From: tip-bot for Dominik Brodowski <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: bp@alien8.de, tglx@linutronix.de, hpa@zytor.com,
torvalds@linux-foundation.org, jpoimboe@redhat.com,
luto@kernel.org, dvlasenk@redhat.com, brgerst@gmail.com,
linux@dominikbrodowski.net, mingo@kernel.org,
linux-kernel@vger.kernel.org, peterz@infradead.org
Subject: [tip:x86/pti] x86/entry/64: Interleave XOR register clearing with PUSH instructions
Date: Mon, 12 Feb 2018 02:16:57 -0800 [thread overview]
Message-ID: <tip-e922c091d34db9dec1eeb6e7b923043ae4d366e3@git.kernel.org> (raw)
In-Reply-To: <20180211104949.12992-4-linux@dominikbrodowski.net>
Commit-ID: e922c091d34db9dec1eeb6e7b923043ae4d366e3
Gitweb: https://git.kernel.org/tip/e922c091d34db9dec1eeb6e7b923043ae4d366e3
Author: Dominik Brodowski <linux@dominikbrodowski.net>
AuthorDate: Sun, 11 Feb 2018 11:49:44 +0100
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 12 Feb 2018 08:06:35 +0100
x86/entry/64: Interleave XOR register clearing with PUSH instructions
Same as is done for syscalls, interleave XOR with PUSH instructions
for exceptions/interrupts, in order to minimize the cost of the
additional instructions required for register clearing.
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dan.j.williams@intel.com
Link: http://lkml.kernel.org/r/20180211104949.12992-4-linux@dominikbrodowski.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/entry/calling.h | 40 +++++++++++++++++++---------------------
arch/x86/entry/entry_64.S | 30 +++++++++++++++++++++---------
2 files changed, 40 insertions(+), 30 deletions(-)
diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h
index 3bda317..a05cbb8 100644
--- a/arch/x86/entry/calling.h
+++ b/arch/x86/entry/calling.h
@@ -101,44 +101,42 @@ For 32-bit we have the following conventions - kernel is built with
addq $-(15*8), %rsp
.endm
- .macro SAVE_REGS offset=0
+ .macro SAVE_AND_CLEAR_REGS offset=0
+ /*
+ * Save registers and sanitize registers of values that a
+ * speculation attack might otherwise want to exploit. The
+ * lower registers are likely clobbered well before they
+ * could be put to use in a speculative execution gadget.
+ * Interleave XOR with PUSH for better uop scheduling:
+ */
movq %rdi, 14*8+\offset(%rsp)
movq %rsi, 13*8+\offset(%rsp)
movq %rdx, 12*8+\offset(%rsp)
movq %rcx, 11*8+\offset(%rsp)
movq %rax, 10*8+\offset(%rsp)
movq %r8, 9*8+\offset(%rsp)
+ xorq %r8, %r8 /* nospec r8 */
movq %r9, 8*8+\offset(%rsp)
+ xorq %r9, %r9 /* nospec r9 */
movq %r10, 7*8+\offset(%rsp)
+ xorq %r10, %r10 /* nospec r10 */
movq %r11, 6*8+\offset(%rsp)
+ xorq %r11, %r11 /* nospec r11 */
movq %rbx, 5*8+\offset(%rsp)
+ xorl %ebx, %ebx /* nospec rbx */
movq %rbp, 4*8+\offset(%rsp)
+ xorl %ebp, %ebp /* nospec rbp */
movq %r12, 3*8+\offset(%rsp)
+ xorq %r12, %r12 /* nospec r12 */
movq %r13, 2*8+\offset(%rsp)
+ xorq %r13, %r13 /* nospec r13 */
movq %r14, 1*8+\offset(%rsp)
+ xorq %r14, %r14 /* nospec r14 */
movq %r15, 0*8+\offset(%rsp)
+ xorq %r15, %r15 /* nospec r15 */
UNWIND_HINT_REGS offset=\offset
.endm
- /*
- * Sanitize registers of values that a speculation attack
- * might otherwise want to exploit. The lower registers are
- * likely clobbered well before they could be put to use in
- * a speculative execution gadget:
- */
- .macro CLEAR_REGS_NOSPEC
- xorl %ebp, %ebp
- xorl %ebx, %ebx
- xorq %r8, %r8
- xorq %r9, %r9
- xorq %r10, %r10
- xorq %r11, %r11
- xorq %r12, %r12
- xorq %r13, %r13
- xorq %r14, %r14
- xorq %r15, %r15
- .endm
-
.macro POP_REGS pop_rdi=1 skip_r11rcx=0
popq %r15
popq %r14
@@ -177,7 +175,7 @@ For 32-bit we have the following conventions - kernel is built with
* is just setting the LSB, which makes it an invalid stack address and is also
* a signal to the unwinder that it's a pt_regs pointer in disguise.
