Patch "x86/entry/64: Use PUSH_AND_CLEAN_REGS in more cases" has been added to the 4.14-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    x86/entry/64: Use PUSH_AND_CLEAN_REGS in more cases

to the 4.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     x86-entry-64-use-push_and_clean_regs-in-more-cases.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 30907fd13bb593202574bb20af58d67c70a1ee14 Mon Sep 17 00:00:00 2001
From: Dominik Brodowski <linux@dominikbrodowski.net>
Date: Sun, 11 Feb 2018 11:49:46 +0100
Subject: x86/entry/64: Use PUSH_AND_CLEAN_REGS in more cases

From: Dominik Brodowski <linux@dominikbrodowski.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@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/20180211104949.12992-6-linux@dominikbrodowski.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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
 
 	/*


Patches currently in stable-queue which might be from linux@dominikbrodowski.net are

queue-4.14/x86-entry-64-interleave-xor-register-clearing-with-push-instructions.patch
queue-4.14/x86-entry-64-merge-the-pop_c_regs-and-pop_extra_regs-macros-into-a-single-pop_regs-macro.patch
queue-4.14/x86-entry-64-remove-the-unused-icebp-macro.patch
queue-4.14/x86-entry-64-use-push_and_clean_regs-in-more-cases.patch
queue-4.14/selftests-x86-disable-tests-requiring-32-bit-support-on-pure-64-bit-systems.patch
queue-4.14/x86-entry-64-fix-paranoid_entry-frame-pointer-warning.patch
queue-4.14/x86-entry-64-merge-save_c_regs-and-save_extra_regs-remove-unused-extensions.patch
queue-4.14/selftests-x86-do-not-rely-on-int-0x80-in-single_step_syscall.c.patch
queue-4.14/selftests-x86-fix-vdso-selftest-segfault-for-vsyscall-none.patch
queue-4.14/x86-entry-64-indent-push_and_clear_regs-and-pop_regs-properly.patch
queue-4.14/selftests-x86-clean-up-and-document-sscanf-usage.patch
queue-4.14/selftests-x86-do-not-rely-on-int-0x80-in-test_mremap_vdso.c.patch
queue-4.14/x86-entry-64-get-rid-of-the-alloc_pt_gpregs_on_stack-and-save_and_clear_regs-macros.patch
queue-4.14/x86-entry-64-introduce-the-push_and_clean_regs-macro.patch