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Message-Id: <20180221124527.894424371@linuxfoundation.org>
Date: Wed, 21 Feb 2018 13:47:53 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org,
Linus Torvalds <torvalds@...ux-foundation.org>,
Dominik Brodowski <linux@...inikbrodowski.net>,
Andy Lutomirski <luto@...nel.org>,
Borislav Petkov <bp@...en8.de>,
Brian Gerst <brgerst@...il.com>,
Denys Vlasenko <dvlasenk@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>,
Josh Poimboeuf <jpoimboe@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>, dan.j.williams@...el.com,
Ingo Molnar <mingo@...nel.org>
Subject: [PATCH 4.14 062/167] x86/entry/64: Use PUSH_AND_CLEAN_REGS in more cases
4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Dominik Brodowski <linux@...inikbrodowski.net>
commit 30907fd13bb593202574bb20af58d67c70a1ee14 upstream.
entry_SYSCALL_64_after_hwframe() and nmi() can be converted to use
PUSH_AND_CLEAN_REGS instead of opencoded variants thereof. Due to
the interleaving, the additional XOR-based clearing of R8 and R9
in entry_SYSCALL_64_after_hwframe() should not have any noticeable
negative implications.
Suggested-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@...inikbrodowski.net>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: dan.j.williams@...el.com
Link: http://lkml.kernel.org/r/20180211104949.12992-6-linux@dominikbrodowski.net
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
arch/x86/entry/calling.h | 6 ++--
arch/x86/entry/entry_64.S | 65 ++--------------------------------------------
2 files changed, 6 insertions(+), 65 deletions(-)
--- a/arch/x86/entry/calling.h
+++ b/arch/x86/entry/calling.h
@@ -137,7 +137,7 @@ For 32-bit we have the following convent
UNWIND_HINT_REGS offset=\offset
.endm
- .macro PUSH_AND_CLEAR_REGS
+ .macro PUSH_AND_CLEAR_REGS rdx=%rdx rax=%rax
/*
* Push registers and sanitize registers of values that a
* speculation attack might otherwise want to exploit. The
@@ -147,9 +147,9 @@ For 32-bit we have the following convent
*/
pushq %rdi /* pt_regs->di */
pushq %rsi /* pt_regs->si */
- pushq %rdx /* pt_regs->dx */
+ pushq \rdx /* pt_regs->dx */
pushq %rcx /* pt_regs->cx */
- pushq %rax /* pt_regs->ax */
+ pushq \rax /* pt_regs->ax */
pushq %r8 /* pt_regs->r8 */
xorq %r8, %r8 /* nospec r8 */
pushq %r9 /* pt_regs->r9 */
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -223,35 +223,8 @@ ENTRY(entry_SYSCALL_64)
pushq %rcx /* pt_regs->ip */
GLOBAL(entry_SYSCALL_64_after_hwframe)
pushq %rax /* pt_regs->orig_ax */
- pushq %rdi /* pt_regs->di */
- pushq %rsi /* pt_regs->si */
- pushq %rdx /* pt_regs->dx */
- pushq %rcx /* pt_regs->cx */
- pushq $-ENOSYS /* pt_regs->ax */
- pushq %r8 /* pt_regs->r8 */
- pushq %r9 /* pt_regs->r9 */
- pushq %r10 /* pt_regs->r10 */
- /*
- * Clear extra registers that a speculation attack might
- * otherwise want to exploit. Interleave XOR with PUSH
- * for better uop scheduling:
- */
- xorq %r10, %r10 /* nospec r10 */
- pushq %r11 /* pt_regs->r11 */
- xorq %r11, %r11 /* nospec r11 */
- pushq %rbx /* pt_regs->rbx */
- xorl %ebx, %ebx /* nospec rbx */
- pushq %rbp /* pt_regs->rbp */
- xorl %ebp, %ebp /* nospec rbp */
- pushq %r12 /* pt_regs->r12 */
- xorq %r12, %r12 /* nospec r12 */
- pushq %r13 /* pt_regs->r13 */
- xorq %r13, %r13 /* nospec r13 */
- pushq %r14 /* pt_regs->r14 */
- xorq %r14, %r14 /* nospec r14 */
- pushq %r15 /* pt_regs->r15 */
- xorq %r15, %r15 /* nospec r15 */
- UNWIND_HINT_REGS
+
+ PUSH_AND_CLEAR_REGS rax=$-ENOSYS
TRACE_IRQS_OFF
@@ -1382,39 +1355,7 @@ ENTRY(nmi)
pushq 1*8(%rdx) /* pt_regs->rip */
UNWIND_HINT_IRET_REGS
pushq $-1 /* pt_regs->orig_ax */
- pushq %rdi /* pt_regs->di */
- pushq %rsi /* pt_regs->si */
- 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
+ PUSH_AND_CLEAR_REGS rdx=(%rdx)
ENCODE_FRAME_POINTER
/*
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