*
- * NOTE: This macro must be used *after* SAVE_REGS because it corrupts
+ * NOTE: This macro must be used *after* SAVE_AND_CLEAR_REGS because it corrupts
* the original rbp.
*/
.macro ENCODE_FRAME_POINTER ptregs_offset=0
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 7351c91..07692b4 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -565,8 +565,7 @@ END(irq_entries_start)
1:
ALLOC_PT_GPREGS_ON_STACK
- SAVE_REGS
- CLEAR_REGS_NOSPEC
+ SAVE_AND_CLEAR_REGS
ENCODE_FRAME_POINTER
testb $3, CS(%rsp)
@@ -1114,8 +1113,7 @@ ENTRY(xen_failsafe_callback)
UNWIND_HINT_IRET_REGS
pushq $-1 /* orig_ax = -1 => not a system call */
ALLOC_PT_GPREGS_ON_STACK
- SAVE_REGS
- CLEAR_REGS_NOSPEC
+ SAVE_AND_CLEAR_REGS
ENCODE_FRAME_POINTER
jmp error_exit
END(xen_failsafe_callback)
@@ -1159,8 +1157,7 @@ idtentry machine_check do_mce has_error_code=0 paranoid=1
ENTRY(paranoid_entry)
UNWIND_HINT_FUNC
cld
- SAVE_REGS 8
- CLEAR_REGS_NOSPEC
+ SAVE_AND_CLEAR_REGS 8
ENCODE_FRAME_POINTER 8
movl $1, %ebx
movl $MSR_GS_BASE, %ecx
@@ -1211,8 +1208,7 @@ END(paranoid_exit)
ENTRY(error_entry)
UNWIND_HINT_FUNC
cld
- SAVE_REGS 8
- CLEAR_REGS_NOSPEC
+ SAVE_AND_CLEAR_REGS 8
ENCODE_FRAME_POINTER 8
testb $3, CS+8(%rsp)
jz .Lerror_kernelspace
@@ -1399,18 +1395,34 @@ ENTRY(nmi)
pushq (%rdx) /* pt_regs->dx */
pushq %rcx /* pt_regs->cx */
pushq %rax /* pt_regs->ax */
+ /*
+ * Sanitize registers of values that a speculation attack
+ * might otherwise want to exploit. The lower registers are
+ * likely clobbered well before they could be put to use in
+ * a speculative execution gadget. Interleave XOR with PUSH
+ * for better uop scheduling:
+ */
pushq %r8 /* pt_regs->r8 */
+ xorq %r8, %r8 /* nospec r8 */
pushq %r9 /* pt_regs->r9 */
+ xorq %r9, %r9 /* nospec r9 */
pushq %r10 /* pt_regs->r10 */
+ xorq %r10, %r10 /* nospec r10 */
pushq %r11 /* pt_regs->r11 */
+ xorq %r11, %r11 /* nospec r11*/
pushq %rbx /* pt_regs->rbx */
+ xorl %ebx, %ebx /* nospec rbx*/
pushq %rbp /* pt_regs->rbp */
+ xorl %ebp, %ebp /* nospec rbp*/
pushq %r12 /* pt_regs->r12 */
+ xorq %r12, %r12 /* nospec r12*/
pushq %r13 /* pt_regs->r13 */
+ xorq %r13, %r13 /* nospec r13*/
pushq %r14 /* pt_regs->r14 */
+ xorq %r14, %r14 /* nospec r14*/
pushq %r15 /* pt_regs->r15 */
+ xorq %r15, %r15 /* nospec r15*/
UNWIND_HINT_REGS
- CLEAR_REGS_NOSPEC
ENCODE_FRAME_POINTER
/*
next prev parent reply other threads:[~2018-02-12 10:17 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-11 10:49 [PATCH v3 0/7] x86/entry: simplify and unify SAVE/POP_REGS Dominik Brodowski
