: mark.rutland@arm.com (Mark Rutland) Date: Wed, 28 Oct 2015 18:08:36 +0000 Subject: [PATCH] [v2] arm64: efi: make sure vmlinux load address aligned on 2MB In-Reply-To: <1446053844-27281-1-git-send-email-timur@codeaurora.org> References: <1446053844-27281-1-git-send-email-timur@codeaurora.org> Message-ID: <20151028180836.GB26777@leverpostej> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Oct 28, 2015 at 12:37:24PM -0500, Timur Tabi wrote: > The vmlinux image load address must be aligned to 2MB, as documented > in Documentation/arm64/booting.txt. Otherwise, __create_page_tables > in head.S will create incorrect page table entries. > As I mentioned previously, this isn't quite correct. How about rewording this to: --- arm64: efi: ensure kernel is loaded at correct address The kernel image needs to be loaded text_offset_bytes from a 2M-aligned base, per Documentation/arm64/booting.txt. If loaded at the wrong offset modulo 2M, __create_page_tables will create incorrect page tables. The EFI stub implicitly assumes that dram_base (i.e. the lowest address with a EFI_MEMORY_WB attribute) is 2M-aligned, and tries to load the kernel at dram_base + TEXT_OFFSET. If dram_base is not 2M-aligned, the kernel will be loaded at the wrong offset from 2M. --- > Signed-off-by: Timur Tabi > Tested-by: Shanker Donthineni > --- > arch/arm64/kernel/efi-stub.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/kernel/efi-stub.c b/arch/arm64/kernel/efi-stub.c > index 816120e..37118f4 100644 > --- a/arch/arm64/kernel/efi-stub.c > +++ b/arch/arm64/kernel/efi-stub.c > @@ -42,7 +42,8 @@ efi_status_t __init handle_kernel_image(efi_system_table_t *sys_table_arg, > * Mustang), we can still place the kernel at the address > * 'dram_base + TEXT_OFFSET'. > */ > - *image_addr = *reserve_addr = dram_base + TEXT_OFFSET; > + *image_addr = *reserve_addr = > + round_up(dram_base, SZ_2M) + TEXT_OFFSET; We also need to fix the test for whether we need to relocate the kernel: (*image_addr != (dram_base + TEXT_OFFSET)). When dram_base is not 2M aligned, that is broken, and it's been broken since it was introduced in commit 3c7f255039a2ad6e ("arm64: efi: add EFI stub") in v3.16. It's a bit hideous to fix the general case, though, it seems. Thanks, Mark.