From: tip-bot for Dominik Brodowski <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: peterz@infradead.org, torvalds@linux-foundation.org,
jpoimboe@redhat.com, tglx@linutronix.de,
linux-kernel@vger.kernel.org, linux@dominikbrodowski.net,
bp@alien8.de, brgerst@gmail.com, dvlasenk@redhat.com,
mingo@kernel.org, luto@kernel.org, hpa@zytor.com
Subject: [tip:x86/pti] x86/entry/64: Introduce the PUSH_AND_CLEAN_REGS macro
Date: Tue, 13 Feb 2018 01:01:55 -0800 [thread overview]
Message-ID: <tip-3f01daecd545e818098d84fd1ad43e19a508d705@git.kernel.org> (raw)
In-Reply-To: <20180211104949.12992-5-linux@dominikbrodowski.net>
Commit-ID: 3f01daecd545e818098d84fd1ad43e19a508d705
Gitweb: https://git.kernel.org/tip/3f01daecd545e818098d84fd1ad43e19a508d705
Author: Dominik Brodowski <linux@dominikbrodowski.net>
AuthorDate: Sun, 11 Feb 2018 11:49:45 +0100
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 13 Feb 2018 09:04:53 +0100
x86/entry/64: Introduce the PUSH_AND_CLEAN_REGS macro
Those instances where ALLOC_PT_GPREGS_ON_STACK is called just before
SAVE_AND_CLEAR_REGS can trivially be replaced by PUSH_AND_CLEAN_REGS.
This macro uses PUSH instead of MOV and should therefore be faster, at
least on newer CPUs.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
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: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dan.j.williams@intel.com
Link: http://lkml.kernel.org/r/20180211104949.12992-5-linux@dominikbrodowski.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/entry/calling.h | 36 ++++++++++++++++++++++++++++++++++++
arch/x86/entry/entry_64.S | 6 ++----
2 files changed, 38 insertions(+), 4 deletions(-)
diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h
index a05cbb8..57b1b87 100644
--- a/arch/x86/entry/calling.h
+++ b/arch/x86/entry/calling.h
@@ -137,6 +137,42 @@ For 32-bit we have the following conventions - kernel is built with
UNWIND_HINT_REGS offset=\offset
.endm
+ .macro PUSH_AND_CLEAR_REGS
+ /*
+ * Push 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:
+ */
+ 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 */
+ 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
+ .endm
+
.macro POP_REGS pop_rdi=1 skip_r11rcx=0
popq %r15
popq %r14
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 07692b4..cf4a9ae 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -564,8 +564,7 @@ END(irq_entries_start)
call switch_to_thread_stack
1:
- ALLOC_PT_GPREGS_ON_STACK
- SAVE_AND_CLEAR_REGS
+ PUSH_AND_CLEAR_REGS
ENCODE_FRAME_POINTER
testb $3, CS(%rsp)
@@ -1112,8 +1111,7 @@ ENTRY(xen_failsafe_callback)
addq $0x30, %rsp
UNWIND_HINT_IRET_REGS
pushq $-1 /* orig_ax = -1 => not a system call */
- ALLOC_PT_GPREGS_ON_STACK
- SAVE_AND_CLEAR_REGS
+ PUSH_AND_CLEAR_REGS
ENCODE_FRAME_POINTER
jmp error_exit
END(xen_failsafe_callback)
next prev parent reply other threads:[~2018-02-13 9:08 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:x86/pti] x86/entry/64: Interleave " tip-bot for Dominik Brodowski
2018-02-13 9:01 ` 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 [this message]
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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