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

x86/entry/64: Introduce the PUSH_AND_CLEAN_REGS macro

to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: x86-entry-64-introduce-the-push_and_clean_regs-macro.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 3f01daecd545e818098d84fd1ad43e19a508d705 Mon Sep 17 00:00:00 2001

From: Dominik Brodowski linux@dominikbrodowski.net Date: Sun, 11 Feb 2018 11:49:45 +0100 Subject: x86/entry/64: Introduce the PUSH_AND_CLEAN_REGS macro

From: Dominik Brodowski linux@dominikbrodowski.net

commit 3f01daecd545e818098d84fd1ad43e19a508d705 upstream.

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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- arch/x86/entry/calling.h | 36 ++++++++++++++++++++++++++++++++++++ arch/x86/entry/entry_64.S | 6 ++---- 2 files changed, 38 insertions(+), 4 deletions(-)

--- a/arch/x86/entry/calling.h +++ b/arch/x86/entry/calling.h @@ -137,6 +137,42 @@ For 32-bit we have the following convent 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 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -560,8 +560,7 @@ 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) @@ -1106,8 +1105,7 @@ 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)

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