From: Andy Lutomirski <luto@kernel.org>
Date: Sun, 28 May 2017 10:00:11 -0700
Subject: x86/mm: Change the leave_mm() condition for local TLB flushes
Git-commit: 59f537c1dea04287165bb11407921e095250dc80
Patch-mainline: v4.13-rc1
References: bsc#1068032 CVE-2017-5754
On a remote TLB flush, we leave_mm() if we're TLBSTATE_LAZY. For a
local flush_tlb_mm_range(), we leave_mm() if !current->mm. These
are approximately the same condition -- the scheduler sets lazy TLB
mode when switching to a thread with no mm.
I'm about to merge the local and remote flush code, but for ease of
verifying and bisecting the patch, I want the local and remote flush
behavior to match first. This patch changes the local code to match
the remote code.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Nadav Amit <namit@vmware.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Borislav Petkov <bp@suse.de>
---
arch/x86/mm/tlb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -311,7 +311,7 @@ void flush_tlb_mm_range(struct mm_struct
goto out;
}
- if (!current->mm) {
+ if (this_cpu_read(cpu_tlbstate.state) != TLBSTATE_OK) {
leave_mm(smp_processor_id());
/* Synchronize with switch_mm. */