From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matt Fleming Subject: [PATCH] x86/efi: Fix 7th argument to efi_call Date: Fri, 13 May 2016 21:34:42 +0100 Message-ID: <1463171682-13881-2-git-send-email-matt@codeblueprint.co.uk> References: <1463171682-13881-1-git-send-email-matt@codeblueprint.co.uk> Return-path: In-Reply-To: <1463171682-13881-1-git-send-email-matt@codeblueprint.co.uk> Sender: linux-kernel-owner@vger.kernel.org To: Ingo Molnar , Thomas Gleixner , "H . Peter Anvin" Cc: Alex Thorlton , Ard Biesheuvel , linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org, Matt Fleming , Borislav Petkov , Dimitri Sivanich , Ingo Molnar , Mike Travis , Russ Anderson , stable@vger.kernel.org List-Id: linux-efi@vger.kernel.org From: Alex Thorlton The efi_call assembly code has a slight error that prevents us from using arguments 7 and higher, which will be passed in on the stack. mov (%rsp), %rax mov 8(%rax), %rax ... mov %rax, 40(%rsp) This code goes and grabs the return address for the current stack frame, and puts it on the stack, next to the 5th argument for the EFI runtime call. Considering the fact that having the return address in that position on the stack makes no sense, I'm guessing that the intent of this code was actually to grab an argument off the stack frame for this call and place it into the frame for the next one. The small change to that offset (i.e. 8(%rax) to 16(%rax)) ensures that we grab the 7th argument off the stack, and pass it as the 6th argument to the EFI runtime function that we're about to call. This change gets our EFI runtime calls that need to pass more than 6 arguments working again. SGI/UV is the only platform that passes more than 6 arguments. Signed-off-by: Alex Thorlton Cc: Dimitri Sivanich Cc: Russ Anderson Cc: Mike Travis Cc: Borislav Petkov Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: x86@kernel.org Cc: linux-efi@vger.kernel.org Cc: [ Updated changelog. ] Signed-off-by: Matt Fleming --- arch/x86/platform/efi/efi_stub_64.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/platform/efi/efi_stub_64.S b/arch/x86/platform/efi/efi_stub_64.S index 92723aeae0f9..62938ffbb9f9 100644 --- a/arch/x86/platform/efi/efi_stub_64.S +++ b/arch/x86/platform/efi/efi_stub_64.S @@ -43,7 +43,7 @@ ENTRY(efi_call) FRAME_BEGIN SAVE_XMM mov (%rsp), %rax - mov 8(%rax), %rax + mov 16(%rax), %rax subq $48, %rsp mov %r9, 32(%rsp) mov %rax, 40(%rsp) -- 2.7.3