From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967907AbeE2WQ7 (ORCPT ); Tue, 29 May 2018 18:16:59 -0400 Received: from mail-pf0-f195.google.com ([209.85.192.195]:33898 "EHLO mail-pf0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S967860AbeE2WQz (ORCPT ); Tue, 29 May 2018 18:16:55 -0400 X-Google-Smtp-Source: ADUXVKLAIoPB9qtIf76zzdZ+i4Fd8yg4lMmvrGSsTC7KuaEoPZyDXLamFE4WymWXm3zlcWSxccLVqQ== From: Thomas Garnier To: kernel-hardening@lists.openwall.com Cc: Thomas Garnier , Skip Josh Poimboeuf , Skip Dave Hansen , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Andy Lutomirski , Dominik Brodowski , Borislav Petkov , "Kirill A. Shutemov" , Tom Lendacky , linux-kernel@vger.kernel.org Subject: [PATCH v4 06/27] x86/entry/64: Adapt assembly for PIE support Date: Tue, 29 May 2018 15:15:07 -0700 Message-Id: <20180529221625.33541-7-thgarnie@google.com> X-Mailer: git-send-email 2.17.0.921.gf22659ad46-goog In-Reply-To: <20180529221625.33541-1-thgarnie@google.com> References: <20180529221625.33541-1-thgarnie@google.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Change the assembly code to use only relative references of symbols for the kernel to be PIE compatible. Position Independent Executable (PIE) support will allow to extend the KASLR randomization range 0xffffffff80000000. Signed-off-by: Thomas Garnier --- arch/x86/entry/entry_64.S | 18 ++++++++++++------ arch/x86/kernel/relocate_kernel_64.S | 8 +++----- 2 files changed, 15 insertions(+), 11 deletions(-) diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 3166b9674429..1cbf4c3616a8 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -191,7 +191,7 @@ ENTRY(entry_SYSCALL_64_trampoline) * spill RDI and restore it in a second-stage trampoline. */ pushq %rdi - movq $entry_SYSCALL_64_stage2, %rdi + movabsq $entry_SYSCALL_64_stage2, %rdi JMP_NOSPEC %rdi END(entry_SYSCALL_64_trampoline) @@ -1276,7 +1276,8 @@ ENTRY(error_entry) movl %ecx, %eax /* zero extend */ cmpq %rax, RIP+8(%rsp) je .Lbstep_iret - cmpq $.Lgs_change, RIP+8(%rsp) + leaq .Lgs_change(%rip), %rcx + cmpq %rcx, RIP+8(%rsp) jne .Lerror_entry_done /* @@ -1481,10 +1482,10 @@ ENTRY(nmi) * resume the outer NMI. */ - movq $repeat_nmi, %rdx + leaq repeat_nmi(%rip), %rdx cmpq 8(%rsp), %rdx ja 1f - movq $end_repeat_nmi, %rdx + leaq end_repeat_nmi(%rip), %rdx cmpq 8(%rsp), %rdx ja nested_nmi_out 1: @@ -1538,7 +1539,8 @@ nested_nmi: pushq %rdx pushfq pushq $__KERNEL_CS - pushq $repeat_nmi + leaq repeat_nmi(%rip), %rdx + pushq %rdx /* Put stack back */ addq $(6*8), %rsp @@ -1577,7 +1579,11 @@ first_nmi: addq $8, (%rsp) /* Fix up RSP */ pushfq /* RFLAGS */ pushq $__KERNEL_CS /* CS */ - pushq $1f /* RIP */ + pushq $0 /* Futur return address */ + pushq %rax /* Save RAX */ + leaq 1f(%rip), %rax /* RIP */ + movq %rax, 8(%rsp) /* Put 1f on return address */ + popq %rax /* Restore RAX */ iretq /* continues at repeat_nmi below */ UNWIND_HINT_IRET_REGS 1: diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S index a7227dfe1a2b..0c0fc259a4e2 100644 --- a/arch/x86/kernel/relocate_kernel_64.S +++ b/arch/x86/kernel/relocate_kernel_64.S @@ -208,11 +208,9 @@ identity_mapped: movq %rax, %cr3 lea PAGE_SIZE(%r8), %rsp call swap_pages - jmp *virtual_mapped_addr(%rip) - - /* Absolute value for PIE support */ -virtual_mapped_addr: - .quad virtual_mapped + movabsq $virtual_mapped, %rax + pushq %rax + ret virtual_mapped: movq RSP(%r8), %rsp -- 2.17.0.921.gf22659ad46-goog