diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2017-12-31 00:13:54 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2017-12-31 14:12:51 +0300 |
| commit | decab0888e6e14e11d53cefa85f8b3d3b45ce73c (patch) | |
| tree | 196714f4f52e557ae7374a04e9d7fabbf9d3c06a | |
| parent | 322f8b8b340c824aef891342b0f5795d15e11562 (diff) | |
| download | linux-decab0888e6e14e11d53cefa85f8b3d3b45ce73c.tar.xz | |
x86/mm: Remove preempt_disable/enable() from __native_flush_tlb()
The preempt_disable/enable() pair in __native_flush_tlb() was added in
commit:
5cf0791da5c1 ("x86/mm: Disable preemption during CR3 read+write")
... to protect the UP variant of flush_tlb_mm_range().
That preempt_disable/enable() pair should have been added to the UP variant
of flush_tlb_mm_range() instead.
The UP variant was removed with commit:
ce4a4e565f52 ("x86/mm: Remove the UP asm/tlbflush.h code, always use the (formerly) SMP code")
... but the preempt_disable/enable() pair stayed around.
The latest change to __native_flush_tlb() in commit:
6fd166aae78c ("x86/mm: Use/Fix PCID to optimize user/kernel switches")
... added an access to a per CPU variable outside the preempt disabled
regions, which makes no sense at all. __native_flush_tlb() must always
be called with at least preemption disabled.
Remove the preempt_disable/enable() pair and add a WARN_ON_ONCE() to catch
bad callers independent of the smp_processor_id() debugging.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linuxfoundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20171230211829.679325424@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | arch/x86/include/asm/tlbflush.h | 14 |
1 files changed, 8 insertions, 6 deletions
diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h index b519da4fc03c..f9b48ce152eb 100644 --- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -345,15 +345,17 @@ static inline void invalidate_user_asid(u16 asid) */ static inline void __native_flush_tlb(void) { - invalidate_user_asid(this_cpu_read(cpu_tlbstate.loaded_mm_asid)); /* - * If current->mm == NULL then we borrow a mm which may change - * during a task switch and therefore we must not be preempted - * while we write CR3 back: + * Preemption or interrupts must be disabled to protect the access + * to the per CPU variable and to prevent being preempted between + * read_cr3() and write_cr3(). */ - preempt_disable(); + WARN_ON_ONCE(preemptible()); + + invalidate_user_asid(this_cpu_read(cpu_tlbstate.loaded_mm_asid)); + + /* If current->mm == NULL then the read_cr3() "borrows" an mm */ native_write_cr3(__native_read_cr3()); - preempt_enable(); } /* |