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Message-Id: <20171011203027.11248-7-thgarnie@google.com>
Date: Wed, 11 Oct 2017 13:30:06 -0700
From: Thomas Garnier <thgarnie@...gle.com>
To: Herbert Xu <herbert@...dor.apana.org.au>,
"David S . Miller" <davem@...emloft.net>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H . Peter Anvin" <hpa@...or.com>,
Peter Zijlstra <peterz@...radead.org>,
Josh Poimboeuf <jpoimboe@...hat.com>,
Arnd Bergmann <arnd@...db.de>,
Thomas Garnier <thgarnie@...gle.com>,
Kees Cook <keescook@...omium.org>,
Andrey Ryabinin <aryabinin@...tuozzo.com>,
Matthias Kaehlcke <mka@...omium.org>,
Tom Lendacky <thomas.lendacky@....com>,
Andy Lutomirski <luto@...nel.org>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
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Cc: x86@...nel.org,
linux-crypto@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-pm@...r.kernel.org,
virtualization@...ts.linux-foundation.org,
xen-devel@...ts.xenproject.org,
linux-arch@...r.kernel.org,
linux-sparse@...r.kernel.org,
kvm@...r.kernel.org,
linux-doc@...r.kernel.org,
kernel-hardening@...ts.openwall.com
Subject: [PATCH v1 06/27] x86/entry/64: Adapt assembly for PIE support
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 extended the
KASLR randomization range below the -2G memory limit.
Signed-off-by: Thomas Garnier <thgarnie@...gle.com>
---
arch/x86/entry/entry_64.S | 22 +++++++++++++++-------
1 file changed, 15 insertions(+), 7 deletions(-)
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 49167258d587..15bd5530d2ae 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -194,12 +194,15 @@ entry_SYSCALL_64_fastpath:
ja 1f /* return -ENOSYS (already in pt_regs->ax) */
movq %r10, %rcx
+ /* Ensures the call is position independent */
+ leaq sys_call_table(%rip), %r11
+
/*
* This call instruction is handled specially in stub_ptregs_64.
* It might end up jumping to the slow path. If it jumps, RAX
* and all argument registers are clobbered.
*/
- call *sys_call_table(, %rax, 8)
+ call *(%r11, %rax, 8)
.Lentry_SYSCALL_64_after_fastpath_call:
movq %rax, RAX(%rsp)
@@ -334,7 +337,8 @@ ENTRY(stub_ptregs_64)
* RAX stores a pointer to the C function implementing the syscall.
* IRQs are on.
*/
- cmpq $.Lentry_SYSCALL_64_after_fastpath_call, (%rsp)
+ leaq .Lentry_SYSCALL_64_after_fastpath_call(%rip), %r11
+ cmpq %r11, (%rsp)
jne 1f
/*
@@ -1172,7 +1176,8 @@ 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
/*
@@ -1383,10 +1388,10 @@ 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:
@@ -1440,7 +1445,8 @@ 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
@@ -1479,7 +1485,9 @@ first_nmi:
addq $8, (%rsp) /* Fix up RSP */
pushfq /* RFLAGS */
pushq $__KERNEL_CS /* CS */
- pushq $1f /* RIP */
+ pushq %rax /* Support Position Independent Code */
+ leaq 1f(%rip), %rax /* RIP */
+ xchgq %rax, (%rsp) /* Restore RAX, put 1f */
INTERRUPT_RETURN /* continues at repeat_nmi below */
UNWIND_HINT_IRET_REGS
1:
--
2.15.0.rc0.271.g36b669edcc-goog
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