2018-02-11 10:49 ` [PATCH v3 1/7] x86/entry: merge SAVE_C_REGS and SAVE_EXTRA_REGS, remove unused extensions Dominik Brodowski
2018-02-12 10:15 ` [tip:x86/pti] x86/entry/64: Merge " tip-bot for Dominik Brodowski
2018-02-13 9:00 ` tip-bot for Dominik Brodowski
2018-02-11 10:49 ` [PATCH v3 2/7] x86/entry: merge POP_C_REGS and POP_EXTRA_REGS Dominik Brodowski
2018-02-12 10:16 ` [tip:x86/pti] x86/entry/64: Merge the POP_C_REGS and POP_EXTRA_REGS macros into a single POP_REGS macro tip-bot for Dominik Brodowski
2018-02-13 9:01 ` tip-bot for Dominik Brodowski
2018-02-11 10:49 ` [PATCH v3 3/7] x86/entry: interleave XOR register clearing with PUSH instructions Dominik Brodowski
2018-02-12 10:16 ` tip-bot for Dominik Brodowski [this message]
2018-02-13 9:01 ` [tip:x86/pti] x86/entry/64: Interleave " tip-bot for Dominik Brodowski
2018-02-11 10:49 ` [PATCH v3 4/7] x86/entry: introduce PUSH_AND_CLEAN_REGS Dominik Brodowski
2018-02-12 10:17 ` [tip:x86/pti] x86/entry/64: Introduce the PUSH_AND_CLEAN_REGS macro tip-bot for Dominik Brodowski
2018-02-12 13:29 ` Denys Vlasenko
2018-02-12 13:36 ` David Laight
2018-02-12 13:43 ` Denys Vlasenko
2018-02-12 16:51 ` Linus Torvalds
2018-02-13 9:01 ` tip-bot for Dominik Brodowski
2018-02-11 10:49 ` [PATCH v3 5/7] x86/entry: use PUSH_AND_CLEAN_REGS in more cases Dominik Brodowski
2018-02-12 10:17 ` [tip:x86/pti] x86/entry/64: Use " tip-bot for Dominik Brodowski
2018-02-13 9:02 ` tip-bot for Dominik Brodowski
2018-02-11 10:49 ` [PATCH v3 6/7] x86/entry: get rid of ALLOC_PT_GPREGS_ON_STACK and SAVE_AND_CLEAR_REGS Dominik Brodowski
2018-02-12 10:18 ` [tip:x86/pti] x86/entry/64: Get rid of the ALLOC_PT_GPREGS_ON_STACK and SAVE_AND_CLEAR_REGS macros tip-bot for Dominik Brodowski
2018-02-13 9:02 ` tip-bot for Dominik Brodowski
2018-02-11 10:49 ` [PATCH v3 7/7] x86/entry: indent PUSH_AND_CLEAR_REGS and POP_REGS properly Dominik Brodowski
2018-02-12 10:18 ` [tip:x86/pti] x86/entry/64: Indent " tip-bot for Dominik Brodowski
2018-02-12 20:13 ` [PATCH] x86/entry/64: Remove unused icebp macro Borislav Petkov
2018-02-13 7:36 ` Ingo Molnar
2018-02-13 9:04 ` [tip:x86/pti] x86/entry/64: Remove the unused 'icebp' macro tip-bot for Borislav Petkov
2018-02-13 9:03 ` [tip:x86/pti] x86/entry/64: Indent PUSH_AND_CLEAR_REGS and POP_REGS properly tip-bot for Dominik Brodowski
2018-02-11 10:49 ` [PATCH v3 8/7] TESTING_ONLY x86/entry: reduce static footprint of idtentry Dominik Brodowski
2018-02-12 9:37 ` Ingo Molnar
2018-02-12 19:17 ` Linus Torvalds
2018-02-13 12:41 ` Ingo Molnar
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