Patch "x86/mce: Make machine check speculation protected" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

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

    x86/mce: Make machine check speculation protected

to the 4.9-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-mce-make-machine-check-speculation-protected.patch
and it can be found in the queue-4.9 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 6f41c34d69eb005e7848716bbcafc979b35037d5 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Thu, 18 Jan 2018 16:28:26 +0100
Subject: x86/mce: Make machine check speculation protected

From: Thomas Gleixner <tglx@linutronix.de>

commit 6f41c34d69eb005e7848716bbcafc979b35037d5 upstream.

The machine check idtentry uses an indirect branch directly from the low
level code. This evades the speculation protection.

Replace it by a direct call into C code and issue the indirect call there
so the compiler can apply the proper speculation protection.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by:Borislav Petkov <bp@alien8.de>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Niced-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1801181626290.1847@nanos
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/entry/entry_64.S        |    2 +-
 arch/x86/include/asm/traps.h     |    1 +
 arch/x86/kernel/cpu/mcheck/mce.c |    5 +++++
 3 files changed, 7 insertions(+), 1 deletion(-)

--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1064,7 +1064,7 @@ idtentry async_page_fault	do_async_page_
 #endif
 
 #ifdef CONFIG_X86_MCE
-idtentry machine_check					has_error_code=0	paranoid=1 do_sym=*machine_check_vector(%rip)
+idtentry machine_check		do_mce			has_error_code=0	paranoid=1
 #endif
 
 /*
--- a/arch/x86/include/asm/traps.h
+++ b/arch/x86/include/asm/traps.h
@@ -92,6 +92,7 @@ dotraplinkage void do_simd_coprocessor_e
 #ifdef CONFIG_X86_32
 dotraplinkage void do_iret_error(struct pt_regs *, long);
 #endif
+dotraplinkage void do_mce(struct pt_regs *, long);
 
 static inline int get_si_code(unsigned long condition)
 {
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -1754,6 +1754,11 @@ static void unexpected_machine_check(str
 void (*machine_check_vector)(struct pt_regs *, long error_code) =
 						unexpected_machine_check;
 
+dotraplinkage void do_mce(struct pt_regs *regs, long error_code)
+{
+	machine_check_vector(regs, error_code);
+}
+
 /*
  * Called for each booted CPU to set up machine checks.
  * Must be called with preempt off:


Patches currently in stable-queue which might be from tglx@linutronix.de are

queue-4.9/futex-prevent-overflow-by-strengthen-input-validation.patch
queue-4.9/x86-mce-make-machine-check-speculation-protected.patch
queue-4.9/x86-pti-document-fix-wrong-index.patch
queue-4.9/timers-unconditionally-check-deferrable-base.patch
queue-4.9/x86-apic-vector-fix-off-by-one-in-error-path.patch
queue-4.9/objtool-improve-error-message-for-bad-file-argument.patch
queue-4.9/kprobes-x86-disable-optimizing-on-the-function-jumps-to-indirect-thunk.patch
queue-4.9/x86-mm-pkeys-fix-fill_sig_info_pkey.patch
queue-4.9/x86-tsc-fix-erroneous-tsc-rate-on-skylake-xeon.patch
queue-4.9/sched-deadline-zero-out-positive-runtime-after-throttling-constrained-tasks.patch
queue-4.9/module-add-retpoline-tag-to-vermagic.patch
queue-4.9/kprobes-x86-blacklist-indirect-thunk-functions-for-kprobes.patch
queue-4.9/x86-retpoline-fill-rsb-on-context-switch-for-affected-cpus.patch
queue-4.9/x86-retpoline-add-lfence-to-the-retpoline-rsb-filling-rsb-macros.patch
queue-4.9/x86-retpoline-optimize-inline-assembler-for-vmexit_fill_rsb.patch
queue-4.9/retpoline-introduce-start-end-markers-of-indirect-thunk.patch
queue-4.9/x86-cpufeature-move-processor-tracing-out-of-scattered-features.patch
queue-4.9/x86-cpu-x86-pti-do-not-enable-pti-on-amd-processors.patch